$4500 vs $9k for insulation

[tinysparky]

Would you rather have fiberglass insulation at $4500 and r 11 or closed cell foam insulation for 9k and r7?

Western wa. Not currently heated...

Admins...wish polls were still around

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[2011laramie]

Seems like alot of natural gas can be bought for 4500 bucks.

 

[finn]

If the quoted r values are correct, fiberglass wins hands down.

Why would you pay more for poorer performance?

 

[MrSurly]

It sounds like you should get some more bids and info on the foam. According to my info, it actually *difficult* to install foam at R7.
Closed cell is about R7 per inch; minimum install seems to be 1.5-2”.
Open cell is about 3.7 per inch and minimum install is about 3-3.5”.
Unless you are spraying it into a 1” framework and then trimming it flush, it’s tough to spray it only 1”.
At least that’s what multiple foam guys told me.
Get second opinion maybe


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[yeldogt]

On smaller jobs foam can be 2x the cost of fiberglass -- but, it's typically not that much on larger. You are giving odd r numbers ....

The only people who would recommend fiberglass are people who have never used or lived in a house/ building with foam. The air sealing properties of foam change the game -- R values don't take into account air movement .. none w/foam ... much with fiberglass.

 

[Showkey]

Even if it’s a typo and the foam is R17.........the cost increase and the diminished return on increased R value likely makes the low cost fiberglass a better deal. There are online calculators to determine the diminishing values and payback time increasing R values.

 

[stm317]

How are you getting R11 fiberglass? Normal batts for 2X4 framing are R13. Is your framing not even 3.5 inches deep? Are these blankets that are just really thin?

 

[ace10]

Rockwool R15 for something in between the $$.

 

[alexb2000]

I'd rather have the foam. R value is often skewed by marketing. An R-13 batt is R-13, but there are a lot of areas of the wall that are less because of the lumber and voids that you can't get a batt into. There is also air intrusion, which has a big effect on the cost of controlling the temperature of the room and foam is superior in this respect.

 

[86turbodsl]

Don't overlook that air moves freely through fiberglass and doesn't through foam. The Rvalues on foam are deceivingly low. My house only has 2-2.5 inches of foam in the walls and performs very well.

 

[strutaeng]

If the quoted r values are correct, fiberglass wins hands down.

Why would you pay more for poorer performance?

Yeah, seems silly to ask which is better: R11 vs R7?

Even with thermal bridging of the fiberglass, I'm sure it it still better than R7 overall with the fiberglass. Who uses R11 by the way? All I see locally is R13.

So the spray stuff is like 1.5" in thickness? I would consider that just an air barrier.

I'm not a fan of the spray stuff due to the high cost. You can achieve the same or better thermal performance with a combination of fiberglass, mineral wool, continuous rigid insulation for way cheaper.

Please read this article:

https://www.greenbuildingadvisor.com/article/spray-foam-insulation-is-not-a-cure-all

 

[tonyciambrone]

I hope your building is absolutely enormous. $4500 of r13 or even r19 goes a long way. I wouldn't even dream of paying someone to hang fiberglass for me. It's not hard.

Second I guess your building is not recent, because I believe washington requires continuous exterior insulation like rigid board.

Personally I would not even bother doing any insulation at all if the options were r11 or r7. I would want r-21 or better in the walls and like r39 or better in the ceiling

 

[finn]

On smaller jobs foam can be 2x the cost of fiberglass -- but, it's typically not that much on larger. You are giving odd r numbers ....

The only people who would recommend fiberglass are people who have never used or lived in a house/ building with foam. The air sealing properties of foam change the game -- R values don't take into account air movement .. none w/foam ... much with fiberglass.

I have foam in my house and fiberglass in two shops.

I’ll reiterate: Foam, at double the cost and 2/3 the performance is a bad deal, and not worth it

 

[strutaeng]

Here's a great article and logic of why the spray foam folks think that "less is more."

https://www.greenbuildingadvisor.com/article/its-ok-to-skimp-on-insulation-icynene-says

 

[yeldogt]

I have foam in my house and fiberglass in two shops.

