How much cooler will my shop be with closed cell foam?

[cajunfirehawk]

About to bite the bullet $ for closed cell spray foam, these two pics represent an august day around 3pm showing roof inside temp and wall facing sun inside temp Wondering how much of a difference it will be?

 

[Captain Spaulding]

That's hard to say. Insulation doesn't stop the heat from transferring through the walls and ceiling, it just slows it down. If it is cool at night, then the inside temperature will tend to cool slowly overnight and warm slowly during the day. But at some point during the day it will likely be just as hot as it is now, but that point will be later in the day.

My insulated shop is usually noticeably cooler than the outdoor temperature until early afternoon during the summer, and noticeably warmer most of the day during the winter. The actual temperature depends on sun, wind and outdoor temperature though.

 

[kd3pc]

8-10 degrees in that scenario...there is more to comfort than the temp of the metal..

You are measuring the surface temp of the metal..

You want to measure ambient at ceiling level, and at your work level.

Moving air may make more sense than spending a ton on foam. Per dollar spent.

 

[theoldwizard1]

It depends o the thickness of the foam. 2" should give you at least a 10 degree drop. 4" obviously more.

Is it going to be comfortable at 3PM in the middle of August ? No. You will have to do the walls (2" of foam and then fiberglass) AND air conditioning. Being by the coast you know that humidity is half of the battle.

 

[rsanter]

About to bite the bullet $ for closed cell spray foam, these two pics represent an august day around 3pm showing roof inside temp and wall facing sun inside temp Wondering how much of a difference it will be?

Put it on thicker on the west and south sides.
A building we have on site that has 4-6 inches of foam really keeps the heat out. Till you open the roll up door, then it rather quickly equalizes temp with the outside

Bob

 

[Chopperpilotjeff]

Having lived for a few years in spray foam structures in Afghanistan, I have lots of good things to say about it. Our tents were sprayed there and would be torture chambers without that protection. It slowed down the shrapnel, too!

Everybody above is right about air temperature equalization, but that isn't your biggest battle. As you illustrate with your surface thermometer readings, the more immediate enemy is radiant heat.

The ambient outside air temp (OAT) where you live is not 119°, but that metal roof in the sun sure is that hot. You will quickly become heat stressed working under it and your inside temp will soon exceed OAT, just like a car in a Walmart parking lot. Foam insulation will provide tremendous relief.

I think it's money well-spent. I'm studying foam applications for my Florida wooden garage roof now.

 

[skippydoo]

What would happen if you put down something to radiate the heat back out such as attic foil? http://www.atticfoil.com
Then spray foam over the foil.

 

[Captain Spaulding]

What would happen if you put down something to radiate the heat back out such as attic foil? http://www.atticfoil.com
Then spray foam over the foil.

Problem with the foil is it has to have an air gap between it and the metal, and it has to stay clean. A little dust pretty well renders it useless.

 

[chruler]

Open the windows at night to let the cool air in, then close them in the morning to help keep it in. That will help too.

 

[Jeepster04]

It depends o the thickness of the foam. 2" should give you at least a 10 degree drop. 4" obviously more.

Is it going to be comfortable at 3PM in the middle of August ? No. You will have to do the walls (2" of foam and then fiberglass) AND air conditioning. Being by the coast you know that humidity is half of the battle.

Ive never understood it but some local contractor claims that anything about ~3" of spray foam is a waste... .

He also talks everyone into just insulating the rafters in the attic and not the ceiling joists. So then everyone is heating and cooling their attic and their units were not sized for that extra space... Nor do they even have vents in the attic...

 

[yeldogt]

Ive never understood it but some local contractor claims that anything about ~3" of spray foam is a waste... .

He also talks everyone into just insulating the rafters in the attic and not the ceiling joists. So then everyone is heating and cooling their attic and their units were not sized for that extra space... Nor do they even have vents in the attic...

That's the correct way -- I spray my crawl space as well. The whole house becomes conditioned space ....... it's especially important if you have any HVAC in the attic.

