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Old 09-30-2010, 09:51 PM   #1
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Proper installation of sister joists


Hi,

My contractor is in the process of putting in sister joists to strengthen and level the floor. I've attached a picture and was wondering if he was properly installing the sister joists?

Any feedback is welcome.
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Proper installation of sister joists-imag0199.jpg  

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Old 10-01-2010, 11:36 AM   #2
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Proper installation of sister joists


The 2x4's will do more to level the floor then to add strength. What size joists do you have and what length do they span?
What's the reason for the project?
Ron

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Old 10-01-2010, 11:46 AM   #3
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Proper installation of sister joists


I don't have joist size on hand, but they span about 20'. The primary reason is to level the floor, not really strengthen it.
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Old 10-01-2010, 12:30 PM   #4
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Proper installation of sister joists


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I don't have joist size on hand, but they span about 20'. The primary reason is to level the floor, not really strengthen it.
Span is the length that the joists are unsupported. These are traditional 2x8's or 10's so 20feet would be too far to be unsupported.
For leveling, this is fine.
I'd have used T&G 3/4" plywood, glued and screwed.
Ron

Last edited by Ron6519; 10-01-2010 at 12:33 PM.
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Old 10-01-2010, 12:33 PM   #5
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Proper installation of sister joists


I'd be extremely surprised if an engineer signed off on that one. What I see in the photos doesn't make any sense. Also I wouldn't call a 2x4 a joist. Especially when it's cut right near the center of the span (I see two 2x4's butted together there). And neither could I call that scheme reinforcement, because it's on the chord in compression, not the chord in tension.

Do your self a favor, call a local engineer and get a quick reinforcement scheme put together before the subfloor goes back on. You've spent all that money on taking the floor apart, you should make absolute sure that what's getting put in will work.

Also, make sure he puts the bridging back in.
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Old 10-02-2010, 08:20 PM   #6
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Proper installation of sister joists


The contractor already put the new subfloor on. I'm extremely unhappy with it. Some areas squeak and the room you see in the picture has a lot of bounce near the center. I noticed they weren't using glue or screws, but nails with threads on the ends.

What would be my options now that the subfloor is already on. How can I convince the contractor that the subfloor installation is subpar?
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Old 10-02-2010, 08:59 PM   #7
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Proper installation of sister joists


As stated, 20 ft is too far for 2x8 or 2x10 joists. There should be something midspan to support them (simplest is a perpindicular beam running crosswise below the old joists). A legitimate contractor should have known that.

When you hired this contractor, did you put down anything about the job in writing?

Were you supposed to get a building permit, and did you or your contractor do so? Was it part of the deal that the contractor would know and take care of that?

Here's what I'd do:

(1) Hire a structural engineer to assess the floor. In particular, what was the reason the old joists were out of level in the first place? Was it just because they are over too great a span, or is there something else going on too, such as a problem at the foundation or rim joists? The engineer will create a plan to address the problems.

(2) Check out the first guys license if any
See New garage floor with pooling water

(3) Before you withhold payment or get too heated with the first guy, organize answers to above questions and then consult with an attorney familiar with mechanics liens.

Steve El
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Old 10-02-2010, 09:17 PM   #8
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Proper installation of sister joists


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Originally Posted by carbon View Post
The contractor already put the new subfloor on. I'm extremely unhappy with it. Some areas squeak and the room you see in the picture has a lot of bounce near the center. I noticed they weren't using glue or screws, but nails with threads on the ends.

What would be my options now that the subfloor is already on. How can I convince the contractor that the subfloor installation is subpar?
You have multiple issues. Bouncy floors are due to excessive spans of undersized joists. Squeaks are due to wood riding up and down on nails. Or plywood panels too close together, rubbing against each other. This should not be happening on a floor that's been down for a few heartbeats.
Sounds like the floor should come up. Additional support added and a T&G 3/4" plywood glued and screwed down.
Ron

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