If you have any questions you want answered, feel free to drop me a note. If you’ve got a question, chances are, there are lots of others out there with the same question. So ask away!
Note: all comments are moderated unless I’ve approved one of your previous comments. Almost everybody gets thrown off by this, but I moderate comments to avoid spammers. The downside of this is that you won’t see your comments post until I’ve had a chance to review and approve them. Sometimes this can take days (sorry!) Thanks for your patience.
Ted's Energy Tips 
I have a question regarding cathedral ceilings. I’m reveiwing a ceiling that has dark shadows moving up about 12 inches from the side wall on the drywall at every ceiling joist of a cathedral ceiling. Could you help me determine if this could be cause by moisture and improper insulating.
Thank you, John
John,
I’m trying to envision this, a photo would be great (you’d have to post a link to a photo elsewhere because I don’t have any way of uploading one here).
However, if I’m imagining it correctly, I have a guess. But first a couple questions.
– what room is this?
– Does the occupant burn candles/fire or smoke in that room or do anything else that might produce soot?
– Is the roof vented (soffit vents and ridge vent?)
Here’s the guess – I’ve seen something like this a couple times. Each time it involved candles or smoking which generate very fine soot particles that float around the room. Normally, they’d form a uniform layer on all the surfaces, but if some surfaces are “stickier” than others, the soot will accumulate at those locations.
Note that this doesn’t necessarily indicate anything wrong, it just means something different is happening there.
Here’s where it gets a little tricky. If the roof is soffit vented, then the drywall is going to be coldest down near the vents – exactly as it should be. As the air travels up the joist bays, it warms up, so the inner drywall won’t be as cool.
Now, recall that condensation increases the colder the surface. So the chance of condensation on the inner drywall is greatest where it’s coldest – down near the side walls.
Again, this doesn’t mean something’s wrong, a little condensation is easily evaporated or absorbed by the walls. But it will capture those soot particles (or any dust in the air), which could lead to shadowing.
It is possible that the insulation at the bottom of the ceiling joists is getting “wind washed” by the air coming in the soffits. It may also be that the insulation doesn’t come all the way down. These things could cause the drywall to be very cold, making this effect much more prominent.
If you were able to use thermal imaging, you might find these cool spots, corresponding to the shadowing. You could also use an inexpensive IR thermometer during the winter to measure the ceiling temperature from the side wall up towards the peak. This would also be telling.
Hey, Ted – We are undergoing a kitchen renovation and I need help understanding how our insulation may influence (i.e., constrain) my range vent/hood options. The attic – actually, the entire house – has been blown with that foam spray insulation. The kitchen currently has one of those microwave range vents, but it’s a noisy beast with poor lighting. I’ll move that over to the beverage station and replace it with a more functional vent/hood. My question is whether the blown-in foam insulation in the attic affects what type of range vent/hood we can get. I don’t really want to cut through that insulation (if it ain’t broke …), can I vent directly into the attic? Or would that create a moisture issue? Thanks for your help!
Great questions.Easy answer first – NO! Don’t vent directly into the attic! That’s both a moisture issue and potential fire hazard since you’d be spraying all that oil into the attic, coating everything up there with that yucky goo.
If the access in the attic is good, I wouldn’t worry about cutting through the insulation. Just run the vent pipe up through the hole and out. Just be sure to check your local codes regarding the venting of that fan.
When the vent is all installed, you should be able to air seal around it, where you cut out the foam, using inexpensive canned foam to fill the gaps if the hole was cut neatly.
Another option for venting is side-wall venting. Depending on access you might be able to go up and out horizontally. Your contractor should be able to tell you if this is feasible.
-Cheers
Thanks, Ted, that clears things up nicely and keeps us from making a really bad decision. We’ll check with the contractor about the side-wall venting option. The range will be on an interior wall only about 4 feet from an outside wall but about 25 feet through ceiling, fiberglass, attic dead space, and foam insulation (that appears to be about 10 inches thick) to vent out the roof. Seems intuitively less problematic (and expensive) to go that way. Thanks for suggesting it!
Great! Hope they can figure out a nice short path for the vent. Good luck!
Ted,
My home is in western PA and is post and beam construction, built in 2000. The ceiling is 3″ thick x 6″ wide laminated pine tongue and groove decking throughout the home and it is leaking air at the peak.
The roof is comprised of (from interior to the shingles) the tongue and groove pine decking, tar paper, 3 1/2″ rigid insulation in 4’x8′ sheets, 1″ x 3″ x 1/2 inch sleepers (for air space) then 7/ 16″ plywood sheathing, tar paper and roofing shingles, with continuous ridge vent and continuous soffit vent On the inside of the house the peak of the ceiling is above a laminated hip rafter beam. My problem was discovered during an energy audit door test, the auditor pointed out a significant amount of heat coming into the house at the peak, just above the hip rafter along the complete length of the rafter. The house is about 90′ long. Above that area is the continuous ridge vent.
I suspect the 4×8 sheets of rigid insulation are not “coped” to seal against each other at the peak and instead the sheets form a “v” gap at the peak between adjoining sheet of the insulation. Also the roof decking likely is installed similarly with a “v” gap, with only point contact between adjoining decking at the peak. Since the ridge vent is above that, with an opening thru the sheathing to allow the air coming up from the soffit to ventilate the air space, we literally have our house open to the outdoors thru the ridge vent. There are no ice damming problems or other issues in the winter, with the exception that the ridges are the first to clear of snow. I plan to pull the ridge vents up inspect the space below and if I find the “v” notch between the rigid insulation sheets, I plan to fill the length of the notch with insulating foam sealant (g.stuff). I am concerned however that this gap which allows air to migrate into or out of my house, may be a good thing, that it takes moisture away. We do have bathroom and kitchen vent fans to the outdoors and the clothes dryer also vents to the outdoors. We have a b-vent gas fireplace in the living space which is rarely used, I close off the stack above the fireplace logs unless it is in use.
My question is this….if I seal the “v” gap between the rigid insulation sheets and stop air movement thru the peak of the ceiling could I subsequently cause a moisture problem on the interior surface of the pine ceiling causing mold to develop and then rotting the decking on the inside surface?
Thanks in advance for your advice,
Rich
Your assessment sounds spot on. It’s tough to seal properly with that type of construction unless it’s designed in from the start. When you’ve got the two sides of the roof butting against the central beam, that’s difficult.
I’m uncomfortable with the foam approach – you’ve got multiple building elements each with different coefficients of expansion. The roof experiences extreme temperature variations, hence large amounts of differential movement between the parts. Foam or even high quality silicone caulk will likely separate over the course of a year or two. The forces can be *huge* so it’s not “if”, it’s “when” this will occur.
