Help! Sagging garage roof - will this work?

Reply

  #1  
Old 11-03-12, 11:43 AM
Member
Thread Starter
Join Date: Mar 2003
Location: NE Pennsylvania
Posts: 296
Received 0 Votes on 0 Posts
Help! Sagging garage roof - will this work?

I have a 20 x 26 garage. Past owner replace some roof rafters with 2 x 4's, roof is sagging in areas with 2x4's (3 areas) I was wondering if i "lift" the 2x4 to correct position and sister the proper size rafters to them, will this resolve sagging?.

If this is possible - should the lift be done gradually (like leveling a house) or can I do it all at once?

A contractor told me the roof will never fail - this could be true I would like to beef up all the rafters. The ridge board looks like a 1 x 6 -

questions
1. Does it make sense to sister larger rafters to 2 x 4's
2. If so can I push 2 x 4 up all at once or does it need to be gradual
3. What about ridge board? to thin to consider repairs of rafters?
 
Sponsored Links
  #2  
Old 11-03-12, 12:02 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 23,368
Received 228 Votes on 210 Posts
Yes, you can sister larger rafters. Yes you can likely do it all at once, but you would want to keep an eye on the old 2x4 rafter connection on both ends as you jack to make sure that you are not simply pulling one side of the rafter away from the ridge or top plate as you raise it. You would also likely need to raise all the rafters that you want to correct, not just one. The size of the ridge board is irrelevant, since each set of opposing rafters and their connecting ceiling joist are what form the triangle that gives the roof its strength. The ridge simply connects them laterally. No it's not up to today's standards, but in old buildings, few things are.

Something else that would stiffen the roof is to install collar ties. If you don't know what that is, go to google images and look for an illustration of what I mean.
 
  #3  
Old 11-03-12, 12:09 PM
Member
Thread Starter
Join Date: Mar 2003
Location: NE Pennsylvania
Posts: 296
Received 0 Votes on 0 Posts
Hmmm maybe put the new rafter in place (unattached) and support it before i lift 2 x 4's,,,,
 
  #4  
Old 11-03-12, 12:24 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 23,368
Received 228 Votes on 210 Posts
That won't work, since your new rafter needs to fit tight to the ridge AND sit on top of the top plate. It will be too long to do that. There are several ways to raise the roof. Easiest way would probably be to build a header and lay it on top of your ceiling joists. Then install some sort 2x4s under each rafter (cut an angle on top to match the roof pitch). If you cut them a little long, you will be able to hammer them in (raising the roof as you do) and then temporarily screw them into place. Your header can be as long as you need... and you can support the ceiling joists and keep them from bowing under the added weight by adding some 2x4's down to the floor.

The best way to get them perfectly straight with one another would be to build a temporary header, place it perpendicular against the bottom of all the sagging the rafters, block it so it doesn't slide, then jack that header up. That would ensure that all the rafters will be straight with one another. But then you would need to block the rafters as mentioned above... and then remove this temporary header so that you can sister the rafters. Your rafters will need to be cut to the exact length, with a plumb cut on top and a level seat cut (and birdsmouth) on bottom, then they will need to be positioned into the rafter bay diagonally and then pry them / beat them over into place.
 
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
 
Ask a Question
Question Title:
Description:
Your question will be posted in: