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Ted's Energy Tips 
Hi Ted. I have a small roof repair business. You helped with a leak issue a client of mine had which was warm moisture from their hood range of their stove meeting the cold path within the cathedral ceiling area which was leading to condensation leaks. I opened the roof, spray foamed the hood range pipe exhaust and covered everything back up. No issues since then. Hopefully that remains that way! Thanks for your side on that.
I recently did some work for another customer that has been having damp drywall on the wall above her fireplace. She doesn’t use the fire place. The chimney was redone by a company a couple of years ago along with the top. They didn’t do a very good job as they smeared the mortar flat where it meets the bricks instead of grooving it out as should be done with proper tuck-pointing. However I don’t see any gaps, Im just wondering if this could be a cause for moisture. Also at the top they didn’t do a proper overhanging cap but simply mounded moral over like a hill. Again, no gaps or cracks (at this point). There are 3 flues, ones filled with concrete, 1 with a top hat and 1 where the hot water tank exits. I checked the attic, no condensation issues in there or around the chimney area. The flashing and caulking is tight and the shingle step flashing is done right and the shingles are in good condition. Anything that I might be missing? I sprayed the whole chimney in a type of waterproofer for masonry but the moisture has still reappeared inside the house. Short of giving her, her money back or installing an entire proper chimney cap the only other thought I have is to get a wider top hat for the one open flue where water may be finding its way through somehow.
Any input would be appreciated, Thanks Ted. Jake
Hi Jake,
Glad you were able to help them out. Hope it continues to work out.
Chimneys can be a real pain. We have a similar issue with ours after a mason didn’t do flashing correctly under a fake stone facade was installed.
One thing to keep in mind is that concrete and bricks are actually fairly moisture permeable and even without cracks, water can work its way through and get behind the flashing. So the best thing I’ve found is to do your best to minimize water sitting on the top, which can stand there, soak down and drip behind the facade (bricks, stucco, etc.) and sneak into the house behind the flashing if there’s any gaps.
I did something similar to you and used a lot of waterproofing rubberized coating on the top of the chimney. Even though it’s got a large cap, any blowing rain can sit on the horizontal surface under that.
One question is when is the wetting occurring? Is it definitely after heavy rainfalls? That would greatly increase the confidence that it’s a flashing/drainage issue with the chimney.
If she’s willing, a good way of troubleshooting is to cover the top with a tarp (after fire season, of course, and ensuring you’re not covering a boiler/furnace flue!) Cover maybe the top foot of the chimney so there’s no chance of water getting in from the top. Then you can simulate a heavy downpour using a hose to soak the chimney. You might have to use quite a lot of water to really simulate a hard soaking rainfall. If you don’t get any wetting inside, then you’ve determined pretty confidently that it’s getting in through the top.
The trick here is that you really don’t want so much water getting in behind the drywall that it soaks it, so you’re best off cutting back the strip of drywall that gets damp, which probably has to be replaced anyway since it’s been repeatedly getting wet. Then you can see when the water starts coming in, and how much. Even better, if you have a helper, they can spray the hose while you watch. Have them methodically spray one section, while you look. Then spray another section and so on, so you can see which part of the chimney is leaking.
If none of those leak, then try wetting the top carefully so you don’t pour a ton of water down the flue. Again, being methodical as possible so you can determine exactly what area is causing the leak.
An afternoon of detective work should point you in the direction of the trouble spot so you can then fix the right problem.
Do the recommendations make sense? Could the roof work make the problem worse? Any ideas would be appreciated. Also, where would you find a building science specialist. A home inspector with an engineering back ground said they would come out and access for a fee.
It’s tough to find people with this experience. What I usually do is search for independent companies specializing in energy audits. Then call and explain your situation and see what they suggest. A good person should be knowledgeable in moisture issues and understand the science and be willing to talk to you a bit. Then they should be willing to come out for an evaluation for a consulting fee which might be a few hundred dollars. If they know what they’re doing, they should be able to spend a few hours with you, take moisture measurements and suggest some potential courses of action.
Thank you for your assessment.
We have a vaulted ship-lap type ceiling in our great room(24 ft high). We are getting dripping from fixtures and between boards, and most recently from the main beam. A roofer wants to remove roof and put in proper vents and re-insulate, and HVAC said a mini-spit on the back side of the room that faces outside where there’s no ducts, will help. The dripping generally happens when its below 30 outside, but recently happened on a 60 degree early March day in coastal S. Jersey.
Before you do anything drastic, see if you can get access to the area around the fixtures where the dripping is occurring. If you can remove the trim piece (which should easily pull off), you may be able to see if the ship-lap boards are covering a sheet-rock ceiling or if it’s just boards nailed directly to rafters. If that’s the case, adding more ventilation and just reinstalling fiberglass insulation will cost a lot and may make the problem worse as the air flow will suck the warm humid air from the house up into the cavity which will then condense on the nearest cold surface then drip back down.
If you can’t tell by looking around the light fixture, carefully remove a couple of the ceiling boards so you can see what’s going on above it. This can be done with minimal damage, but the boards might have to be replaced.
As for solutions, if it’s just boards nailed to the rafters then you need to address the issue – moisture getting up into the cavity from inside the house. There are a couple of ways to do that.
Method 1 – most expensive. Rip the roof, spray foam insulation onto the back of the ship-lap boards. Replace any recessed light fixtures with flush mount LED lights. The foam should completely air-seal the cavities so no moisture can get in there.
Method 2 – easiest but still a fairly big project but should be much less expensive than method 1. Remove recessed lights and replace with a junction box so you can mount new flush-mount lights. Make sure the existing fixture housing is completely air sealed. It could be filled with spray foam or something. The housing will remain in the ceiling since you can’t remove most of them without tearing up your ceiling. Add a layer of drywall directly on to your existing ceiling. You could add a layer of 1/2 foil faced poly-iso board foam between the ship-lap ceiling and the new sheet rock. That will stop moisture from getting into the roof cavity. The main thing is that you need to seal any possible area that moisture could get from the inside of the house up into the cavity above the ceiling.
Note – if this has been going on for a long time, it’s likely that the area behind the ceiling has substantial mold growth and possibly the wood has rotted. If this is the case, you’ll have little options than ripping open the ceiling or roof and repairing all the damage. Big expensive job. Hopefully this hasn’t occurred.
