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 
Hi Ted, I live in a condominium in Miami Florida. We were affected by hurricane Irma and are having a new roof put on. The building was built in 1964 and has always had a flat roof. When it rains, water pools at the top and causes leaks in units do to the weight and not pushing water to the drain holes. Due to this, we have decided to do a diamond shape roof so that it tapers toward the drain holes on the roof. The roofer chosen by the board isn’t going to insulate the roof because he said the engineer said it wasn’t a good idea. Is this true? Should the roofer not put insulation down? I always thought that it was the insulation that kept the units cool when it is hot and warm if it ever gets cold. Your advice is appreciated. Looking forward to hearing from you.
Glad you’re switching roof styles. Flat roofs are a real challenge because if they’re not constructed perfectly they leak. So you’re making the right choice.
Is there no insulation in the roof now? If there wasn’t then the people on the top floor would bake in the sun. It could be that they don’t want to have two different insulation systems competing which could lead to unintended consequences. It all depends on the specific situation.
In theory though, now is the time to add insulation while the roof is being amended. It would be easy to add a layer of insulation right over the top of the flat roof before the new diamond shaped roof is added. Adding a few inches of spray foam could really increase the comfort and energy efficiency of the top floor units.
Another caution – since your roof has been leaking, that means that water has been getting underneath the roof membrane (I’m assuming that the top layer is rubber coated with some protective layer like they are around here). That water can get trapped under the rubber and slowly rot out the roof structure underneath. This may not have happened in the past because the sun heats the roof so much that it can drive the water right through the roof where it would then dissipate naturally. If you put another roof over this roof, that water could stay in there longer, leading to major damage. It would seem prudent to have a roof expert take samples of the roof at the low spots where water would likely pool to ensure that water is not trapped in there. Better would be to strip off the existing roof and allow it to dry fully before fully enclosing it under the new roof. The trick is then how to protect the roof during construction. The logistics could be hairy.
hello ted, hope al is well, have a question about heating an extension we built. it is over a existing deck about 16 x 30 size connected to house but outside so to speak. the walls are basically sliding doors wrap around for a 3 season room effect. need a reccommendation for supplemental heat in there in winter for occasional weekends. was planning on cranking my woodburning stove and opening door to this room from main house to allow air to flow in ,but feel i want a plug in heater .(110 ) do i want a blower style or radiant type. also should i lay down rug or deck tiles to close off any air flow from floor up. thanks for your help
Hey Bruce, having an unusually warm autumn here in Eastern PA.
I would definitely put something on the floor to stop air flow. The first thing that comes to mind is to get thick carpet padding cut to the size of the room that you could roll out for winter and store for non-heating season. This will provide an excellent air block and some R-value. Then some carpeting or other surface covering on top of that. If you do that, you may even find that you need minimal heating if the room gets ample sun.
Do you have propane or gas? If so, you could get a wall-mount system or freestanding unit that’s cost effective and it would throw off plenty of heat to take the edge off. You could use 110v heaters but in a room that size, you’d need several and you might have to have several electrical circuits to power them. Hard wired electric baseboard heaters are a possibility too.
None will be cheap to run, but if it’s only for occasional use, I think the installation cost and convenience would outweigh the operational expense.
As for blowing vs. radiant – it’s a large space. I’d probably use something that circulates the air if you get a freestanding unit. OTOH, if you use electric baseboards, they’ll wrap around the room so natural convection will help distribute the heat.
Hi Ted, 2 questions if that’s ok…….?
1) we have insulated between the wooden floor joists in our 1930’s house using celotex foil backed insulation – sealing as many gaps with foam where we could. The suspended floor has had extra air bricks installed to try and up air flow. I would like to check whether there is a possibility of condensation gathering between the top of the insulation and the floor boards of it is not completely sealed & should we use extra ventilation in the downstairs area (I.e single room wall mounted HRV fans)?
(ps I have sucked up as much of the cavity wall lint insulation out as possible as it was causing mould problems).
We are building a large exterior workshop/studio with cold roof, the plan was to insulate between the studs with rock wool, place a vapour barrier on the exterior side of the stud, install marine ply and then clad. The interior will be dry walled. Would you say this is the correct sequence of layering, do you have any pointers?
Thanks Rob
From my understanding, the Celotex is down between the joists, so just above the ceiling of the floor below. Sealed tightly, minimal moisture should pass that, so there would be very little chance of condensation above it, especially if you are allowing free air flow around the floorboards are above the insulation. As long as you don’t install any moisture/air barrier, like plastic right below the floorboards, the minimal moisture should flush out.
In your exterior workshop, you almost definitely don’t want the vapor barrier on the “cold” side of the insulation – that would be a prime condensation target. Unless you live in a hot, humid climate, like Florida, then the warm side is towards the roof and that’s where the vapor barrier goes. But in any cold climate, you want the vapor barrier as close to the interior of the house as possible.
Ahhh I think maybe my explanation on the first part didnt read correctly (hazards of small phone screens): the insulation is on the ground floor, which is a suspended timber floor, about 2ft off the ground level. But thank you that puts my mind at ease!
We are in the SW of England so the climate is mild to cold most of the year, vapour barrier on the warm side then. Really appreciate your quick response and you’re doing great work. Rob
cheers!
Hi Ted,
My husband and I just purchased our first home which was built in 1967. The upstairs is freezing and we found out we have about 5″ of insulation in the attic from when the house was built. We want new and updated insulation and I received two quotes which were like comparing apples and oranges. The first company wanted to blow in cellulose over the existing insulation. The second wanted to remove old insulation clean and sanitize the attic and lay down fiberglass batts. No rodent problems but he did say he saw old droppings. I have a small child and baby on the way and am respiratory sensitive so we want to make the most health conscious choice. Removing old insulation sounds like a no brainer and I don’t love the idea of blow in as I feel and have read it can be dusty and get into the vents of the house. I also don’t love the idea of fiberglass, cause of well fiber glass. I asked about rock wool and both companies seemed hesitate and said it was more money. I’m not sure if they are hesitate because its not their specialty or because it can also be bad for your health. What would you suggest is the best choice for in home air quality? Thanks!