The only thing I can think of at the moment that might work is adhesive roofing membrane. It’s flexible, meant for high temperature applications, and is water/air proof if you give it a good seal. In theory, you could lay this from one side of the roof, under the ventilation gap (i.e. towards the living space) then up and over the central beam and adhere to the other side of the roof. Depending on the construction, this would leave the intended ventilation unaffected while stopping the free-flow of air from the living space to the outside.
If you went this route, I’d strongly recommend having the blower-door/thermal scan done after sealing and while someone is there to further seal the remaining leakage areas.
It’s hard to know just how tightly this would seal, but as you’ve described it, it would probably be much better than it is now. However, if there’s gaps between the sheets of foam or other issues like that, then you’re likely out of luck.
Personally, with that type of construction, I probably would have gone with a fully sealed, unventilated roof structure. I know this makes a lot of people uncomfortable, but when implemented correctly, it’s the safest roof design.
Hi Ted,
Just wanted to say thanks for your insight on your solar installation! We’ve featured it on our Facebook page: https://www.facebook.com/pages/Energy-Upgrade-California-in-Los-Angeles-County/140594779319684?hc_location=timeline
Awesome, thank you!
Ted, i tore off the molding around the door. Oddly, the only place with black/rotted wood was the backside, bottom of the one piece of molding. The wood was bone dry, the darkened wood was almost crispy.
I looked inside the wall with my flashlight and everything looked fine. I poked the surrounding wood with my screw driver to see if i felt any soft spots – nothing. I stuck my fingers in all the gaps and absolutely no moisture.
Is it possible this one piece of wood was the only wood affected by the prior window leak from above? I even had my painter (who also specializes in replacing rotten wood on the outside of the house) take a look. He acknowledged the piece of molding had to be replaced (he’s already replaced it), but he also thought everything else looked fine. I guess i’ll just keep an eye on this one spot. When it rains (as it’s doing right now) i’ll check on it.
I think i’ve encounter one of those mysteries.
I copied all your advice above. If anything changes i will do as you suggest. Thank you for taking the time!
Ted, it’s on the inside, the trim on the bottom-left of the double door. Last year i had an issue with the palladium window right above this door. The palladium window was leaking for about 8 months if the rain hit it just right. I suspect this window above the door was probably leaking down inside the wall.
Yesterday i was getting ready to paint when I found this soft spot on the molding on the bottom-left of the door. I noticed the paint looked slightly bubbled. It felt soft and when i picked at it, the wood underneath looks dark. I stick my finger into the sift wood on the molding at it’s bone dry (and it’s been raining the last couple of days).
I was just wondering who i can call in to assess the situation. I’ll do as you say and call in a general contractor. I can deal with internal walls. I don’t want to mess with external walls.
Ah, that’s a problem. I’ve seen a fair number of these types of issues – bad flashing/bad install of windows allowing water to leak down through the walls.
Unfortunately, this often turns into a “specialty” fix because almost no contractors have the training or equipment or diagnostic skills to track down the true problems. No offense to them, but it’s out of their realm of expertise. It’s kind of like going to the dentist when you’re having kidney pains.
What you really want to do is track down a “building science” person. This can be difficult but fortunately an increasing number of people are getting into this niche. If you’re friendly with contractors in the area, especially those who advertise “green building” skills and BPI (building performance institute) training, ask them who the best troubleshooter is in the area. You need someone with moisture meters – a non-invasive and a “probe” type that has 6″ long moisture probes. With these, they can stick the probes through your inside sheetrock after drilling small (1/4″ holes) for the probes. They’ll be able to track the moisture up through the wall to the approximate source. Even then, these can be a bear to find and will likely involve cutting out strips of sheetrock to see what’s going on inside the wall. But sheetrock is cheap, much cheaper than having to replace the wall studs when they’ve rotted out 😦 Trust me, you really want to get to the bottom of this. My first job diagnosing a problem of this sort resulted in learning that ALL of the flashing around a house was bad, leading to them having to rip off all the siding. When they did, they found wall rot all over the place! Yuck!
Hi Ted. I was reading your article on rotten wood (https://tedsenergytips.com/rot/) and i may have a minor issue with some rotting wood on the bottom-left of my glass doors, behind the door mold. If i wanted to have somebody come in to inspect, who do i call? A general contractor? A window specialist? There must be a name for those who specialize in such detective work. Thanks. – Mason
Mason, a good general contractor should be able to help fix it. The trick is finding a good person to determine why it rotted in the first place.
Is that rot on the inside or outside? Outside is usually caused by wood in contact with the dirt or landscape mulch. if this is the case, then you should take out the mulch or dirt to give 3 to 6 inches of clearance between the wood and the ground. I would also recommend inspecting it during the rain to ensure that water isn’t piddling up. Draining properly around the house is really important.
i have a crawlspace in my house, which i bought 3 years ago. am just wondering why the flooring is made of concrete in 2/3 of the area, and the rest is just a dirt floor covered with plastic. in the crawlspace, i have a furnace and water heater in addition to pipes hanging upon the joists. may i know the reason why there is a dirt floor?
Hmm, good question!
I’ve seen things like this before but don’t know why. Perhaps the house had undergone some renovations at some point, increasing the foundation’s footprint and they didn’t take the time to pour a slab in the rest.
If radon is an issue in your area, you’ll probably want to have it tested because dirt floors are notoriously porous to radon, and plastic laying on the dirt that isn’t very carefully sealed does little to stop the radon from entering the house.
Maybe someone else reading this can provide an explanation for the partial dirt floor.
Ted,
This is so helpful! Thanks a million.
Initially the HVAC guy was suggesting just this. And it sounds really good for just the reasons you say– that you can heat or cool just the kitchen if you’re in the kitchen, etc. The only down side I see is that to make it work for our whole house, we would need 3 compressors (I think that’s the name) outside the house– which seems like a lot of things coming out of the house. But this is the solution I was leaning towards, so it’s very reassuring to hear that you agree.
Thanks again,
Annie
I’m glad that there seems to be a general agreement about this. I’m always a bit hesitant to give advice sight-unseen.
My brother also took this advice with his home and he’s been overjoyed with the results.
Talk to your HVAC contractor about “multi-headed” mini splits. Mitsubishi has a variety of units that use a single outdoor unit to drive several indoor blowers. They are less efficient than the best one to one mini splits but sometimes the tradeoff is worth it.
Good luck with the project! I hope that you’ll come back and let Mr know how it works out.
Hi Ted,
We just read your article on heat pumps, and we have a question about the Carrier Greenspeed Infinity 20 Heat Pump. We live outside of Boston in a 3000 square foot old home. It has newer blown-in cellulose insulation and good storm windows. The current heating system is oil powered steam heat. It is a one-zone system and very expensive.
