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Message
Issues with new insulation
Posted on 8/18/24 at 9:52 pm
Posted on 8/18/24 at 9:52 pm
Hi all, first-time poster, long-time lurker. I’m hoping maybe there is an HVAC knowledgeable person to give some advice. Or maybe suggest a company that is great in the Houston area.
I recently bought a home and started renovating it. The house was a tad bit of a fixer-upper but otherwise in good shape. The house is 1988 two story brick with 2900 sq ft. The prior owner loved his AC and had two 3-ton Carrier Infinity Systems that are about 8 years old. He had also redone the ductwork and I think the insulation when he put in the new systems. The insulation was traditional carbon fiber on the floor of the attic and blow insulation on top. It looked pretty gross up there though when we went though it.
As part of our remodel, my general contractor said he has a guy who does spray foam. They removed all the insulation and spray foamed the attic lining with the roof. The attic looked great. They also replaced traditional canned lighting with LED wafer lights.
Now there are three problems in the attic and I’ve had multiple HVAC companies tell me different things.
1. The ducts now sweat, usually in the morning and it dries out by 12 pm or so. I think this is attributable to the new vent fan we put in (solar) running, as it stops running at night when the sweating starts to happen.
2. There is now humidity in the attic. It ranges from 61%-78% throughout the day. Again it tends to be higher in the morning right before the vent fan clicks on.
3. Air is seeping through the new wafer LES lights in the second floor (right below the attic). So you can smell the attic throughout the second floor (I think the air gets pulled through whenever the unit is running). Alternatively, I think humidity may be seeping up through the lights whenever the unit isn’t running.
I have two insulation companies coming on Tuesday to give me advice (I’ve had multiverse HVAC companies come out. Two suggested I need a 90% system). My general contractor had his AC guy come and install a fresh air intake but it didn’t work. He said they’ve spray foamed many similar attics like this without issue and without switching to 90% units.
I appreciate any advice y’all can give.
I recently bought a home and started renovating it. The house was a tad bit of a fixer-upper but otherwise in good shape. The house is 1988 two story brick with 2900 sq ft. The prior owner loved his AC and had two 3-ton Carrier Infinity Systems that are about 8 years old. He had also redone the ductwork and I think the insulation when he put in the new systems. The insulation was traditional carbon fiber on the floor of the attic and blow insulation on top. It looked pretty gross up there though when we went though it.
As part of our remodel, my general contractor said he has a guy who does spray foam. They removed all the insulation and spray foamed the attic lining with the roof. The attic looked great. They also replaced traditional canned lighting with LED wafer lights.
Now there are three problems in the attic and I’ve had multiple HVAC companies tell me different things.
1. The ducts now sweat, usually in the morning and it dries out by 12 pm or so. I think this is attributable to the new vent fan we put in (solar) running, as it stops running at night when the sweating starts to happen.
2. There is now humidity in the attic. It ranges from 61%-78% throughout the day. Again it tends to be higher in the morning right before the vent fan clicks on.
3. Air is seeping through the new wafer LES lights in the second floor (right below the attic). So you can smell the attic throughout the second floor (I think the air gets pulled through whenever the unit is running). Alternatively, I think humidity may be seeping up through the lights whenever the unit isn’t running.
I have two insulation companies coming on Tuesday to give me advice (I’ve had multiverse HVAC companies come out. Two suggested I need a 90% system). My general contractor had his AC guy come and install a fresh air intake but it didn’t work. He said they’ve spray foamed many similar attics like this without issue and without switching to 90% units.
I appreciate any advice y’all can give.
8
Posted on 8/18/24 at 10:33 pm to Yesterdaysnews
I have no spray foam experience but curious. Is there still air intake on soffit vents, or is the attic space all sealed up?
Also, you mentioned the old insulation looked gross. Was it experiencing moisture issues before the foam update?
Also, you mentioned the old insulation looked gross. Was it experiencing moisture issues before the foam update?
Posted on 8/18/24 at 11:10 pm to RaginCajunz
When they spray foamed they left the soffit vents open, although they were small and little air was getting in. Yesterday my GC came with his AC guy and opened the soffit vents a bit more and also installed an air intake directly into the AC units. However that didn’t seem to affect the situation (either positively or negatively).
There wasn’t moisture in the old insulation to my knowledge. But he had stored trash and other items up in the attic so when we moved in we wanted to clean it out because we had no idea what could have been living in it/potential growth had formed.
