You guys have piqued my interest. But is it true that you cannot have a whole house fan like Dixie states? I do not know if it is worth it if I cannot use my WHF to lower my usage of the AC. (I prefer the breeze of the WHF to the AC any way.)
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Spray Foam attic insulation
- Thread starter tjboby
- Start date
JHV...it can be done, and it's pretty simply done.
I assume you open your windows while running the WHF. And I assume you have turn on a WHF without opening a window and seen how it shudders from the negative pressure, right? If you seal up the attic completely, you will the reverse of not opening a window - the pressure in the attic will start putting backpressure on the fan. It would sound roughly the same as not having the window opened, and it would greatly reduce the actual air movement as well.
The solution is very simple though. The best way would be to have some sort of attic ventilation like gravity vents (preferably NOT a ridge vent) with electrically-operated dampers that was wired into the circuit with your whole house fan. With a simple logic controller, when you turn the fan on the dampers would open automatically, and when you turn off the WHF, the dampers would close, maintaining your sealed attic.
A good HVAC guy could set that system up in no time flat...it's done all the time with typical commercial A/C systems. The parts shouldn't be ridiculously expensive either.
I work in architecture...and I approve this message.
Yes. The whole point of the insulation in the attic is to create a sealed up environment. If you want a WHF then you should build a vent for it. You don't want to pull hot air into the attic space. Think of it like a refrigerator where it is completely sealed.
If you are asking can you use the whole house fan if you seal the attic, I guess you could retain it, but it would certainly be counter productive and reduce the efficieny of the new insulation.
My experience with a whole house fan is there just aren't that enough cool nights/hot days to make it worthwhile.
My company has installed for the gov't primarily for about 7 years. there are three types of foam. closed cell, open cell and retro wall foam. open cell is water permeable and has an r value of 3.1 per inch. closed cell is not water permeable and makes a waterproof, bugproof, air proof seal with an r value of 6.5 per inch. retro foam is similar to closed cell but r value is 5.1 I am not doing much residential work, but i can give you a rough estimate on actual material costs.
closed cell $2,100 and covers 4,000 board feet a board foot is a square foot one inch thick
open cell $2,100 and covers 15,000 board feet
retro foam $555 and covers 4,000 board feet
remember, if you want to calculate actual material costs to multiply by depth material will be sprayed. hope that helped.
closed cell $2,100 and covers 4,000 board feet a board foot is a square foot one inch thick
open cell $2,100 and covers 15,000 board feet
retro foam $555 and covers 4,000 board feet
remember, if you want to calculate actual material costs to multiply by depth material will be sprayed. hope that helped.
Good to know the numbers. I specify the stuff all the time for certain applications, but I've never really seen the breakdown for just the material.
I'm about to install it and had three different contractors tell me three different things. One said use open cell in attic, the other said closed, third said just thermal wrap it...
Any recommendations Nelsonatlbuilders on which material? Any contractor recommendations too in Sandy Springs?
I'm about to install it and had three different contractors tell me three different things. One said use open cell in attic, the other said closed, third said just thermal wrap it...
Any recommendations Nelsonatlbuilders on which material? Any contractor recommendations too in Sandy Springs?
if you are confident that your attic will never leak, then open cell is ok. what i did to my house is this. I removed the blown in insulation. i vacuumed it out of an area the width of my house by 3-4 ceiling joists deep. so basically about 8' at a time. i piled the insulation up behind me and caulked any light fixtures or cracks that the foam may find its way into the living areas. i sprayed one inch on the attic floor. after i finished with all the sections i blew the insulation back over the spray foam. i added an r value of 6.5 or so and sealed any and all drafts that allowed attic heat to permeate the living space, and also trapped heat in during the winter. i plan on focusing on residential work next year and working locally instead of all over the country. there are ways an average homeowner with average income can greatly reduce utility bills. i foamed my house, tankless waterheater, reflective tint on windows and my energy bills are approximately 40% of what they used to be. my hvac unit is 2.5 ton unit. i have a 2500 s.f. house with no trees, so i get direct sun all day. before i sprayed i could not cool to less than 78 degrees, and the a/c ran 24/7, now it kicks on approximately 12-15 minutes per hour "i actually timed it" and can get my house in the 60's with that said, spray foam is pretty sensitive stuff, it has to be preheated, mixed properly at the appropriate pressures to work properly. having the right competent contractor is a must!!! its all fun and games until some dip**** gets the pressures wrong and ruins all your drywall. just another $.02
Any recommendations Nelsonatlbuilders on which material? Any contractor recommendations too in Sandy Springs?
if you are confident that your attic will never leak, then open cell is ok. what i did to my house is this. I removed the blown in insulation. i vacuumed it out of an area the width of my house by 3-4 ceiling joists deep. so basically about 8' at a time. i piled the insulation up behind me and caulked any light fixtures or cracks that the foam may find its way into the living areas. i sprayed one inch on the attic floor. after i finished with all the sections i blew the insulation back over the spray foam. i added an r value of 6.5 or so and sealed any and all drafts that allowed attic heat to permeate the living space, and also trapped heat in during the winter. i plan on focusing on residential work next year and working locally instead of all over the country. there are ways an average homeowner with average income can greatly reduce utility bills. i foamed my house, tankless waterheater, reflective tint on windows and my energy bills are approximately 40% of what they used to be. my hvac unit is 2.5 ton unit. i have a 2500 s.f. house with no trees, so i get direct sun all day. before i sprayed i could not cool to less than 78 degrees, and the a/c ran 24/7, now it kicks on approximately 12-15 minutes per hour "i actually timed it" and can get my house in the 60's with that said, spray foam is pretty sensitive stuff, it has to be preheated, mixed properly at the appropriate pressures to work properly. having the right competent contractor is a must!!! its all fun and games until some dip**** gets the pressures wrong and ruins all your drywall. just another $.02
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