Rock wall is one of the “insulations of choice” by many green builders, whereas fiberglass is the least favored. I normally like blown in cellulose, however it can be very dusty and from your description, that should be avoided. The same goes for blown in fiberglass.
My personal favorite is Bonded Logic insulation. It’s made from recycled denim so it’s not likely to have any microscopic fibers. It’s great to install because it’s not itchy. And it’s heavy and dense, so it’s good at stopping air leakage when installed properly. It has two downsides: 1) it’s more expensive than fiberglass; 2) it is tough to cut because it’s blue jean material!
On the price point, much of your cost is for the labor, so the cost of materials is less important. OTOH, it will definitely add to the cost.
Depending on where you live, it might be more difficult to find a contractor who has worked with the Bonded Logic insulation, but you could contact the company to see if they have any names in your area.
Regarding removal of the insulation, depending on how its stood up, you could just lay the new batts over it, perpendicular to the existing insulation if it fills the cavities. If it doesn’t fill the cavity, you could lay it right over it. The cost to remove the existing insulation and clean out the area will probably be at least as much as the premium you’d pay for the Bonded Logic insulation.
You normally don’t have to worry about dirt/contamination of the fiberglass getting into your living space unless all your ductwork is up in the attic, in which case, the system can suck the dust into the ducts and blow it around your house. If you don’t have ducts and the air handler in the attic, you typically don’t have to worry about it.
You may also wish to have an air quality specialist come and run a test on the indoor air quality since you have sensitivities and a baby on the way. Best to know what you’re moving into before you start doing a lot of other work.
Thank you!
Hi Ted, I have a Mitsubishi Mr Slim Split air conditoner/heater. Has always worked perfectly. So it cooled all summer (live in NH) and went to put heat on today and no air will come out. It will however still push out cool air on AC. I changed the temp correctly but no air will push out on AUTO or HEAT. Remote batteries all good? Can you help? Ccccold day here today. thanks Ellen
Sounds like you need a service call. It must not be switching into heating mode properly.
http://i0.poll.fm/js/rating/rating.jsHi Ted, we have a classic cape in the northeast. We’re looking into spray forum for the attic. The contractor is telling me that they’ll seal the entire attic-from the soffits to the ridge vent, gable vents too. Is this correct?. They’ll apply to the roof deck. I’d welcome your advice.
This can be a great way to go. it often results in a easier to implement job as well as giving you an attic that is much more temperature controlled. it also greatly reduces the chance of your roof deck rotting out due to humidity for me inside the house getting up into the attic. do you have any equipment like the air conditioner in the attic? If you do, then insulating in this way will help that run more efficiently.
The one warning – I recently had another person get in touch after an insulation crew botched the job. The foam didn’t cure properly causing the house to smell and the job had to be redone. Make sure your crew is experienced. They should have hundreds of jobs under their belt. Get references and talk to them. Foam can be tricky and a lot of contractors got into it to make a quick buck.
https://polldaddy.com/js/rating/rating.jsHi Ted,
I’m really hoping you can help me. We had to completely gut our home, due to water damage from a really bad winter. The contractor then installed Thermoseal Sprayfoam insulation in the walls and attic. We also had a new HVAC system installed. They did not install the HVAC system with any sort of fresh air supply, such as an HRV or ERV. Since we had the work done (one year ago now) we have been experiencing a very bad odor, and it gets worse when the weather is warmer and also when we turn the attic HVAC unit on. I had an air quality company come out and the VOC levels were 10 times higher than what they should be in a normal home. They did not apply the insulation correctly and it never cured properly causing the odor and very toxic air. My daughter has since experience a chronic cough, and I have developed multiple chemical sensivity, causing me to have headaches, fatigue, and a sore throat when I’m in my home.
The insulation company has been working with us and has removed the old spray foam in the attic, and added a SES Spray foam instead. That work was overseen by the manufacturer, and was done properly. We added an HRV to the basement unit and a fresh air intake system to the attic unit. We also added a bathroom fan in the attic to exhaust the attic air. I also had the HVAC company seal all of the duck work and returns, to make sure they are not leaking.
The VOC levels have gone down, but are not quite at normal levels yet, and unfortunately, the smell is still here. It still gets bad when it is warm out, or when we turn the ac on. Also, I had to shut off the fresh air supply, because I can smell the odor when it is coming through the ductwork.
I am at a total loss. Do you have any advice on how to overcome this situation? I was wondering of drywalling the attic ( we live in a cape, so it is a very small attic), and adding windows in order to add ventilation on nice days, and possibly an air conditioner in the windows on hot days, might help. It is a warm attic, so I know you aren’t supposed to have much ventilation, but we really need do get fresh air into the attic, and let out the smelly air.
Any advice you have would be greatly appreciated!!
Thank you so much!
Sorry to hear about your woes. I’m glad that they figured out the curing issue and had the manufacturer supervise reinsulation. That problem is what kills inexperienced foam contractors.
It sounds like your air handler in the attic is still sucking in tainted air. I would have them pressure test the entire system for air leaks then insure that everything is sealed with duct mastic.
Keep flushing the attic with fresh air. You need a place for fresh air to get in as well as the fan to flush it out. Preferably at opposite ends of the attic. I’d also get a much higher volume fan to do the work -at least the size of a normal attic fan. Flush the air continuously for a week or two. The outgassing should exponentially decrease over time. After the smells have diminished, you can coat it with a thick, ‘green’ (low VOC) paint which will greatly reduce any further smells.
It’s likely that there’s going to be some residual odors but this should be vastly better.
Also, on nice weather days, flush out the house opening lots of windows. An ERV that is independent of the HVAC would work well also.
Hi Ted,
Thank you so much for your quick response!! I’m really grateful for your advice.
Do you have a product in mind for the attic fan, as well as, the item needed to bring in the fresh air into the attic? I just want to make sure I am using the correct equipment. Also, will I need a dehumidifier in the attic to make sure the air coming in does not bring in too much moisture?
Finally, how would the ERV work if it is independent of the HVAC system? Do you need special venting for it, and is it okay that the air coming through will not be heated or cooled, as it would be when it is connected to the HVAC? I really like this idea, but just want to make sure I know what needs to happen before I hire someone. We’ve used two HVAC companies now and are still having problems, so I want to make sure I’m knowledgable on how it all should work.