Hi Ted.
I have a customer that was having ceiling leaks on a bungalow with a 3/12 pitched roof. It was once a standard attic but it was converted to a vaulted cathedral style ceiling. Since then the leaks started occurring. The soffits are vented and each cavity has baffles running the entire lengths from bottom to top, fibreglass insulation underneath them. He had standard ridge vent. I installed a ventilation maximum cathedral style ventilation system. Things were good over the winter but in recent rains he’s getting moisture occurring on the ceilings again. I read your section on moisture potentially getting through lights or other places, do you think this might be the case here or maybe something else. I’m thinking if that is the case the system I installed would deal with it. Any thoughts would be helpful. Thank you, regards, Jake.
https://ventilation-maximum.com/en/products/sloped-roof-ventilators/vmax-cathedral/
Interesting that they didn’t have issues during the winter, since that’s usually the hardest time to control condensation on a cathedral ceiling since the ceiling and roof cavity can get very cold. Is the water you’re seeing condensation beading up on the surface of the ceiling or are you getting dripping through openings, like recessed lights?
Is the ceiling sheet rock or some sort of T&G or lapped planks?
During the cold weather, the water vapor can freeze inside the cavity, leading to a buildup of ice. Then, when you get a warm spell, the ice can melt, dripping down however it can get out of there. That can cause pretty serious moisture “events” when the ice melts.
Depending on the ceiling material, it may be worth cutting out a small section so you can look in and inspect the insulation and cavity near the peak, in an area where you’re seeing the water issues.
Another possibility – on cold winter days, the absolute humidity of the air is often very low which tends to dry out the air inside the house as well. It can be dry enough that you don’t get any condensation. When you have a sudden warm spell, the air can contain a lot of moisture which can lead to condensation problems if the humidity inside the house suddenly rises. This often happens in homes with forced air heating and leaky return duct systems. When the HVAC with leaky returns runs, it sucks in all that outdoor moisture and dumps it into the house, leading to very high humidity and condensation issues. If that’s the problem, then they’ll need to fix the HVAC ductwork or the condensation problem will be nearly impossible to remedy. You might ask your customer if the air in the house gets really dry in the winter and changes quickly to be humid when it’s humid outdoors. That can be a hint of leaky ductwork.
Hope that helps. If you learn more about the situation, feel free to post more and bounce ideas off me.
Thanks Ted. I appreciate the reply.
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So the leak is primarily on the drywall seam about 4′ below their range hood (vaulted ceiling) that exhausts out through their attic space. I had him run his hood range and it exhausts just fine out the roof vent. The next step I’m going to undertake is opening up the roof and boards around where the range exhausts and check to ensure there are no exposed seams on the range hood connection itself. Im also thinking that the range hood piping that goes through the attic space would need to be adequately insulated as that is often warm air passing through it. It’s a vaulted ceiling so naturally there must be the standard roof insulation around it. I find it somewhat hard to believe it could condensate in such a short attic span but the results will be found out. Any thoughts as to insulating around a rangehood?
Oh, that is interesting. Since the range hoods are typically sheet metal. They conduct heat/ cold very effectively. So it is very possible that the coldness is conducting down down the sheet metal and any moisture in the air condenses on it. The best and probably most effective solution would be an application of spray foam on the metal ductwork exterior from the point it goes through the roof down to where it meets the living space ceiling. I can imagine access to this could be very difficult however.
We have a 2×12 rafter vaulted ceiling. We have the pockets completely sealed up (no ridge vent and no vented soffit). We filled each pocket with R38 batts. Then put on the tongue and groove. No vapor barrier whatsoever. We have the dripping problem and took everything down to dry it all out. We want to do 4” closed cell spray foam and then put our ship lap back up. Do we need to put up drywall before or plastic? We also have the low profile recessed lights. 8 total. Will doing the spray foam and then just go back with ship lap still do the same thing? There will be a about 7” gap between but it will be controlled space
If you use enough spray foam to get the r value up then the inner surface exposed should be warm like the inside of the house so the moisture problem shouldn’t occur. Just don’t make the mistake that some people do and think that adding some extra fiberglass insulation on the inside will help matters. In fact, adding a permeable insulation on the interior side causes the other insulation to get colder leading to the same problem. So just spray foam and you should be good to go. If you are in a extreme climate with very cold Winters, you may want more than the 4 in. But for most modest climates it shouldn’t be a problem.
hi ted
i live in climate zone 4a outside of NYC. i had my attic ceiling sprayed with open cell spray foam r44 and the brick attic walls (i believe r13).
we have higher humidity in the house. i did have high humidity before at times but we had air flow and properly sized ac to combat. now our ac is too large for the house and we had terrible damp and moisture issues this past spring and summer. i am nervous the attic has no air flow. the company sealed all soffits/gables. i have been advised to install and erv in the house and smaller ac unit..4 ton down to a 3 ton for a 2300 sf 2 floor slab. any other advice? should we add some vents to attic or does that defeat the purpose. the company that installed has no guidance. the reply is that we have done thousands of attics and your the first to mention to these issues.
It can be tricky when the dynamics of the home are changed. As you noted, adding vents to the attic, will defeat the purpose of the insulation. The spray foam has considerably tightened up your house, so as you said, there is less overall airflow, and so moisture and proper air conditioning becomes more of an issue. Older, leaky houses were much more forgiving in that sense.
The advice you were given sounds correct, you really need a smaller air conditioner that runs more in order to properly deal with the humidity. Alternatively, you could run a dehumidifier which would be a lot less expensive than installing a completely new air-conditioning unit.
The ERV will not necessarily help the problem. In fact, it might worsen the issue during the summer, because even the best ERV systems are going to increase the humidity of your house during the summer, and will decrease the humidity of the house during the winter. Since you mentioned air-conditioning, I am assuming the humidity issue is primarily during the summer.
If you are having winter humidity issues because of the tight house, you would want to check for interior, moisture sources, like house, plants, showers and cooking, which can add a lot of moisture to the air. Proper ventilation in those cases will help considerably.
So, to summarize, for summer, humidity issues I think a dehumidifier should be the first choice. If you have to replace the air-conditioning system regardless then definitely install a smaller unit will run for longer periods and more effectively dehumidify the air.
