DIY spray foam kits

[MtnLivin]

Does anyone here know anything about DIY spray foam insulation? I'm building a couple of new rooms and want to go the spray foam route. I've found some pen cell stuff that will do 1350 SF for $700 or some closed cell foam that will do 600 SF for $565. Is it that much better to go with the closed cell over the open cell?

This is the open cell stuff I'm thinking about going with.

http://www.energyefficientsolutions.com/Open_Cell.asp?item=FOAM1350-OC

 

[queequeg152]

you have to start from the bottom up with retrofit insulation...

why do you want foam anyway? for R value? speed?

there are many reasons to shell out for spray foam, and it usually begins and ends with air sealing and ease of installation.
you dont spray foam a wall or ceiling because you want a shit load of r value. if you want a shit load of r value you go with 2" foam boards or flash with closed cell about 1" deep and dense pack like 12" of cellulose. its like half the price.

yes it has a very high installed r value, but the r value per unit of cost is not competitive if all you want is r value. if this is a scratch built room you have a shit load of better options, namely cellulose and rockwool bats and maby foam boards.

open cell foam is typically bidded to lower cost builds. its not terribly compelling unless you are trying to retrofit something like a roof deck in a hot humid climate.

i am too about to buy a 600 dollar spray foam kit. not because of the high r value... but because it would take me hours to insulate my attic facing interior gable walls (vaullted ceiling). the stud spacing is WILDLY inconsistant, and very hard to access in places.

 

[queequeg152]

i should also add that spray foam makes sense in areas that are extreely shallow and cannot accept full width bats. or in circumstances where space is a premium.

if cost were no factor, pretty much all insulation save for maby insulated attic ceilings in low dead load retrofit jobs- would be foamed in. its great shit.

but it costs a shit load.

 

[MtnLivin]

Thanks Q! I guess I should have elaborated a little more. I'm in fact building these rooms from the ground up. It's a couple of 12 light rooms inside an open warehouse. The reason for the spray foam is definitely for sealing purposes.

 

[who dat is]

Thanks Q! I guess I should have elaborated a little more. I'm in fact building these rooms from the ground up. It's a couple of 12 light rooms inside an open warehouse. The reason for the spray foam is definitely for sealing purposes.

If you are worried about sealing purposes than don't even be fooling with the open cell stuff. It's not an air or vapor barrier where as the closed cell foam is. It's spendier but really the only foam to use in my opinion. Regarding sealing why don't you just caulk and use cans of great stuff to seal any wall and ceiling penetrations and then insulated over that with traditional R-19 or 21 batt fiberglass (I'm assuming 2x6 walls) It would accomplish the same thing that you are going for I think and it will be significantly cheaper.

 

[queequeg152]

how many board feet are you looking for? 2x4 studs?

if it were me personally id go with roxul bats, 24" oc studs and a 1" EXTERIOR foam board cladding. this will yield an r18-r21 wall assembly which is pretty good here in the south. not amazing, but good and cheap.

you can upgrade to 2" XPE foam board cladding for like r27? or maby its r24 i cant remember. thats pretty fucking good unless you live in north Dakota.

pro tip... buy a 18" electric turky carving knife. it cuts rockwool bats like butter. i used a cuisenart one to fit bats for my mbath reno.

 

[who dat is]

how many board feet are you looking for? 2x4 studs?

if it were me personally id go with roxul bats, 24" oc studs and a 1" EXTERIOR foam board cladding. this will yield an r18-r21 wall assembly which is pretty good here in the south. not amazing, but good and cheap.

you can upgrade to 2" XPE foam board cladding for like r27? or maby its r24 i cant remember. thats pretty fucking good unless you live in north Dakota.

pro tip... buy a 18" electric turky carving knife. it cuts rockwool bats like butter. i used a cuisenart one to fit bats for my mbath reno.

I think he's after more of the air sealing and insulation is taking a back seat? Maybe just what I'm picking up. It sounds like he's trying to run sealed rooms.

 

[Shmavis]

+1 for closed cell.

A couple of winters ago we had a brutal one. Circulation pump on my hot tub gave out, which caused the heater to give out, which resulted in “in-foam leaks” from the frozen lines that burst. To repair I had to dig out the existing foam first. After completing my repairs I re-foamed using this:

https://sprayfoamkit.com

Really happy with this stuff. If I seal my room up, it’s what I’ll be using.