Thank you again!!
Amy, for now, you just need a gable vent or similar opening at one end of the attic. At the other end, you’d just use an exhaust fan, like this: https://www.lowes.com/pd/Air-Vent-18-in-Dia-Electric-Gable-Vent-Fan/1082639
The important thing is to install it properly so that it will effectively move lots of air. The photo shown along with the fan demonstrates this:
This is just a temporary solution to flush lots of air through. Right now, the health of your family is the most important issue.
Moisture shouldn’t be a problem for now as you will be flushing fresh air through the attic space. Once the VOCs in the foam have been flushed, you should be able to close up these holes and get back to normal life.
The best method for an ERV is for it to have its own duct system that takes stale air from a few places around the house and puts fresh air into other areas. The problem with having it connected to the ductwork of the main HVAC is that the air pressures in that ductwork can mess up the balanced flow of air from the ERV, which has it’s own blowers that are trying to move the same amount of air in and out of the system.
I’ve installed one in my home in this manner. You are correct however that the air coming from the unit will be warmer (in the summer) and colder (in the winter) than your normal HVAC air. I have my main fresh air supply entering a hallway near the main return of my HVAC. In this way, it’s not blowing the air directly on anyone yet can enter the house in a controlled manner and some is sucked into the air return and cooled/heated by the central system. Works great!
Hi Ted,
I hope you are well! Last fall I contacted you for your advice on what I should do in my home to get fresh air in the upstairs. We had a bad sprayfoam installation and we were without any fresh air. You had recommended an ERV for the upstairs with a dedicated system. We just had one installed today. However, they put the supply in the hallway, with the ERV return only 2.5 feet away from the supply. I am aftraid the fresh air will immediately be sucked back into the ERV return without actually providing fresh air for the bedrooms. We definitely need fresh air in the bedrooms, as we are trying to midigate the moderate VOC levels due to the insulation.
Are you comfortable with the ERV return being so close to the supply air?
Thanks so much for your help!
Best,
Amy
yikes! You are exactly right. The return should be where there is stale air and the supply should either in one of the bedrooms or very close to the return for your frunace or air conditioner so that it can suck in the air and distribute it around the house.
Hi Ted,
Thanks so much for your quick response! I really appreciate your help! I did forget to mention that the return for the HVAC system is also in the hallway. Does that help, or should we still have them move the supply or the ERV return to one of the bedrooms? I wish I could hire you to do the work. Hahah. This is our third HVAC company and it seems as though no one knows what they are doing?
Thanks,
Amy
Well, if the supply is right next to the air return for your system, you’re probably ok, but it would be much better if the stale air return were across the house somewhere so there was no chance of the fresh air immediately exhausting from the house.
http://i0.poll.fm/js/rating/rating.jsHi Ted, I am having a small pool house built. The builder installed soffits and an attic fan and then spray foam insulation in the roof and all over the soffits sealing them off. Am I better off removing the attic fan and sealing off the hole with more spray foam to make the attic airtight or leaving the attic fan and cutting away some of the foam to allow air to enter through the soffits to the attic? Should I be worried about moisture in the attic if I don’t circulate air there?
Thank You,
Andy
If I were charitable, I’d call that builder’s behavior “bizarre.” Why in the world would they install an attic fan and spray foam the attic? Maybe I’m misunderstanding. Did the builder spray foam the “floor” of the attic space, or the ceiling (under the roof)?
If you insulate the attic ceiling with foam, then ventilate it, you are completely negating the purpose of the foam and you’ve just wasted thousands of dollars on it.
On the other hand, if they insulated the attic floor, which is the ceiling of the room below, then fine. But then they should have left the soffit vents open so the attic fan would do its job. But, with insulation like that, the attic fan is worthless – it should just have matched soffit vents and a good ridge vent, like the Cor-a-vent products.
Could you describe the construction in more detail – where the insulation is and so-forth?
You’ve perfectly described a phenomenon called “depressurization!”
When you turn on the fan, it is exhausting air from the house. Actually, the clothes dryer does this too – it takes the damp air from the cloths and exhausts it through the outside vent. Every bit of the air that gets blown out of the house gets replaced by air getting sucked into the house from wherever it can come in. This is called “uncontrolled ventilation.” In other words, air is pulled in through any cracks. It might be working its way through your walls, a layer of insulation, past come mouse droppings or whatever.
So the question is: “where is the air coming in to your master bedroom?”
Since the effect is so immediate, it’s likely that there’s a fairly large air leak. Here’s a couple things to try to diagnose the issue:
0 – turn off any air conditioning or fans in the house. You want the bedroom to be filled with fresh air for this experiment. You might open the windows for a little while.
1 – to confirm that the fan is sucking stale air into the bedroom, close the windows in the master and the door to the bedroom and put a towel at the base of the door to block the air that might get sucked through. Then have someone turn on the fan and see if the bedroom still gets smelly. Wait the normal amount of time (with you in the bedroom smelling the air) and see what happens.
2 – If the smell doesn’t appear, or it’s much weaker than normal, then open the door and quickly sniff around the room, especially near air conditioning vents. While it can be difficult to exactly locate the source of a smell, you might be able to locate the source.
My theory is that you have leaky ducts or duct connections (I’m assuming you have central air) near the master bedroom. Typically, upstairs condo room have ductwork running through the attic and often this ductwork has been abused over time or was poorly installed. You can usually remove the air vent cover in your ceiling with a couple of screws. You might have to cut the paint around the edge that seals the cover to the ceiling or you’ll rip the paint. The sheet-metal part that connects the duct to the ceiling is called the “boot.” This boot is often not sealed to the ceiling, so there might be a big gap between it and the ceiling material. Or the duct may be poorly attached. Stale air from the attic, which normally wouldn’t get sucked into the room, gets pulled in when the fan runs.
There may also be a grill somewhere else in the room – often on the wall. This grill is typically for air getting sucked back to the air conditioner. The same notes apply to that. Basically, any holes in the walls or ceiling are prime candidates for bad air getting into the room.
There is a second way to test the theory which is to tape a piece of plastic to each of these grills. It should lay limp. Then, turn on the fan in the laundry (turn on the dryer too to accentuate the effect). If the plastic bulges inward towards you, it indicates a leaky duct because the system really shouldn’t allow this to happen.
