ADDING NON-STRUCTURAL DEPTH TO RAFTERS FOR INSULATION

[ChiefUserDQ]

I need to add depth to my 2x8 rafters for insulation depth (12" for R-38). Shown is a purlin added to the ROOF PLANE ceiling finish. Is there any way to create a 2x furr-down that is aligned with the rafter but is non-structural?

We finish attic spaces often so it would be great to find a way to represent this correctly.

 

Thank you for any help you can give.

[DRAWZILLA]

You might try a ceiling plane slopped the same as the roof but installed lower than the roof.  of course, remove the drywall under the roof. the ceiling plane has its own framing to make any size and direction you need.

[Joe_Carrick]

A couple of comments:

1. Please fill in your "Signature" so we know what version and hardware you're using.
2. Please post Questions in the Q&A Forum.  Tips and Techniques is for sharing your tried and true methods.
3. You could do one of two things to solve this:

• Use 2x12 Rafters
• Use 2 Framing Layers (2x8's and 2x4's) for the Roof Framing. (the framing would be stacked but only 11" thick so you might want a 1" air gap between)

OTOH, if this is an existing attic and you just want to furr-down then Perry's method would probably best.

 

[ChiefUserDQ]

That worked! Thank you so much. I had never used the ceiling plane feature. My rafter continues as 2x8 to exterior wall and I was able to align new ceiling structure with framing reference and roof rebuild. Perfect. Thank you Perry.

 

[ChiefUserDQ]

Sounds good Joe. It was important that the 2x8 alone continued past kneewall and to the ridge so adding depth to the roof framing wasn't a choice for me. Thank you for your pointers.