Best of luck!

 

[queequeg152]

I think he's after more of the air sealing and insulation is taking a back seat? Maybe just what I'm picking up. It sounds like he's trying to run sealed rooms.

you can airseal in a myriad of ways though. foam is just the easiest.

taped foamboard ontop of taped OSB should be sealed enough and alot cheaper.

you can technically omit the osb... being this is not a structural wall, but if you want to use the ceiling for stroage or as a mezzanine i highly reccomend you do full OSB sheathing for racking resistance.

you can also let in corner bracing, but its not as strong as structural sheathing.

i think the OP will find out when he prices the his insulation that spray foam kits are simply not reasonable.

 

[MtnLivin]

Ok here's the run down. I have roughly 2k in square board feet to insulate. I'm going for maximum seal and insulation here. So I'll go closed cell. Each kit says it can do 600sf so I'm sure I can make 3 work for me. Now I'm only putting 1" of foam in the wall, would it be beneficial to put a layer of fiberglass insulation on top of the spray foam? I am using 2x4 studs by the way. Thanks for all the input!

 

[who dat is]

Yeah, you could probably stuff an R-11 batt over top the 1" foam to fill the cavity.

 

[queequeg152]

i dont think they even make r11 batts anymore.

but yea you could compress some r13 bats into that cavity.

this method is called flash and batt. its not a fast way to insulate, but it will be airtight.

not my cup of tea, but if money is no option its a very valid way to go.

you could probably get to like r17-19 this way.

 

[who dat is]

i dont think they even make r11 batts anymore.

but yea you could compress some r13 bats into that cavity.

this method is called flash and batt. its not a fast way to insulate, but it will be airtight.

not my cup of tea, but if money is no option its a very valid way to go.

View Image

you could probably get to like r17-19 this way.

Nice diagram. They do still make R-11 batts too but I think that's the lowest/thinnest batt you can get.

 

[queequeg152]

Nice diagram. They do still make R-11 batts too but I think that's the lowest/thinnest batt you can get.

ah yea i see that they do now.

 

[MtnLivin]

Thanks for the input guys. I'm still trying to figure out which way to go about this. I can spray foam 1" on both rooms for around $1800. I'd rather be close to 1k for insulation costs honestly. So all in all which way should I go to seal up 10' 2x4 walls?

 

[queequeg152]

if you can buy roxxul batts in your area i would do that.

yes foam is expensive like i said earlier its the convenience of a foam job that makes it very compelling especially in rough areas that are hard to cut batts and air seal for.

ive no clue what your proposed construction is, but i always reccomend the roxxul r15 batts if you can get them.

if you cannot get them, see how much a special order will cost you. i special ordered like a pallet from home depot once for a bathroom renovation and it was like 60 bucks a bail, with a bail only covering 60 sq. feet of wall area not including stud area... assuming 10% waste, one 60 dollar bail covered around 54 square feet.

if roxul is readily available in your area is usually ranges from like 40-50 a bail? i think lowes carries the 16" r15 batts now and i think they are charging like 43.99 +tax. they are usually cheaper the farther north you go.

you can usually get r15 fiberglass batts also, which are usually a bit cheaper, but roxxul has very little itch and it cuts FAR better than fiberglass.

so yea call it around a buck a square foot WORST case scenario.

+ a 50 dollar foam gun + 2- 30 dollar cans of enerfoam.

thats going to be your cheapest bet here.

also highly reccoment air tight electrical boxes, and highly reccomend you caulk your sill plate with that tremco acoustical sealant front or back or both, and use ureathane adhesive on your sill plate to.

 

[queequeg152]

gun

https://www.awarehousefull.com/dow-great-stuff-pro-14-foam-dispensing-gun/

https://www.awarehousefull.com/dow-great-stuff-pro-enerfoam-sealant-and-adhesive-30oz-pro-can/

enerfoam is the best for air sealing smallish gaps. trust me ive used all foams except for the adhesive foams from OSI and the pest blocking foams. the enerfoam is the best with regards to resiliance. its very gluey and less brittle.

the window foam is good because its more spongy, but its also prone to tearing and it seems to have less adhesive ability. the big gap foam is friable and very stiff. good for large holes, though id rather fill large holes over with sheet metal or some backing material and foam over it.