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Old 02-08-2012, 02:24 PM   #1
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Cracked Rafter


I'm slowly fixing up our unfinished detached garage and after I installed some lights inside, I noticed that one of the rafters had a 2-foot crack in it. The former owners had a bad habit of hanging things on the rafters and ties even though it is framed with 2x4s, I'm also sistering 2 cracked rafter ties that they overloaded. Anyway, I just wanted to confirm that the following steps I take for the rafter are right (I took most of them from other related posts).

1. Apply construction adhesive to the rafter's crack.
2. Jack the rafter to close the gap.
3. Sister 2x4x8s to either side of the rafter. Nails or screw?
4. Lag Bolts? Should I also drill and install these through the bottom of the rafter to keep it in place?

Thanks,
Alfredo

Cracked Rafter-rafter.jpg

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Old 02-08-2012, 02:59 PM   #2
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Cracked Rafter


Is it only one that is cracked? Are others bowed?
If it is because of hanging things and the 2x4's are strong enough for the roof, sistering another 2x4 is a good idea.
I just used screws from the bottom to screw the crack together. No need for lag bolts.
The strength is in the new 2x4 sistered to the old one.
Nails or screws does not really matter.
I like to go full length if at all possible.

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Old 02-08-2012, 03:20 PM   #3
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Cracked Rafter


I am guessing that rafter cracked because of the knots. As you already figured out, the existing rafter has no strength left, so it is only useful as a point to attach sister rafters. Personally I wouldn't spend any time gluing it, lagging it or anything else, I would jack it to position, then attach two sisters as you suggested on either side, nailed, screwed or bolted through so they are attached to each other. As Mae Ling said, full length rafters will do the trick. Of course, your 2x4 rafters may be undersized, but that is a different discussion.
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Old 02-08-2012, 05:56 PM   #4
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Cracked Rafter


@mae-ling: yes and no, this is the only rafter with a crack on this side of the ridge board; there's another rafter on the other side that had a smaller crack, but they used a couple of screws to close it from underneath.
@Daniel: you're right, this might have been due to the knots as there are no signs of holes from utility hooks on this rafter (unlike the other ones).

Thanks for all your replies. Looks like I'll be sistering the rafter on both sides after screwing the crack closed. I'd like to go full length with them but these rafters end right on the top plate with a piece of blocking on either side or a rafter tie on one side, so there isn't a sound area to rest on.
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Old 02-08-2012, 06:12 PM   #5
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Cracked Rafter


Looks like that roof had metal a roof on it at one time and someone removed it, sheathed it and used shingles instead.
Not a great move with 2 X 4's and that low a slope.
May want to think about adding diagnals from mid point of the roof to the rafters for added support. If your using that area for storage build a knee wall.

Are those 2 X 4's 24" or 16" apart?
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Old 02-08-2012, 11:05 PM   #6
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I'd sister that other rafter too.

Also are there collar ties on all the rafters? doesn't look like it by the pic.
Are the cracked ones ones without the collar ties?
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Old 02-09-2012, 12:09 PM   #7
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@mae-ling: Will do on sistering the other rafter. There are collar ties on every 3rd rafter. Should it be on every one?
@joecaption: I've no idea what the previous roof was, we bought it 8 months ago and it looks like the roofs are relatively new. I've no plans for using the area for storage, the only thing I need to install is a garage door opener and I bought a pair of 2x6x20' to put across the rafter ties for the opener and will connect them to the rafter ties with hurricane ties to give them some rigidity.

Here are a couple more pictures:

View from the front of the garage.
http://zariab0y.smugmug.com/Other/El...P1000094-L.jpg

Side View. Notice all the utility hooks they used. There's a 4x8 plywood sheet at the end that held the remnants of a train set and was loaded with junk sitting on the top plate and the rafter tie, I believe this caused the tie to crack on a knot and they just nailed that 1x6 to the rafter to prevent a collapse. I've removed all that junk and that rafter tie is one I'll be sistering with a full lenght piece.
http://zariab0y.smugmug.com/Other/El...P1000086-L.jpg
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Old 02-09-2012, 12:12 PM   #8
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Wrong size nails were used on that roof.
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Old 02-09-2012, 12:15 PM   #9
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Quote:
Originally Posted by Daniel Holzman View Post
I am guessing that rafter cracked because of the knots.
Could of cracked because of load too. Has there been any heavy snow or anything else on the roof?
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Old 02-09-2012, 12:20 PM   #10
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@Jasin: I'm in Southern California, so no snow just rain. In scrutinizing some pictures I took after we moved in, it appears the crack was already there when we moved in but didn't see it because there was inadequate lighting in the garage. Could you elaborate on why the nails are wrong for that roof?
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Old 02-09-2012, 12:58 PM   #11
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Quote:
Originally Posted by Zariab0y View Post
Could you elaborate on why the nails are wrong for that roof?
Many are way, way to long ... I see a full 1" extra of length on those nails. And it is really hard to tell from the picture so I could be mistaken but they do not look like roofing nails.

You should have a look at this thread here for more information on roofing nail length.
Roofing nail length...

Last edited by jasin; 02-09-2012 at 01:09 PM.
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Old 02-09-2012, 01:03 PM   #12
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Quote:
Originally Posted by Zariab0y View Post
@Jasin: I'm in Southern California, so no snow just rain. In scrutinizing some pictures I took after we moved in, it appears the crack was already there when we moved in but didn't see it because there was inadequate lighting in the garage.
Hard to say then.
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Old 02-09-2012, 02:00 PM   #13
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Cracked Rafter


Do not worry about the roof nails.

Last edited by M Engineer; 02-09-2012 at 02:14 PM. Reason: Did not want to take the thread a new direction
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Old 02-09-2012, 02:41 PM   #14
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Quote:
Originally Posted by M Engineer View Post
Do not worry about the roof nails.
We should always worry about anything that is done wrong. We do not want stuff breaking, costing us more in the long run, etc.

Last edited by jasin; 02-09-2012 at 02:44 PM.
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Old 02-09-2012, 03:24 PM   #15
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Cracked Rafter


Having nails that are too long isn't going to cause any damage in this case.

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