One solution I was going to pose to my GC (or insulation professionals when they come on Tuesday) is to spray foam around the new LED lights to seal them. That would prevent air seepage and potential reduce any humidity from rising into the attic, mitigating the issue a little bit. But I don’t know if there should be fire concerns with spray foaming around LED lights.
There wasn’t moisture in the old insulation to my knowledge. But he had stored trash and other items up in the attic so when we moved in we wanted to clean it out because we had no idea what could have been living in it/potential growth had formed.
One solution I was going to pose to my GC (or insulation professionals when they come on Tuesday) is to spray foam around the new LED lights to seal them. That would prevent air seepage and potential reduce any humidity from rising into the attic, mitigating the issue a little bit. But I don’t know if there should be fire concerns with spray foaming around LED lights.
Posted on 8/19/24 at 5:44 am to Yesterdaysnews
The trouble with foaming the LEDs is you will have to replace them at some point. Not sure if even IC ( insulation contact) rated fixtures mean spray foam. They should have a thin foam gasket that keeps them fairly tightly sealed
It sounds like an issue with airflow in the attic if the problem resolves when the solar vents kick on. I personally am a fan of attics that breathe well. Do those solar vents allow passive airflow when they’re not running?
Not sure what air intakes into the AC units means (again not an expert, just trying to logically help think through it) is it an extra air intake in the house with a filter? Trying to get more airflow through the AC itself?
It sounds like an issue with airflow in the attic if the problem resolves when the solar vents kick on. I personally am a fan of attics that breathe well. Do those solar vents allow passive airflow when they’re not running?
Not sure what air intakes into the AC units means (again not an expert, just trying to logically help think through it) is it an extra air intake in the house with a filter? Trying to get more airflow through the AC itself?
This post was edited on 8/19/24 at 8:11 am
Posted on 8/19/24 at 6:14 am to Yesterdaysnews
Did they spray the roof of the attic or the floor of the attic?
Posted on 8/19/24 at 9:01 am to RaginCajunz
The LEDs don’t have any thin foam gasket. I think my contractor went cheaper on the job with it so now I’m trying to find an affordable fix.
The solar vent doesn’t really allow much airflow when it’s off, but we also have two non-electrical vents that turn by wind power. They just don’t seem to do much.
My GC said the air intake into the AC units would bring more warm air into the unit. They think the condensation in the ducts is because our house is getting too cold and the AC unit is pulling in cold air/not getting enough pressure to push the air through hard enough. As a result there’s super cold air in the ducts. I think the ducts are sweating more from the humidity though rather than through sucking in cold air.
The solar vent doesn’t really allow much airflow when it’s off, but we also have two non-electrical vents that turn by wind power. They just don’t seem to do much.
My GC said the air intake into the AC units would bring more warm air into the unit. They think the condensation in the ducts is because our house is getting too cold and the AC unit is pulling in cold air/not getting enough pressure to push the air through hard enough. As a result there’s super cold air in the ducts. I think the ducts are sweating more from the humidity though rather than through sucking in cold air.
Posted on 8/19/24 at 9:02 am to Yesterdaysnews
This is the biggest drawback of the spray foam. I had my older house sprayed about 10 or so years ago now and dealt with similar issues. I've sense added a whole home dehumidifier for about $2k and it's paid for itself multiple times over in cost savings and comfort level in the home.
Posted on 8/19/24 at 9:03 am to diat150
They sprayed the roof of the attic. The floor of the attic doesn’t have any insulation, which is partly why there is air seeping in/out to the second floor. I have an insulation company coming tomorrow and I’m sure they’ll tell me to lay carbon fiber on the floor. I’d prefer to keep spray foam but don’t know if it’s common to spray foam the floor of the attic.
Posted on 8/19/24 at 9:05 am to Yesterdaysnews
Do you have a dehumidifier?
I am in the building industry, different discipline, but from what I can gather, dehumidifiers are pretty much standard with spray foam roofs now.
I am in the building industry, different discipline, but from what I can gather, dehumidifiers are pretty much standard with spray foam roofs now.
Posted on 8/19/24 at 9:28 am to Yesterdaysnews
quote:
They sprayed the roof of the attic. The floor of the attic doesn’t have any insulation, which is partly why there is air seeping in/out to the second floor. I have an insulation company coming tomorrow and I’m sure they’ll tell me to lay carbon fiber on the floor. I’d prefer to keep spray foam but don’t know if it’s common to spray foam the floor of the attic.
not sure if things have changed but my understanding was that your attic should be sealed off from the outside. you should not have any vents or soffits open to the outside air. the whole idea is that you make the attic sealed off like an ice chest. those leaks and also sometimes a vent is added that blows into the attic to keep it cool. I dont understand why you would put spray foam and have hot humid air flowing into the attic at all.
