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

How far do sistered floor joists have to extend passed damage?

How far do sistered floor joists have to extend passed damage?

Reply

  #1  
Old 03-20-18, 09:55 AM
Member
Thread Starter
Join Date: Jan 2015
Location: USA
Posts: 34
How far do sistered floor joists have to extend passed damage?

A family member moved a trailer onto our property and we're repairing some water damage. Water was able to get behind the siding or soak up through the bottom edge which lead to damage of the last ~6" of the floor joists over a 10' section of the header joist running parallel with the exterior wall that they tie into. The header joist is gone and will be replaced, but we cannot replace the floor joists or sister them full length because of ductwork and water and electrical lines running perpendicular through the floor joists.

It's a mobile home, 16' wide with full length 2x8 joists at 16" spacing set on 2 steel I-beams (also the trailer used to transport it.)
8' span between the I-beams with the remaining 4' on each side just hanging.

I can only get the sister joist to the first I-beam which is 3.5' of contact with the original joist. Will enough nails over that length be able to support the exterior wall or do I need to add another beam?
 
Sponsored Links
  #2  
Old 03-20-18, 01:08 PM
Forum Topic Moderator
Join Date: Mar 2005
Location: USA
Posts: 43,395
If I understand correctly that you only have the last 6" of the joist that is damaged, then your 3.5' of sistered joist will be plenty good.
 
  #3  
Old 03-20-18, 08:23 PM
Member
Thread Starter
Join Date: Jan 2015
Location: USA
Posts: 34
Okay, thanks.

Yes, the last 6" of the joists are gone along with the rim/header joist from what actually appears to be fire damage instead of just water damage.

I was thinking that the sister joists may need to be supported on both ends in order to reliably substitute a singular unbroken joist, so I was worried about the weight of the roof, ceiling, and wall overburdening the fasteners and allowing the short sister joists to pivot with the I-beam as a fulcrum because the new sister joists don't run far enough passed the I-beam to allow the building itself to hold down the other end.

Anyway, I've got it installed and it seems sturdy enough.

Thanks, again.
 
  #4  
Old 03-21-18, 02:41 AM
Forum Topic Moderator
Join Date: Mar 2005
Location: USA
Posts: 43,395
The sistered joist is supported by the original joist provided the new is secured to it well.
 
Reply

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
'