Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Insulation

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 06-13-2012, 07:06 PM   #1
Member
 
Join Date: Apr 2012
Posts: 34
Rewards Points: 25
Default

The Correct Blocking of Knee Wall Stud Bays That Meet a Sloped Roof


The 2x4 studs in the knee walls of the finished attic room in my 1950's 1.5 story house are cut to the roof angle and tacked to the rafters. The stud bays have no horizontal blocking at the top...
Name:  Knee-Wall-Top-Joint.jpg
Views: 1438
Size:  22.0 KB

It appears to me that to properly block the stud bays in order to enclose the insulation batts, a simple 2x4 block will not suffice.
The Correct Blocking of Knee Wall Stud Bays That Meet a Sloped Roof-knee-wall-blocking.gif
A horizontal 2x4 block will leave a gap at the corner. An angled 2x4 block will not provide sufficient surface for sealing to the sheathings. A 2x6 trimed to a parallelogram in profile seems to be a solution. Is there better technique?

Lascaux is offline   Reply With Quote
Old 06-25-2012, 01:44 PM   #2
Member
 
AGWhitehouse's Avatar
 
Join Date: Jul 2011
Posts: 1,378
Rewards Points: 500
Default

The Correct Blocking of Knee Wall Stud Bays That Meet a Sloped Roof


Option 1 (left) is easiest and the "empty" zone can easily be filled with insulation prior to drywall installation. It gives you nice flat nailing surfaces for both the drywall faces as well.

The 2x6 method would also work, but will be more money and more labor time for minimal thermal gains.

__________________
Life's too short...so enjoy it!
AGWhitehouse is offline   Reply With Quote
Old 06-26-2012, 02:20 AM   #3
Member
 
Join Date: Nov 2011
Posts: 513
Rewards Points: 500
Default

The Correct Blocking of Knee Wall Stud Bays That Meet a Sloped Roof


How about option 1 and fill the void with spray foam?
Evstarr is offline   Reply With Quote
Old 06-26-2012, 07:06 PM   #4
Member
 
AGWhitehouse's Avatar
 
Join Date: Jul 2011
Posts: 1,378
Rewards Points: 500
Default

The Correct Blocking of Knee Wall Stud Bays That Meet a Sloped Roof


Quote:
Originally Posted by Evstarr View Post
How about option 1 and fill the void with spray foam?
No real need for it there and there is no backing to contain it upon expansion. The 2x6 rafter will have a 4" batt. in it already per that detail, so cutting the batt to the length/angle/etc. to accomodate the void would suffice.
__________________
Life's too short...so enjoy it!
AGWhitehouse is offline   Reply With Quote
Old 06-27-2012, 11:37 PM   #5
Registered User
 
Join Date: Mar 2009
Posts: 9,968
Rewards Points: 2,000
Default

The Correct Blocking of Knee Wall Stud Bays That Meet a Sloped Roof


I've always framed knee walls as Option 2, the drywall doesn't require fastening to the top plate unless a special shear/fire wall. Check with your local AHJ. Be sure to air-seal the joint at bottom plate/drywall/floor, per minimum Code.

Gary
__________________
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.
Gary in WA is offline   Reply With Quote
Old 06-30-2012, 03:50 PM   #6
Member
 
Join Date: Apr 2012
Posts: 34
Rewards Points: 25
Default

The Correct Blocking of Knee Wall Stud Bays That Meet a Sloped Roof


Quote:
Originally Posted by GBR in WA View Post
I've always framed knee walls as Option 2, the drywall doesn't require fastening to the top plate unless a special shear/fire wall. Check with your local AHJ. Be sure to air-seal the joint at bottom plate/drywall/floor, per minimum Code.

Gary
Wouldn't one also want to air seal at the top, in order to completely enclose the cavity? It seems to me that option 2 is the least preferable because it delivers the smallest contact surface and therefore the most potential for air leakage both at construction and if later shifting occurs.
Lascaux is offline   Reply With Quote
Old 07-04-2012, 11:09 PM   #7
Registered User
 
Join Date: Mar 2009
Posts: 9,968
Rewards Points: 2,000
Default

The Correct Blocking of Knee Wall Stud Bays That Meet a Sloped Roof


I have ripped plates at an angle to fill the front top gap before (similar to 3). My reasoning is the rafters (roof) are directly tied to the studs/plates (wall) with less chance of drywall tape cracking at that joint when the roof flexes with the changing seasons/wind pressures. Solid framing holding the joint rather than paper tape.... You should also caulk the ceiling/wall drywall joint (at drywall install) to help as in ADA: http://www.buildingscience.com/docum...wall-approach/

Be especially careful at any electrical outlets and use a foam pad there, that 1/8" hole around it is about 1-1/2" square; Fig. 4; http://www.buildingscience.com/docum...wall-approach/
Any moisture in the wall would dry to the room side without a vapor barrier (not needed because of f.b. keeping cavity warm), but why let it in anyway?

Gary

__________________
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.
Gary in WA is offline   Reply With Quote
Reply

Tags
blocking, framing, insulation, knee wall


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Built-in cabinets/shelves in bonus-room knee wall flamtap Remodeling 2 10-26-2009 09:14 AM
Finding angle where two roof slopes meet lindllc Roofing/Siding 4 11-10-2007 04:49 PM
% total roof load on interior bearing wall? Grommet Building & Construction 1 03-29-2007 07:37 AM
Atlantic-need your opinion on markd's comments about my vapor barrier? yummy mummy Building & Construction 11 03-07-2007 09:47 AM
Roof Sagging wall bowing christy123 Carpentry 37 12-29-2006 04:16 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.