This post was edited on 8/19/24 at 9:32 am
Posted on 8/19/24 at 9:37 am to diat150
quote:
you should not have any vents or soffits open to the outside air.
This, when you foam an attic, your contractor should be fully encapsulating that space. You either need a multi stage AC system or a dehumidifier to account for this in homes that weren't originally designed for an encapsulated attic space.
This post was edited on 8/19/24 at 11:00 am
Posted on 8/19/24 at 10:47 am to Yesterdaysnews
Sounds like they foamed the roof sheathing but kept the attic vented? I think I've heard of people doing this but it seems silly. Why not go all the way and completely encapsulate the attic and condition it with the ac? They must've had some reason. Gas water heaters up there? And even if you foam the sheathing but continued to vent the attic through the soffit with exterior air, you still should have some sort of insulation on the ceilings.
But the reason the ducts are sweating is the attic is no longer hot enough to keep the outer foil of the duct insulation above dewpoint. Oddly enough, the solar heating of an attic is needed to "heat up" the foil to prevent the cold air inside the duct from dropping the outer foil temperature below the ambient dew point. In Houston this time of year the dew point is probably around 70. All that's needed for condensation is for the surface temp of the foil to drop below that temp. Not difficult when the air inside the ducts are around 40-50* All that separates those temp is an inch or 2 of fiberglass insulation around the duct.
I don't think the LED leaking air are a significant issue. Air coming from inside the home should be lowish humidity and usually those wafer lights hang tight to the ceiling anyway.
Not sure what adding the fresh-air vent or where they are getting the "fresh air". Maybe they are trying to get the temp on the supply side of the ac to a higher temp to try and keep the outer foil on the ducts from getting below dewpoint. Which is a legit partial solution but not sure the "fresh air" vent is a good way of going about it.
Honestly kinda sounds like shitshow. I would ask about fully encapsulating the attic.
The good thing is we're coming up on Fall and you should have until next Spring to consider your options.
fyi, "carbon fiber" insulation isn't a thing for an attic. you mean fiberglass fiber.
But the reason the ducts are sweating is the attic is no longer hot enough to keep the outer foil of the duct insulation above dewpoint. Oddly enough, the solar heating of an attic is needed to "heat up" the foil to prevent the cold air inside the duct from dropping the outer foil temperature below the ambient dew point. In Houston this time of year the dew point is probably around 70. All that's needed for condensation is for the surface temp of the foil to drop below that temp. Not difficult when the air inside the ducts are around 40-50* All that separates those temp is an inch or 2 of fiberglass insulation around the duct.
I don't think the LED leaking air are a significant issue. Air coming from inside the home should be lowish humidity and usually those wafer lights hang tight to the ceiling anyway.
Not sure what adding the fresh-air vent or where they are getting the "fresh air". Maybe they are trying to get the temp on the supply side of the ac to a higher temp to try and keep the outer foil on the ducts from getting below dewpoint. Which is a legit partial solution but not sure the "fresh air" vent is a good way of going about it.
Honestly kinda sounds like shitshow. I would ask about fully encapsulating the attic.
The good thing is we're coming up on Fall and you should have until next Spring to consider your options.
fyi, "carbon fiber" insulation isn't a thing for an attic. you mean fiberglass fiber.
Posted on 8/19/24 at 10:59 am to Turnblad85
usually the fresh air intake is usually to assist the inside with air exchange after sealing the building envelope. but its probably not needed on an older home where you only do the attic. I think its mostly for totally sealed off homes that arent leaky like what you would get on a new build with new high quality windows and doors, along with foam in the walls and a sealed attic.
Posted on 8/19/24 at 11:00 am to diat150
quote:
you should not have any vents or soffits open to the outside air.
I am no insulation/HVAC expert but this was my understanding. When you remove the insulation from the attic "floor" and spray foam the actual roof, you're essentially creating a conditioned space.
My father had done this to his house. They sealed off the vents and he has no issues with condensation in the attic.
Posted on 8/19/24 at 11:43 am to LNCHBOX
So would the simplest/cheapest solution be to fully seal-off the attic (including all soffits/other vents and the floor of the attic) and add a dehumidifier? One HVAC company quoted me for a whole home dehumidifier which ran about $5k. Its capacity is around 4,500 sq ft so it should be good for the whole house + the attic. I’ve also read online that I could potentially get by with a dehumidifier just for the attic space which would run around $600 (without installation) and it can be hooked up to a drain line so I wouldn’t have to go empty it out every couple of days.
I’m just trying to find a way to not have to redo all of the insulation (I’m fine with adding more) or upgrade the system to a 90%.
I’m just trying to find a way to not have to redo all of the insulation (I’m fine with adding more) or upgrade the system to a 90%.
Posted on 8/19/24 at 11:49 am to Yesterdaysnews
Completely seal attic from outside air and add a supply vent in the attic. If you can seal home from outside air well then a fresh air intake would also benefit you. You can also add a dehumidifier with fresh air intake on it. If you can’t seal the attic from outside air then it’s going to be tough to make it right.
Edit to add: cheapest way to get by immediately would be to seal all vents in attic to the outside and cut a small hole in the supply plenum. That should decrease humidity in the summer if you have a single stage because it’s running a lot in the summer. In the spring and fall when temps are better your AC might not run as much, thus allowing humidity to rise. That is where a dehumidifier comes into play, or a variable speed unit.
Edit to add: cheapest way to get by immediately would be to seal all vents in attic to the outside and cut a small hole in the supply plenum. That should decrease humidity in the summer if you have a single stage because it’s running a lot in the summer. In the spring and fall when temps are better your AC might not run as much, thus allowing humidity to rise. That is where a dehumidifier comes into play, or a variable speed unit.
This post was edited on 8/19/24 at 11:54 am
Posted on 8/19/24 at 11:54 am to Turnblad85
Regarding the sweating ductwork. If I fix the humidity issue (fully-deal off the attic and add a dehumidifier) wouldn’t the attic being better insulated make it permanently cooler which would cause the vents to sweat more often?
When fully sealing off the attic, does that include closing off any solar vents as well?
I apologize for all the questions. I’ve just been told different things from a couple different HVAC professionals.
When fully sealing off the attic, does that include closing off any solar vents as well?
I apologize for all the questions. I’ve just been told different things from a couple different HVAC professionals.
Posted on 8/19/24 at 1:49 pm to Yesterdaysnews
quote:
permanently cooler which would cause the vents to sweat more often?
Not really because you'll be "conditioning" the air with either the AC or dehumidifier...or both. This will drop the dewpoint down to around 50 degrees. But you are close to correct because sometimes when people do fully encapsulate their attic with foam they have some sweating until they add a dehumidifier to drop the dewpoint down those few more critical degrees. Sometimes the AC deals with the humidity and the dehumidifier isn't needed. Really depends on what you got going on in your home.
fyi the AC is just a dehumidifier that dumps its heat outside via the condenser aka outside unit.. A dehumidifier is both an inside unit and an outside unit all in one. IIRC when Willis Carrier was messing with air conditioning a hundred years ago his primary concern was removing the moisture from the air. This was because he a good understanding of psychometrics and knew that excess humidity was a primary reason for discomfort in the home.
quote:
When fully sealing off the attic, does that include closing off any solar vents as well?
absolutely . You're completely sealing off the humid hell of Houston the best you can. there is sort of an exception to this in that too tight of a home isn't healthy and you need fresh air from somewhere. Especially so if you have gas appliances. They may have taken care of this with the fresh-air vent. Solar vent is not something to accomplish this.
Hopefully you can find someone who has a background in building science whether in your AC guy or insulator or just finding an independent guy. Gleaning info from the internet can only get you so far. You might be interpreting the situation a bit off and then I might be misinterpreting the info you're giving. Doesn't sound like your builder has much background in it. Though if he's a decent person he'll stick around and try to learn from the issue he's help create and maybe get you right at his expense or a discount.
Posted on 8/19/24 at 1:59 pm to Turnblad85
If you still feel lost after you've spoken to people you might try an online consultation from Corbett Lunsford. I think he's at $200hr for you to explain what is going on and for him to give recs. Get all your ducks in a row and yall should be able to come up with a solution in the hour. He might also have people that work for him too not sure. From the small interactions I've had with him and everything I've heard, he's solid and knows his stuff. Only thing to be aware of is he might make a ton of suggestions that are not cheap. But he won't be profiting from any suggestion which is a piece of mind versus a contractor,
Posted on 8/19/24 at 2:11 pm to Turnblad85
Thanks all. I really appreciate the help. Hopefully one of the (now three) different insulation folks I have coming out tomorrow can provide some insight and competitive pricing. If anyone has good HVAC recommendations in the Houston area please let me know and I may reach out to them as well.
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