We are in need of air conditioning, and have come to the conclusion that if we install central air conditioning, it would be worth it to replace our heating system as well. That has led us to the Greenspeed Infinity 20 Heat Pump as an efficient and environmentally sound solution to heat and cool the house. We have found a good HVAC guy, I think, but he has never installed this system before and was unaware of it until just recently. He works a lot with Mitsubishi mini-split systems, which we have have also considered.
We went online and found a lot of very bad reviews for the Carrier Greenspeed system. We’re wondering what your thoughts are on this, and what you would recommend as the best solution for both our a/c and heating needs.
Thanks a lot!
Annie and Kevin
Unfortunately, I haven’t had any personal experience with the unit so I’ll have to look up the reviews and see what people have to say. One thing I can say is heat pumps, in general, often get bad raps due to improper installation and/or use. Unlike an oil or gas system, which keeps a relatively constant efficiency regardless of use, heat pumps revert to backup heat if you push them too hard, which can drive up operational cost 3-4x! Over the years, I’ve heard a lot of people griping about how expensive heat pumps are or how poorly they function due to these types of issues.
Regardless of what new system you install, you may want to keep the oil system in operation for backup heat. I did this in my own home and am very happy I kept the baseboard heat. I don’t use it often, but when the temperature drops into the teens or lower and the heat pumps are at the limit of their ability to satisfy my home’s heating needs, I turn on the baseboards and the house is comfortable again. If not for that, I’m sure I’d be griping about poor heat pump performance!
At the cost of the Greenspeed, you might very well install quite a few mini-splits around the house. Typical installed cost for a high quality mini-split is about $3,000-$4,000 per unit so you could get 4-6 for the price of the Greenspeed (at prices I’ve seen quoted). Since mini-splits allow room-to-room zoning, something you’re not likely to get with the Greenspeed, you can completely customize the heating/cooling as best suits your needs.
Another consideration of the mini-splits vs. a fresh central air system is running of ductwork. Retrofitting an older home that doesn’t have ductwork can open a Pandora’s box. It’s hard work and often, it’s nearly impossible to run ducts everywhere you want them due to space considerations. Try crawling around a dirty attic on your stomach while trying to do a neat job of installation… so what happens is that you get “out of sight, out of mind” syndrome. I.e., a really crappy installation job because the installer knows their work will never be inspected.
With mini-splits, you have none of these problems. You mount it on the wall, drilling a couple holes through the wall to run the refrigerant lines down to the outdoor unit. It’s in plain sight, so if installation is sloppy, you’ll probably see it immediately.
To summarize, if it were my home, I’d seriously consider installing a few mini-splits to augment the existing oil system, which I’d use as little as possible. In fact, this is exactly what I did do in my own home, even though I have central air and a geothermal system attached to it.
Ted,
I recently painted my son’s bedroom and took the time to re-caulk around the windows and foam the outlets on the outside walls, both of which made a difference in that drafty room. The room has hydronic baseboard heat. Do you have any recommendations regarding caulking/spray foam around baseboard units? I was planning to caulk the bottoom of the baseboards when we get around to replacing the carpet in the room, but I was wondering if I’d get any advantage (or if there’s a problem) from putting a bead of low-expanding foam or caulk behind it.
Thanks,
J
There’s very often a big gap between the wall board (plaster or sheetrock) and the floor. Typically, this is included to allow expansion/contraction throughout the year though I’ve seen huge gaps and lots of drafty situations, so I personally sprayed foam in there in my house. The foam will compress with the expansion cycles. As you note – low-expansion foam is best to avoid putting too much pressure on the various components and risking cracking wall board.
As far as caulking the baseboard itself, I typically wouldn’t bother. Just fill in any obvious holes leading into the walls such as might have been drilled for wiring or pipes.
It doesn’t sound like Josh is headed this way, but just a word of warning when foaming around baseboards. I have hot water baseboard heat that was installed in an house with hybrid post&beam and stud-framed construction. There were huge holes bored through beams and plates to install the pipes and I thought, “Heck, why not foam these holes?” Well, the foam locked the pipes in place and the next time the heat came on and the 15′ long baseboards expanded, they accordioned in several places, as much as an inch. Two ended up springing leaks, one leak was inside a corner and went undetected for long enough for carpenter ants to find the wet old beam and set up a nest. All in all quite a repair challenge. So…don’t ever foam around hotwater baseboard pipes.
Yikes! That’s a lot of thermal expansion. I definitely hear the expansion noises in my baseboards when they come on and have observed the free-hanging supports, so that sounds like good advice – don’t do anything that would lock the parts in place without knowing how they’ll behave throughout the year and heating cycles.
Thanks for the insights!
Hi again Ted, first thanks for all of the helpful information regarding making it a conditioned space. The pros seem to outweigh the cons for this at the moment.
One of your responses brought up another question, you said:
“Note too that once you’ve insulated in this way, the cellulose on the attic floor is extraneous and could even be harmful. Typically, it is recommended that you remove that insulation so that you don’t have a pocket of air (the attic space) between the roof and the ceiling of the living space. You really only want insulation in one location.”
and my question is this, don’t they typically insulate between the ceiling of the first floor and flooring of the second floor in a home or am I mistaken? I’m just thinking that logic would follow for second floor ceiling to attic floor.
If/when I do condition the space I will put some type of sub-flooring down to make it safe to walk on, at least where I can. That heat exchange unit in the attic is a beast and I don’t think I would be able to pick it up to put flooring under it. Plus the areas around the conduit, most of it is flex conduit so I should be able to work around that myself.
Typically, there’s only insulation in the spaces adjacent to the “outdoor conditions” – sometimes they may use insulation as sound deadening material between floors or in walls. That doesn’t cause a problem because the spaces on either side are heated/cooled the same. It’s a problem because moisture rises and if the attic is sealed AND cold, the moisture can lead to condensation/mold problems. This is one of the most important reasons why attics are usually ventilated.
If you remove the floor insulation, then the attic will get some of the warmth from the house. It still won’t be warm (I’m talking about winter), but it will at least get some warmth. With the insulation on the floor, very little heat will get up there so the attic will get quite cold, even if you insulate under the roof. Now, the moisture will be much more likely to condense. Sometimes, they will put a small heating vent into the attic space to keep the air moving and minimize the chance of condensation. People often object to this asking “why would I heat this space, isn’t that a big waste?” Basically, the anser is no – if you do a good job insulating under the roof, you’ll save so much more energy overall that the small amount of energy used to ensure the durability of your home is worth it.
Don’t worry about the subfloor areas around ducts and the blower. Small amounts of insulation left over will cause no problems because the heat moving through the uninsulated areas is vastly larger than the loss prevented by the insulation.
Hello Ted,
First off let me be the first to wish you a happy new year. Thank you for the great information provided on this site and a way to post questions and your replies.
A little back story before my question… I have recently purchased a two story home in California and I have an unconditioned attic with gable (I think that is what they are called) vents, no soffit or roof line vents, pretty standard here. It gets hot here in the summer up to 118 deg. and I’m sure it’s much toastier in the attic. I have a central AC outside and a large heat pump in the attic with all the duct work. I’ve been doing my own energy auditing because the whole house is electric, there is no natural gas in my city and I don’t want to retrofit to propane appliances. Up in the attic I’ve been locating air leaks and deficiencies with the blown in cellulose insulation easy fixes, but after going through your site (and others) I understand now that the ducting in an unconditioned space is a lot less efficient due to the differences between inside and outside temps.
My question is this, would it be a good idea to use closed cell spray foam the underside sheathing of the roof in the attic to act as an insulator, vapor and radiant heat barrier? If it’s okay to do are there any pitfalls to this like leaving a space near the eves and roof line for air to vent around? Would you recommend something else like just installing a radiant heat barrier on the rafters under the sheathing?
I have read in a conditioned space this is good, but not a lot of info if this is acceptable or even good practice in an unconditioned attic. I wasn’t looking to retrofit my attic to a conditioned one either. The roof isn’t high enough to stand in. I’m just thinking of this from an energy savings point of view.
My main goal is to reduce the temperature inside the unconditioned attic and do it so that I don’t cause any future issues like rotting the sheathing.
I appreciate your feedback and insight.
Best regards and good fortune,
Arthur Robinson
Hi Arthur – what a great note! Thank you.
It sounds like you’ve been doing your homework and you’ve got a really valid question/concern.
The short answer:
If you insulate under the roof sheathing, you’re turning the attic into part of your living space so the insulation job should be complete – no more venting of any sort in the attic and you must insulate/seal every surface that is in contact with the outdoors. That means under the roof and along the gable ends.
Some details
If you use a sufficient amount of closed cell foam, you really shouldn’t worry about other insulation like radiant barriers. Just use sufficient foam – typically about 6″ thick, on all surfaces exposed to the outside. The actual amount you use is a point of some controversy. Building code in most areas calls for about R-40, which would be about 6″. However, this can get pricey since you pay by the thickness sprayed. A lot of contractors argue for using less than code, asserting that you’re reaching a point of diminishing returns. For example, 4″ gives about R-25 (which equals 4% heat energy transmission). 6″ gives about R-38 (= ~2.6% heat transmission). So you’re paying considerably more to reduce the energy loss by about 1.4% – not a heck of a lot.
On the other hand, the underside of the roof gets really hot, so the amount of energy savings are amplified compared to, for example, the walls of the house. So that 1.4% could be meaningful.
Sometime the building inspectors allow this, sometimes not. If I were you, I’d check the options and pricing and decide based on your overall goals.
Note too that once you’ve insulated in this way, the cellulose on the attic floor is extraneous and could even be harmful. Typically, it is recommended that you remove that insulation so that you don’t have a pocket of air (the attic space) between the roof and the ceiling of the living space. You really only want insulation in one location.
As for roof rot etc., the roof sheathing is less prone to moisture damage doing this because most roof damage is due to interior moisture moving up from the living space and condensing on the cold roof sheathing. When you spray foam the roof, you’re making it impossible for this moisture to get to the wood.
However, many people worry about roof leaks and rotting from the top. This is far less likely but still possible. If I were you, I’d periodically inspect my roof for missing singles or other things that could cause water intrusion. The most common place is around flashing, like roof vents and chimneys.
Hope that helps,
Good luck with your project!
Hi Ted,
Yeah I’ve been doing my homework and you gave me the answer I suspected. I guess have to think about this and see if I want to make it a conditioned living space or just leave it as is and seal around the canned lights and then add some more blown in insulation.
I’ll look at overall cost of each, pros and cons, and then go from there.
Any idea on the potential energy savings in an unconditioned vs. conditioned space??? I’ll google it and see if I get any results that seem valid. I know that there are probably too many variables with that question that make it hard to answer.
I appreciate the prompt reply and wish you a great week.
Best regards and good fortune,
Arthur Robinson
Even if you’re not going to use it as living space, your AC in the attic will be much more efficient if it doesn’t have to deal with 140F temperatures. Plus it will last longer because motors and electronics really don’t like hot conditions.
Regarding how much is “much” more efficient, it depends on too many variables as you note. For example, I’ve seen duct systems that leak on the air intake side (sucking in hot attic air) that lose about 50% efficiency. Unfortunately, this is more common than you’d think. Any little leak in the attic ductwork is amplified by the extremely high temperature air. Worse, if you have high humidity, that humidity gets sucked in and distributed into the house, making the AC work harder and contributing to uncomfortable summer conditions. Things like this greatly outweigh the basic thermodynamic analysis that you’d get if you looked at simple duct thermal losses due to being in the attic.
Even if it only made sense to add a couple inches of foam, you’d be amazed at how much cooler the attic is and thus how much less the losses would be for the air distribution system.
Hi Ted,
We have a humidifier connected to our heating system. For the last couple of years now, when we turn it on early in the season, and then a subsequent few more times, we get a smell that reminds me a pencil shavings. We’ve had the H&A/C people in to check it out, but they don’t ever smell it and have nothing to offer in the way of an explanation. It does eventually go away, but my husband is concerned it might be unhealthy for us and our five-year old. Any ideas? I appreciate your pondering this!
-Karen Hoffman
Karen – central humidifiers can be a breeding ground for all sorts of nasties because they provide a perfect breeding ground for them.
These central systems have a removable cover that gives you access to the humidification element. Often, they’ll have something like a sponge that gets soaked with water in a chamber that the air runs through. This chamber and element should be dry during the off-season otherwise it will likely be quite disgusting – full of slime and mold. It’s beneficial to inspect this before activating the humidifier at the start of the season. You can then clean it out and replace the element as necessary.
Here’s a link to the manuals for one of the most popular brands of humidifiers. It’s worth reading through the maintenance section of the manual.
Ted: about 80% of my business is installing Mitsubishi heat pumps for heating/cooling in a cold climate. I liked your video on heat pumps but I can probably educate you a bit on their application.
Call me at your convenience.
Thanks.
John Onstad, CEO
Hubbell Electro-Mechanical
Santa Fe, NM
800-658-5939
Thanks John,
You could do even better and submit an article for me to review. Your knowledge and experience would be appreciated by my readers.
Hello Ted, I just read your post on cleaning the Fujitsu filters, which I did about a month ago but I did not see the pleated filter you describe? How do I find and clean it?