If this is the problem, you’ll have to have someone check out your ducts, especially around the master BR. You want the boots thoroughly sealed to the ceiling and the ductwork leading from the central system to the room checked and sealed.
Hope this helps!
https://polldaddy.com/js/rating/rating.jsI will try that thank you. 2 things though… I don’t have a/c and the smell always starts in the master bathroom (on suite?) does that change anything?
https://polldaddy.com/js/rating/rating.jsI will try that thank you. 2 things though… I don’t have a/c and the smell always starts in the master bathroom (on suite?) does that change anything?
Monica, no A/C definitely changes one thing – there’s no ducts to test! Unless you have other ducts for central heating which could still have the same issues.
Glad you mentioned the bathroom. Do you have anything in there that required holes cut in the ceiling or walls? For example, you should have a bath fan. Usually, they cut a large hole in the ceiling that is unsealed around the fan. If you do, you can pull down the plastic grill and look at the connection between the fan and the ceiling. Usually there’s a big gap there. Sometimes the bath fan doesn’t even have a duct attached to it, so that it just blows moisture into your attic, which would cause all sorts of mold etc up there.
Regardless of whether you have a bath fan (you really should, if you don’t!) do you have recessed lights? Those are usually very leaky and allow nasty attic air to get sucked into the house if there’s any depressurization of the sort I mentioned.
You can run the same type of test I mentioned in the bathroom if you can close the door and put a towel under that door crack before someone runs the fan in the laundry. Try your best to locate where exactly the smell is coming from.
Anything else you can tell me about the bathroom that might be of interest?
http://i0.poll.fm/js/rating/rating.jsI had the attic of our 100 year old house insulated a bit better (3 stories). Then I felt my basement was warmer and had mold. The improvement in draft was from 800 to 650 or so. I was told to put a better dehumidifier and air purifier. Which I just ordered. Is it possible that the insulation created this problem or just that we had more humidity in the past few weeks (hurricanes etc…). We are in the North East however.
It could be a combination of factors. If they tightened up the house when insulating, that would flush less of the humidity out. However, it would also let less humidity in! So usually tighter is better.
Where do you think the moisture is coming from? Do you have a damp basement or crawlspace under the house?
https://polldaddy.com/js/rating/rating.jsHi, I’m going insane in trying to figure out what to do with my insulation…especially since the people giving me the info will be doing it and stand to make a profit. I have a 1500sqft cape in NY built in 1939. The humidity averages 45-50% and sometimes reaches 60% in the summer (I got a dehumidifier and am getting mini split systems throughout the house to take care of that). With the dehumidifier running at full I get it down to 41-43%. I ripped out all the insulation on the rafters in the attic that were in the kneewall portion because they were old and falling apart. It seemed like a wool type insulation in paper bags. The insulation on the ceiling joists in the attic remain. The house has lath walls (except the portions I punched holes in for new wiring), the outside aluminum siding on 3 walls and stone on the front. Two gable vents directly across from each other on the sides of the house, soffit and ridge vents. The few places I punched holes in the wall I see the insulation type that are bags with the wool type material in them.
1/ My house is FREEZING! Seems like the insulation is useless. I was going to get dense packed blown in cellulose done, until I read what you said about, “That air gap allows water to drain and dry out. But yet we see people putting cellulose and other non-water resistant insulation into that gap. That’s like sticking a sponge in there. It will soak up the water and likely end up in a moldy, rotten mess and useless insulation.” So how do I insulate the walls then, or with what? Foam might not be done properly, and can pull away from the walls over time, I have to rip open the walls for the pink stuff, and the wool isn’t as good. Do I go forward with the dense packed cellulose (note, when they blow in the cellulose they won’t be removing what’s on the ceiling joists and they don’t know about what’s in the walls, but I assume it will remain.)? They plan on insulating the usable area…meaning the knee wall area and rafters will not be insulated.
2/ My bedroom is above the garage. I was going to put the Corning faced fiberglass in the joists above the garage, and then put the moisture resistant drywall to finish. Do I have the face of the fiberglass face the ceiling since the heat is in my bedroom, or the garage area since that’s where moisture would rise from…same question for the drywall? You may ask why not put a moisture barrier instead? Reason being, I want access and don’t want to be bothered with replacing or patching the barrier if I go up there.
Thanks for any help.
Hey Larry, sounds frustrating!
There’s a lot in your note, so I’ll just comment in the order you wrote.
Humidity levels sound very typical for this area of the country. Nothing too extreme that makes me worry.
Often when you have a cold house that appears reasonably well insulated, there are significant air leaks, leading to a lot of cold air infiltration as well as difficulty maintaining humidity. Running dehumidifiers costs a lot of money, so tightening up the house will help reduce your electric bill too.
The general rule on vapor barriers/insulation facing, is that the barrier is to face the primary warm/humid area. In our climate, this is the inside of the house. Even though there’s humidity outdoors, the outside gets much colder in winter, which means surfaces exposed to those low temperatures are where condensation will be likely to form. The moisture barrier helps reduce moisture from the house from getting out to the cold area. So in your garage ceiling/bedroom floor, the facing should be up against the floor. On the surrounding bedroom walls, it would go against the backside of the interior walls.
In your construction, as long as the walls are normally framed, with aluminum siding, exterior sheathing, a wall cavity, then your interior wall, blowing the cavity with dense packed cellulose would be a good way to go. However, they would need to pull out the insulation that’s in there. It’s really hard/virtually impossible, to do a good cellulose job with complete fill when there’s already insulation in there. They do this by removing some of the exterior siding then cutting back a strip of the sheathing. They can then pull out the existing insulation, replace the sheathing, and blow cellulose in there.
On the side with stone, you’ll have more difficulty. Obviously you don’t want to damage the stone so for those areas, they’d have to go from the interior. It might not be worth the effort.
If I were you, I’d have an energy auditor come in once the weather gets colder. You want to run the tests when it’s below 40 for best results. Have them do a blower door test and thermal imaging scan. This is the only proper way to determine what’s really causing your home’s coldness. Avoid anyone who wants to come in and give you a visual only inspection. A legitimate energy audit by an independent auditor will run $300-$500 and is worth every penny. They will be able to analyze your home, show you exactly where the problem areas are, and suggest specific methods for improvement that avoid causing problems.