Spray foam stops all air leakage and it's an unbelievable radiant barrier -- unless you see and feel it you can't understand what a difference it makes. I did a 2" flash coat and batt project and even in a 100 degree day the 2" of foam was amazing ... this was before the r13 batts went in.

Stoping the leaks is as important as the R value.

The OP is going to be pleasantly surprised -- my guess is the inside foam temp will match the interior temp regardless of the outside.

I can stand in my attic and place my hand on the foam and not feel the heat.

 

[kj_mustang]

Ive never understood it but some local contractor claims that anything about ~3" of spray foam is a waste... .

He also talks everyone into just insulating the rafters in the attic and not the ceiling joists. So then everyone is heating and cooling their attic and their units were not sized for that extra space... Nor do they even have vents in the attic...

Studies have been done in really cold climates that show that adding more closed cell foam than 4" doesn't really affect the condensation permeability and R value. It is essentially a total waste of money given the very small gain. If you plan for a conditioned attic space it can make hvac units in that space more efficient. Key word is planning. A conditioned attic is unvented to the exterior and relies on the hvac unit for its climate control.

 

[mrpizza]

I am spraying my pole barn house with a 3/4 pound hybrid spray foam. I will be spraying 5" in it, walls and roofline. I expect to have utility bills well under $100 per month. I am doing a 20 SEER heat pump.

 

[kcelectrician]

i am wanting to do this to my shop, I need to do a little for research on it.

 

[DC73]

Ive never understood it but some local contractor claims that anything about ~3" of spray foam is a waste..

Because that contractor doesn't want you comparing the cost of spray foam to more conventional insulation. R-value is r-value and is a measure of heat transfer through conduction. If your climate requires R30, then that's how much you need. Period. Now, closed cell spray foam does a superior job of eliminating heat gain (or loss) through convection (air movement). But, with proper attention to detail, you can air seal before insulating with conventional insulation and get near the same result. That said, if money wasn't a factor, I'd choose closed cell spray foam.

To answer the OP's question. Your shop will be much better once insulation is installed. My well insulated shop (mineral wool) will approach 87 degrees on 100 plus degree days and generally runs around 83 or so until I fire up the AC. It also will never approach freezing temperatures even if I don't run the heater.

DC

 

[Whiskeymike]

Is there a machine rental DIY option for this?

 

[mrpizza]

For spray foam? No.


Also, there is a website that will list comparable r values and comparisons and such that you can print out for the code inspector if you are using a different product like foam. I will look for it tomorrow. 1 inch of closed cell might be rated a 6.5 r per inch, but actually performs much higher due to the air sealing qualities.

 

[James-W]

Spray foam is expensive, but in the long term it will more than pay for itself in heating/cooling cost savings. But if you want a comfortable working space you still need to heat/cool it.

 

[cajunfirehawk]

Spray foam is expensive, but in the long term it will more than pay for itself in heating/cooling cost savings. But if you want a comfortable working space you still need to heat/cool it.

Correct, I suspect after I insulate the shop, either a mini split or some other form of cooling will be installed. The fact of the matter is, in my area its only decent temp wise about 3-4 months of the year and all the others are usually hot.

 

[hpw]

Is there a machine rental DIY option for this?

https://sprayfoamkit.com/

 

[Black Oak]

The DIY spray foam options usually cover 600 sq. ft. under ideal circumstances.Many things will make that tough. Tempatures must be right, the plastic gun tips clog easily, and one must quickly learn how to get it only to your desired thickness. I would try a "flash and batt " { 1 inch thick }, but on a full blown shop getting done, I would hire it done. I used the Frost-Pak kit for a small project in a crawl space. A big job would cost alot with DIY kits.

 

[stm317]

The DIY kits cost at least $1/ board foot. With an R value around 6 per inch, doing anything with substantial sq footage or depth gets very expensive very fast

 

[bczygan]

About to bite the bullet $ for closed cell spray foam, these two pics represent an august day around 3pm showing roof inside temp and wall facing sun inside temp Wondering how much of a difference it will be?

No cooler at all.

