Spray foam insulation on new-construction walls

[TheGorf]

My shop is located in the greater Seattle, WA area. It is 24x36 and I have just completed putting up hardie plank on the outside (Tyvek underneath). The sheathing on the wall is plywood, not OSB. My electrical is all done and my mind is turning to the interior and how to insulate before I drywall. I've been thinking about spray foam. Seems like a good product and good R rating. Any cons to it? Also, when I put my trusses in, I put in the vents. But a lot of what I am reading online says that spray foam goes right on the roofline. Sealing the envelope airtight.

 

[kj_mustang]

Having a conditioned air space in the attic is a separate decision from using spray foam. If you have HVAC equipment in the attic, then you should consider having a conditioned attic space for the efficiency and long term savings that it would provide. Conditioned attics are unvented. And conditioned space means year round, heat and a/c. If you already have a vented attic space and you do not plan on having any hvac equipment in the attic, then expense wise you are better off insulating at the ceiling. What type of insulation you use in any area is another decision.

 

[TheGorf]

Sounds good. I don't have any HVAC gear in the attic. I was hoping to use it as some storage without the heat. And frankly, expense is not an issue.

Either way, any thoughts or opinions on the foam in the walls?

 

[Onewolf]

The only downside to (closed cell) foam insulation is the HIGH initial cost.

 

[NUTTSGT]

The only downside to (closed cell) foam insulation is the HIGH initial cost.

Which is why it should be considered an investment. One that will continually give you a return on your money as you heat and cool your space for years to come.

 

[sean Buick 76]

Sure spray foam while you are at this point and never look back!

 

[Elginz]

It sounds like what you are doing is right, with the venting. There is blocking to prevent insulation from the attic going in the eves. The other thing the blocking does is keep out air infiltration that point. So spraying up to the attic, soffit, eve vents is beneficial.

 

[jvitez]

I have high density polyurethane spray foam in my house. It's about R7 per inch, acts as a vapour barrier by itself, and really strengths the walls. I'd do it again. Expensive yes, but it's definitely the best way to insulate stick built walls.

Cons: initial cost. Pros: everything else.

 

[kj_mustang]

Closed cell spray foam of at least 2" thickness is a terrific wind and water vapor blocking and insulating product. The downsides of using it is:
If you are filling your wall cavities you really can not add plumbing or electrical in the wall later, plan ahead for the future or deal with it on the outside of the wall.
It must be covered for fire safety.
You need an experienced installer to get uniform and desired coverage.
Expensive

 

[MisterMike]

Apart from the cost, I can't see a downside. We have a 30' x 48' Cleary building with 14' sidewalls. It's located in SW Wisconsin, and, as yet, we have no heat in it (except for a heated bathroom in one corner). Compared to the pre-insulation days, it's a huge difference--no dust or dirt blowing through, and comparatively consistent temperatures throughout the year. One thing that I'm at a loss to explain is that it retains a temperature that's generally well above the outdoor ambient air temperature throughout the winter; my guess is that the ground below the concrete floor simply doesn't freeze and has remained a bit warmer than exposed ground. Once we scratch together the money to install heat, I'm guessing that it won't be too crazily expensive to run (we're looking at LP-fired infrared tubes, which we'd use on an on-demand basis).

 

[MagKarl]

Please get some quotes for spray foam and traditional batts/blown in and share them here. It would be educational to compare thicknesses, R values, and prices to see just how the initial cost and return on investment pencil out.

 

[theoldwizard1]

Any cons to it?

Cost ! When it come to insulation you want to install as much as physically (or economically) possible.

Sealing the envelope airtight.

This can be an issue in homes. Smells tend to be trapped and can linger for a long time (days). Humidity (or lack of humidity) can be an issue.

 

[yeldogt]

Use it once and you will never use anything else again.

 

[kd3pc]

cost is the only con.

go for it, and enjoy!

 

[woodzy]

In my house that was built last year, framing was 2 x 4 on 16 centers. Outside was Vinyl siding, tyvek wrap (Michigan code), 7/16 OSB, 1/2-1" spray foam, Fiberglass insulation, Visquee, and drywall.

Last months gas bill for a 2230 square foot ranch home set at 72° 24-7 was $112.00 and it was a very cold month. I think the spray foam was the best idea - no air leakage.

I just started to finish the basement and have them spray foam once I put the walls in. I agree - expensive up front but savings the rest of my life will pay for it. My final trip out of this house is on a gurney.

 

[yeldogt]

In my house that was built last year, framing was 2 x 4 on 16 centers. Outside was Vinyl siding, tyvek wrap (Michigan code), 7/16 OSB, 1/2-1" spray foam, Fiberglass insulation, Visquee, and drywall.

Last months gas bill for a 2230 square foot ranch home set at 72° 24-7 was $112.00 and it was a very cold month. I think the spray foam was the best idea - no air leakage.

I just started to finish the basement and have them spray foam once I put the walls in. I agree - expensive up front but savings the rest of my life will pay for it. My final trip out of this house is on a gurney.

What climate? I had to go thicker with my foam when I did a hybrid ... and I'm not sure about the plastic. It any moisture does get in the wall .. it can't dry out?

I kept the normal kraft faced

 

[Milton Shaw]

Before you button up the walls run a few extra lengths of conduit and box for unexpected tools/equipment that you might eventually get. Believe me its a lot easier now than after the fact. Even if you just run in cat 5/6 or coax you will be a good step ahead to have the conduit there. Way less than $5 a conduit and box now, $100 would put extras on every wall.

 

[soapii]

My wife and I built our house 2 years ago and did the entire thing in closed cell spray foam. After a year of living there I was convinced that is what I wanted to do in my garage and I couldn't be happier. Cost me $10-15 a month to heat the garage during the winter (natural gas).

--Joe

 

[pablo94sc]

How are you guys getting fresh air into the house for heating/fireplaces/etc? Do you have a dedicated intake somewhere? Do you have a dedicated exhaust as well for circulation? Just curious how all that works. My knowledge is limited to how it makes plumbing and electrical work a nightmare if you don't plan ahead. LOL

 

[woodzy]

What climate? I had to go thicker with my foam when I did a hybrid ... and I'm not sure about the plastic. It any moisture does get in the wall .. it can't dry out?

I kept the normal kraft faced

Well, the picture I supplied was the basement area I'm working on. They sprayed it 2" thick where it was above grade and about 1" below grade (there was 2" of foam placed on the concrete before backfilled).

Area is SE Michigan

On the rest of the house it was about 1/2" thick around the entire house including the garage and then the fiberglass insulation.

Furnace has it's own air supply but hot water tank is normal B-Vent.

 

[soapii]

How are you guys getting fresh air into the house for heating/fireplaces/etc? Do you have a dedicated intake somewhere? Do you have a dedicated exhaust as well for circulation? Just curious how all that works. My knowledge is limited to how it makes plumbing and electrical work a nightmare if you don't plan ahead. LOL

Code requires a non-combustible air source. So yes we have a vent from outside into the mechanical area of the basement. Water heater is natural gas and has a powered vent and we have geothermal heat so no combustion there. We have no fireplace either.

--Joe

 

[jvitez]

Our house has two Heat Recovery Ventilators, so exhaust air is balanced with equal amounts of pre-heated make up air. Our NG fireplace has it's own air intake.

 

[Peter Mc Mahon]

I spray foamed my house but crazy expensive. Yes you need a air handler not just a furnace. The building will be very tight so humidity gets trapped and mould can be a issue. I priced foam for my shop ( about 1300 sq foot of wall area ) and it was $3.00 a sq ft ( Canadian ) since it won't be heated all the time I will never save that so I will use fiberglass batts.

 

[yeldogt]

Well, the picture I supplied was the basement area I'm working on. They sprayed it 2" thick where it was above grade and about 1" below grade (there was 2" of foam placed on the concrete before backfilled).

Area is SE Michigan

On the rest of the house it was about 1/2" thick around the entire house including the garage and then the fiberglass insulation.

Furnace has it's own air supply but hot water tank is normal B-Vent.

I needed 2" in PA -- that was the determined thickness to maintain temp above dew point ... I then back filled with fiberglass for code. I don't like plastic... I'm not familiar with only doing 1/2 inch.

 

[JimL]

Call it flash and batt here. 1/2-1" of foam then put in kraft faced batts.