There is one more option that is in between these two. You could install a mini split heat pump (which does heating and cooling) in the largest room of the house, usually the living room. By using this for air-conditioning during the summer you will greatly reduce the humidity issues throughout the house. The main unit will only kick on as needed And so you get a double benefit of much higher efficiency of a smaller mini split heat pump, and much better dehumidification. The systems have gotten quite expensive, but should still be less expensive than replacing the main system.
Another possible option which is much less expensive is a standalone heat pump that has two small ducts that go out of a window. These are less than $1000 and just sit in the room and provide heating or air-conditioning. You want the type with two duct connections, rather than just the single one because they are much more efficient and work better. The downside is the unit sits in your living space so it can be noisy and not very aesthetically appealing. However it is a way to handle the problem without breaking the bank.
Ted,
Happy New Year! I hope you and your family are happy and well!
I’m going to be building a soffit/dropped ceiling area in one of my rooms over existing ceiling drywall. I would like to use some rigid foam insulation in the space, only like 1.5-2″, so a single layer. I’d prefer to use EPS as opposed to XPS, since it’s substantially cheaper, but the EPS now comes with a plastic/foil facing on it. I imagine this will affect it’s permeability. Does this make it better or worse than XPS and do you think it would cause any issues being up against a finished ceiling with faced insulation above (normal ceiling build up).
Thanks for the insite!
Thank you Andy, you too!
Good question. I think you’ll be fine since you’re working on the warm side and the ceiling is insulated above. In fact, I’ve considered doing something like this for my own ceiling. There’s a slight risk if the indoor humidity is high and it gets so cold that the existing ceiling (now on the cold side of the foam board) drops below the dew point temperature. I’d just be careful about taping seams to minimize air flow directly getting in there. I’d be tempted to use construction adhesive or caulk around the perimeter of each of the foam boards to both support them and further reduce the risk of air sneaking into the gap.
Hi Ted – I live in Connecticut and the exterior wall of my second story bathroom has R30 fiberglass backed insulation installed in the cavity. At least 20 years ago, part of this wall was extended inwards about 4 inches to make the tub look built-in, but this extension is not insulated and pipes run up this area. The faced insulation is behind the pipes but there is plenty of room for more insulation. We haven’t had an issue with the pipes freezing, but now that we’re doing a little plumbing work in the wall, the plumbers recommend I fill the extra 4 inches with more insulation. Is this necessary? If so, can I put new unfaced insulation (I have some of that thermafiber wool stuff) up against the faced insulation or do we have to rip out the facing? Your help is very much appreciated. Thank you! -Chris
If it already has R30, then you’re at the point of diminishing returns since R30 means it slows down energy loss to 1/30th, or about 3%, additional insulation will at best save you another percent or two. Plus, as you noted, with the facing, that’s reducing moisture movement to the cold outer surface of the wall, so I wouldn’t want to disturb it and adding more insulation would put the vapor retarder in the midst of the insulation which isn’t good.
Ted, I read several of your replies on the cathedral ceiling moisture issues and i am in the process of building my house and its a modern “shed roof ” design with all exposed rafters and beams. There will be tongue and groove 2×8 cypress boards ontop of the rafters. i have really been reading and watching Joe Lstiburek but he doesnt talk too much about tongue and groove. my intentions were to put two layers of 30# tar paper on top of the tongue and groove and then r30 batts on top of that. There will be 2″ nominal lads running on top of the 2×10’s that are being used for the insulation space to screw the metal roof to. What is your thoughts on this? i was thinking that since this was going to be a vented space i would not have an issue however after reading so many of your replies I am unsure at this point.
Definitely a case of “better safe than sorry.” The best solution would be to use a normal sheetrock ceiling and put the T&G on that as just an aesthetic inner surface. However that may seem excessive. Another good option would be a layer of 1/2″ polyiso board foam, with seams taped. The foam would stop moisture from moving through the T&G into the space above and provide the added benefit of a “thermal break” which greatly improves the effective insulation in the ceiling. The board foam would be lightweight and easy to install and should give you peace of mind that the T&G won’t cause moisture issues in the future. The tar paper should also work as it will greatly reduce moisture and air movement through the T&G, but personally, I’d use the board foam to get the added thermal break.
Hi Ted,
I live in Wisconsin and have an older house (1977). There’s a room above the unheated garage that gets very cold in the winter. I’m wondering if there’s anything I can put on the ceiling of the garage to help keep the bedroom above warmer in the winter. The bedroom getting too hot in the summer is not a concern, just too cold in the winter. I’m looking for something like rolled sheets or boards that I can put directly over the existing ceiling.
I’m also debating insulating the garage door and walls, because it gets a bit chilly in the entryway by the door to the garage. Again, I’m looking for something I can put directly over the drywall and garage door. I don’t want to rip anything out or drill holes and use spray fillers.
What materials can I use for the ceiling, walls, and garage door? Are there any materials that are white, so the garage doesn’t end up looking like a spaceship?
Thank you so much for your help!
Best,
Syl
That’s a common problem because many garages aren’t properly insulated when they’re below bedrooms.
The first thing I’ll mention is that anything you plan to do should be discussed with your local building code enforcement officer. Some insulation materials might be flammable, for example. If you have the misfortune of having a fire in the garage and it is found by the insurance inspector that you have used a non-compliant insulation, they might refuse you coverage. So rule #1 is always conform to local building codes.
The reason why most bedroom floors are cold above garages isn’t because there’s no insulation in the garage ceiling. It’s actually because the insulation is located at the wrong place. Insulation should be installed directly below the floor of the bedroom. In many cases, when they install insulation, either batts or blow-in, it is on the garage ceiling, leaving a big gap above the insulation and below your floor. Any cold air that gets into this cavity will cool off your bedroom floor. I mention this because the solution you’re asking about, adding insulation to the garage ceiling, is an example of this. It might work if the cavity above is well sealed but it probably won’t work very well.
I have a very similar insulation issue with cold floors in my own home. Our living room overhangs the basement, so that about 6′ of the floor is exposed below to the outside cold air. When we did renovations, I had exterior insulation applied below the overhang and loose fill blown into the cavity. They were supposed to fill the cavity full of blown in insulation but it just sits on the low side, leaving a gap above it (right below my living room floor). When winter came, our floors were still freezing cold even though we should have had a good R-value under it. Very frustrating!
