Spray Foam in Attic

[double bogey]

The blower door and house tightness test will be a requirement in the not to distant future for new construction, or existing modifications, like system replacement. In some states they are required now. We seem to lag behind in the building technology departments. Its like "aint nobody going to tell me what I have to do"

Its not like we don't know it needs to be done, we don't seem to be told we have to do it. As a lifelong multigeneration Texan, I think its a Texas thing.

[Banded Drake Calls]

If it's open cell foam how can it be air tight?

Doesnt matter open cell or closed cell, each foam is sprayed to the required thickness that it is deemed to be an air barrier. Open cell has micro air pockets inside of it that make it expand more and create a lesser R value. In closed cell the "air bubbles" if you will, inside the foam are much much tighter together creating a much more rigid foam which creates the vapor barrier, but must be sprayed at a minimum of 1 to 1.5 inches thick.

"Air tight" is a term that has been picked up in the spray foam world and is misleading, or should I say people take it literally. It doesnt mean no air can pass through the foam at all. You will still get air passage through open cell foam, but it's very minute, which is what a blower door test will show in any house that is complete spray foam vs a home that is not.

The key is that the foam has to be a certain thickness. Thick of it as swiss cheese. If you stacked layers and layers of it staggering the holes, eventually you make it very difficult for anything to pass through it. Same way with open cell but on a microscopic level. At thicknesses of 3 to 5 inches it makes it very difficult for air to be able to pass through it, but not 100% impossible. It's just really "tight"

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[Jaker]

If you have entergy as a service provider they will come spray foam in your attic for free, my brother had it done two years ago not sure how much it saved him monthly though.

[GA Bowhunter]

The blower door and house tightness test will be a requirement in the not to distant future for new construction, or existing modifications, like system replacement. In some states they are required now.

We have had it here in GA for 6 years or so.

The insulation guy does it for $250 per house. He says he has never failed a house he insulated yet.

Waste of money. More leftist red tape and bureaucracy. They whine about "affordable housing" and then do everything the can to make housing more expensive.

Houses are so tight now that a fire won't burn in the fireplace without a fresh air intake. Sometimes you have to crack a window open to get them to draft.

[crash8005]

I will be following this thread. I'm building right now (early stages, foundation work). Have friends that have built using foam and they love it. My builder isn't too keen on it. I only want the roof deck done. Fear of roof failure and mold scare the hell out of me. I'm insulating 2900 sq ft.

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[elliscountyhog]

I will be following this thread. I'm building right now (early stages, foundation work). Have friends that have built using foam and they love it. My builder isn't too keen on it. I only want the roof deck done. Fear of roof failure and mold scare the hell out of me. I'm insulating 2900 sq ft.

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Go with the variable speed units. Make sure your hvac guy has a proper load calculation done.

Here is the 3 biggest things when foaming a house and HVAC
1. FRESH AIR.... You have to have a mixture with outside fresh air and conditioned air in the home. There is several options to do this. The best is a E.R.V. system which can be tied into your bathroom exhaust and outside air. Great set up.
2. 90% or better GAS Furnace. If you have a gas system then the normal 80% open flame furnaces are not good for your attic. Basically the flames are like having a small camp fire in your attic and if the combustion has no way to escape then your attic/home could become a serious issue with carbon monoxide. Use a 90% closed flame furnace.
3. MOLD! if the unit is not sized correctly then yes the biggest issue with foam houses we see is they are not sized correctly and mold becomes a problem. We will NOT install nothing less then a 2 stage system but highly recommend the complete variable speed units. The variable speed units allow the system to run at the best desired capacity to maintain not only temperature but the humidity in the home.

[bermise]

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Maybe they are supposed to do that, but most of the contractors that were involved in our build chose to cut corners whenever they could. My wife is a numbers hawk. She made the guy that sold us our trim and doors look like an idiot when she confronted him in front of our contractor about the sq ft'age of trim. We had hundreds of extra sf that he couldn't answer for, including allowances. Most home owners would never know about those little thing, but they add up. Seems like you need to know the job that you are hiring for, so you know if it was done properly.

Square footage of trim? I have to meet this guy

[SaintBlaise]

Typically negative pressure is caused by a supply duct leaking. Of course if it is leaking into the sealed envelope that most likely isnt the case. Other causes are, bath exhausts, and kitchen exhausts. Should be remedied by supplying some outside air through a whole house ventilator / heat xchgr. You set it up to bring in more than it exhausts to make up for the negative pressure.. If your house is super tight, you must have some form of outside air. There are blower tests that can be done to determine duct leakage, and house envelope leakage.

Most structures need to be slightly positive pressure. You will lose a little cool air out, but when you are negative pressure, air finds its way in, and it isn't filtered or conditioned. Lots of perpetually dusty houses have supply ducts leaking into the attic, making the interior negative. Air finds its way in, bringing the dirt with it, bypassing the filter.


And the post I quoted, shouldn't be that difficult bringing in some outside air. Some of the 100° air we have now will certainly take care of the oversized ac system. I jest, but hopefully your expert will help you out, and you will not have to spring for a new system. Good luck.

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Do you know the name of a whole house ventilator? We have an Aprilaire system on each AC unit in the attic. This brings in outside air to the unit for a time period you set on the dial. It can be set between 0 and 60. So, if you set it on 60 it never stops. Or, 5, then it runs 5 minutes per hour. Seems like it would work better if it would pull air when the unit was running. I don't think we have proper ventilation. thanks for your help

[ecallarman]

If you have entergy as a service provider they will come spray foam in your attic for free, my brother had it done two years ago not sure how much it saved him monthly though.

I just looked on their website and could not find any information that supports this statement. If they will pay for it, I would be keenly interested in finding out how I take advantage of this offering. Please send information.

[double bogey]

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Do you know the name of a whole house ventilator? We have an Aprilaire system on each AC unit in the attic. This brings in outside air to the unit for a time period you set on the dial. It can be set between 0 and 60. So, if you set it on 60 it never stops. Or, 5, then it runs 5 minutes per hour. Seems like it would work better if it would pull air when the unit was running. I don't think we have proper ventilation. thanks for your help

I don't have a product I could recommend. I would ask my contractor about interlocking it with my system. Aprilaire also makes a controller for their ventilators, and a temp control that controls both. Don't know which model you have, but here is the website.

https://www.aprilaire.com/whole-house-products/ventilation/model-8100

[timoub007]

Originally Posted by Jaker
If you have entergy as a service provider they will come spray foam in your attic for free, my brother had it done two years ago not sure how much it saved him monthly though.

Originally Posted by ecallarman
I just looked on their website and could not find any information that supports this statement. If they will pay for it, I would be keenly interested in finding out how I take advantage of this offering. Please send information.

I'm with ecallarman, please send this information along.

Tim

[Jaker]

I'm with ecallarman, please send this information along.

Tim

I found this just now

https://www.entergy-texas.com/your_home/save_money/ee/home-energy-efficient/

They have bandit signs up all around town (splendora) I can get the number tomorrow I’ve been meaning to get mine and my rental done.

[MarkV]

Go with the variable speed units. Make sure your hvac guy has a proper load calculation done.

Here is the 3 biggest things when foaming a house and HVAC
1. FRESH AIR.... You have to have a mixture with outside fresh air and conditioned air in the home. There is several options to do this. The best is a E.R.V. system which can be tied into your bathroom exhaust and outside air. Great set up.
2. 90% or better GAS Furnace. If you have a gas system then the normal 80% open flame furnaces are not good for your attic. Basically the flames are like having a small camp fire in your attic and if the combustion has no way to escape then your attic/home could become a serious issue with carbon monoxide. Use a 90% closed flame furnace.
3. MOLD! if the unit is not sized correctly then yes the biggest issue with foam houses we see is they are not sized correctly and mold becomes a problem. We will NOT install nothing less then a 2 stage system but highly recommend the complete variable speed units. The variable speed units allow the system to run at the best desired capacity to maintain not only temperature but the humidity in the home.

What about a heat pump furnace instead of gas?

Just asking because that's we have on our newly completed house. 2x6 walls all spray foamed. Variable speed system and it draws fresh air in from the outside and thermostat has humidity control on it too.

[double bogey]

If the heat pump is sized correctly you will be fine. ECH is talking about combustion air. The 90+% furnaces pull their combustion air from outside, therefore not affecting the attic. Did the have any air feeding the attic, usually you need some conditioned air to eliminate moisture problems.

The other good thing about the attic being inside the envelope, is that the duct and equipment are not exposed to the higher heat of an open attic. You lose and gain lots of heat through the duct and equipment.