Reduced wood beam depth
Reduced wood beam depth
(OP)
Hi,
I designed a new 3.5"x11.25" ceiling beam in an existing house spanning almost 20 feet and the beam supports roughly 8 feet of ceiling tributary loads (10 psf of dead and live loads).
Initially, we were going to replace the existing ceiling beam with a new one and it would've been exposed and protrude below the ceiling finish.
Now, the owner wants the bottom of the beam to be flushed with the ceiling. The existing roof rafters are 2x4s and we will have to reduce depth tremendously by the support.
Flexural and shear demands aren't critical but the deflection is. Is reducing the depth by 7.75 inches even possible? Attachment for a quick sketch.
Roof slope is 7:12 if that helps any.
I designed a new 3.5"x11.25" ceiling beam in an existing house spanning almost 20 feet and the beam supports roughly 8 feet of ceiling tributary loads (10 psf of dead and live loads).
Initially, we were going to replace the existing ceiling beam with a new one and it would've been exposed and protrude below the ceiling finish.
Now, the owner wants the bottom of the beam to be flushed with the ceiling. The existing roof rafters are 2x4s and we will have to reduce depth tremendously by the support.
Flexural and shear demands aren't critical but the deflection is. Is reducing the depth by 7.75 inches even possible? Attachment for a quick sketch.
Roof slope is 7:12 if that helps any.






RE: Reduced wood beam depth
None of this will affect your deflection in any meaningful way.
RE: Reduced wood beam depth
RE: Reduced wood beam depth
Shallower ply is doable. The beam sits on a post at the other end and is located in the middle of the building, so the depth is not a concern on the other end.
RE: Reduced wood beam depth
RE: Reduced wood beam depth
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.