With those warnings, polyisocyanurate board foam is considered to have a better fire rating than other board foams. Here’s their industry organization website discussing fire rating: https://www.polyiso.org/page/FirePerformance
Dow makes a white Thermax polyiso board foam for exactly the reason you mention. It’s much nicer looking than the silver coated material. It might be hard to find but you could probably have your local building supply house order it for you. Here’s Dow’s website for the material: https://www.dupont.com/products/thermax-white-finish.html
Hi, I’m a renter of an apartment built in 2006. I have cigarette and weed smoke coming into my apartment from neighbors particularly in my primary bedroom and bath. I am a 48 year old who has never smoked and has high blood pressure. Are there any ways that I can create positive air pressure. Management does nothing and speaking to the neighbor did not help either. Everyone I’ve tried seeking help from can’t or or chooses not to do anything. I’ve tried 2 different types of air purifiers, leaving our bathroom fan on, but nothing I’ve tried prevents it from coming in. Am I simply SOL? I’ve literally spent more than $3,200 to move here from an apartment where all 3 neighbors around me smoked weed.
Sorry to hear about your troubles. The solution depends on how the smoke is getting into your unit. Is there any chance that the ductwork for the bath fan is connected together with theirs? If you’re smelling it in the bath then there may be an issue there. But if it is coming in the bath that way you could just leave the bath fan running for a day as a test to see if that improves the odor in there. Of course, that will create a negative pressure elsewhere, which could tend to suck in more fumes, but it is worth a try. It is also quite possible that there are gaps under the wall where smoke is coming in. Often sheetrock is left a little above the floor and then trim is installed just to hide the gap. But that still leaves a gap which would allow fumes to come in from. The key really is to figure out how the smoke is getting in so you can target your mitigation most effectively.
Creating a positive pressure in your unit is certainly possible but would require bringing in outside air. Typically this would be done through something like a heat recovery ventilator that is purposely set to create a positive pressure. However, for an apartment, this probably wouldn’t be practical.
Thanks so much for your response. Nothing is working. I’ve left the bathroom exhaust fan on for several days now and even with other fans running at full blast the smoke is in our primary bath practically 24/7. No smoke coming in anywhere else even when I also left the exhaust fan on in the other bathroom as well. Mgmt refuses to simply ask the smokers to smoke outside of the bldg. We’re on the 4th floor in an end unit so we have 1 neighbor sharing a common wall & 2 apts beneath on each floor to the ground level. I cannot smell the smoke coming out of any of the electrical outlets, light fixtures, exhaust fan (large 3″ x 7″ gap on one side) or plumbing connection areas going into the wall. I’m guessing it’s coming in through the floor or walls but am not sure.
Ugh. There must be gaps in the walls between the apartments. Honestly, that sounds like a potential fire hazard that a fire Marshal might want to get involved with. I’m not an expert in this but it sounds sketchy enough to get someone official involved.
Hi Ted,
I’m looking for some advice on an energy retrofit on a 1.5-story, wood-framed house in Vermont (a cold climate) built in the second half of the 19th century. My main question is about how to avoid condensation issues in the exterior walls. The house has some one-story additions built on dirt (no foundation, not ideal) over 100 years ago. The walls are old plaster and lath. The exterior was re-sided by the previous owner (a landlord using it as a rental property). Outside the studs there is ~1″ polyiso paneling with foil facing on both sides. There is fiber cement clapboard on top of that. There’s likely something else between studs and foil but I haven’t explored. I’m looking into adding dense-packed cellulose to the wall cavities. It would be blown-in by a pro from the interior. I’m beginning to worry about creating condensation problems on the interior of the foil-faced polyiso in winter and the walls not drying out enough seasonally. I don’t want to make a huge mistake, of course. The internet offers a mix of alarm and bombast on these sorts of questions.
Thanks for any guidance you can offer. If there’s an old post I should read, just point the way.
This is a really tricky one. I’ve seen similar construction around here in PA and am very hesitant to suggest retrofits. The walls have been working (other than being poorly insulated) for a century. They’re designed for ample airflow through the cavities which carries away the moisture. It’s so easy to create unintended consequences by adding insulation to the interior. The foil faced polyiso does act as a moisture impermeable barrier, so if moisture gets trapped in the wall it will almost certainly condense on the backside of the polyiso if you fill the cavities with something. The only viable solution that I see is high density spray foam (which also effectively blocks moisture). But doing that properly would require ripping off all the exterior coverings so that the back of the lath is visible and spraying foam to the back of it.
The only other method that I’d see as potentially viable is building inward from the existing plaster walls. Adding interior walls and adding a couple inches of inches of polyiso over the plaster. But this is a big hassle also because it requires extending all the door/window jambs and makes the rooms even smaller. So it’s more theoretically possible than practically so.
To summarize, I’d be afraid of doing anything more to the walls for fear of creating problems. Maybe adding wall hangings (tapestries?) to take some of the edge off in winter.
Sorry I can’t be more helpful.
Hi Ted I’ve been subscribed for years and enjoy reading your posts. I changed my email (due to spam), but I don’t see an “unsubscribe” option for that old email (I can subscribe with the new email). I’m still keeping the old email but not using it, in case some emails slip through. How do I unsubscribe that email? Thanks!
Thank you! I’m not sure but I will check the control panel and see if I can fix it up for you. Thanks again!
ok, I’ve removed your email but I just realized I might have deleted your new one! Is the Yahoo email address your old address ?
Hi Ted, was reading your article on cathedral ceilings and I’ve got a somewhat similar situation, with a pretty major twist, and I wanted to pass this by you to see what kind of professional I should contact to solve our current problem.
I’ve got a New Jersey home built in 1962, built in a California Ranch style, and most of the roof is standard joists, except for the living room’s cathedral ceiling.
In this portion of the house, the roof basically is the ceiling, as it’s 4” wide tongue and groove planks, 1.5” thick. Those are laid vertically from the outside eaves across the top of 3 oak beams that are each 16” tall by 5 7/8” thick, with the top beam being at the peak of the roof. Each of these beams run across the entire length of the room and are fully exposed inside the room. Thus, there are no joists and no cavity above the ceiling.
Originally, there was a cork like layer on top of these planks, about 2-3” thick, and shingles rested directly on the cork layer. There was also a tar paper layer – can’t remember if the tar paper was between the planks and the cork, or between the cork and the shingles.
