Rock wool insulation

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toddspolaris

Member
Has anyone had experience with the rockwool insulation over the standard fiberglass?? We going to build a brand new cabin in northern MI. I did get some quotes on spray foam, ouch! Ive done tons of reading about all the insulations and trying to figure out the way for me to go. We do plan on sealing the exterior osb as we put it up with silicone on each stud and then plan to use siga wigluv tape to cover all exterior seams trying to make it air proof from the outside, thus the reason I was thinking of going with the rockwool insulation as I can get R-23 out of my 2x6 walls plus its better sound proofing. Just wanted any thoughts?? Thanks
 
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Tim in Indiana

Active member
I've used it several times. The only complaint I had is that it was dirty to install. Dusty, gritty, whatever you want to call it. Working overhead you need to wear glasses to keep it out of your eyes. Other than that minor thing it is a good choice.

You might want to consider Zip sheeting instead of straight OSB. It costs more but the plastic coating and tape works very well.
 
goofy600

goofy600

Well-known member
I’ve used spray foam on my last two additions and yes it seems pricey but it’s worth it for me. Have you added up all the extra costs if silicone and the tape and labor of installing the insulation and extra time of all the other things. Just my two cents on this and depending on where you are at I had some very big differences in quotes, so see if you can get a few estimates.
 
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Dirty70Firebird

Member
silicone or seal the horizontal joints as well, like where the bottom plates of a stud wall attach to a subfloor, or where the 2 top horizontal plates mount to the bottom side of the trusses. Also seal between any vertical studs where 2 studs join lengthwise, like around windows or corners.
 
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bobt

Active member
Think about 1" 4x8 foam board for outside walls with 1/2" plywood for wind bracing and 1/2" foam board over that on corners.

Just imagine putting all your 2x6's put together at 1 1/2" wide and you'll see how much uninsulated wall you have. Not much R value to even 5 1/2" of pine.
 
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chunk06

Active member
I did a remodel last year and the customer wanted Rock wool, I was very impressed. If you're that anal about air sealing make sure your exterior is finished before you insulate. I have found a few good air leaks from "air nails" from siding or other things on the exterior. Also like said consider a rigid foam on the exterior
 
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Sweep800

Active member
Built my place 11 years ago in St Germain. Went with 2x6 walls but made sure sheeting lapped all joints(always lapped plate lines and vertical studs. Used blown in cellulose and put 1/4” foam fan fold on entire exterior for a little extra protection for the wind. The house is so nice and quiet as well. I’ve been a framing carpenter for 35 years in the western suburbs of Chicago and it’s mostly gone to Zip wall sheeting and cellulose for the higher ($1.5m) end guys and osb, tyvek and fiberglass for the less expensive$700k)ones
Definitely spend the $$$ on good windows. I went with the Marvin integrity and kinda wish I went with the higher end Marvin’s. But it’s not terrible!
 
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ezra

Well-known member
bobt said:
Think about 1" 4x8 foam board for outside walls with 1/2" plywood for wind bracing and 1/2" foam board over that on corners.

Just imagine putting all your 2x6's put together at 1 1/2" wide and you'll see how much uninsulated wall you have. Not much R value to even 5 1/2" of pine.
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Urs ago we built houses like that . They were always a bit sketch to me . Then they would slap vinal over them lol .
I get the thermal break aspect . But you could do tge same with 1/2 to 1 in over the 1/2 osb . So r21 then say another r3 with the added thermal break .
Or f it all icf that thing and heat it with a candel .
 
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