I’ll reiterate: Foam, at double the cost and 2/3 the performance is a bad deal, and not worth it

Sorry .... just don't agree. Properly done .. nothing comes close to closed cell. The bigger the space the more important it is ... comfort and smaller equipment -- lifetime of savings.

 

[yeldogt]

Here's a great article and logic of why the spray foam folks think that "less is more."

https://www.greenbuildingadvisor.com/article/its-ok-to-skimp-on-insulation-icynene-says

The various negatives are typically with poor installation -- as in your first link. The foam manufacturers are always trying to try to get the price down -- so they have been trying different things for years.

Although I did do one foam with skim coat of 2.5" and then use R13 batts to keep the inspector happy so I could get the state rating. I don't think I got much out of the batts.

Ideal is 4" around me .. that what I typically do.

 

[b-boy]

Personally I would not even bother doing any insulation at all if the options were r11 or r7. I would want r-21 or better in the walls and like r39 or better in the ceiling

I used unfaced R11 in conjunction with rigid 2" XPS at R10 to get to R21. I sealed all gaps with spray foam. It's pretty airtight, and cost a lot less than spray foam. It was a lot of work though.

 

[DC73]

You don't need a poll. Science shouldn't be a popularity contest.


Cellulose and mineral wool are both superior insulation materials compared to fiberglass.


Heat is lost or gained through radiation, convection, and conduction. R-value handles heat transfer through conduction. Air sealing handles heat transfer through convection. Once you have the correct r-value and air sealing for your climate any residual heat gain or loss due to radiation is very likely to not be cost effective to correct.


Fiberglass is less effective when air is allowed to flow through it so the r-value must be de-rated in that situation.


In order to compare fiberglass properly versus closed cell foam, you must factor in the cost of 100% air sealing so that no air can flow through the fiberglass. Closed cell foam completely blocks the flow of air and that's why it can seemingly outperform fiberglass even at lesser r-values.


That said, r-value is r-value and I would install the recommended r-value for your climate regardless of which insulation you choose.


All this means is that you should not be comparing R11 fiberglass to R7 closed cell foam. You should be comparing the same r-value and air sealing levels between any insulation materials on your list of options.


Another option is what they call "flash & batt". In this option, you spray the minimal amount of closed cell foam for your climate to both stop air infiltration and to keep condensation at bay, and then finish up with another less expensive insulation material.



Good luck,


DC

 

[skippydoo]

Just got my 30x40x13 tall pole building spray foamed. 3 inches in roof and 2 inches in walls. $7800. I asked the guy if I should go thicker and he said no. I then asked if it was his building . He said he'd do it the same. Sunday the sun was out and I checked the outside metal temp on the one wall and it was 138, inside the foam was 80. I'm in north west NJ.

 

[yeldogt]

Just got my 30x40x13 tall pole building spray foamed. 3 inches in roof and 2 inches in walls. $7800. I asked the guy if I should go thicker and he said no. I then asked if it was his building . He said he'd do it the same. Sunday the sun was out and I checked the outside metal temp on the one wall and it was 138, inside the foam was 80. I'm in north west NJ.

My township (NJ) requires an efficiency audit (forget what it's called). My architect had to fill out and sign (another cost --- it can't be done by the homeowner). One item is the "R" value .. so 2" will not get to the requirement -- that's why I had to go to the the flash and batt. With foam you can build with 2x4 walls ..

"R" value needs to be tossed and we need to have new research done -- so people understand what is required with various products. I have no idea what the actual difference is between R14 in the various insulation products -- I can only tell you between closed foam and fiberglass -- it's huge. I also don't know how thick fiberglass needs to be before it's a reasonably effective barrier against air flow .. just know that R25 is not enough.

Think of those cheap foam coolers filled with ice out in the sun all day -- the delta is high and the effective area large again the space inside .. and they are under R7. But there is not stack effect and no wind effect -- it's pure R.

It's why I can heat (maintain) my 1700sf studio with 13k BTUs.