Other than the roof being quite old and in need of replacing, this arrangement wasn’t that bad, other than having horrible insulation characteristics.
The problems began when we re-roofed the entire house, including this portion of the roof. We used a reputable local roofer that’s been around for over 30 years that happened to use GAF products. When the workers starting pulling the shingles off the cathedral ceiling’s roof, I was called up to see that the cork layer was disintegrating as the shingles were being removed, and debris was raining down into the living room. Naturally, you could see through the planks now in many places where the grooves had fallen apart over the years. You could see the sky from inside!
GAF didn’t really provide any guidance into what should be done at the time, and we couldn’t leave the roof open like that, so the roofer just used the layers they would have used on a normal joisted roof with a plywood deck.
Now we have moisture build up on the inside surface of the ceiling planks, which freezes in the winter months and, if conditions are just right, will melt as soon as the sun comes up, run down the planks to the first beam and “rain” off that beam in a line across the room. You can also see stains slowly creeping down the sheet rock from the bottom edge of each beam, although if I test them with a moisture meter, they always register as not being wet, both inside the sheet rock and on the surface.
So my questions are:
– Why didn’t this happen with the original arrangement? Was the moisture just going through the gaps between the planks and through the cork?
– What kind of professional should I consult with to get this rectified?
– Any ideas on what solutions would be possible for this sort of construction? In terms of both eliminating the moisture and increasing the insulation for the roof?
Curious as to your assessment.
Gordon M
Yikes Gordon, that sounds like a nightmare.
I’ve seen one other house in NJ with a roof/ceiling like that. That material would have provided a bit of R-value and would keep the roof pretty air tight and may have been water permeable enough to absorb and distribute the moisture harmlessly. It was probably just enough to keep the ceiling warm enough to hold off the condensation. With the new construction, you’ve probably got an effective R-1, maybe R-2 so the outside cold just sucks any heat out and the ceiling gets well below the condensation temperature.
I’m a bit surprised (but glad for you) that the moisture meter isn’t reading high levels of moisture. The air in your home must be dry enough to evaporate the moisture out of the materials. That’s fortunate. Otherwise, this could be a rotten, moldy mess.
There are two approaches – an easy one that will change the interior aesthetics, and a more difficult one that requires ripping off your new roof but leaves the interior unaffected.
Option 1 is to add the insulation directly to the current ceiling. You’d use a layer or two of 2″ XPS foam board (that’s the blue or pink foam board). That gives you ~R-5 per inch of thickness, so two layers gives a pretty decent R-20 for the ceiling/roof. You’d use ample amounts of construction adhesive around the perimeter to adhere it to the ceiling and reduce the possibility of interior moisture getting trapped between the insulation and the existing ceiling. With two layers, you stagger the layers so the seams don’t align, further providing resistance to moisture getting in there. The key thing is attention to detail in order to prevent moisture from getting up where it can contact any cold surface (i.e. your original ceiling above the insulation).
Then you can add an aesthetic inner layer. That could be wood for a nice looking wood ceiling or drywall. You could install nailer boards over the foam (i.e. facing the inside) with long screws going up to your existing wood ceiling, for mounting whatever interior you want.
The alternative is to keep the interior exactly as it is, remove the shingles and put the layers of foam above. This gets tricky because then you need to install plywood/roofing board above the insulation. With 4″ of foam, the shear forces can be substantial when snow is sitting on the roof. Imagine thousands of pounds of force trying to slide the plywood down. I’m personally not very comfortable with that solution though I have read of it being done. A better solution adds horizontal pieces bolted directly to the existing roof , then the insulation goes in between those. If you go this route, you’d definitely need a structural engineer to craft the details. Last thing you’d want is your entire roof to slide off during a snowstorm.
A variation on this idea is to use a SIP (structural insulated panel) roof. Those are designed for this application and come with ample insulation between layers of wood. Those get attached to the existing sturdy roof structure. I don’t have personal experience with doing a SIP retrofit, so you’d definitely need to contact a SIP contractor to see if it’s appropriate for your application (they’re quite specialized but Google showed a number in NJ).
As for contractors who do this type of thing, that’s more tricky. A normal contractor could do the job of insulating the interior and so forth. But while they might be able to do the mechanics of it, they might not understand the physics involved and accidentally create problems. Ideally, you’d want a contractor familiar with building science and “green building” or “sustainable building” techniques. Those should be well versed in the physics of moisture/condensation/insulation etc. One of the common certifications is from the BPI (building performance institute). I checked their website (https://locate.bpi.org/) and there appears to be a number around NJ. That would be a good starting point.
This should give you some options to pursue this further. Note that my suggestions are fairly general and the details for your specific situation will need to be developed by your contractor. They’ll also be able to advise you on the local codes etc.
Thank you so much for your insights and the good resources – I’ll pursue those.
I should also note that I accidentally cut out the progression from when the new roof was put on, which happens to mirror portions of what you noted in your first possible solution:
Once we realized what was happening on the surface of the planks after the re-roofing, we tried having a contractor add insulation to the underside of the planks by layering:
– InSoFast Flat Panel 2.5 RW Interior / Exterior (EXi) (R-10.5) interlocking panels with embedded studs, screwed and construction adhesived to the planks
– On top of that, 2″ XPS foam boards attached with screws into the studs of the InSoFast panels, and generous construction adhesive
– Finally, application of 4′ x 8′ lightweight panels with the appearance of planks for a finished look
A few oversights:
– We did NOT fill in cracks/gaps/holes with any kind of insulating foam, especially at the locations where the InSoFast panels touched the upper and lower beams – this gap approaches 1.5″ at the contact point between the panels and the beams simply due to the geometry. Since the InSoFast panels also have grooves in them on both sides (for potential wiring needs), this means that moist air can easily travel up the side of every beam and along the entire insulation panel thus having direct access to these grooves and the cold/hot planks they’re attached to. Bleh.
– The lightweight panels are no longer very lightweight – they seem to absorb water from the moist air like a sponge, and are beginning to sag – one has even fallen. It’s weight had at least doubled from when it had been applied.
What we’re going to pursue, now that I can look for the right kind of local professional that I can talk to about possible solutions:
– Rip off the lightweight panels to expose the insulation underneath
– Look for a contractor that can use a closed cell foam to seal every single nook, cranny and hole along the beams and seams in the insulation panels/sheets.
