Spray foam insulation comparison

[Christianhuff]

3700 sq. Ft on a Co-op, 2 fridges, 2 washers, 2 dryers, keep it 69 in summer, no shade, and never had an electric bill over $250. Also have a 10 and 5 yr old, Spray foam is the stuff!

[RutnBuk]

IMO, waste of money. In most homes, heat gain from walls is a small percentage of the total.
But by foaming under the roof decking, you all but eliminate ceiling and duct heat gain. If I were to do one but not the other, it would definitely be the roof.

Makes perfect sense.

[double bogey]

Putting the attic inside the house envelope is different from what we have always done here. It is better, but the system design is different, a/c designer needs to be familiar.

[mattjproc]

Foam is good but it’s actually pretty poor for sound dampening. We decided to go bibs insulation because it has the same r value as foam with a lot better sound dampening qualities.

[Atfulldraw]

IMO, waste of money. In most homes, heat gain from walls is a small percentage of the total.
But by foaming under the roof decking, you all but eliminate ceiling and duct heat gain. If I were to do one but not the other, it would definitely be the roof.

This is the correct answer.

[Banded Drake Calls]

Anyone ever sprayfoamed the walls and just did blow in on top of the ceilings? I have a customer on a house I’m building that wants this. I’ve never had this requested and not sure about it.

Most of your energy loss is through the attic space, not the walls. In my opinion as a spray foam applicator it's a waste if you're not going to go all the way. Now on the reverse of that, we have done homes where we only did the attic space, doors and windows get sealed. It's not as effective as spraying the whole house, but you will make the building more efficient.

As far as health hazards, the greatest is when the foam is being applied and the vapors it puts off. After that, only risk is mold but a good HVAC guy that knows what hes doing with a foamed building should eliminate any issues from the start. There should also be a blower door test performed to find any leaks. But I've seen too many times homeowners and builders think they know more than the guys installing this stuff and they want to go as cheap as possible and skip things.

Spray foam will hold its value for many years and at a point where traditional insulation will settle and begin to quit performing as well, spray foam will continue to do what it's designed to do. When you're $150k or more into a house with everything you want out of it, what's another $2-3k extra.

If you say your friend spends almost $800 more a year on electricity, the extra cost you put into spray foam at that rate will be recouped a lot quicker than 10 years. You're going to spend at least $.80 to $1 per sq ft of wall and attic insulation anyway, so depending on the size of the house, the first $2-4k is money you would have spent anyway just because you're building a house. Spend a little extra and do it right and recoup your money in energy savings in 3-5 years

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[BrianL]

I have foam and thought the difference would have been more. I know my pool pumps and pool equipment added about $800 year in electric cost. If all equal except the pool, there is very little difference.

[cj7zrcool]

We built our house 2 years ago and used 2" of closed cell foam in the walls & 6" of open cell foam under the decking, cost was about $9K. My average monthly electric bill for 2018 was $234 to power the 3280sft house, 2400sft shop, and 28K gal. pool. We keep the thermostat @ 70* in the winter and 68* in the summer and have 7 ceiling fans throughout the house.

[batmaninja]

I want to say another plus of spay foam is that it is better at keeping mice/rats out better than bat.

[tps7742]

We built our house 2 years ago this month 3080 sq ft. We keep our thermostat at 68 in the summer and 64 during the winter. Our hot water heater and stove top are C3 (rural). The highest electric bill has been $218. Needless to say I am a fan of spray foam and was very skeptical of the stories told about how efficient it was prior to experiencing it myself. Our ac was designed for foam with an outside fresh air duct.

[Rex]

Closed Cell?

Would spraying foam under a beach house be beneficial when the attic is just regular insulation? Home sits about 4' off the ground about 3 blocks off the coast.

[Banded Drake Calls]

Would spraying foam under a beach house be beneficial when the attic is just regular insulation? Home sits about 4' off the ground about 3 blocks off the coast.

Yes, you'll seal any air leaks through the floor that you dont notice

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