Go Back  DoItYourself.com Community Forums > Interior Improvement Center > Framing, Flooring and Sub-Flooring
Reload this Page >

Load carrying capacity of 2X4 Framing of Attic Floor

Load carrying capacity of 2X4 Framing of Attic Floor


Old 06-06-07, 10:04 PM
Thread Starter
Join Date: Oct 2004
Location: USA
Posts: 114
Load carrying capacity of 2X4 Framing of Attic Floor

The question of the load carrying capacity of the framing on a project I am working on came up in my post to a different forum.

I am working on a 1910 era Craftsman style house. I am cleaning the attic, eliminating the knob and tube electric and re-insulating.

I would like to have dead storage up there (you really can’t stand – max head room is probably 5 feet under the peak) and was thinking of adding ¾ inch plywood screwed to the 2X4 joists.

The joist construction is 2X4 with 16 inch spacing and lath and plaster on the underside. The longest run between a load carrying wall is probably 10/11 feet.

From a practical point of view can the structure withstand the weight of the plywood and storage? What would be the live/dead load limits? Are there some simple solution that could be designed that would strengthen the assembly without compromising the space?

Sponsored Links
Old 06-07-07, 01:31 PM
Join Date: Jan 2007
Location: Central Indiana
Posts: 389
What are the live/dead load limits on a 2x4 joist structure? -
2x4 on 16" centers, asuming E = 1.2x10^6 (SPF of today), 10'3" span, L/240 deflection, allowable loading = 10 psf live/5psf dead load. In other words, you can't (or shouldn't) use it this way for storage.

2x6's alone would up this to over 20 psflive/10 psf dead. My suggestion - sister 10' 2x6's to the existing 2x4's with an air nailer, this would up the capacity even more.

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

Thread Tools
Search this Thread
Display Modes