Built up beam


Old 10-24-19, 08:34 AM
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Built up beam

My MBR is stripped to the studs. Removing the sheetrock revealed a built up tripled 2X6 beam that was boxed in with sheetrock. The beam is 17' long and is supporting the 2X8 ceiling joists that form the attic floor. The attic is unfinished. The joists are 2X8X12' lapped over the support beam.

I have had 3 contractors look at the house and one mentioned that built up beams are no longer allowed and that the triple 2X6 beam was undersized anyway.

FWIW The house is 36 years old and there was no sagging or cracks in the sheetrock around the beam.

My questions are - are built up beams still allowed? I used a tripled 2X12 built up when I built my garage 10 years ago and it passed inspection. My second question is the beam undersized for a ceiling/attic floor?
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Old 10-24-19, 09:50 AM
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Built up beams are very, very common and certainly permitted in my area.

I'm sorry I couldn't quickly find a more accurate chart for your needs and have to get back to work. It's much more common for attic joists to be supported by a wall so beam charts are harder to find for your application.

You didn't provide all the needed info but here is a span table will get you thinking in the right direction. I think table 13 is your situation. Looking at the charts you'll see that you not only need to know your beam length but also the length of the joists the beam is supporting.

Some areas only calculate attics as having to support 10 psf (pounds per square foot) dead load while other locals include a live load requirement in addition knowing that people may use the attic for storage. The 40 psf live load in this chart may be more than what is required in your area. 20 psf is a common live floor loading requirement for attics.
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