Framing Basement Wall Underneath Beam
 

I am considering framing a basement wall that would run underneath (parallel to, not perpendicular to) one of the laminated beams. It is supported by lally's, which I would leave in place. Is it okay to do this without compromising the support of the beam? If so, how should I attach the wall's top plate to the underside of the beam? TIA!

Assuming the laminated beam is properly designed and properly supported, and you are not planning to remove any of the lally columns, there is no need to structurally connect the wall to the beam, as the beam is already adequately supported. You can use a few nails through the top plate of the wall into the beam to keep the wall stable. Or did I misunderstand you? If you plan to remove the lally columns and replace with a wall, that is a totally different discussion.

Thanks. No, I wasn't going to replace the lally columns with a wall. I just want to build a wall (for a room) and wondered if I could attach it to the beam (to stabilize the wall). I have never nailed or screwed anything into a beam. But would framing nails (say 3-1/4") be fine for that?

It is very common to attach non-load bearing walls to beams to stabilize the wall. Use of 10d or 16d nails are common. My house is built that way, there is a non-load bearing wall in the basement underneath a massive wooden beam, and there are a few nails through the top plate of the wall into the beam, just to keep the wall from moving. This works fine for sawn lumber beams, check with the manufacturer for nailing details if you have an I joist beam or a glulam.

Thanks again. I'm not sure how to define what type of beam this is. It's made of about 40 thin layers, each about 1/8" thick. Can you tell me what it is from that description? TIA!

From that description, you probably have a parallam beam. Should be a manufacturer's logo on it somewhere. Contact the manufacturer, or check their website, for specific instructions on how many nails and at what spacing you can install into the beam.