Insulation in my 30x40x12

[tpndrcn]

I had a local spray foam company come quote me for spray foam insulation and wanted to see what you all thought. My building is 30'x40'x12'6" and is house wrapped and has dripstop on the ceiling steel. I have a vented soffitt and ridge vent, 5 36"x36" windows, 1-36" walk-in door, and 1-18'x10' door. To spray 4" of open cell foam (R-15) on just the walls is $2185 and to spray 4" open cell foam (R-15) on walls and ceiling us $3895. He also said he was going to cover my vented soffitt area and ridge vent which concerned me because my building wouldn't breathe then. What are all your thoughts?

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[stm317]

One of the biggest benefits of spray foam is that it creates a totally sealed envelope that no air will penetrate or work its way around. Sealing the soffit and ridge vents are standard procedure with spray foam.

Spray foam is typically priced by the board foot (12"x12"X1" thick). National average for Open cell is usually around $0.50/bd ft while closed cell is $1-1.50/bd ft.

Your building has around 1434 sqft of wall space, and 1200sqft of ceiling (assuming a flat ceiling). Multiply those by the thickness that you want (4inches in this case) to get the total board feet for your project.

 

[Olympus]

I have a 30x36x12 and I used roll insulation for the walls. Super easy to do yourself and super cheap. Save the spray insulation for the attic and soffits.

 

[dshop]

I think you are missing the whole point/ mission of spray foam insulation. Yes, spray everything from the floor all the way around to the other floor...totally sealed.
Therefore, no outside temp will intrude and no inside temp will escape. Your space is 100% sealed.
I have a 40x60 stick built near Raleigh NC... hot and humid summer, winter sometimes in the 30's. With the foam it maintains 80 in the summer and 50 in the winter with no heating or cooling equipment; works for me.

 

[8mpg]

Seems a little more expensive than my area. I just paid $5300 for my shop which is 1980sqft. 6" roofline and 3.5" walls.

Id focus more on the ceiling or roofline that I would the walls.

 

[cantupshift]

If you spray your walls and seal up your soffit and ridge vent won't it cause condensation and drips on the ceiling?

 

[stm317]

If you spray your walls and seal up your soffit and ridge vent won't it cause condensation and drips on the ceiling?

It shouldn't. Condensation is the result of temperature differences between the inside air and the metal which is either warmed or cooled by the outside air. So in cool weather, if you have warm, moist air inside the building contacting cool metal, you'll see condensation. Same can happen if it's cool inside/warm outside.
If the air never gets to the metal, because the foam insulates well enough that there's no drastic temp difference, then you don't get condensation.

 

[rburke65]

Don’t know where you live....may not have read it.....but spray foam does a great job, as said, of sealing all the little gaps and creates a much 5ighter build.

 

[skippydoo]

I'm starting my 30x40x13 in NJ and I will be spray foaming. I know its expensive , but I want a warm building in the winter and a cool building in the summer. I'm building once and want to get it right.

 

[930dreamer]

What about closed foam vs open foam?

https://www.thomasnet.com/articles/plastics-rubber/closed-cell-open-cell

 

[n20junkie]

My 30x50 12 feet tall walls with R19 and R30 ceiling cost 1,800 for fiberglass.

I personally like a little bit of air movement. Air carrys away any moisture that may be present, I can easily add utilities in the walls with fiberglass and additions/repairs are easy.

I know I will get dog piled by the spray foam lovers, but I believe a building should breath a little. My heating bills as is are completely reasonable, and I don't have any reason to keep the shop 50 all winter. I run the furnace when I need heat, and roll it off when I don't.

 

[climb.on]

I don't agree with sealing the soffit and ridge vents...unless they are spraying the underside of the roof deck and creating a conditioned attic space. If you still have an unconditioned attic, you absolutely need to have it ventilated. I used 2" of closed cell spray foam on the ceilings of my house as an air-sealing measure and it's great for that. But it's not magic...it doesn't stop all heat transfer. So why would you seal the ridge and soffits? I don't think code would even allow that. If I am wrong, I would love to understand why.

 

[Diesel Dan]

Did the house portion of the build with closed cell.
2" on the walls and 3 on the roof deck so the vents were all sealed.
Basically it's a 24x40-16 building envelope and cost $7k.

Out of 3 companies only 1 would give a written quote.

 

[tpndrcn1]

One of the biggest benefits of spray foam is that it creates a totally sealed envelope that no air will penetrate or work its way around. Sealing the soffit and ridge vents are standard procedure with spray foam.

Spray foam is typically priced by the board foot (12"x12"X1" thick). National average for Open cell is usually around $0.50/bd ft while closed cell is $1-1.50/bd ft.

Your building has around 1434 sqft of wall space, and 1200sqft of ceiling (assuming a flat ceiling). Multiply those by the thickness that you want (4inches in this case) to get the total board feet for your project.

Stm317 if am doing the math correctly I would take the total sq.ft. of 1434+1200=2634 sq.ft X 4" = 10536 bd. ft. Then take 10,536 x .$50 for open cell = $5268

So in this case if the contractor quoted me $3895 to do the whole thing I am getting a pretty good price?

