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Unread 09-20-2011, 11:47 AM   #1
ucgakmb
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Ceiling/floor joists

I recently bought a place in upstate ny which needed quite a bit of remodelling/refurbishing at the back end of the house (an old extension). My husband and i planned to put in a mudroom downstairs and add an ensuite to the bedroom upstairs.

Unfortunately, starting to look closer we have discovered a number of problems with the ceiling/upstairs floor joists. This part of the house suffers quite extensive floor deflection (bounce). Now we know why. The room is roughly 16 x 9.5 and the joists are only 2x6, and run lengthways!!!!!

Plus, the wood obviously was not long enough so all the joists are two peices of wood bolted together about 1/3 of the way across.

Help! What should we do? Sistering the joists would be an obvious fix, but how (given they are already bolted together at one point), would we even do that.

Oh, and I forgot to add, that end of the extension sank about 6 inches after it was built... so the floor slopes too!

Absolutely any suggestions are welcome at this stage.

Thank you!

P.s. Extra info: I just used the deflect-o-lator, and depending on which wood (im uncertain about ours, buts its dark brown and looks fairly good condition) I got a rating of L-91 or L-120
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Last edited by ucgakmb; 09-20-2011 at 01:31 PM. Reason: additional info
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Unread 09-20-2011, 03:32 PM   #2
HooKooDoo Ku
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Not that I'm a building codes expert, but from everything I see, you've got a sub-standard floor and you need to have it inspected by a structural engineer before you attempt to use that floor for habitable space.

While span tables require you know exactly the type of wood and the woods grade, from what I've seen, you can use span tables for No.2 visually graded Southern Pine to get an estimate of what allowed spans are.

As a personal example of how this "average" holds up, I've got a bouncy living room with 2x8s on 12" centers on a 14'6" span. When I look at span tables for a rating of 40psf(pounds per square foot) live load, 10psf dead load, and 360 deflection, the maximum allowed span is 14'2" (sounds like my builder s-t-r-e-t-c-h-e-d that standard). (If I drop to the tables for 30/10/360, the max span is 15'7").

When I start looking at 2x6s, if I drop to the minimum table (30/10/360), the 2x6 on 12" centers, the allowed span is only 11'10". (And lets keep in mind this is for solid timbers, you've got cut-up pieced bolted together, so I don't know how that changes things).

To even find an allowed 16' span with 2x6, I've got to drop to 20/10/240 tables for ceiling joists... and then, only the highest graded lumber allows for a 16' span. The No.2 grade lumber is only 13'6". To get above 16' with No.2 grade, you've got to drop to the lowest ceiling joist table (10psf/5psf/240). At that level, 2x6 on 12" centers allow for 19'6" spans.

So as best as I can tell (based on my limited knowledge of the subject and your limited description), you have a "floor" that is only rated as a low-end support for a ceiling. Add settling of 6" and this sounds like a disaster waiting to happen. You can be assured no building permits were pulled for this addition, and I'd be afraid of what other corners were cut besides sub-standard lumber and sub-standard footings.
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Unread 09-20-2011, 04:23 PM   #3
dhagin
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Welcome Kay.

Well, an older home with 2x6's 16' long as floor joists? Sounds like maybe a wall or 2 was taken out at some point, leaving what was once a perfectly fine floor, now over-spanned. Although you certainly can hire a structural engineer to look at the place, any good experienced professional contractor should be able to sort it out.

A fairly easy solution, would be to replace the wall or add a beam to cut the spans down to no more than about 8' or so. To repair the joists, it may be easier to just double up the ones that are pieced with full length joists with full bearing on each end of the new joist. To be clear about recommendations, though, we need some more info.

What is the spacing of the joists?
What shape are the joists in? Any big knots or cracks?
Can you post some photos of the floor joists and floor in general?

For the slope, tell us about how far from level it is. Any idea? Might need to find a straight section of floor/ceiling along a wall to get a real idea.
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Unread 09-20-2011, 04:34 PM   #4
jadnashua
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A joist gets its strength only when it is a continuous length. It does that by putting the bottom in tension and the top by compression. Bolting them together is WAY less than a continuous length. The middle is just there to keep the top and bottoms aligned and in place - that's why you can cut holes in the middle of a joist and not compromise it much, if any (as long as you abide by the rules.

Without seeing it, and knowing the ceiling heights and your tolerance for asthetics, it's hard to say what you should do to strengthen it.
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Unread 09-20-2011, 05:27 PM   #5
chuck stevenson
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I would reframe it and run the joists in the 9'6" direction.

As Joseph recommended, get an engineer involved.
You have more issues than those joists.
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Unread 09-20-2011, 09:38 PM   #6
dhagin
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Quote:
Originally Posted by Kay
Oh, and I forgot to add, that end of the extension sank about 6 inches after it was built... so the floor slopes too!
Missed that earlier today. Yes, I'd say you've got bigger problems than overs-panned joists, and i agree with getting an engineer to have a look see. Fixing the joist issue is the easy part here.

Good catch you'all.
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Unread 09-24-2011, 08:36 AM   #7
ucgakmb
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Smile Thanks

Thank you so much everyone! You have confirmed my worst suspicions, but at least we know where we stand and that my fears were in fact justified.

We now plan to get someone in over the next couple of months to take a look and give us some options (and costs). In the meantime I will try take some pictures this week and put them up here.

We have now decided that it looks like it was once (a long time ago) a single story extension that was subsequently (and somewhat foolishly) built on top of to extend the upstairs living space. All of this, however, seems to have been done at least 30 years ago, perhaps even longer.

Anyway, thank you again. What an amazing forum this is.

Kay
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Last edited by ucgakmb; 09-24-2011 at 08:54 AM.
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