ECN Forum Forums General Topics of the Trade General Discussion Area Engineered Wood Joist

Has anyone wired a residential basement with the new engineered wood joists? They look like an I-Beam made out of wood, with a 2x3 on the top and bottom, and CDX plywood 1/2 X 12 in the center. I was wondering where you attach the boxes, and what do you use to staple the Romex to them.

Ron,
We had a thread titled "Drilling Beams" about 2 months back that had lots of info on these products, including a link to manufacturers.

Here is that link:

https://www.electrical-contractor.net/ubb/Forum1/HTML/000607.html

I think that thread was about "Glulam" which differs from the I-beam with an "OSB" web and cap strips made of actual lumber...

Most that I've seen have "knock-outs" about every four feet, I would guess by the location of the KO's that anywhere along the web, dead center vertically, is fair game.

Just MHO...

These joists are used widely in our area. You can pretty much drill any where on the web of these joists, provided that your hole isn't larger than 1" You are permitted to make larger holes, but you must stay away from either end of the joist. Most lumber yards/suppliers will provide you with a schedule of how far you have to be from the ends of the joist to make a larger diameter hole. Naturally, the wider the joist, the better support it provides, and the closer you can drill at either end of the joist. Also as pointed out earlier, some manufacturers have premade 'knockouts' running at 2-4' intervals along the span of the joist. Just take a hammer and punch them out. A really ingenious idea and saves much drilling. As far as mounting of the boxes and stapling, we use the lower part of the 2x3 for this, just as you would on a normal wood joist.

Cheers!

[This message has been edited by Sandro (edited 01-30-2002).]

I think the link addresses both types of products (I-joists & Glulam).

Doh... You're right Redsy, it does...

(Boy I should read more thouroughly before I speak...)

I received this answer from a Enginer at Boise Cascade Wood Products.
It is ok to attach lightweight items like light boxes to either the
bottom flange or web of BCI joists. Generally, 8d nails are the best to
use for light loads such as yours. Drywall/wood screws less than 3/16"
in diameter are good too. The most important thing is to not use too big
a nail/screw as you could split the flange. Page 31 of our specifier
guide http://www.bcewp.com/ssg2001-31.pdf has a table showing the
closest allowable nail spacings.

Frank Powell, Jr. P.E.
Product Application Engineer
Boise Cascade

We use these a lot. The general rule we've been asked to follow is that any conduit larger than 1" must be supported by the top flange. (w/ angle bracket and rod)

[This message has been edited by electure (edited 02-01-2002).]

For attaching larger things like fan support boxes use a couple of pieces of 3/4" blocking on either side of the OSB web with a little construction adhesive and screws long enough to go through to the other blocking piece. This allows you to put screws in the bottom runner as well as above in the web area. Builders always have scraps of 3/4" OSB sheathing laying around that are perfect for this.