– Add an air intake for this room to the A/C, as the attic is adjacent to the highest point in the peak of the ceiling, so this could remove some/most of the moist air; at present, there is no air intake at all, so the air just sits in the peak forever
– Wait for a few freeze/thaw cycles in the winter to ensure that we don’t get any more “rain” in the room
Once we know we’re “good”, we’ll look for some kind of ceiling system with that has a plank look to it, to preserve the asthetics, but is some sort of moisture impervious/resistant material – got some research there.
Anyway, that’s the whole story as it stands today – as you say, it’s fairly rare, especially in the NorthEast – seems this style of roof would be more appropriate in a desert climate, but who knows?
ugh, the devil’s in the details, I’m afraid.
I just checked those InSoFast panels. Looks interesting and easy to work with. Sorry to hear about the issues you’re having with it.
What type of material are the “lightweight” panels that it absorbs water like that? Sounds really bad.
The general rule to minimize condensation in our climate is to seal everything inside as air-tight as possible to prevent indoor air (which contains a lot of moisture) from coming in contact with anything that might be cold. When possible, allow things to ventilate on the cold side with outside air so as to flush out any moisture that might get in with the cold, dry winter air.
One of the trickiest parts is that the water molecule is tiny, one of the smallest in nature. So airborne moisture travels through any crack as if it’s an open door. Once the airborne moisture comes in contact with a cold surface, it condenses to liquid water, which is much larger. Imagine it as clumps of water molecules bound together. That’s how materials like Tyvek work. They let water vapor travel through slowly, letting surfaces dry over time. And, they are impermeable to liquid water, so it protects from rain or other large quantities of water.
With a ceiling, when the water vapor get inside then condenses into liquid water, the water can then drip down and soak into other materials, which can hold them like sponges and not dry out. If this cycle happens every day-night, the material gets water logged.
If you seal things up the way you’re talking about, it sounds like you’ll be in good shape but, as you plan, it’s prudent to monitor it over time to ensure no new issues crop up.
Hello Ted, I was hoping that you might be willing to have a quick phone conversation regarding summertime water on the inside of a cathedral ceiling in upstate ny. I’m an architect working on a renovation so we’ve inherited this problem. If you can contact me via email we can outline your fee and I can send you photos and drawings. Thank you. John
Hey Ted: I was hoping to get your insight on a vexing moisture problem at my 1957 raised ranch. I had a contractor make a big mistake undermining the support for my house. I have spent the last year trying to put the house back together. The house did sink 1.5″ and we were able to raise the house but did not get all of the 1.5″ back. Anyway, during that process, I had to reattach all of the duct work and tape and seal with mastic. Also, all of the duct work in the garage was wrapped with insulation and the ceiling was insulated with R30 in the garage. In the conditioned space some of the duct work has R30 insulation and the laundry area is open to the conditioned space. I also had to install all new soffit and fascia to get more air in the attic and I had a company close the holes and re-insulate the attic to R40 – blown-in insulation. All of the holes on the sill plates in the basement have also been insulated. The basement does not have high humidity or moisture through the floor as I tested it to look for moisture to determine the new type of floor. Despite all of those changes, I still have a moisture problem in the first floor living area. It is not humidity as I have two de-humidifiers that are set to run and they don’t as the humidity ranges between 35-50 percent. My experience is cold air or warm air depending on the season in the duct work that is mixing with the heat or a/c air when it runs causing the air to be high moisture content and cold or warm air coming out of the vents. The only way my fabrics dry out is when the system is not running and windows are open with a breeze. I have tried the fan in the on position, circulate only and auto. Circulate provides the least amount of moisture but not great. This is a very high efficient furnace and A/C and only 9 years old. Do you think this is just the house itself and not a bug or could this be a problem with the furnace -I do get loud bang and clicking sound from the a/c unit both inside and outside before the heat comes on. HVAC people don’t understand the banging and clicking (showed them a video for proof) as it does not happen all of the time. I am at a lose to diagnose this issue. I covered the cold air vent in the basement to see if that air would cause my issue. My house feels like a cave – gets to temperature but does not feel warm, A/C ran for 5 hours (5 pm-10pm outside temp was in the 60’s) to move the thermostat from 78-77 degrees. Low humidity outside as well. Can you help with any ideas on the issue or is the function of the house and I need to introduce outside air into the house through two 6″ holes in the house to the funace? Any ideas or help would be appreciated. I had several people who specialize in air comfort and with this construction I fixed all of the issues they identified except for replacing my cook top. The moisture on the fabrics is throughout the house so not sure the cook top is the issue. When the A/C runs, the dehumidifiers come on which should not happen. I did see the basement dropped several degrees and the humidity jumped to 53 or so percent from 40-45 percent. Anyway, your help would be so appreciated with this vexing problem. Last example, the heat runs -ramps up and runs for about 15 minutes and then turns off – so for two minutes the air is cold, then warms, then furnace turns off and the air being circulated from the furnace turns cold again – reverse happens in the summer. To me that explains the moisture for the temperature change but not sure where the cold air is coming from – Furnace not running enough – bad thermostat – thermostat is high end and uses decimals for the temperature. Thermostat is in the hallway of the house. Thanks in advance for any help you can provide or any additional questions that come to your mind.
Ouch! Sorry to hear about the foundation issues. Yikes!
It sounds like you’ve been quite thorough in your troubleshooting and remediation, so your problem is indeed vexing.
One thing to consider – even though the relative humidity outside is “low” it is still possible for outside air to contribute to the problem when it’s warm out. For example, 80F air that is 50% humidity is close to 80% humidity when cooled to 70F. OTOH, if it’s cold out, bringing the cold air in will dry out the house. So if the problem was due to outside air infiltration, then you’d find everything to be dry in the winter and moist during the summer. That same effect could be what’s causing the humidity in your basement to jump to 53% from the forties when it gets cooler – same quantity of moisture equals higher relative humidity as the temperature decreases. So that sounds like a “red herring.”
The other issues you mention, like the air conditioner/furnace changing the temperature very slowly sounds like a real issue. The way I would test the system is to measure the temperature of the air going into the system and coming out of the system when it’s running. For best results, you’d do this by putting two remote read thermometer probes in – right on either side of the air handler/furnace/air conditioner. I do this on my systems and it’s been a lifesaver. Any time the system seems to be working improperly, I can look at those two temperatures and know immediately if the temperatures “look right.”