Since you already have insulation in your walls, they’ll probably tell you that it’s not worth removing it. The thermal scans and blower door test will let you focus your efforts on just those areas that are causing problems. So start there.
Thanks for responding.
1/ What are your general thoughts on just blowing the insulation around the existing stuff? I’m guessing the cost would go up considerably…enough to bother me at least…if I have them take out all the existing insulation, and I don’t see how it could hurt. A/ I’m only paying for what they blow in (I believe), B/ its still more insulation. Or am I over simplifying it?
2/ I have my garage below my bedroom, and an unfinished basement with my burner below my living room. I’ve been told not to insulate my basement ceiling. Why not if that will prevent hot air from escaping to the basement, and cold air from coming up?
Thanks.
The problem is, it’s extremely difficult to properly fill the walls when there’s already insulation in there. Someone experienced with dense-packed cellulose may be able to do it because they blow it in under high pressure, but more often than not, they try to blow it in, it stops where the existing insulation is, and you get a poor cavity fill.
The only way I would do that is if you have an infrared test done before and after, during cold weather, that shows proper cavity filling. Trust me, without that, you’re likely to just get ripped off.
2 – Unless the basement is really cold and leaky, you’re better off not insulating it like that. Cold air doesn’t rise and warm air doesn’t drop. But, if the basement is really drafty, that can force the cold upstairs. Also, you’d be amazed at how much waste-heat comes off most boilers. You may as well take advantage of that.
On the other hand, if your basement is cold and drafty, then you may benefit from insulating. You’d want to be careful however because allowing the basement to get really cold will make it prone to condensation and water buildup which could lead to mold and wood rot. It’s a serious unintended consequence. But it really depends on the basement.
Yes they will be doing infrared test after, nothing was discussed about before. I will ask, just to see, how much to pull out the insulation.
https://polldaddy.com/js/rating/rating.jsTed — your posts have been wonderful and during the last 3 months of building my pole building home in northern Kentucky, I have been able to do a number of things right (all the ducwork inside the conditioned part of the house, etc). I also have soffitt vents installed. I have one last problem: My ceiling joists are not all 22.5 inches apart. If I am going to use batting insulation in the ceiling, I’m going to have to do a lot of pushing and pulling to get where I can staple this stuff in. Enter a new idea: What if I stapled 6 mil plastic (or Tyvek) to the ceiling joists and just blew in all the insulation I needed before installing sheetrock in the ceiling? Am I forgetting something fundamental or would this work? Many thanks- Dan
Thanks! I always appreciate feedback. Glad I can be of assistance.
What you describe with blown in insulation is exactly what many installers do.
The possible catch is that, in order to avoid possible moisture problems, it is best to have a gap between the top of the insulation and the bottom of the roof. It’s not absolutely necessary but there’s much debate on this. One school of thought is that moisture that gets into the roof cavity can condense on the roof deck and soak the insulation. The wet insulation would hold the moisture against the wood and rot the roof. The other school is that the cellulose insulation itself has extremely high moisture carrying capacity which helps dissipate any moisture throughout the insulation. This protects the roof deck unless there is an extreme amount of moisture entering the ceiling cavity.
For what it’s worth, I had my home insulated with dense packed cellulose, including the cathedral ceilings, and I’m not concerned about this issue causing problems.
If you want to play it safe, you would install 1.5″-2″ spacers directly under the roof deck. You would then install board foam to the nailers, creating an air space between the roof deck and the insulation. Then you’d blow the insulation into the cavity between the board foam and the Tyvek. I generally recommend this approach to people these days because building codes vary and some insist on having that air gap so that the air will flow from soffit to ridge, unimpeded, which is certainly the safe way to go.
Cheers,
Ted
Ted – you are the best. The construction fellows asked me where I am getting my education and I turned them on to your blog. Your comment, l 1.5″-2″ spacers directly under the roof deck. You would then install board foam to the nailers, creating an air space between the roof deck and the insulation. Yep — got that. I purchased 24 inch on center 4 foot plastic soffit baffles so I will be able to blow in what I’m calculating to be about R40 and still be well away from the cold wall. Thanks so much! Dan and Sue in Kentucky
I own a 2 story home built in 1936 in Connecticut. The “attic” runs the length of the house with vents on each end. There is not one iota of insulation in that space. It is only accessible through and 18″ square opening in one of the bedroom closets. I made the opening to work on some electrical wiring. This exposed the lack of insulation that was further confirmed when I modified the bathroom ventilation fan to properly exhaust out through the roof. It was venting into the 3′ high attic space!!
The triangular “attic” space is approx 3′ high, 6′ wide by 35′ long and the upstairs hallway sits right below with bedrooms off of that hallway. The bedrooms have sloped ceilings that follow the roof line. So we basically ARE sleeping in the attic the way I see it.
My question(s) is in regards to insulating that space to help keep the house cooler in summer and warmer in winter. I had 3 contractors come take a look. ALL suggest dense pack cellulose in each bay of the sloped ceiling.
?: Is there any concern for moisture in these bays that cellulose will “suck up” and get moldy. What if a roof leak occurs (I know that is whole other problem, but can cellulose “mask” a roof leak in way?) Would blown-in in pink fiber be better here?
Also the recommended treatment of the triangular attic space differs from each vendor:
1. to spray foam inside the sloped ceiling and sealing off the gable vents entirely. They would do nothing with the attic floor.
2. blow cellulose on the attic floor keeping gable vents as is
3. blow pink fiberglass on the attic floor leaving gable vents as-is
?: Do any of these sound better than the other and why?
Lastly 2 of the 3 recommended spray foaming the rim joint/sill along the basement foundation. Makes sense to me but I read here on “how NOT to insulate your home” that maybe that impedes some need for breath-ability of the house.
?: Would our furnace, water heater, AC, etc be “choked” by doing this?