 

[sweetk30]

my 1800sq ft shop was already built and sheet rocked 5/8 inside when i purchased this place . i would go out in the winter and fire up the big wood stove crammed with 8-10 chunks of fire wood . i would fire it off and run full open for all day and hardly stay to warm to take off a sweater .

i found .5% insulation in the shop via empty beer cans in the walls and ceiling area i could see in . .

well i called up the local spray foam guys and had them swing down to quote me up . since i could not tear open the walls to insulate with the 5/8 drywall on them and all electric run in conduits on top of the drywall i had to do foam fill in the walls and spray foam in the ceilings .

boy was i glad i did . in the windy season around here this building would creek and shake in heavy wind days . now she is rock solid

and as to the wood stove 4 maybe 5 smaller chunks of wood and in 3-4 hr's i am sweating my but off .

now i do have a modine hot dawg hearer in the shop to keep it at just 50* temp in the cold season . this unit hardly runs out there . i have been out there for a full day and maybe heard it kick on 3 times at most if i keep the door's shut .

my shop has insulated doors via them spray foaming them for me cheeper than new doors . the 4 windows in the shop are single pain glass 38"w x 45"t thats a lot of heat loss there . there getting new double pain windows this year before winter seats in . then tighten up the 1 garage door gap at the top a hair and she will be even more efficient .

so in short i am a BIG fan of spray foam

my buddy had a metal building put up all metal trusses and beams . he had the same place do his 2" thick top to bottom and he can heat his place no problem to 50* with a 65-70k btu modine unit and go threw 2-3 100lb propane per winter season .

 

[tonyciambrone]

I used unfaced R11 in conjunction with rigid 2" XPS at R10 to get to R21. I sealed all gaps with spray foam. It's pretty airtight, and cost a lot less than spray foam. It was a lot of work though.

It definitely is a lot of work but to me, and like others have said here, it is lifetime payback. Every year you have a crappy insulation job it costs money and comfort. Do it one time well and the rest of the buildings lifespan things are good.

To me, 100% closed cell would be my vote every time if cost were no option.

2"XPS + r13 with spray foam sealing the XPS

2" XPS + r15 mineral wool with spray foam sealing the XPS

2" XPS plus Polystyrene

And on and on...

2 XPS" plus r15 mineral wool turns out the best but it ***** the most. Mineral wool is harder to work with than fiberglass but IMO it is a superior product. (but heavier and more costly as well)

 

[Voi]

Mineral wool is harder to work with than fiberglass but IMO it is a superior product. (but heavier and more costly as well)

Curious to hear why you think mineral wool is harder to work with? I have only used it for one job but I really liked it. The wall in question was an interior wall at my cabin that I needed to insulate since I want to heat the mechanical room behind it all winter.

The wall was full of electric, Pex and vent stacks and mineral wool was perfect for scribing and/or notching around all that stuff all while keeping the Pex on the warm side of the insulation.

I could see batts being easier for a typical 16" O.C. stud bay with minimal electric but once you have non-standard spacing or a lot of wires or boxes I think mineral wool is an easier DIY job.

 

[kk7xx]

It definitely is a lot of work but to me, and like others have said here, it is lifetime payback. Every year you have a crappy insulation job it costs money and comfort. Do it one time well and the rest of the buildings lifespan things are good.

To me, 100% closed cell would be my vote every time if cost were no option.

2"XPS + r13 with spray foam sealing the XPS

2" XPS + r15 mineral wool with spray foam sealing the XPS

2" XPS plus Polystyrene

And on and on...

2 XPS" plus r15 mineral wool turns out the best but it ***** the most. Mineral wool is harder to work with than fiberglass but IMO it is a superior product. (but heavier and more costly as well)

Any thoughts if 2" XPS between the girts only and then closed cell spray foam over the top would be good enough for Michigan climate? Have a 40x60 pole barn w/ metal walls (no vapor barrier) and shingled roof I'm trying to figure out what to do with. Friend of mine that is handyman-type said 2 layers of XPS might be enough if space was left between the foam board and if drywalled over.

I was originally going to just go all closed cell spray foam but that was when I thought I had to have it done by early Oct, have a little more time to work with now.