For example, the air conditioners should show about a 25F temperature difference between incoming air and cooled air coming out. Also, the air getting sucked in should be the same as the air temperature measured at the return register(s). If you see a big discrepancy between the temperature at the return register and the temperature right at the input side of the unit, you know it’s sucking air in from elsewhere.
For example, you could use something like this if you wanted something permanently installed in the airflow:
Or, for something simpler and temporary, you could use this, or something similar
That could just be “poked” into the ductwork right before and after the system.
That’s where I’d start. My guess, based on what you’ve noted, is that most of your problems are due to a combination of leaky return air system (i.e. system sucking air in from the outside) and an inadequately functioning air conditioner (leading to poor moisture removal).
Hey Ted: Thanks for your reply. I am not able to see your suggestions for devices so can you resend or send the name? Also, one HVAC guy measured the humidity to be 41%in the cold air return while the A/C was running and 55% coming from the supply side of the a/c (duct work outside of the furnace).
The gentlemen felt both those numbers were high for the a/c to be running. I don’t have the temperatures at that time. He was not familiar with my equipment so I have another company coming on Monday. In the past, the temperatures at the furnace – cold and supply were at the right temperatures as you indicated.
The problem is the unit either runs too long in the case of a/c or too short for heat and the air in the duct work gets cold and then spreads that cold air throughout the home. I believe that is what is causing the moisture, the mixture of the heat and cold coming from the duct work. Issue is I had the duct work all redone so there aren’t any areas of major leaks. The only other leak has to be coming either from the a/c lines coming into the home or through the fresh air intake into the furnace.
The duct work is now insulated so can’t get cold or warm that fast. The only other items could be the unit is also running the a/c in the winter and some heat in the summer. Would it be possible for the unit to be using the a/c or the furnace to maintain or satisfy the thermostat requirements? I did put the thermostat on heat only and the banging and clicking of the a/c lines and outside a/c unit occurred before the heat turned on to satisfy the thermostat. Thanks so much for your help as this vexing issue continues and needs to stop!
Humidity levels alone don’t tell me much. Since the air coming from the A/C is cooled, it can have a higher relative humidity at that temperature but much lower relative humidity when it’s at room temperature. Did your person check the condensate lines? They should be dripping water when the A/C is running. If there’s no condensate dripping, then the system isn’t doing its job dehumidifying your home when it runs.
Ideally, air conditioners should run long as that removes more moisture from the air. Long running should reduce humidity, not increase it. But, based on what you mentioned before, taking forever to cool things down, it seems like it’s not running at the proper capacity. Most A/C systems should have about a 25F temperature drop between incoming air and outgoing air and should be able to reduce the temperature in your home relatively quickly if it’s not super-hot out.
The banging definitely doesn’t sound right.
I forgot about the fresh air intake. Ideally, they should be drawing the air directly into the furnace, not through holes in the walls in the furnace room. Modern, high efficiency furnaces all do this. They are ducted, usually using a large PVC pipe, from the wall into the furnace. If you have any air leaks in the furnace/air handler that allows that outside air to get sucked in from the room, that is going to drastically reduce the efficiency of the system. This often occurs if the filter slot on the air handler/furnace/A/C unit isn’t sealed air-tight. Any small opening on the air handler/furnace is going to pull in a lot of outside air through those vents because the suction of the fan is strongest right there.
By the way, the probe thermometers I was referring to are these:
ThermoPro Wireless Meat Thermometer
Yes, it’s a meat thermometer! It just has a couple of probes which can be stuck into the air stream to make a measurement and the wireless capability is nice because you don’t have to actually be right next to the unit to see the temperature. Amazon has it for $40 which seems like a good deal.
Hey Ted: In my on-going attempt to determine what is causing the high moisture in my living space. As you know I had to remodel my entire basement area including re-attaching and using mastic on the entire HVAC duct work after a contractor damaged the support beams for my house. I did find an open in one of the cold air returns in the basement which is going to be fixed, on area in the garage is open to the insulation as I am waiting for a new electric panel. Several HVAC folks don’t believe these items would be contributing to the excess moisture. I believe the Furnace and/or the A/C evaporator is not working correctly or is just oversized. Therefore, I took your advice and purchased the meat thermometer to monitor the cold air return and the supply side temperatures. I did also purchase a device that measures temp and humidity and dew point. I have monitored over the last month with the device in different parts of my home. In general I have noticed that when the A/C runs the temp in the basement drops to 68 degrees while the house is set at 76 degrees upstairs and causes humidity downstairs to rise. Last Thursday with outside temp being 81 degrees and Humidity (69%) and DP 71%, here are the overall results: measured in living space A/C ran for 7 minutes on with 6 minutes of that time with humidity coming from supply being between 80-90%(low) DP(52-58 degrees); temp at 55-58 degrees; (cold air return temp at furnace was 70-71 degrees). Then 11 minutes off-with 10 minutes of humidity at 100% at 60-61degrees. My two dehumidifiers in the home come on right before the a/c turns off (set to run at 50% humidity. Moving device to measure cold air return in living space: temp ranged between 73-75 with Humidity ranging 56-61% DP 57-59%. Moved devices to the furnace and the results are: Supply :results the same as upstairs temp was 55 degrees at highest of 94% when on and when off temp at 64 degrees and 94% humidity DP:53 to 61% -cold air return stays at 71 degrees 62-71% humidity. I am using two different devices to measure the temp (I did not buy two of the humidity measuring device) but I think the numbers are close enough to come to some conclusions. My suspension is the evaporator is not getting that 20 degree difference so not getting cold enough. Also the humidity should do down not up when a/c is off. Could this mean the unit is oversized or do you believe these numbers are typical for any unit? Lastly, could the high humidity coming from the unit clashing with the temp in the basement which is a below ground basement? Temp in the basement gets to 66 degrees at 60-61 humidity. Before summer I checked the basement floor for humidity issues from the concrete and did find any issues. I am hoping you can help as the HVAC people tell me they are not sure what the numbers should be to be working properly -only know about the temp difference between supply and return and not about the humidity levels. Any help would be greatly appreciated. Right now the only fix I have is to install a whole house dehumidifier at 130 pints per day at a large expense. I am OK with spending if it will fix the problem but I have an issue installing such a unit when I have an 18 SEER A/C unit. I can’t cool the house past 75 degree on thermostat as is gets extremely cold and wet in the house. Thanks so much. Please let me know if I need to gather any other type of data cause I have lots of data.
