re: Foam insulation in new construction

I’ll second the rock wool if you don’t want to take fish’s recommendation. FIL used it in his home and talked to me about it. He has an extensive construction background. We used it in a vacation condo after rebuilding. Unbelievable thermal and noise barrier. Also, as fish said, FIL rarely turns his actual heat on, 2500sf home and has a wood-burning stove/fp with blower. Lights a good fire, turns on fan on furnace to circulate and voila.

Friend of mine installs spray foam. He will readily admit, to me, at least, the pros and cons. When sprayed between rafters, the heat between the foam and roof decking can’t easily dissipate. The heat buildup will prematurely age a shingle roof. I Don’t necessarily know about walls pro/con. Just my .02

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Animals will find a way to make up a new home for themselves.

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They absolutely will! A building on piers would be a perfect application for foam, but I think I still would enclose with some sort of chicken wire afterwards.

I sprayed in Rock wool. Couldn’t be any happier. Did some cost/value analysis vs. foam and didn’t see the value needed to pay the extra for spray foam.

Our house is around 3000 living and our electric Bill is typically between $120-$175.

We also keep the lights off durning the day. Relying on natural lighting helps keep the energy costs down.

I’m currently building a pier and beam in Houston and sprayed closed cell foam underneath the house. I am doing sprayed in blankets pretty much everywhere else as opposed to foam for the reasons mentioned already. A climate controlled attic requires a dehumidifier in Houston to prevent moisture buildup in the attic, and that’s one more piece of mechanical equipment I’d have to upkeep for a ROI I don’t think I’ll see.

So to compromise, my attic has radiant barrier on the roof decking, so that will remove a good amount of heat from the attic. Attic floor will be blown in, exterior walls will be blown in, and interior walls that I want sound proofed (bedrooms mainly) will be blown in.

This is the best compromise I could come up with. The closed cell insulation below the sub floor was a must do however based on my research. Everything else was preference.

There are two types of spray foam. Open cell and closed cell. Closed cell imo is better b/c it adds structural integrity and won’t retain moisture.

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There is some people who don't like it. Main rub is it doesn't allow the house to breath.

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Yeah I’ve heard that too but there is another camp that says houses don’t need to breathe. Even with regular fiberglass insulation, houses these days are tight compared to 50 years ago.
I built my house in 2015 and went with spray in from concrete to roof tip. No issues and my heating/ cooling system has no problems. Even went half ton less on the outdoor unit. More and more people are going with the spray in.
I like it because when i go in the attic it is cool and I can see all my wires and plumbing without having to dig around in insulation.

My BIL owns a spray foam insulation company. That shite is an amazing add in both new con and retro.

Yes absolutely pay the extra and spray foam.

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The heat buildup will prematurely age a shingle roof.

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What happens with a tin roof?

From what I understand foam insulation works better than just about any other type of insulation.

BUT

The installer MUST know what they’re doing because too much in an area can give off toxic fumes and become a total nightmare. I really wanted to go with this in my attic but I found multiple videos on YouTube about nightmare scenarios people have had with it and quickly decided against it. The risk is not worth the reward for me. I went with a combination of blown in and lay down bat insulation. Made a giant difference in summer electric bills for me.