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Old 01-03-2011, 01:03 PM   #1
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Ceiling Joist Repair


Hello, I'd really appreciate any advice any of you more knowledgeable guys can give me with this problem.


I bought a retirement home a few years ago which was build back in the 1960s. It is stick framed with a Hip shaped roof. The basic structure is about 85 feet long and 28 feet wide. An internal weight bearing wall runs down the center of the house 14 feet from either exterior wall.


Here's the problem. I had a general contractor doing some electrical work in the house last week and it required him to run some wiring in the attic. He discovered that the ceiling joists which cross the house every 16 inched are comprised of two 14 foot 2 x 6's butted together on the center wall which is about 4 inches wide. Over the years these 2 x 6's have shrunk in length and pulled apart. All are still supported on top of the interior wall but in many cases only by fractions of an inch.

The general contractor says in California, from where he recently relocated, this would be dangerous due to earthquakes but here in Pennsylvania it still maybe acceptable. He said that if it where him, he would 'sister' another (2 x 6), 8 feet in length across the gap .... 4 feet on each side. However when I gave him the okay to do so, he suggested getting another opinion.


Any ideas????

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Old 01-03-2011, 02:57 PM   #2
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Lumber shrinks very little in the long direction as it dries. The ceiling joists should have been nailed together at the overlap and nailed to the top of the bearing wall.

I would look into the possibility that these were never nailed together in the first place, and over time, the weight of the roof has pushed the exterior walls out of plumb.

The tell-tale sign would be if the joists near the middle of the house were bearing less than the joists near the ends of the house. The corners would tend to hold while the middle half of the wall would bow out.

Sistering them properly would halt any further spreading


Last edited by CplDevilDog; 01-03-2011 at 03:00 PM. Reason: More info
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Old 01-03-2011, 03:15 PM   #3
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Thanks for your response.

When the ceiling joists were put up, they really never were 'sistered'. They were placed end to end then nailed down into the middle wall. Now they have spread apart, probably about a 1/2 inch with nails being partially extracted about the same amount.

If an eight foot 2 x 6 was 'sistered', four feet on each side of the 'gap', do you think that would suffice?

Thanks for your feedback.
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Old 01-03-2011, 04:01 PM   #4
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Sorry, I missed the butt joint in the first post.

Sistered should be fine, the fact that it has only moved .5" in 40 odd years suggests another force acting to hold the walls together (collar ties?), but if you have any questions consult an engineer for the exact structural fix.

He'll most likely tell you the same thing, but it will come with a nice diagram and some math.
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Old 01-03-2011, 04:59 PM   #5
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Originally Posted by Schoenly View Post
Thanks for your response.

When the ceiling joists were put up, they really never were 'sistered'. They were placed end to end then nailed down into the middle wall. Now they have spread apart, probably about a 1/2 inch with nails being partially extracted about the same amount.

If an eight foot 2 x 6 was 'sistered', four feet on each side of the 'gap', do you think that would suffice?

Thanks for your feedback.
If possible, clamp these two joists together and then drill holes to bolt them together permanently.
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Old 01-03-2011, 06:47 PM   #6
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Originally Posted by handy man88 View Post
If possible, clamp these two joists together and then drill holes to bolt them together permanently.
Okay, thanks much.
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Old 01-03-2011, 07:00 PM   #7
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Couple of comments.

First, unless I did not understand the post, it would be impossible to bolt the existing joists together, since they fail to overlap. Normal practice is to overlap the joists over the center support, nail the joists together, and nail the joists to the center support.

Second, the comment about wood not shrinking along the grain is exactly correct. It is unlikely that the joists shrunk, more likely is exactly what was suggested, specifically the walls spread apart. You should check the walls to see if they are plumb, however a half inch movement would be hard to catch.

You noted that in some cases the joists are only supported by fractions of an inch. Normal practice is to have at least 1-1/2 inches of bearing for a beam on a support, and for joists, they normally overlap by at least six inches either side of the supporting beam. Since they do not, adding a four foot jsection of joist on either side to make a sandwich would be a good idea, through bolted to keep the whole setup intact.
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Old 01-03-2011, 07:24 PM   #8
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Quote:
Originally Posted by Daniel Holzman View Post
Couple of comments.

First, unless I did not understand the post, it would be impossible to bolt the existing joists together, since they fail to overlap. Normal practice is to overlap the joists over the center support, nail the joists together, and nail the joists to the center support.

Second, the comment about wood not shrinking along the grain is exactly correct. It is unlikely that the joists shrunk, more likely is exactly what was suggested, specifically the walls spread apart. You should check the walls to see if they are plumb, however a half inch movement would be hard to catch.

You noted that in some cases the joists are only supported by fractions of an inch. Normal practice is to have at least 1-1/2 inches of bearing for a beam on a support, and for joists, they normally overlap by at least six inches either side of the supporting beam. Since they do not, adding a four foot jsection of joist on either side to make a sandwich would be a good idea, through bolted to keep the whole setup intact.
If the joists do not overlap, they can be sandwiched between two outer boards and then that setup needs to be clamped together, holes drilled, and then bolted together.
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Old 01-10-2011, 10:48 AM   #9
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I want to thank all who have given me their advice, I really do appreciate it. Let me summarize what I understand should be done, then please point out anything you see in error.

Where the existing ceiling joists are butted together, I will sandwich that section between two four foot sections of 2"x 6" segments, clamped together then drilled and bolted. Correct????

What size bolts should I use and how many for each joint, (4)?

Thanks.

Schoenly
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Old 01-10-2011, 02:23 PM   #10
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A sandwich using bolts is a good plan. I always use 1/2 inch bolts for this type of repair. Oversize the holes by 1/16 inch to allow an easy fit. Preclamp the sandwich prior to drilling to insure that the holes line up. For this type of sandwich, I recommend four bolts on each side of the sandwich, total of 8 bolts. No bolt should be closer than 2 inches to the end, and in this case the bolts can be set about 1-1/4 inches from the edges of the 2x6. Once you have made the fix, you should consider adding an L bracket to attach the joist sandwich to the main beam. Simpson makes a variety of brackets for exactly this purpose.

By the way, this will do NOTHING to bring the walls back to plumb if they are out, which you definitely should check. Also, 2x6 is pretty minimal for a 14 foot span, whether it meets code depends on the load above. Again, sandwiching will do nothing to improve the strength of the joists. You may want to check the adequacy of 2x6 for your specific load condition before you undertake this repair.
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Old 01-10-2011, 03:00 PM   #11
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Thanks again for all your advice. It's been a great help to me.

- Schoenly
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Old 01-10-2011, 03:35 PM   #12
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Quote:
Originally Posted by Schoenly View Post
I want to thank all who have given me their advice, I really do appreciate it. Let me summarize what I understand should be done, then please point out anything you see in error.

Where the existing ceiling joists are butted together, I will sandwich that section between two four foot sections of 2"x 6" segments, clamped together then drilled and bolted. Correct????

What size bolts should I use and how many for each joint, (4)?

Thanks.

Schoenly
If you don't feel like bolting, you can put some construction adhesive into the sandwich first on both sides of the 2x6 bread, and then clamp together. Then, use a framing nail gun and put some nails on both sides of the sandwich, or drive wood screws.

If you use bolts, I would recommend at least 3/4" and make sure you use washers. It may actually be easier to prenail and then cross drill the studs before bolting. I would recommend at least two bolts every two feet on each side of the joint.
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Old 01-13-2011, 03:12 PM   #13
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Thanks much, I appreciate it.
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Old 01-14-2011, 06:02 PM   #14
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Thanks much, I appreciate it.
Make that lag screws, not wood screws.

You'll probably need to predrill and use an impact wrench to drive.

Last edited by handy man88; 01-14-2011 at 06:24 PM.
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Old 01-14-2011, 06:23 PM   #15
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Got it, thanks.

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