Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Building & Construction

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

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-21-2011, 11:24 PM   #1
Newbie
 
Join Date: Feb 2011
Posts: 14
Rewards Points: 0
Share |
Default

HELP reinforce a cracked rafter


Help DIYers...!

I'm a first time home owner in Southern California, total newbie in home repairs but I'm very motivated to learn..

Pls help me figure out how to reinforce my sagging garage roof. I noticed a huge crack in one of the rafters, and another 1 is starting to appear on a second one. Im thinking of sistering the rafter... and I need suggestions how to properly do it. You may also have other additional tips or suggestions how to accomplish the task, other than sistering... I really would appreciate your help.

Pls see image below:
Attached Thumbnails
HELP reinforce a cracked rafter-garage-ceiling.jpg  

Wolfen is offline   Reply With Quote
Old 02-22-2011, 12:39 AM   #2
Member
 
Join Date: Jan 2011
Posts: 215
Rewards Points: 0
Default

HELP reinforce a cracked rafter


cut some 3/4 plywood and glue screw it to the rafters

bluebird5 is offline   Reply With Quote
Old 02-22-2011, 12:44 AM   #3
Member
 
Join Date: Dec 2008
Location: Fairbanks, AK
Posts: 1,847
Rewards Points: 0
Default

HELP reinforce a cracked rafter


Wolf: Wood cracks. A crack is different, in my mind, from a split. A split is where the board has been stressed beyond its strength limit and is failing. Are any of the boards you see severely bent? Ends broken, and splitting/tearing apart? If the ends of the boards are solid (not going anywhere), then you probably have nothing to worry about. However, keep an eye on them, and if you see signs of complete failure, like pulling apart or tearing, then get excited. I am not an engineer; just a DIY guy.
jklingel is offline   Reply With Quote
Old 02-22-2011, 06:35 AM   #4
Member
 
Join Date: Dec 2008
Location: Wilmington, DE
Posts: 3,118
Rewards Points: 0
Default

HELP reinforce a cracked rafter


Not sure what I am looking at in the pic. I see 6 boards coming together at one point and nothing supporting that point, or am I wrong?? Is the 2x6 a single board??? Is the roof sagging at this point??? I also agree with the above, a split is not necessarily a crack.
Just Bill is offline   Reply With Quote
Old 02-22-2011, 08:34 AM   #5
Member
 
Join Date: Jan 2009
Location: Vermont
Posts: 762
Rewards Points: 0
Default

HELP reinforce a cracked rafter


I believe the reason it cracked is because it is such a low pitch. From your pics it looks like a 3:12 or even 2:12. I'd turn your last set of common rafters into a truss with a vertical support to support the end of the ridge. Once
you've fixed the cause, then you can fix the resulting damage
mrgins is offline   Reply With Quote
Old 02-22-2011, 09:02 AM   #6
Newbie
 
Join Date: Feb 2011
Posts: 14
Rewards Points: 0
Default

HELP reinforce a cracked rafter


jklingel & Just Bil - The opposite ends of those rafters rest on the garage wall. The opposite end of the main joist (the one i captioned "2 x 8 JOIST") rests on the main wall of the house. Only the main joist is in perfect horizontal position, the rafters are angled down to the garage walls. i'll try to upload some more images later..

so yes, it seems more of an end split because it spans about 3 feet from one end of the rafter. Does that mean it is more serious?

mrgins - yes, it does seem to have a low pitch (my understanding of that is that the angle of the rafters is not acute enough). Also, it seems like the splitting was caused at one time when the previous owners had a huge airconditioning unit placed on top of the garage roof - maybe too many men on the roof at the same time. The part where the arconditioning unit rests seems stable though and is far from the meeting point of these rafters.
Wolfen is offline   Reply With Quote
Old 02-22-2011, 09:19 AM   #7
Newbie
 
Join Date: Feb 2011
Posts: 14
Rewards Points: 0
Default

HELP reinforce a cracked rafter


here's one perspective of the garage roof... sorry about the poor drawing
Wolfen is offline   Reply With Quote
Old 02-22-2011, 09:29 AM   #8
Member
 
Join Date: Jul 2009
Posts: 951
Rewards Points: 0
Default

HELP reinforce a cracked rafter


looks to me like that board is split from that point to the end.

If that's the case, then the best thing is to probably cut a new one to fit right next to it, jack it up a little more than necessary to remove the sag, and glue (with construction adhesive) and screw the two together.
pyper is offline   Reply With Quote
Old 02-22-2011, 10:27 AM   #9
Newbie
 
Join Date: Feb 2011
Posts: 14
Rewards Points: 0
Default

HELP reinforce a cracked rafter


Hi, I noticed some of you suggested "screwing" the rafter instead of just nailing.. Why and What type of screw should I use?
Wolfen is offline   Reply With Quote
Old 02-22-2011, 12:01 PM   #10
I ask the impossible!
 