I appreciate you feedback
Thank you
http://i0.poll.fm/js/rating/rating.jsHello Ted:
I recently did a new addition on my home in PA. We did a vaulted ceiling off the back of the house and a month after the addition finished we found out the hard way that my son’s window had a crack in it and water was allowed to run done the old wall into the new construction. We immediately did new siding, windows, and drainage off the back of the house. No new leaking has occured. My problem lies in the moisture that is up there and have been researching ridge vents for the new construction. The moisture that is stuck up there has manifested as stained dry wall on the ceiling in the new construction area. While considering ridge venting on the new construction I have sealed the room off when everyone is gone for the day running a dehumidifier within the sealed area. I wanted your opinion on my dehumidifying idea or if you would say “Quit over thinking and just do the ridge venting”. Thanks in advance for any insight or ideas you might have for this bummed out dude in PA.
That’s a bummer.
If you think a substantial amount of water got into the ceiling cavity, you should consider cutting open a rectangle of the ceiling drywall where it has discolored anyway. This would let you remove any water that might remain and air out the cavity so as to ensure that it’s dry an there aren’t any other issues. Dehumidifying the room without opening up the cavity will do little to dry out what’s hidden in the cavity.
Removing drywall is less traumatic than it seems and can save you a lot of agony since it will allow direct inspection of the affected area. I’ve had pipe leaks in several areas of my ceiling and had to do this and it was well worth the trouble!
Tip: locate the rafters that the drywall is attached to and do your best to cut the drywall carefully so that you can attach a new piece back to the rafters. Normally, they will be 16″ apart, but some construction has it 24″ apart. Cut out a nice section, maybe 2′ long and the rafter width and it will be easier to replace.
https://polldaddy.com/js/rating/rating.jsHello Ted, I live in Florida and have 14 ft vaulted ceilings. My house was built in 1959 and I had the roof replace 5 yrs ago. The existing material under the roofing felt is a board similar to porous concrete with string like fibers. The roofer installed a plywood sheet over top of the existing material so the nails would hold as the previous roof could just be pulled up by hand. The interior beams are painted with sheet rock between them. The beams have been showing mold for a year which was not a problem before the re-roof (21years). The mold is easily removed with vinegar but reoccurs in about 8 months when it becomes hot outside. Where we live is a very humid environment. I am not sure but don’t believe there is any insulation under the sheet rock. In your opinion should the rock be removed and foam sprayed in and re-install the sheet rock? Do you think that would stop the beam molding issue?
Thank you,
Very humid environments like that are extremely challenging from a mold/moisture perspective. What happens is that the beams are heavy and change temperature much slower than the air. So if the beam is cooler, say after night, then the morning air comes into the house, laden with moisture, you will get dew formation on the beams.
As for why this would happen after the re-roof, I have to wonder if anything else changed at the same time because I don’t see why the mold issue would crop up after that type of change. I have one idea but it’s a wild guess – the added roofing material could be increasing the R-value of the roof just enough to allow the beam to be cold enough for the moisture formation.
The main thing I’d suggest before doing anything dramatic to the house is to do what you can to keep the humidity down inside the house. This means use the air conditioner regularly because it is a giant dehumidifier. You also want to avoid opening windows in the morning or other times when there is lots of moisture in the air. The combination of keeping the house closed up and using the air conditioner should greatly reduce any mold issues since it will control the moisture in your air.
Ted,
I have a room addition on a cinder block crawlspace. The main house is on a full poured basement. I have pea stone on the floor of the crawlspace, plastic sheeting over that, caulked and taped, 2″ rigid foam on the floor and walls, all spray foamed, including the rim joists. The only connection from the crawlspace to the basement is a hole where the heating duct runs from the main trunk in the basement into the crawlspace to the register for that room. Should I drill holes in the rim joist/joist bays where the basement and crawlspace connect so the air between the two spaces can co-mingle, exchange, etc.? I’m concerned with the space being a virtual dead-air space since I have it pretty close to air tight, other than the small gap where the duct work passes through the rim. I have also considered running a 4″ duct from the main trunk into the crawlspace to heat/cool the space to hopefully keep the floor warm/cool, but this would potentially pressurize the space with no where for the air to go. Any advice on how to best handle the air flow for this space?
Best Regards,
Andy
I like your second idea of running a small duct and supplying conditioned air in there. Put it on the far side and don’t worry about a return. There’s enough leakage through the opening where the duct enters. You shouldn’t need a lot of air to flush it out.
Just keep an eye on the space during wet season to ensure that the humidity doesn’t build up. It’s probably fine given what you said but it’s always good to double check.
Hey Ted.
I’ve got a problem. It’s been very rainy recently, I have a septic tank that was repaired (3 years ago) it seems to be working fine. Then I remodeled my kitchen, a deeper sink, had to change the outflow under the sink. I have a disgusting smell coming from my 1/2 basement. There were also some water issues during a recent deluge. Water came into the basement (minimal). I’ve seen no leaks in the sewage pipes to septic tank. I cleaned/spray minimal mold off the basement walls, ran fans to dry the cinderblock up, even ran a charcoal exhaust filter. But it still stinks. Gassy like and putrified like. After all this work to remodel the kitchen (which I love) I feel like I can’t stand the smell. House is 30 years old, I have under foundation drains into a sump pump that works fine and have a dehumidifer running in the basement, filter cleaned.
Thanks for your forthcoming advice.
It does sound like sewer gas. I battled for a long time with sewer gases/smells from bad seams on my ejector pump in the basement under my kitchen.
When you say you had to change the outflow under the sink, what exactly do you mean? And the smell is coming from your 1/2 basement. Is that under the kitchen?
It’s quite possible that when they redid the drain from the kitchen that they cracked one of the pipes which would allow sewer gases to escape. These cracks can be nearly impossible to see when they’re on parts of the pipes hidden from view. I had an old cast-iron main drain line that cracked and stunk up my house for a couple years! We searched and searched and I finally found it after sticking a camera up and taking pictures where I couldn’t inspect.
The key is to follow your nose and isolate where the smell is coming from. You won’t necessarily be able to find the exact location as the smell can move around based on air currents and other conditions. But you should be able to narrow it down to a small-ish area, maybe 10×10′. Then a very careful check of any drain pipes in that vicinity. Use your eyes as well as hands – the fingers running down hidden pipe surfaces can be extremely sensitive for finding cracks.
