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-   -   Does adding SPF to LVL beam reduce deflection? (http://www.diychatroom.com/f19/does-adding-spf-lvl-beam-reduce-deflection-115633/)

maggiedane 08-29-2011 05:57 PM

Does adding SPF to LVL beam reduce deflection?
 
I am new to this forum and am hoping somebody may have an answer.
qI have just uncovered a beam down the centre of a 24' wide building. It is a drop beam with a 17' 8" clear span with only the floor above being supported (no roof load) supported at each end by concrete block wall - aprox 4" each end.
The beam in place consists of 3 laminated 1.9E LVLs 1.75x11.875 which, going by i-Level's tables, is not sufficient for that span. The original builder also laminated an SPF 2x10 to this beam, does this strengthen the LVL beam enough to span the gap or should I be replacing the beam completely or adding an extra ply?

TrapperL 08-29-2011 10:52 PM

You can approach this 2 ways.
1. Hire an engineer who may be able to work with what is already there.
2. Hire an engineer who will tell you what you need to remove the faulty materials and what to use to replace it with.
Regardless, you need to hire an engineer to design and give you a letter in regards to the structural integrity of the repairs. You'll need that letter should you sell the house.

havalife 08-29-2011 11:34 PM

How did the original builder laminate the 2x10 to the beam? Do you know if he glued it, what type of glue did he use? Is it nailed properly with approved nails and nail pattern? I agree with TrapperL you will need an engineer to give a proper response to your question.

maggiedane 08-31-2011 07:27 AM

In reply to havalife, I have no idea if glue was used to laminate beam to beam - he certainly used it to attach the drywall to the beam. The beams are nailed in what appears to be a regular pattern.
Since posting the original question I have had the beam dimensions run through the LVL manufacturers software which comes out with Live Load Deflection at 0.763 where 0.583 is allowed.
According to the software, if I add a fourth lvl bolted through at 4' intervals the beam will pass, so I guess that is my route.
As a matter of interest, does anyone know how to calculate what adding different members to existing beams does to the deflection? I expect to be told to hire an engineer again but there has to be an equation out there that will allow someone to calculate how to reinforce a beam with non similar material. For example, adding metal angle to a dimensional lumber beam in order to stiffen it, or like in this case, how much a length of dimensional lumber would stiffen up an lvl beam.


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