Jack Leonard
Here Jack – I couldn’t insert the images in my reply so I added a new post.
I will let you know after the heating season how it all works out. The third heat pump should be installed soon and that will cover the three somewhat seperate sections of the house. I think that these heat pumps are the wave of the future but it will take time to get folks in Maine to realize that you don’t necessarily have to burn something to produce heat. Geothermal exists here but it is very expensive, way beyond what I could afford. There was a company that made cold climate air source heat pumps in Bangor ME but they were unrelialble and the company went out of business. Fujitsu seemed to be the way to go but Mitsubishi makes very efficient units and I’ve noticed LG units on a building here also. We’ll see what the future has in store!
Hi Ted, I came across your video on heat pumps while I was researching the Fujitsu RLS 2 system and found it interesting. I live in southern Maine and have since installled two RLS 2 systems and have a third on the way. So far they have performed better than expected although it has only been down to 22 F. I have a propane fired hot water system and I know that when it gets really cold (this is Maine after all) it will have to take over but the mean temperature here from November through March is around 30 F and I believe that the heat pumps will provide at least 80% of my heat requirement. The expected savings should be $1500 per year which amounts to a pay back in 6.6 years at last years propane price. It should also extend the life of the boiler! The best part is that I can sit in my living room and it’s 70 F and I don’t even think about turning the thermostat down and a fire in the woodstove will be for ambience, not survival. Thanks for your informative website and videos and I hope this blurb will be of interest to your readers.
That’s great “real-world” feedback Gerry. There’s nothing like hearing about how these systems actually work for people. Thanks too for mentioning your potential cost savings. That does help to put things in perspective for people. I’m doing the same thing, displacing my oil fired boiler for most of the winter. Nothing like telling the oil man “nope, I don’t need a delivery, call me next year!”
We are considering a Fujitsu Ductless mini-split for our primary heat source. We have gotten a few estimates and a few different opinions on what to install (mutli-zone vs. mutiple single-zone units). We live in CT and have a 2 story 1940’s brick cape with full dormer (3 bed/1 bath upstairs), full unconditioned basement. The house is about 1200 sq. ft. Our current heat source is an oil-fired boiler with steam radiators. However, the boiler has a hole in it and needs to be replaced. Money to replace (and run) our heat source is a huge consideration.With oil prices as they are, we are having a hard time time trying to justify replacement. Here are my questions:
-Is a mini-split a viable option as the only heat source? The average low in January is 18F and we get few days of near zero lows.
-multi-zone vs. multiple singe-zone units? The single zone units seem to be more efficient, but we are a little concerned about the air flow into the upper bedrooms. (The upper unit would be in the corner of the master and feed across a short hall into the other bedrooms) We like the idea of being able to have mutple wall mounts upstairs to avoid any potential cold-spots.
-Any concerns about the units operating in wet or blizazrd conditions? Would we be able to negate some of these effects by having a roof overhang above the unit?
Mike, those are all great questions.
First, with heat pumps, you always want your home as well insulated as possible to ensure the best comfort. In the old days, heating systems were vastly oversized for the home, so they were able to comfortably combat poor insulation, and drafty construction. With heat pumps, you’re designing much closer to the capacity of the units, so comfort will suffer, especially during cold, windy weather, if the home isn’t tight and insulated.
The Fujitsu and similar heat pumps have a fully variable speed compressor, which is great – they adjust output to the need and can squeeze more heat out than the older units. However, they can’t work miracles – you really want one unit in each space/bedroom to really do the job. That can get pricey with lots of single units, so sometimes it’s worth getting the multi-headed units and give up some efficiency.
I always recommend a backup heat source to help the heat pumps on those bitterly cold days. In conventional central heat pumps you use electric heat strips. For mini-splits, you install electric baseboard heaters. Yes, it’s way less efficient (4-5x less than these heat pumps!) so you only use them when needed. But when you do need them, you’ll be glad you have them! An alternative is to use those little, inexpensive plug in oil-filled electric radiators. Those are only about $50/each, so you can get a few for winter backup and use them as needed. Then, after you have a winter’s worth of use and you see where you needed to use the radiators, you have real electric baseboards installed in those rooms.
Note – in some jurisdictions, the building officers *require* installed backup heat for heat pumps. This is actually a good thing. Think about the next owner of the home. If they don’t know about the portable heaters, they’ll suffer in the cold thinking that the mini-splits aren’t doing their job. Then some contractor will sell them a whole new heating system and maybe rip out the mini-splits. So I really prefer a long-term solution that survives along with the home.
Thank Ted. As usual great information. We do have space heaters (1 oil-filled as you described and an infrared tower, probably another as well to avoid having to move them often) to use as back-up for the time being. We do plan on installing a permanent back-up.
Sounds like you’ve got the bases covered. I hope to hear from you after your project. Sharing your experiences would be great for others. A lot of people have wanted to do exactly what you’re discussing so learning from your real-world experience would help many others.
I have a 2 story home built in the early 1930’s in the midwest. The first level is brick and the 2nd story is stucco. It has a full basement made of stone. I have started the process of making sure it is properly insulated. The first level with the brick seems to do pretty well as is. The second story however is a freezer in the winter and an oven in the summer. The second story has a mix of knee walls cathedral ceilings and regular walls.
I’m not sure where to start with insulation. Im preparing to remove most of the walls ceiling and the floor however there is one room with the original hardwood floor in place. I know for fact there is no insulation underneath this floor and the ceiling below is original plaster and lathe. Each stud bay end of this floor opens up into a small knee wall with little to no insulation. In the summer the floor of this room is HOT. Would putting rigid foam in the ends of the stud bays be a good idea? Or would I essentially be making a terrible place for moisture to gather since its not vented and there’s the original plaster and lathe below?
On my knee walls there is no venting from the underside eaves . Im guessing there is no point in adding any underside baffles on the roof deck.
I plan to take my time and use fiberglass while sealing all the holes I can find. I plan on using unfaced fiberglass and putting my own vapor barrier under the sheetrock. Is there any risk to the life of the stucco by adding a vapor barrier. The house doesn’t have much if any of a moisture problem currently and I sure don’t want to make one by doing something wrong.
Your website is by the far the most informative I have found. Any guidance would be greatly appreciated.
Wow, so sorry for the long delay. Your question slipped through the cracks.
Revitalizing homes of this vintage can be very tricky. Sometimes, even great plans can result in unexpected problems. Let me try to give you an overview of what problems can happen and why they do. I’m going to start with a general discussion then move on to some of your specific questions…
First, remember – warm air carries more humidity than cold air. This is one reason why older, less insulated homes often have fewer moisture problems than better insulated homes do. In the home with less insulation, the warmth from inside helps warm the air in areas like attics and behind knee walls. This then helps dry out and carry away moisture that might otherwise accumulate. Now, suppose you add insulation and it does its job. Then these attic and other areas, that are “supposed” to be cold, are. But now, the moisture isn’t driven out, leading to moisture related issues.
Second, often these homes are very leaky. In conjunction with the first point, this leakiness can help flush out moisture. This is also why these homes can be very dry in the winter. The cold, dry winter air comes in, flushes through the house and out the leaks. This is horrible for comfort and energy efficiency but it can help to flush moisture from where it shouldn’t be.
Put these together: if you tighten the house and add insulation, you’ve made it much more important for the house to be engineered properly. From your questions, it sounds like you understand this, but it’s important to repeat this for new readers. I’ve run into a lot of problems created by well meaning contractors or DIY’ers, who insulate and air seal without considering how the house acts as a complete unit.
Since most problems of this sort are related to moisture entering cold spaces (usually attics in the winter), it’s critical to do a great job air sealing between the living space and the attic. This means any access doors or hatches need to be carefully weatherstripped along with hidden “holes” like electrical boxes, recessed lights, leaky ductwork etc. Doing this single thing can make the house significantly more comfortable and efficient even before adding insulation.
Leading to your question about blocking off the joist bays – this is usually a very good idea. You’re right to consider the possibility of moisture buildup, but if you don’t have holes poked through the plaster, then the moisture movement through painted plaster is pretty minimal. Given the age of the house, you’ve probably got about 50 layers of paint, so that’s the least of your worries. Just patch the holes because vastly more moisture is carried by air movement than moving through the ceiling itself.
Regarding the area of the roof behind the knee walls – I’m always hesitant to suggest putting insulation right up against the underside of the roof unless it’s closed cell spray foam because moisture will get in there and the insulation can trap it against the cold underside of the roof. In the “old days” this often worked because roofs were usually very “open” – they had slate or wood shingles attached to nailers so the air circulated well. But now, most of those open roofs have been replaced by plywood or OSB covered by either a rubber membrane or heavy paper. This is vastly more susceptible to trapping moisture. So I would be very conservative in how you insulate the roof.
When putting up new walls and using vapor barriers, I would consult local building codes. Position and use varies considerably by climate. I will say, many building professionals recommend avoiding vapor barriers since they often don’t work in the way they’re intended and can cause problems with inappropriately applied.
Hope this helps and sorry for the delay in getting back to you.
I’ve been reading your blog all evening, trying to absorb enough info. I think I’m going in a good insulating direction, but wanted to run my thoughts by your expertise!
So recently bought a 1.5 story ranch with two upstairs bedrooms (mostly under adormer) in northern NJ. In one upstairs bedroom, we removed the contact papered over wood paneling, thinking there was sheet rock underneath. This turned into a bigger job than expected, because only 1/3rd of the room was sheetrocked. I’ve already put in place the sheet rock for the entire room (except a piece or two). A guy at work heard what I was doing, and is strongly incouraging me to upgrade the insulation (sad looking R13? between 2×6 roof rafters). So now, I’m trying to figure out if we have the budget to insulate well enough to make a difference. Or if there is a two phased approach I can take.
The roof has soffits along the eaves but no vent at the top of the roof. And due to the roof lines, I don’t think the soffit’s air flow would even hit this portion of the roof. So I’m wondering if this is actually a poor unvented section. The other bedroom has one knee wall exposed to the soffits/uninsulated garage (which I need to tackle later).
I was thinking of taking down the new/old sheet rock in this bedroom, sealing the rafters with rigid foam blocks at the top/bottom (and foam sealing), putting in fiberglass or mineral wool batts, lining over the rafters with 1″ (?) polyiso foam, and then recovering with sheetrock. I’m thinking it would give me ~R30. Not exactly the R39 I would like, but it wouldn’t eat up the headroom of the sloped walls (this bedroom is primarily sloped) and the poly would create a thermal break and air seal.
Do you think this would cause issues in the long run?
Great questions. Increasingly, people are having similar issues/questions, so I’m happy to try to give you some pointers.
Ideally, you’d attack this problem before putting up the sheet rock as it’s much easier to do a proper job, so your thought about taking down the rock is on target. If you’re going through that trouble, you might consider having a foam company come in and just fill the cavities with spray foam, then re-rocking the ceilings. The advantage of this is that the foam will minimize the chance of rotting out your roof deck if moisture gets in there. You are talking about blocking out the areas to minimize the chance of this happening, so you could probably get away without the full spray foam job, but I’m always a little nervous about suggesting approaches that require perfect craftsmanship in order to work. But what you describe would be a pretty decent way to go if you’re going to do the work yourself.
A different approach that would make the roofers and building inspectors happier would be to create an air channel all the way from the soffits up to the (currently non-existent) ridge vent using furring strips along the 2×6’s, then build the channel with 2″ poly-iso foam. You could then fill the remaining few inches of cavity with batts of your choice and complete as you describe with 1″ polyiso and sheetrock. That would give you 3″ polyiso plus about 3″ batts for the same total of about R30 AND give you an air channel under the roof deck. This would be a pretty conservative approach that would give you decent insulation and a safety net for your roof.
The main important detail is that the channel would need to extend all the way to the soffit vent and be sealed so as to minimize the chance of pulling moist air from the house into the vent. I’ve seen that type of thing cause serious issues with walk-in kneewall attic spaces. Lots of moisture getting sucked into that space comes into contact with the cold roof = mold and rot.
The key thing is to stay conscious of what the moist air wants to do. It wants to go up and it wants to condense on cold surfaces.
I’m definitely leaning towards your conservative approach. The air gap would remain, just in case. I’ve been trying to figure out if any of the soffits vent into this space, but I don’t think so. But there was a huge air gap there now, and no moisture issues and we definitely don’t want any in the future. The polyiso sandwiching a batt would definitely be decent insulatio not quite R50 but its a lot cheaper than spray foam. Thank you for the help.
Still haven’t decided what to do…mulling over the costs and returns
But I came across some discussions regarding double layers of polyiso foam with batting in the middle (like I was leaning towards -using roxul and at least one foil lined polyiso layer). One person mentioned using XPS instead but others said not to have the layer that I was planning to be for the venting. A concern was that over time, air would be introduced despite the sealing and moisture would be trapt between the layers. In theory I can see this happening and even probable.
Do you have any thoughts on this? or on improvements?
If I get rid of the poly next to the venting (which I’m almost 100% does not connect to the soffits in anywhich way) would there be too much air circulation to get a good R value out of the Roxul? Or can I wrap the Roxul in an air barrier like Tyvek?
