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Old 04-20-2012, 09:25 AM   #1
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Uneven Floors and Joist Spacing


I have a new construction home (8 months old), and ever since we've moved in we've had significant grout cracking, drywall cracking. Also, our floors have a number of dips and slopes. In some spots we've tested, it dips as much as a 1/2 inch over 4 feet.

We've spent a lot of time pondering why this is all occuring, etc. I was in my unfinished basement, looking up at the trusses and noticed that they seemed to be spaced at varying distances. In several spots, the trusses are spaced at 28" OC. In other spots its 20, and in other 24, or 25 or 26. Our subfloor is 3/4 inch plywood. We have open web trusses with a depth of 16 inches

I know the plywood is rated for 24" on center, so it would seem to me that it would never be permissible to go beyond 24" and everyone I talk to seems to indicate that you can never go over 24". Looking at the span tables, there is not even a listing higher than 24" on center. When I walk across the floor in some rooms all of our furniture shakes\vibrates.

Also, looking at the joists, it appears some have a small wood shim, others don't, and others are sitting on another layer of plywood. It looks haphazard, as I would have thought it would be consistent across.

My builder is building the same model across the street, and the spacing appears to be vastly different. In this other house, a lot of it appears to be spaced at 19.2, and never goes over 24", there are no shims, and the joists all look to be at the same level.

- Is there any other reason that it would be ok to space more than 24" apart?
- Is the space ok if it is slightly over 24". We have a number of spots at about 24.75
- What remediation options are there to fix this? Can this ever be fixed correctly, or will our house never be the way it should have been if spaced correctly?
- What actions should I request from my builder?
- Is the long term viability of this house greatly diminished?
-

Thank

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Old 04-20-2012, 09:40 AM   #2
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Uneven Floors and Joist Spacing


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Originally Posted by ATL12 View Post
new construction home (8 months old)
significant grout cracking, drywall cracking.
floors have a number of dips and slopes.

In some spots we've tested, it dips as much as a 1/2 inch over 4 feet.

Our subfloor is 3/4 inch plywood... (on) trusses with a depth of 16 inches
In several spots, the trusses are spaced at 28" OC.
In other spots its 20, and in other 24, or 25 or 26.

...it appears some (joists) have a small wood shim, others don't,
and others are sitting on another layer of plywood. It looks haphazard

We've spent a lot of time pondering why this is all occuring, etc.
Did the home come with a warranty by the builder?
Do you know what the law in your state requires?
Do you have a family lawyer?

Ask your family lawyer to recommend an attorney who specializes in construction and real estate. Call them for a consultation.

Among other suggestions... that RE & construction attorney should recommend you to a structural engineer they know to be competent to do a full on inspection and prepare a report.

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Old 04-20-2012, 09:53 AM   #3
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Uneven Floors and Joist Spacing


You actually have a couple of possible issues. The spacing greater than 24 is not always a issue if the trusses are strong enough and the floor is thick enough. In your case 3/4 plywood is only rated to span 24 inches. But I cannot see how this would cause a 1/2 deflection in the floor. You should only see deflection between the trusses not along the trusses with this problem. This will make he floor feel spongy and break tile floors if you have them.

The allowed maximum allowed deflection is x/360 so if you have 4 ft which is 48 inches you get .13 inches allowed. Now in 20 feet you can get well over 1/2 inch. This is why most builders exceed the code and build to x/400 or even x/600. Now this all assumes a fixed load not someone jumping or even walking around. This is why you get a bouncing floor even if it would meet the minimum code.

You may want to pay a engineer to see if the building meets minimum code which you could then force the builder to correct. If he just built to the minimum then you have a large issue. You either support put in more floor joists or somehow reduce the span by supporting the joist at some point in the middle.

The floor itself you could just add a second layer of plywood but that will not by itself fix the bouncing and shaking.
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Old 04-20-2012, 09:56 AM   #4
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Uneven Floors and Joist Spacing


Thanks -- My house is still under warranty and my builder is planning to come out and look at it with the Truss Company. I'm guessing they will recommend some sort of solution, but we're concerned that any potential solution other than a completely pulling the house to pieces will never suffice.