Join Date: Aug 2010
Location: Royal Oak, Michigan
Posts: 1,069
Rewards Points: 0
Blog Entries: 7
Default

HELP reinforce a cracked rafter


With a 3 foot span, if that's what I'm reading, it probably doesn't matter one way or the other, but putting in a ridge support isn't necessarily a good idea because you may have different expansion rates going on with rafters than joists, and tieing a ridge to a joist can create loading under certain conditions:

http://www.buildingscience.com/docum...od-but-strange

Another point to make... where you've pointed to a 2x8 "joist" actually that would be a ridge board I think.

I'd tend to suggest nailing if you have an air nailer you can get in there. Otherwise screwing might be easier due to the ergonomics - not much space to swing a hammer. But a nail will tend to be better able to handle shear stresses whereas screws are better for tensile loading. Note how much easier it is to break off a screw by bending it while a nail will tend to bend without breaking.
WillK is offline   Reply With Quote
Old 02-22-2011, 01:38 PM   #11
Member
 
Join Date: Jan 2009
Location: Vermont
Posts: 762
Rewards Points: 0
Default

HELP reinforce a cracked rafter


Quote:
Originally Posted by Wolfen View Post
Hi, I noticed some of you suggested "screwing" the rafter instead of just nailing.. Why and What type of screw should I use?
As a remodeler, I screw more than I hammer, if you'll excuse the expression. Less pounding and shaking, easier to set a screw with an impact driver than trying to swing a hammer, better gripping power. Use an exterior decking screw, 2 1/2" long
mrgins is offline   Reply With Quote
Old 02-22-2011, 02:21 PM   #12
Member
 
Join Date: Jul 2009
Posts: 951
Rewards Points: 0
Default

HELP reinforce a cracked rafter


Quote:
Originally Posted by WillK View Post
stresses whereas screws are better for tensile loading. Note how much easier it is to break off a screw by bending it while a nail will tend to bend without breaking.
Depends how many of each you use

I tend to use screws for stuff like this because they resist pulling out a lot better than nails, and because it's easy to get out a cordless drill/driver than it is to get out and put away an air compressor. I definitely wouldn't pound nails into a broken board with a hammer.

Looking at the photo, I think I see a problem.

The "2x8 rafter" is not supported at the end. It's actually a structural element (a beam), not a ridge board (if I'm understanding the photo and the drawing correctly) because there are no ceiling joists to resist the lateral forces created by the roof pressing down -- over time the roof will sag and the walls will lean out at the top.

Or is there something not shown?
pyper is offline   Reply With Quote
Old 02-22-2011, 02:57 PM   #13
Registered User
 
Join Date: Mar 2009
Posts: 9,968
Rewards Points: 0
Default

HELP reinforce a cracked rafter


The 2x8 "joist" is actually your ridge board. The last set of common rafters before your hip rafters (at corners) join should have a horizontal rafter tie (or ceiling joist) to keep the walls from spreading and the hip rafters from sagging at the top union.
I see the 2x holding up the back-hang for the garage door track, and a stiffener strut of metal for shear resistance.
Plywood on the sides will probably work, glue and screws or nails.

I am concerned for wall spreading, could you post another picture of the same, from laying on the floor looking up at the union, please?

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 02-22-2011, 03:40 PM   #14
Member
 
Steeler99's Avatar
 
Join Date: Jan 2011
Posts: 120
Rewards Points: 0
Default

HELP reinforce a cracked rafter


I agree with GBR, and I'd suggest measuring the room dimensions at the floor and at rafter bearing height. Measure from the house to the outside wall, at the floor and ceiling. If the upper dimensions are larger than the lower dimensions, then you have a bigger issue than the "split" rafter.

I believe this is splitting because of two reasons

First, the low pitch is causing alot of lateral force on the top of the wall, causing the roof to sag at this particular point. It's minimal sag now, but I believe it will just get worse with time.

Second, the rafters are topping out...anyone see the space at the bottom where they all come together. This would cause natural weakness IMO...This gap may have been caused by the wall moving outward.
Steeler99 is offline   Reply With Quote
Old 02-22-2011, 03:52 PM   #15
Newbie
 
Join Date: Feb 2011
Posts: 14
Rewards Points: 0
Default

HELP reinforce a cracked rafter


Ok, yeah the main 2 x 8 is a ridge board not a joist - Ive just googled it

Gary - I'll take another photo from laying on d ground later, here below are some that I took before leaving earlier, I hope I can provide u guys better info. The last image with multiple rafters altogether is the spot where the aircondition unit is sitting. There are no other weight on d roof other than maybe the pull force of my garage opener..
Attached Images
    

Wolfen is offline   Reply With Quote
Reply


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
Rafter tie adjustment albanello Building & Construction 10 11-20-2010 10:26 PM
removing rafter ties: garage conversion neil_9 Introductions 0 09-29-2010 07:55 PM
Rotted Lookout Beam Supporting Barge Rafter rwbil Building & Construction 1 08-15-2010 11:40 AM
Rafter Ties on Vaulted Ceiling timsgills Building & Construction 2 01-07-2010 03:02 PM
Moving Attic Access -- Same Rafter or Different ?? wrldruler Carpentry 1 10-19-2008 06:03 PM




Top of Page | View New Posts

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