I appreciate everyone's responses on here and please keep them up. There seems to be some debate on whether or not to spray the soffit and ridge vent. I live in Northwest Illinois and plan on putting a flat steel ceiling in. The contractor planned on spraying the roof deck and filling the soffit area and ridge vent with 4" of open cell and then the walls 4" of open cell as well.

 

[stm317]

Stm317 if am doing the math correctly I would take the total sq.ft. of 1434+1200=2634 sq.ft X 4" = 10536 bd. ft. Then take 10,536 x .$50 for open cell = $5268

So in this case if the contractor quoted me $3895 to do the whole thing I am getting a pretty good price?

I appreciate everyone's responses on here and please keep them up. There seems to be some debate on whether or not to spray the soffit and ridge vent. I live in Northwest Illinois and plan on putting a flat steel ceiling in. The contractor planned on spraying the roof deck and filling the soffit area and ridge vent with 4" of open cell and then the walls 4" of open cell as well.

That math seems right to me. The price I gave is basically the national average. I'm guessing you live in an area with a pretty low cost of living, so the national average price may be pretty high compared to quotes you'd get. Best to get multiple quotes for your specific area and go from there.

 

[tomski]

Do you think there's any benefit of doing a 1" spray job? I was thinking about buying a DIY kit that Lowes carries ($600 for 600 sq. ft. at 1"). Or having a local guy spray the whole thing for me. I'm in Oklahoma, so winters are not bad, but Summer will kill you.

Sorry, didn't mean to hijack the thread.

 

[cjcocn]

Do you think there's any benefit of doing a 1" spray job? I was thinking about buying a DIY kit that Lowes carries ($600 for 600 sq. ft. at 1"). Or having a local guy spray the whole thing for me. I'm in Oklahoma, so winters are not bad, but Summer will kill you.

Sorry, didn't mean to hijack the thread.

Different zones / areas require different minimal thicknesses of spray foam to meet the moisture barrier requirement. In my area the minimum thickness is 2" - once I spray 2" of spray foam, I do not have to apply any poly as the spray foam acts as a moisture barrier.

I would use the minimum thickness for your area (this is for the OP as well as tomski) and then insulate the rest with regular batt insulation. That way you get the total seal, the moisture barrier, and can also save costs by using batt insulation (or blow-in for the attic).

In regards to the air flow - I would definitely have some form of air exchange to remove moisture from the building. This is more important in a home where more moisture would be created with showers, cooking, etc., but is also important for a garage where heating and cooling of air can occur simply by opening and closing doors - this creates moisture.

Using a minimal thickness of spray foam lowers your costs while giving you the total seal (much, much less thermal breaks) that you are after.

 

[Emery]

I have the same size shop, 30'x40'x12'6". I spray foamed the walls with open cell and the ceiling with closed cell. The first summer here in Louisiana I had a mold problem due to the high humidity. I had to keep a fan running with the door cracked to combat it. Just this past week, I ordered a packaged HVAC system with 2 speed compressor to keep it cool and control the humidity. In my opinion, depending on where you are located, spray foam should only be used in a constantly climate controlled building. For a shop with occasional air conditioning, traditional insulation may be sufficient.

 

[tpndrcn]

I have the same size shop, 30'x40'x12'6". I spray foamed the walls with open cell and the ceiling with closed cell. The first summer here in Louisiana I had a mold problem due to the high humidity. I had to keep a fan running with the door cracked to combat it. Just this past week, I ordered a packaged HVAC system with 2 speed compressor to keep it cool and control the humidity. In my opinion, depending on where you are located, spray foam should only be used in a constantly climate controlled building. For a shop with occasional air conditioning, traditional insulation may be sufficient.

Emery

Do you have vented soffitt and ridge vent? Did they spray them closed when they did the insulation? So are you having regrets of doing the spray foam now or were you able to figure out your issues?

Thanks

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[kj_mustang]

Different zones / areas require different minimal thicknesses of spray foam to meet the moisture barrier requirement. In my area the minimum thickness is 2" - once I spray 2" of spray foam, I do not have to apply any poly as the spray foam acts as a moisture barrier.

Only for closed cell spray foam, I have read studies that it takes 5"+ of open cell foam to reduce moisture vapor levels to acceptable levels in Northern climates like Toronto and Vancouver.

 

[cjcocn]

Only for closed cell spray foam, I have read studies that it takes 5"+ of open cell foam to reduce moisture vapor levels to acceptable levels in Northern climates like Toronto and Vancouver.

Good point - I should have clarified that I was speaking of closed cell spray foam.

Can't agree on the northern climates part though .... Toronto and Vancouver are considered as being "south" where I come from.

I have some friends on other forums that are from Arkansas, etc. and the temps they experience have me thinking that Toronto and Vancouver are about as far south as I would want to get.

 

[kbs2244]

I would let your building breath and think about IR radiant heat.
I have been in 20 foot ceiling garages with 20hx10h doors open on 30 degree days.
We were in our shirt sleeves.

 

[Emery]

Emery

Do you have vented soffitt and ridge vent? Did they spray them closed when they did the insulation? So are you having regrets of doing the spray foam now or were you able to figure out your issues?

Thanks

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No, there was never a vented soffit or ridge vent. I'm not really regretting the spray foam just yet. My A/C unit should be up and running by the end of the week and I feel like it will take care of the problem.