DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Framing and Foundation > Sagging 2nd Story Floor After Main Floor Load-Bearing Wall Altered Below




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Old 01-25-2012, 03:28 AM  
BridgeMan
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The beam is definitely too small, unless Mr. Carpenter sandwiched in a steel plate. Without knowing a lot of the details (type of wood, loading factors from upper floor, etc.), it's not possible to make a reasonable determination as to what would be required to make a workable beam that's not overstressed. If we assume the 2 x 6s are good for an allowable bending stress of 900 psi (middle of the likely range of normal values), the beam could support a combined uniform load of only 91 lbs. per linear foot, before deflections become noticeable. Not very much, considering that number is the sum of everything that will be carried by the beam, including its weight, possible snow loads from upstairs interior walls partially supporting the attic, floor joists, flooring and floor covering, furniture, people, dogs, cats, etc. And not factored in are the second floor room sizes (larger rooms apply heavier total loads to the beam).

That being said, I think it's time to ask Mr. Carpenter exactly how he determined the size of the beam he installed. Along with asking him how he proposes to make things right.



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Old 01-25-2012, 05:39 AM  
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Thanks for the responses. Initially, he had written in his quote to me that he planned to use LVL. Would 2 2x6 LVL be more appropriate? Also, I'm not sure what has been used as column on either side to support the beam. Any ideas how to look in to what would be appropriate the bear the weight in those columns? Or is that less of a concern than the beam itself?

Also, anywhere good online where there is a chart or something that I can show him as a sort of proof that the 2x6 is not going to work?

I am glad to be figuring this out now... the plan seems to be that he will fix the problem. Then I will follow up on my own with someone else to check out the work.

ETA -- What are the consequences of using a beam that is too small, so that I can discuss with him? That the beam will sag/bow and then, eventually, possibly break? Also, I am just assuming that this is not an immediate problem, where it's likely to snap on me in the next couple of days before any corrections are made. Am I right in thinking that it's safe on a temporary basis? Or should I be taking other precautions?

ETA -- Room sizes above the beam are small (about 7'x9' and 8'x11'). The longer measurements in each room are the ones that meet along the new beam below.



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Old 01-25-2012, 10:29 AM  
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I would have had an engineer look at this job to start with, which the home owner pays for. This is the time that you need him in to have a look. He can figure out weights and loads and make a call as to what needs to be done. I would be looking at a couple feet of temp wall in the center of this. It just isn't enough!

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Old 01-25-2012, 10:47 AM  
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I found this chart a city in BC uses, note there are no 2x6s in the chart.
http://www.nanaimo.ca/assets/Departments/Building~Inspection/Publications~and~Forms/BeamAndJoistSpanTables.pdf

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Old 01-25-2012, 01:34 PM  
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nealtw -- Can I clarify something about the chart with you? I know very little about this which is why I hired someone to do it for me.

In the first section of the chart, when it says "Supported Joist Length", does that refer to the span of the beam? And, in that case, does the chart say that they require 3 2x8s just to cover the 8' span? And what does the "9-8" under the "3-2x8" refer to?

Thanks for this help.

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Old 01-25-2012, 03:14 PM  
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I never read these charts, I let engineers figure this stuff out, but I think that number might be the length of the floor joist that are sitting on it.

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Old 01-25-2012, 04:11 PM  
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Just for example we just had a house fail inspection. A 9 ft header failed and has to be changed out for a beam, it was 3 2x10s and the floor doesn't land on it.

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Old 01-25-2012, 05:17 PM  
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Quote:
Originally Posted by nealtw View Post
Just for example we just had a house fail inspection. A 9 ft header failed and has to be changed out for a beam, it was 3 2x10s and the floor doesn't land on it.
Not that this makes any difference regarding safety and code, but was that 9 ft header showing any signs of actually physically failing?

Also, what do you have to change it out to now?
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Old 01-25-2012, 05:27 PM  
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Check out the header table published by Scott McVicker, a California licensed Professional and Structural Engineer. (www.mcvicker.com) That table shows a double 2 x 6 header with one floor above it as only being good for a 3'-0" span. For your situation, even a double 2 x 12 wouldn't cut it, being good for a 6'-0" span. Granted, his tables may have earthquake loads factored into them, making them somewhat more conservative than non-earthquake country tables would be.

If your carpenter is using LVLs, he needs to refer to a manufacturer's span tables (or helpline technical support) to make sure the size he goes with will be adequate. Trus Joist (Weyerhaeuser) has a good helpline engineering staff, the last time I used them. 1.800.628.3997. If you find a local supplier that sells a lot of Weyerhaeuser, they may have an in-store tech who could come up with a properly-sized member.

To answer your earlier questions for nealtw, the allowable maximum beam span values are numbers shown under the built-up beam sizes. Under Doug Fir, meaning a triple 2 x 8 beam supporting joists 8' long is good for 9'-8". The larger the rooms above, the shorter the allowable span (6'-10" if the joists are 16').

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Old 01-25-2012, 05:43 PM  
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My can sort of be summed up in my signature line.

Definitely get a qualified engineer on it asap. Just reading through this thread made me nervous and angry at the same time

Good luck with it all.



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