Double layers can be problematic because there will always be air leakage which will carry moisture. The first critical question is whether the air will come in contact with any surfaces at or below the condensation temperature. You mentioned using a thinner inner layer and thicker outer layer. Typically, the rule in our climate is to have no more than half your R-value inside of the outermost insulating condensation plane. In your case, that would be the insulation closest to the roof.
So, for example, if you used 2″ polyiso under the roof (as the vent channel), you’d get about R-14 there. Then, you’d have R-7 for the one inch inside, next to your ceiling. And a few inches of Roxul could push you up a bit above the R-14 in your outer layer. So it’s somewhat iffy.
The second critical consideration then is, “what happens if liquid water gets into this cavity between the two layers and is essentially trapped”. This can occur from condensation or roof leaks. With a space like this, if this water built up over time, it would definitely cause problems. Now I remember why I normally just recommend spray foaming inside the vent layer!
Here’s an alternative that would eliminate both these problems – eliminate the Roxul layer and add layers of polyiso or other board foam of your choice. I didn’t recommend this at first due to the added labor. But suppose that instead of:
— Roof
— Air gap (1″)
— Polyiso (2″ = R-14)
— Roxul (<3" ~ R-10)
— Polyiso (1" = R-7)
— Sheetrock
(total insulation R ~ 31)
you have:
— Roof
— Air gap (1.5")
— Polyiso (2" = R-14)
— Polyiso (2" = R-14)
— Polyiso (1" = R-7)
— Sheetrock
(total insulation R ~ 34)
Because the layers of polyiso would be sandwiched, the volume of air and associated moisture in between layers would be essentially nil. The top air gap has been increased which also improves the ventilation under the roof deck.
Usually I don't recommend this method simply because, with the added labor, you may as well get it spray foamed. You might then do:
— Roof
— Air gap (1.5")
— Polyiso (2" = R-14)
— closed cell spray foam (2" = R-13)
— Sheetrock
(total insulation R ~ 27)
The R-value isn't as good but the spray foam seals everything air-tight so there's almost no chance of interior air-borne moisture getting above it. Also, this eliminates the inner poly-iso, reducing labor/material costs as well as the possibility of creating a double vapor barrier and the associated issues, though this is much less of a problem now that you have R-27 on the "cold side".
Nothing's simple!
Everything simple, gets complicated!
I really appreciate your help.
Considering we’re not planning on moving for a very long time, we’re invested in making sure the insulation won’t be hurting the house.
What you just suggested is actually what I had thought about two weeks ago. LOL Full circle. Well maybe it wasn’t thinking to ventilate it…probably not.
I don’t mind the extra work (although less would be a plus!). This is a small room and the only room we’re doing at the moment.
Spray foam isn’t an option (at this exact moment) because of the price and I doubt someone would bid a job this small (less than 250 sq ft of wall surface).
I started looking toward roxul because it seems mold/bug/compression resistant. And the price is great. money always talks. That’s the point I’m at now, comparing prices and r values and mulling over diminishing returns. And I’m cringing at the figid foam costs for this small space. If I could just slap up roxul 5.5″ roxul and a 1″ polyiso I’d be so happy (R value ~29 – if ideal) but the whole venting issue put a crimp into that idea.
Thanks again. This is keeping me up at night and I need to get past it. LOL
Roxul is a good product that many “green” builders have adopted for the reasons you mention, so I wouldn’t discourage you from using it, if done in a manner that will ‘do no harm’ to the house. The most important thing, beyond R-value and everything else, is that what you build should be durable and not cause problems.
So let’s take a step back.
The problem with fully filling the cavity is that the batt insulation, in contact with the roof deck, provides minimal ventilation potential and traps any moisture that condenses right against the roof deck, rotting it out over time. Essentially, the batt is like a wet sponge – leave it sitting on the countertop and the top (air side) dries out but the bottom, in contact with the counter, stays sopping wet and nasty. So we want to avoid that.
In older homes where you often see fully filled cavities and insulation right up against the roof, often the roofs were constructed differently. You might have had wood or slate shingles mounted on slats nailed to the rafters. The system was “open” and vented right to the outside. This washed out any moisture that got that far. As roofing switched to plywood with tar paper then OSB and rubber membranes, we created impermeable surfaces that trapped in moisture, so we had to create a ventilation space underneath to flush out the moisture.
In your case, you mention that you don’t have soffit vents that would ventilate this space just below the roof deck. If possible, it would be really good to address this and install matched soffit/ridge venting to provide an ample air path through. The Cor-a-vent product is great for this. I used it on my own home in one roof section that is fully vented. But sometimes this isn’t possible, so you just have to make the best of it.
In “real life”, I have only seen issues with unvented roof cavities under a few conditions:
A) recessed lights in a cathedral ceiling. Almost every one of these installations leads to a rotten roof because the recessed lights are never truly air/moisture sealed nor (even if rated air tight). Even if they were, they wouldn’t be installed air tight. So they provide a direct path for water vapor to flow up into the space where it immediately condenses on the cold roof sheathing leading to mold and rot.
B) wooden slat ceilings. Often aesthetically attractive, this construction provides no air/moisture barrier. Even with plastic under it (usually filled with holes). Same problem as (A). Even worse when combined with (A)
C) The fully insulated space between ceiling and roof opens behind a kneewall that is used as attic storage. Since these spaces are open to the house and usually not ventilated, moisture gets into these spaces and follows the path up through the roof cavities, being sucked through by a ridge vent. To make matters much worse, in many of these cases, bath fans are venting into this space.
Note: the problems exist and are often made worse by ridge vents because air going out the ridge vent has to come from somewhere. That somewhere is usually the interior of the house. So often I’ll see these problems arise after a well meaning roofer installs a ridge vent on a roof that has functioned properly for decades without a ridge vent.
All of these problems are due to large amounts of INTERIOR moisture ending up in the cavity. That moisture will condense on the first cold surface it comes in contact with, which is usually the underside of the roof deck.
Your idea of internal poly-iso, running between the rafters and the sheetrock is a good one. It will greatly reduce thermal bridging through the rafters, increasing the overall R-value far more than you might think. In addition, since they’re large sheets of foil faced insulation, they will stop virtually all moisture from moving from the house into the cavities from the house. Just don’t poke holes in it (recessed lights). I would NOT eliminate this layer. It’s good insulation at the right place.
Above that, you could put your Roxul. Again, I can’t recommend fully filling the cavity so you’re best off with less R-value and an air-gap than more R-value and insulation in contact with the roof deck. Especially if you have the inner layer of polyiso.