Hope you can narrow it down. Definitely check all drain pipes, they’re your most likely culprits.
https://polldaddy.com/js/rating/rating.jsHey Ted,
Currently I am redoing my back addition. I have added a multi position air handler in the attic above living space, and have cathedral ceilings. The duct work is also in ceiling. I read your article about insulation between the rafters of the ceiling. Currently there are no vents on the soffits.
1.do I need to add vents?
2.is it a must to use foam board to cover insulation? Whomever built this addition made that almost impossible. Any help would be greatly appreciated. Thx, Jp
https://polldaddy.com/js/rating/rating.jsHello Ted I just read a article of the different colors of fiberglass and what it means when it is black. Well we live in military base housing and for yrs I have said we have mold. Well we move in two days and when our movers left we noticed black mold in the laundry room! Inside our hvac system the installation is black and I called yrs ago worrying bc I’d never seen black installation. They said it was normal.
Mold in the laundry room usually means that the dryer isn’t venting out properly. If all that humid air isn’t going outside, it will build up in the laundry and lead to mold growth. This can be caused by clogged or damaged ducts from the dryer.
Black insulation in ducts is quite common. Large amounts of air flow through the ducts and any dust that isn’t filtered out gets caught in the duct walls.
https://polldaddy.com/js/rating/rating.jsTed — I have not read but about 20 of your posts and have not specifically found the exact answer I was looking for, but I am darn sure you are the right person to ask. I’m in northern Kentucky and my property was on a steep grade. I had an 18 x 52 pole building build and my floor is 2×8 connected up on 6×6 drove treated beams. I was able to get a good deal on 3 inch (recovered product) polystyrene foam and installed it between the joists. I will get under the floor and fill any cracks with expanding foam stuff (what a mess). What I do not know is if 1) I need to make that critter proof and how best to do that, and 2) do I need to install some other form of vapor barrier. The construction guy said, ‘a vapor barrier that goes on the ground;’ however, I’m unsure about that. Do I need to put OSB or some hardboard on the bottom of the joists? If you are up for consulting work, I’d love to be able to pay you for some advice. I’m building this place myself, so I’m trying to do as much work myself as I can and yet I don’t want to make terrible errors. Thanks so much. Dan
Hi Daniel, I thought I’d replied to your question but can’t locate the answer. So here goes!
1) Critter protection – polystyrene is very soft and everything can chew through that. Protecting it could be challenging though. If you put wood under it, that will be exposed to ground moisture and would likely rot out. You could put sheet metal under the joists, which would also act as an absolute vapor barrier (besides the seams).
If you did you poly, I’d attache it directly to the joists. Poly on the ground would stop much of the moisture from coming up, but then humid air that got into the gap between the ground and the joists would still have the ability to cause problems. Plus, any water from rain that got under there would just sit on the poly, evaporate and rise up into your home.
Another option is to use foil-faced poly-iso board foam attached to the bottom of the joists. It wouldn’t have to be thick, 1/2″ would do. It would add a little insulation and protect the joists from moisture, as well as sealing out moisture very well, especially if you tape the seams with foil tape. It wouldn’t be as durable as hard metal, but could be much less expensive, easier to install, and provide a bit of a barrier from critters (though still they could chew through if determined.)
Ted– You are helping my wife and I move forward with confidence. Your teaching is so very appreciated. Dan and Sue
Ted,
I don’t know if you have any knowledge in this field, but based on the nature of your site and questions you have answered for me before, you may! I’m heavily redoing my house, interior and exterior. Upon doing so, I’m really tightening it up: rim joist insulation, spray foam, air sealing attic, foam board on basement walls, new windows properly flashed & sealed, etc. It will be extremely tighter than when built in the early 70’s. Anyway, in my basement I currently have a furnace, gas water heater, and gas dryer. I have a vent on the exterior that brings make up air into the cold air return of the furnace, but I do not have any vents for combustion air. This wasn’t a big deal when the house was leaky, but since I’m tightening it up I’m concerned with combustion air, back drafting, carbon monoxide, negative pressure, etc. So I’m looking for confirmation that I do probably need combustion air, and I have read about needing two vents, one high (within 12″ of ceiling) and low (within 12″ of floor), but I don’t know if this still applies. Also, I don’t know of what proximity these vents need to be to the appliances. Obviously my furnace and water heater are near each other, but not the dryer. Should I run separate vents near each?
As always, much thanks in advance!
Andy
That’s a great question. In fact, energy auditor and contractors in my region a required to measure zones of the house for depressurization under a variety of conditions to ensure you don’t get backdrafting or starve these combustion devices of needed air.
Given what you’re doing, it would be useful to get a “combustion zone analysis” to ensure things continue to run safely and efficiently.
There are also some clever way of bringing in combustion air without essentially leaving the window open and negating all that air sealing 🙂
BTW, dryers have very large air requirements, both for combustion and exhaust of humid air. It’s a good idea to bring in an ample fresh air supply for it.
Good to know! Maybe I will drop a combustion air vent right next to the dryer. That could actually make things easier on me.
Thanks again!
https://polldaddy.com/js/rating/rating.jsIn a December 7, 2016, answer on the Ultimate Attic Insulation post, you discuss Roxul with air space behind and faced Polyiso under the Roxul for attic roof insulation. You mentioned you were going to attack this in a full article shortly. Have you posted this article? Could you provide a link? Regards
https://polldaddy.com/js/rating/rating.jsHi, I enjoy reading your articles. We live in a 1968 house in Calgary. We intend to remove the vinyl sidings and sheathing/plywood to remove the existing cellulose insulation, hire a company to do spray foam insulation and put the sheathing /plywood and vinyl siding back on. Is this the right thing to do? My concern is that it would affect the structure of the house when we remove the sheathing/plywood. Another option we have is to remove the vinyl sidings, install rigid foam insulation, and then put the vinyl sidings back on. We are not sure if this is a good idea to leave the old insulation material in place and because we heard rigid board could cause condensation problems. Thanks in advance for your help.
Thank you. I hope you read at bedtime so the articles can help you sleep 🙂
You have a good point about structural considerations since the sheathing does provide rigidity to the walls, though I couldn’t comment authoritatively since I’m not a structural engineer. To be safe, you may wish to consult one.
