Roxul in a 2x3 wall?

[milli...@yahoo.com]

Hi,

My basement has 2" XPS foam against the concrete walls (glued and taped and sealed), with a 2x3 stud wall over that. Can Roxul 3" batts be squeezed into a 2x3 stud wall? Or will that just be an impossible situation and break the 1/2" sheetrock to be intalled over the whole thing?

I have no prior experience with Roxul, so any knowledgealbe comments are greatly appreciated.

Thanks
Theodore

[cl...@snyder.on.ca]

Stud wall tight against the foam??
We set the stud wall about half an inch from the foam, framed with
2X4, and installed Roxul. It in not terribly hard to compress but not
sure how it is sized - I thought 4 inch was for 2X4 (3.5") so 3" would
be for 2X3 (2.5"), which would mean "no problemo"

[Tony Hwang]

I believe if compressed it'll lose R value. Snug fit is best.

[Oren]

On Sat, 19 Sep 2015 12:14:01 -0600, Tony Hwang <drag...@shaw.ca>
wrote:

Agree. OP could slice / split the insulation in half or the thickness
needed. 4" becomes 2" -- use the second piece in the next cavity
space. Something like that.

[cl...@snyder.on.ca]

On Sat, 19 Sep 2015 12:14:01 -0600, Tony Hwang <drag...@shaw.ca>
wrote:

It will lose SOME R value, but it is not linear with the percentage
od compression - and not as serious with roxul as with some other
insulations.

[cl...@snyder.on.ca]

Ever work with Roxul?
Ever try to split it?
It's a lot different than fiberglass.

[Oren]

On Sat, 19 Sep 2015 20:41:36 -0400, cl...@snyder.on.ca wrote:

>>>I believe if compressed it'll lose R value. Snug fit is best.
>>
>>Agree. OP could slice / split the insulation in half or the thickness
>>needed. 4" becomes 2" -- use the second piece in the next cavity
>>space. Something like that.

> Ever work with Roxul?
>Ever try to split it?
>It's a lot different than fiberglass.

Actually, no I haven't. I just learned about Roxul last year, how
it's made and watched some videos. If I were insulating a new space I
would use it, given the water, fire resistance and sound proofing
properties.

It seems obvious to me it needs cutting for installment; perhaps it
may be more difficult to cut, but are you saying it is impossible? <G>

[dpb]

On 09/18/2015 10:14 PM, cl...@snyder.on.ca wrote:
...
> ... It in not terribly hard to compress but not

> sure how it is sized - I thought 4 inch was for 2X4 (3.5") so 3" would
> be for 2X3 (2.5"), which would mean "no problemo"

Product sheet indicates the 2.5" product is produced in 16-1/4" width
for metal studs instead of 15-1/4" width (wood studs). So, _might_ have
to trim width with it...I'd guess a full inch compression would not be
best use of insulation $$ although having not used it no idea just how
hard it would be to install. Couldn't find any data on actual
compression ratio vs resultant R value for it...

--

[cl...@snyder.on.ca]

Not impossible to cut, but extremely difficult to split a 4 inch
batt into 2 2 inch batts. It isn't in nice neat layers like (most)
fiberglass.

[milli...@yahoo.com]

> Product sheet indicates the 2.5" product is produced in 16-1/4" width
> for metal studs instead of 15-1/4" width (wood studs). So, _might_ have
> to trim width with it...I'd guess a full inch compression would not be
> best use of insulation $$ although having not used it no idea just how
> hard it would be to install. Couldn't find any data on actual
> compression ratio vs resultant R value for it...

True. Roxul manufacturer replied to me in the same manner: use the 2.5" product and just trim the width to accomodate 16" o.c. studs.

Their additional concern was that if I compressed a standard batt, it might pop out the sheetrock (in the long run).