So there’s your simplest, lowest cost, safest solution. Sheet rock => poly-iso => Roxul => Air gap => roof sheathing
If you wanted, you could use 2″ of polyiso instead of the 1″ you originally proposed. You’d lose a little more headroom but you’d add R7. You’d also have to use longer screws for the sheetrock. It’s a little more of a pain to install but your overall R-value ends up pretty good.
Hi Ted,
I have a roofing/insulation question. I have a low pitch roof (1.5), live in the Boston area – the new roof needs to be black rubber. My roofer wants to put foam board under the membrane and above the sheath and then keep the vent under the sheath. Between the sheath and my ceiling is 8 inches (cathedral flat roof).
My question is with the rigid foam above the sheath (r20) does it make sense to fill the 8 inch cavity with something (open cell spray foam, dense pack, etc) or should I respect the original roof design (soffits, no ridge/gable venting)? Should I try something else? I’m also trying to avoid taking the ceiling down as well. Will insulation above a vent do anything for me and my house?
Love your blog – it’s been incredibly eye opening!
Allison
Great question! That’s a tricky configuration, one that’s common around Philly also. I’m hesitant to give too much advice without seeing the exact configuration of the roof and the rest of your house. However, there are some general concepts that you’ve hit upon that are worth discussion.
In particular venting between the roof insulation and the living space is a bit counter productive, but not totally. What you’ve described, with roof membrane then insulation will help considerably to reduce heat drive into that space underneath. Without the insulation, the space would probably be something like 130F-150F. Insulating under it will keep the space much cooler. As you noted, venting under that will then allow outside air in so you won’t be insulating from the outside temperature, whether it be 0 degrees or 100 degrees. Without good insulation, your ceiling will be basically the same temperature.
On the other hand, if you didn’t vent that space then any moisture that gets into the area could pose a condensation risk. If you were building a new home, I’d say to spray foam directly to the top surface of your ceiling (i.e. the attic ‘floor’). That would minimize moisture movement and allow you to conventionally vent the space between getting the best of both worlds.
A couple other things – if you’re allowed to use white rubber, you’ll be much better off than black rubber. I inspected an industrial roof like this and was amazed at how cool it stayed.
Also, it sounds like you may have the opportunity to open the roof if you’re considering the possibility of spray foam. If you can do that, that would be my first choice. As noted above, I’d foam right to the top of your cathedral ceiling material.
To put this all in perspective, think about the “jacket” analogy. If you leave your jacket open during the winter, you get cold because there’s nothing stopping the cold air from sucking the heat from your body. So you zip up the jacket to keep the air out. Now you stay warm. Same with your home. Venting between your living space and the insulation is like leaving the jacket wide open.
Good luck with your project. I hope you have a really comfortable and efficient home after that!
I have found a workable alternative to dismantling the unit. I ordered a large brush that is made for cleaning mortar from the holes in the center of bricks as they are being laid. The brush handle is 12″ long, made of heavy, twisted wire. Brush bristles are made of stiff plastic and 5/8″ in diameter. When I insert this brush through the wire grid between the blower and the back of its housing, I can wedge the brush so that it forces its bristles between fins, dislodging the build-up of mold and dust particles. By rotating the brush, the blower wheel can be rotated to get to all the fins.
Butch
Wow, good job!
Just be careful of those thin aluminum fins. They’re really delicate.
Hello Ted, I read the posts about cleaning the 12RLS with interest, when should you do the first cleaning of the filters, or do you replace them? I assume you have to take off the moving cover to get at them?
Jack, the filters pull out and can be washed. They hidden behind the motorized front panel.
Find the manual on the manual page and look at the section on cleaning (P-13).
I keep an eye on it and clean mine when there’s obvious dirt building up.
I read in your reply from a year ago that you have Fujitsu Halcyon splits in your home. I, too, have one of these. Have you ever tried to clean the blower fins? I have found that mold has accumulated on the fins of my unit to the point of large masses after 10 years of normal use. I can’t find any company guidance or diy tips for accessing this blower.
I haven’t looked at mine closely, though all my indoor units were replaced recently due to a power surge.
In general, dust accumulation is expected. This happens worse during air conditioning season when the fins are cold and get wet with condensation, catching the dust. Unfortunately, that also creates growing conditions for mold.
The best thing is routine maintenance – a couple times a season, thoroughly clean the air intake filters and use a shop vac (with a soft brush attachment) to clean the fins. The fins are *very* delicate and you want to avoid damaging them. You can also use a high power blower to force air through the system, dislodging dust and other debris.
When it’s gone as far as you’ve noticed, it likely requires more aggressive cleaning which likely requires dis-assembly and the use of solvents, something I’d leave to the pros. It’s pretty time consuming so it won’t be a cheap operation. If you look on YouTube, you’ll find several videos showing the process – it’s messy and time consuming. Personally, I wouldn’t do it as a DIY job if it’s gotten to this state because you might turn a $250 job into replacement of the unit!
Thanks, Ted. You are right about the DIY part, but dis-assembly seems to be the only way to access the fins on my blower. The only way to reach it is through a wire grille which makes it impossible to keep the wheel from spinning as I try to brush the build-up off the fins.
It unfortunately does look like it needs dismantling. I wonder if you might be able to do it with air pressure alone? Probably not.
When I’ve seen techs clean the fins, they use a foaming solvent/cleaner which then has to be flushed with water. A really messy operation when done indoors!
I have completely gutted and renovated a 100 yr old house, I need your opinion on insulation.
My upstairs (bedrms) has a partial cathedral ceiling, in other words, 5ft knee wall, 6ft sloped ceiling,
then horizontal ceiling. Can I completely fill in the 6inch sloped ceiling with spray foam, just 6ft,
not to the peak, Then put celluouse in the attic, The question is do i need venting from the soffit?
I do have a ridge vent,(new roof). But not sure if thats enough.
There are a couple of schools of thought on this. You might check some of the other discussions we’ve had recently. At the bottom of
I discuss exactly this type of situation.
A couple questions on the specifics of your home:
– do you have an attic space behind the kneewall?
– if yes, is that space vented? Probably not in this vintage home.
– Does the top attic have anything besides the ridge vent? That is, does it have gable vents or any other way for air to get in? If not, the ridge vent isn’t doing much good. In fact, it might be bad.
In general, that little space of sloped ceiling that you’re talking about is one of the most problematic features shared by many homes. If you can spray closed cell foam directly to the underside of the roof deck, you’re usually pretty safe sealing this space up.
Specifics however require a closer look at your home and it’s construction. You also want to take into account the climate zones. Very cold climates have different considerations than very hot-humid ones. In our climate zone, you get hot-humid summers and cold winters, so you have to be pretty careful about issues that can lead to condensation during the winter. However, as noted, closed cell foam applied directly to the underside of the roof deck usually eliminates these worries.