We do not have a lawyer yet, but it sounds like I need to get one.
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Old 04-20-2012, 10:00 AM   #5
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Uneven Floors and Joist Spacing


Speculating on the cause of your problems and the quality of construction is difficult or impossible over the internet. The post suggesting hiring a structural engineer to prepare a full report, then discussing your legal options with an attorney, seems like a reasonable approach. If this house was constructed for you, as opposed to a spec house you purchased already complete, you should have been furnished a set of plans, which your engineer will of course want to review to see if the house was constructed in accordance with the plans. Once you get the inspection and report complete, your attorney may wish to schedule a meeting with the builder, if they are willing to participate, to discuss deviations from approved plans, and options for repair.
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Old 04-20-2012, 10:14 AM   #6
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In some of the spots, I think the deflection may be caused not by sagging along one truss, but where two trusses might meet. There are 5 or 6 spots where we can really feel the dips walking around. In other spots, we cannot feel it as much, but when our inspector put down an 8 foot level, the floor will be about a 1/4" + over the course of the level. Initially, we thought all of this was because they did nothing to prepare or check the subfloor prior to laying down the hardwoods.

Although, now we look back and realize whoever installed some of this flooring had to know of these slopes. In one spot where we have a dip whoever installed the quarter round above the hardwoods basically had to bend/warp the molding to fit the contour of the floor. Where this dip exists, there was about 3/4 inch gap between the the floor and the door frame. The builder had filled this in with white caulk. We now realize, that if the floors had been level, that the floor would have fit snuggly up to the door frame.
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Old 04-20-2012, 03:47 PM   #7
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Uneven Floors and Joist Spacing


I can't contribute much to the OP's problem....but it sure makes me glad that my 2-story addition 2nd floor is done with 2x12's 12"OC with 1 1/8" T&G on top. Pretty much feels like your walking on a concrete slab....
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Old 04-20-2012, 04:04 PM   #8
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I can't contribute much to the OP's problem....but it sure makes me glad that my 2-story addition 2nd floor is done with 2x12's 12"OC with 1 1/8" T&G on top. Pretty much feels like your walking on a concrete slab....
Wow! Curious what's your joist span? That configuration can handle 20', and that subfloor thickness is typically reserved for 48" joist spacing! It certainly sounds like you have a "wood slab" there ;-)
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Old 04-20-2012, 04:09 PM   #9
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Wow! Curious what's your joist span? That configuration can handle 20', and that subfloor thickness is typically reserved for 48" joist spacing! It certainly sounds like you have a "wood slab" there ;-)
At the longest span....a little over 14'.

I raised the same question with the engineer....he pointed out that the family room is going to be right under the bedroom......and my wife is 16 years younger than me...

Oh....and I will also have fiberglass insulation between those floor joists.....

You can see pics in the link in my signature....
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Old 04-20-2012, 04:31 PM   #10
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Uneven Floors and Joist Spacing


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At the longest span....a little over 14'.

I raised the same question with the engineer....he pointed out that the family room is going to be right under the bedroom......and my wife is 16 years younger than me...

Oh....and I will also have fiberglass insulation between those floor joists.....

You can see pics in the link in my signature....
:-)

No concerns of cross-grain shrinkage? Those 2x12s love to lose depth. Sorry OP; we've hijacked your thread. Last question for ddawg16, I promise.
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Old 04-20-2012, 04:38 PM   #11
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Uneven Floors and Joist Spacing


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:-)

No concerns of cross-grain shrinkage? Those 2x12s love to lose depth. Sorry OP; we've hijacked your thread. Last question for ddawg16, I promise.

Oh...you mean like the 1/4" difference in depth (12" side) depending on moisture content?

Yea...that was my biggest issue....that and differences in batches.....

I have learned that when you get lumber....if the stuff is heavier than crap...let it dry out for awhile...

I had one batch of boards that were almost 1/4" more narrow....I ended up using most of those for blocking....one of them I had to rip a 1/4 furring strip to shove between it and the floor sheathing...

Because I'm doing all the work myself, everything has plenty of time to dry out and more or less fall (shrink) into place...

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