Good job! Some real data to work with 🙂
Your last point first, if you’re house isn’t super leaky, there really shouldn’t be a need for a big dehumidifier. As you noted, that’s a band-aid to deal with a problem that is elsewhere.
The humidity at the air output from the system is going to be high because the air is cooler. However, the A/C should be freezing a lot of the humidity out of the air. *** check to see how much moisture is being removed – if the condensate line from the A/C is accessible and you can put a bucket under it, see how much water is coming out. With the humidity levels you have, it should be considerable.
If the system is only running for 7 minutes, then it’s able to regulate the house’s temperature in spite of the smallish temperature differential between air in and out. It is interesting that the differential is low and it’s still acting as though it’s oversized with that short run-time. However, if you can’t cool below 75 since it makes the house uncomfortable humid, that would definitely cause short run times, minimizing dehumidification capacity.
*** Here’s another test that will be telling, I should have mentioned this before. Measure the air temperature and humidity at the input and output of the system with ONLY the fan of the A/C running. You should be able to set this up at the thermostat. Turn the temperature up so the A/C doesn’t turn on and set the fan to the “ON” setting. In a perfect system, the input and output air should be the same temperature and humidity. In a real-life system, it’s likely that the output air will be higher temperature since the ductwork often runs through unconditioned space. However, the humidity of the output air should ALWAYS be equal or lower than the input air. This is because the relative humidity of the warmer output air is, by definition, lower than the input air. If the humidity of the output air is higher, then the system is definitely sucking in outside air, along with all the outside moisture. The only case when this isn’t true is if you have a whole house humidifier built into the system that has accidentally been left on during the cooling season. I’ve seen this before.
The fan-only test will be very telling.
Ted, I will be insulating attic from scratch, hip roof, minimal intake and one 12″ opening in roof for roof vents . Small home 980sq ft. Will spraying cellulose after installing baffles and some air sealing create conditions that encourage mold growth ? I guess my concern is it cuts off the minimal ventilation. Home faces west and gets HOT in summer. If blown in cellulose is not ideal, do you have suggestion? I would like to get this done in April.
Thanks.
Laura, there are two critical things to reduce the risk of moisture issues. First, prevent moisture from getting in the attic from inside the house during the winter. This means sealing up any holes in the attic floor – attic hatch and recessed lights are particularly important.
Second, assume that moisture will get in there and give it a chance to escape. Whatever ventilation you can provide for the roof is good. If you use a power vent, make sure you provide places for the outside air to enter because those power vents will pull moisture from inside the house if you don’t provide adequate air intakes.
Cellulose is good. I use it in my own home. Just do your best with the baffles to allow unimpeded air flow.
Insulation question. Renovating a bathroom. I have a north wall in our bathroom that will be one side of a shower. The outside of this north wall is partially exterior and partially interior due to how the roof slopes along this wall. So the bottom portion of the stud bays are warm and the top portions will be exposed to outside temps. I live in Michigan so we do get seasonal cold and heat.
How would you insulate the stud bays which will be completely covered with backer board and tile?
Thank you
The good thing is that that wall should be highly waterproofed. You absolutely don’t want any of that moisture to get into that wall or it will certainly condense and cause issues. I personally would want to spray foam from the exterior into the cavity (the surface right behind the shower) to ensure that none of the moisture gets in. Unfortunately, that often isn’t feasible. If you’re going to tear out the wall from the inside and insulate from there, you probably want a moisture tolerant insulation like rock wool snug against the inner wall. Another option, in addition to this would be to use a layer of foil faced polyiso board foam after the cavity insulation (just behind the wall, across the studs). Then add your inner wall.
You don’t want to do anything that will trap the moisture in the cavity. For example, you wouldn’t want to put faced batts in the wall with the facing towards the exterior wall! Any facing would have to face the inner wall.
Regarding the article below and the low profile recessed lights. How did you run and position electric before insulating with spray foam? Or did you run electric after and cut slots in the foam to run electric?
Did you then cut out the foam for the junction boxes and lights? Then hang ceiling?
https://tedsenergytips.com/tag/recessed-lights/
Thank you!
Hi Ted, I’ve enjoyed perusing your site and learning from you. I live in north Alabama, and bought a house earlier this year. The house has a room that was added on to the back of the house about 15 years ago. The room has many windows (which may not be sealed very well judging by ladybug intrusions we have observed). It also has a sloped tongue and groove ceiling, which slants downward as you move away from the original back of the house. We had a new roof put on in February, shortly after we bought the house, and in the process, the roofers removed the ridge vent that was previously there. Multiple roofers advised this, because the slope of the roof is pretty small, smaller than what ridge vents are designed for, so it was causing leaks during windy rainstorms, and also it wasn’t a true ridge since it adjoined a two story brick wall. We do still have soffit vents though, so there’s a way for air to get in the soffits, but no other path out.
One afternoon in June (when it was very hot and humid), I noticed that there were streaks of water dripping down from the highest point of the ceiling in this sunroom, along the wall that adjoins the original back of the house, and there were also streaks of condensation on the tongue and groove ceiling, again only near the highest point of the ceiling. There has continued to be a very slow dripping of moisture on this wall during the summer, although I never again have observed condensation on the tongue and groove ceiling. I did not observe any condensation on the windows.
My guess is that humid air from outside was getting into the soffits, traveling upwards and toward the original backside of the house, and then getting stuck there and condensing on the sheetrock wall below and on the tongue and groove. I’m not confident in that explanation though.
Our current plan of attack is to pull down the tongue and groove ceiling, remove the fiberglass insulation batts, assess the mold situation (we’ve removed a couple rows of tongue and groove near the high point of the ceiling and can see that there may be a mold issue), get new closed cell spray foam insulation applied to the underside of the roof decking (and sealing up the soffit vents in the process to create an unvented roof), and then install a new drywall ceiling.
Before we go down this expensive path, I was wondering if you could share your opinion about the source of the problem, and how to fix it? I appreciate any insight you can provide!