Douglass Fir vs. Spruce vs. Framing Lumber

[Jason Roehl]

Check your lumber yard for Glu-lam beam.

As near as I can tell, Phil, Glulam is used more in the context of a supporting beam, not as floor joists. I'm sure you probably could use them as floor joists, but that would probably be prohibitively expensive.

For those that don't know the difference, an I-joist is basically two pieces of yellow pine (or similar), maybe 2x2 or 2x3, laid flat, with a vertical section of OSB between them, to form the shape of an "I". On the other hand, a 4"x12" Glulam would look like a stack of 6 2"x4"s glue together by their faces, running parallel.

I-joist:
http://www.apawood.org/level_b.cfm?content=prd_joi_main

Glulam:
http://www.rosboro.com/glulam.asp

[Rob Russell]

Glu-lams or microlams are overkill for the floor joists. These are the things that look like plywood beams - full width. They are normally used as supporting beams or applications where you need a very stiff floor.

The "I-beam" style joists are far less expensive than the glulams. They aren't as stiff and are cheaper. They are stiffer than normal dimensional lumber.

There is a 3rd option - floor trusses. These are open web trusses - made from 2x4's. The top and bottom chords are flat 2x4's with a bracing web of 2x4's that zig-zag back and forth between the top and bottom. They look a little like those steel bridges with zig-zag trusses. One of the nice things about floor trusses is you can specify how strong (weight load) and/or stiff (vs. bouncy) you want them. I used floor trusses for the floor in our addition because it's all tile floors and I needed it to be very stiff.

[Rob Russell]

On the other hand, a 4"x12" Glulam would look like a stack of 6 2"x4"s glue together by their faces, running parallel.

Jason,

A Glulam looks like a beam made of plywood. It's not a stack of 2x4's.

I can post pictures of both microlam/glulam beams the the floor trusses when I get home.

Rob

[Jason Roehl]

Jason,

A Glulam looks like a beam made of plywood. It's not a stack of 2x4's.

I can post pictures of both microlam/glulam beams the the floor trusses when I get home.

Rob

Rob, check the website I posted for glu-lams. I have seen both--some that look like 6000-ply plywood, and some that look like a stack of 2x4s or 2x6s. The website I linked to shows the 2x4 type.

[John Shuk]

Floor trusses are nice too because it is easy to run pipe abd electric through the open spaces. If you are going with solid wood I would have to lean toward doug fi. My house is mostly spruce and I think there is alot more movement with it. Doug fir is a better spec imho.

[Rob Russell]

Well Jason - this proves you do learn something every day. I didn't know glulams were made that way. I wonder which is stronger - the stacked 2x4/6 variety or the ones I'm used to which are like plywood.

I've attached a picture of the glulam beams supporting our addition and the floor trusses.

[Michael Perata]

Rob

The picture on the left appears to be a LVL (Laminated Veneer Lumber) beam.

LVL is typically made by gluing up the veneers in a vertical fashion. GluLams are typically made by gluing the pieces horizontally.