[Cbishop53]

I’m insulating my 16x20 workshop. I’m currently doing the roof and want to leave the ceiling open to store things above. I have 2x6 rafters. I left a 1” air space for air to pass from my soffit to the ridge and I used 1.5” foam board that I got a really good deal on. It leaves me with 3” of space. I was wondering if fibreglass insulation can be separated in half. Ex: use 6” insulation and separate it in half to get 3”... I’ve searched everywhere online and can’t find an answer. Any help would be appreciated. Thanks

 

[Nealtw]

Better would be to add a 2x3 to the bottom of the rafters and use the 5 1/2" insulation.
Or just a 1x2 and use 3 1/2" insulation.

 

[Marson]

I’m insulating my 16x20 workshop. I’m currently doing the roof and want to leave the ceiling open to store things above. I have 2x6 rafters. I left a 1” air space for air to pass from my soffit to the ridge and I used 1.5” foam board that I got a really good deal on. It leaves me with 3” of space. I was wondering if fibreglass insulation can be separated in half. Ex: use 6” insulation and separate it in half to get 3”... I’ve searched everywhere online and can’t find an answer. Any help would be appreciated. Thanks

You could also use a 3 1/2" batt and install it in a 3" space. Contrary to popular opinion, it's OK to compress a batt, provided the stud cavity is filled completely. (it's not OK to compress a batt and leave an air space.) Greater density of insulation leads to more R value to a point anyway.

 

[Windows on Wash]

+1 on the compression being fine. Actually is a slight reduction in R-Value, but only because of the loss of depth. the actually R-Value per inch goes up slightly with the compressed batt in this case (i.e. 3.5" to 3").

 

[Cbishop53]

I think I’ll just go with the 3 1/2” insulation, but was also curious if pulling apart 6” insulation to make 2 pcs of 3” is ok. I don’t see any info anywhere on doing that.

 

[Windows on Wash]

I think you are making more work for yourself where it isn't necessary.