That said, you could do the job piecemeal, removing some sheathing, spray foaming, replace sheathing and moving to the next bays. Logistics could make this impractical, but it is one option.
If you use high density spray foam, that has been shown to substantially impressive wall strength since it glues together the structure.
On your last point, the construction with foam outside is feasible in some climates but I wouldn’t want to go that method in a cold one. As you mentioned, it could create a condensation risk. Foaming in the wall cabinets would be much safer.
https://polldaddy.com/js/rating/rating.jsHi Ted,
I have a persistent smell in my basement which is worse since having new vinyl siding installed on the house.
– The main floor of the house is 50% vapor barrier and pink insulation, and 50% original 100 year old hollow lath and plaster walls.
– The basement has no drywall or insulation currently
The contractor wrapped the house in 1″ white polystyrene sheets sealed with red tape.
Experiments :
– Part of the basement footing showed higher humidity – a sheet of vapor barrier between 2 studs and a humidity meter inside shows 70% humidity constantly.
– Another basement footing with normal humidity with the same test shows 66% humidity constantly.
– On the main floor a hole in the lath and plaster shows 62% humidity inside.
My suspicion is that this is a double vapor barrier problem, but I am getting conflicting advice from specialists and unsure how to proceed.
First question – what type of smell? Are you getting the musty smell, which almost always is indicative of moisture/mold? Or something else?
My first thought is that the house is tighter now, so there’s less airflow up through the house, which would flush out some of the odors that you’re now smelling. Especially since the smell appears in the basement. Moisture problems in the house main floors wouldn’t be liable to cause odors in the basement.
OTOH, I can imagine some unintended consequences of the insulation job. For example, if they added insulation to the walls that were previously open, that would impede airflow through those wall cavities. I’ve seen lots of plaster walls that are framed in such a way that the air flows from the basement all the way up to the attic. This would flush out moisture and odors from the basement. It also wastes a lot of energy, so people often want to insulate those wall cavities and end up with undesired effects.
From your description, the fiberglass in the walls was already there and the siding contractor just added insulation to the exterior walls, behind the vinyl siding? That would definitely make the walls much tighter, so if there was natural airflow through the wall cavities and out, that would be greatly diminished. In most cases, this is beneficial – tighter house, more energy efficient. But, like noted above, the undesired consequence is that the basement may be much less ventilated, leading to moisture buildup and odors.
The humidity levels your noting aren’t unusual for this type of year, depending on your local weather. Around here, in PA, we’ve had a fair amount of rain, so the ground is wet. That would migrate through the walls and into the cool basement, making the relative humidity high. Because of this, it’s necessary to dehumidify or water-proof the basement walls. The other thing to do is ensure that your gutters are draining properly so that you don’t get water dumped on the ground near the foundation of the house. The roof can gather thousands of gallons of water during a rainstorm. If that isn’t guided by downspouts away from the foundation, that water can saturate the dirt and cause big moisture problems inside the house.
Hi Ted,
Thank-you for responding to my question.
To me it smells like paint – the smell got worse after the siding, which I initially thought was due to the air-tightness. The pink insulation on the main floor was installed 6 years before the vinyl siding. The contractor installed new builders paper over the sheathing, followed by the 1″ polystyrene, followed by the vinyl siding. I brought him back but he said that the moisture in the footing is not caused by his work because it is all taped up properly and he followed the building codes.
From my point of view the new codes calling for exterior insulation don’t allow for any moisture leaks at all otherwise the moisture just stays in there indefinitely.
Previous mold inspections have not shown anything, I am waiting on results of an ERMI test to hopefully give some insight.
Well, I agree that I can’t see how the siding work would affect the foundation moisture, other than side-effects mentioned before. However, your contractor’s reasoning is completely wrong! I think he thinks that the only way moisture could build-up is if water got in through the siding/foam/house wrap.
I agree with your comment about the building code. They really don’t comprehend the true nature of moisture issues.
I’d suggest watching how the water drains next time you have a rain. Make sure the gutters are working and water isn’t pooling around the foundation.
You might also want to actively ventilate the basement (if you have basement windows) during spells when it’s nice and dry outside. Barring that, a good dehumidifier will help. But if there’s water around the outside, you’ll be waging a losing battle because humidity will keep coming through the walls.
You don’t have a high water table there, do you? That’s really hard to battle without seriously waterproofing the basement.
https://polldaddy.com/js/rating/rating.jsHi Ted –
Hoping to get some pearls of wisdom….
I need to address the siding of my house as the paint is failing and looks awful. I have vacillated between painting and vinyl siding a number of times. While cost is certainly a concern, I don’t want to go with the cheaper option (painting) if it means leaving the future owner of my home with issues.
I have a ~1930 bungalow that is built with modified balloon construction as the wall cavities do extend from the basement up through the first floor, but NOT into the attic. It has cedar clapboard siding with 87 layers of failing paint. Some years ago I demoed the exterior plaster/lathe walls in three rooms down to the open studs. I added faced fiberglass to the walls, replaced windows with new construction windows, replaced electrical, added foam blocking to each cavity at floor height (and foamed around each plate), and drywalled.
After I did all that, I then began learning about the possible moisture conundrum I might have setup for myself. So my question is, if I have in fact set my walls up for a moisture fail, how can I correct it? I had considered demoing all the cedar clapboard, adding a housewrap over the sheathing, and then vinyl siding – but would rather not as I’m looking to sell the house sooner than later. I was hoping to get away with painting where I would grind/sand down to bare wood, sand, prime, caulk, paint. Maybe more labor (me) but also far less money.
Thoughts?
Hi again… just saying hello in case you missed me… 🙂
ooops, sorry for the delay. Several similar q’s arrived around the same time and I thought I’d answered.
Given what you’ve done, I wouldn’t tighten up the walls too much on the outside, so as to allow moisture to easily escape. As long as the existing siding construction has worked well thus far and you haven’t had any moisture issues, I personally wouldn’t mess with it. The old saw – if it ain’t broke…applies here. Especially if you’re thinking about selling – you don’t want to risk doing anything that could bite you down the line.
http://i0.poll.fm/js/rating/rating.jstrying to find out hoe I post a Question to you on this site
just like you did. Post something like that and I’ll get a notification and can try to answer your question.