Insulation just slows the transfer of heat to cold. Which saves on the cost of conditioning the space.

There are online calculators to find the savings.

Bill

 

[ticklechicken]

No cooler at all.

Insulation just slows the transfer of heat to cold. Which saves on the cost of conditioning the space.

There are online calculators to find the savings.

Bill

Insulation won't make your average temperature any less, but it will effect your current temperature. The outside temp has a fluctuation during the day that may range between 65° and 95°. The average temp would then be 80°. Insulation moves your indoor temp from the 65°/95° sine wave towards a 80° flat line. More insulation = flatter curve. So insulation does make it colder, but only for ~50% of the day.

With perfect insulation, you are now at a constant 80° in the shop. There are two ways to bring that down. The first is air conditioning. The second is to open your shop at night, let the cold air in, and then close the doors and windows as soon as the outside and inside air temps are the same.

This is an oversimplified example. There's more going on (radiation heating of exterior surfaces, cooling from the floor...), but this is the gist of what insulation does.

 

[semi75]

Add a window unit or better yet, a mini split and you will find that even with an inch and a half of closed cell it will do wonders. I see all these comments that you need 3 plus inches of closed cell and I'm guessing most of those posters never had closed cell foam to tell from experience. Metal buildings just flat out get unbearable in hot weather with no insulation. The metal heats up and it feels like a humid oven. Foam will help reduce the oven effect without ac but it won't cool it alone obviously.

The first metal building I had foamed had 1.5 inches on the ceiling and 1 inch on the walls and it held the temperature I set it too extremely well. That building had a window ac unit and hanging gas furnace for the winter. Keeping the building at 60ish in the winter (Kentucky) cost me very little on my electric bill w natural gas. The line to the garage was not on a separate meter so it was difficult to estimate but I didn't see much of a rise in my bill.

I liked foam enough that I had another building done in June of this year with 1.5 inches of closed. Unfortunately a few areas need touched up to be at peak performance yet. I installed a Mr. Cool diy mini split last weekend and so far it's cooling great and holding. It's too early to give an accurate opinion on the combo but so far it looks promising.

 

[DC73]

Insulation won't make your average temperature any less, but it will effect your current temperature. The outside temp has a fluctuation during the day that may range between 65° and 95°. The average temp would then be 80°. Insulation moves your indoor temp from the 65°/95° sine wave towards a 80° flat line. More insulation = flatter curve. So insulation does make it colder, but only for ~50% of the day.

With perfect insulation, you are now at a constant 80° in the shop. There are two ways to bring that down. The first is air conditioning. The second is to open your shop at night, let the cold air in, and then close the doors and windows as soon as the outside and inside air temps are the same.

This is an oversimplified example. There's more going on (radiation heating of exterior surfaces, cooling from the floor...), but this is the gist of what insulation does.

Bingo. With the addition of insulation, the OP's shop will be cooler and more comfortable during the time of peak outdoor temperatures as shown by his laser thermometer.

DC

 

[cajunfirehawk]

Thanks gents, kind of what I thought...just hard to spend that $4k on foam versus a nice 4 post lift, baby steps I suppose...

 

[Denwood]

I've hired out three spray foam projects now on my home and shop. The price was about the same as DIY kits. The contract in each case took 1-2 hours, no waste propane containers to toss out, and no cleanup.

The other major difference is control of chemical temps before application. The spray foam truck has line heaters that heat the two chemicals over 100F. This ensures correct chemical behavior at the gun for correct density and proper cure. The DIY kits don't have a control method...so another reason I have avoided them for any larger jobs.

My shop roof was converted from stick frame to ridge beam, so the spray foam was applied directly to the roof decking and framing. It adds a ton of resistance to racking once applied in stud/stringer cavities, and has performed well at temps of -30C.

 

[minytrker]

I have my walls and ceiling done in 2-3" closed cell spray foam and it was worth every single penny.

 

[dynahoe]

there is a company that will rent the spray foam truck and equipment to you and a coach to show you how to do it,big drums like the pros

 

[dynahoe]

us spray foam rentals.com