Comments on: Floor Joists: Solid Lumber, I-Joists and Open Web Floor Trusses

By: S.McLaughlin

S.McLaughlin — Sun, 28 Dec 2008 03:07:10 +0000

I am in the beginning stages of building my new home,my contractor has ask
to use web joists.I have read some of the comments on your site,I would think
the enviroment should be considered in any build today.With the proper material in a home ie:5/8 sheetrock on basement ceiling,would slow down any fire.or if
you wish a properly installed sprinkler system will also do the trick (this is being
installed on al floors in my home.).Thanks for the info.

By: sjdehner

sjdehner — Sun, 14 Dec 2008 17:12:05 +0000

Open web wood joists are a great alternative to dimensional lumber although I echo the caveat issued by S. Bauer that it’s best to avoid the laminated/glued products whenever an alternative exists. Personally I avoid even interior plywood at all times (subfloors, cabinets, etc.). Great post.

By: Ethan

Ethan — Fri, 15 Aug 2008 16:00:21 +0000

@S Bauer, I think it’s a trade off. I-joists use less wood and therefore benefit the enviornment / building costs. It’s true that adhesives can give off toxins but typically not harmful levels. Also some plants can be used to eliminate those toxins. Your right to be concerned with burn rates but if it takes 2 hours, I’m not sure how much it will matter. Hopefully your fire dept. isn’t normally that slow. Thanks for the comment.

By: S Bauer

S Bauer — Fri, 15 Aug 2008 15:12:10 +0000

Off-gassing in tighter homes from poisonous adhesives and plastics are a real problem. Most current OSB I joists and other like products do not belong in a healthy home. Also it took 2 hours for the fire department to get to me for a garage fire, that’s a problem. I say real wood joists or perhaps steel.

By: Todd

Todd — Wed, 04 Jun 2008 00:03:04 +0000

The cost difference really isn’t a big deal. Especially when you look at the cost savings in additional framing members that can be eliminated with longer spans. Plus when you start trying to get conventional lumber to meet the same deflection criteria you get in trouble really fast. Then there’s the bonus of using younger growth trees from multiple sources. As far as I’m concerned it’s the only way to go in modern wood framed construction.

By: Ethan

Ethan — Tue, 03 Jun 2008 21:38:30 +0000

@Todd, I knew you were knowledgeable in this area and had hoped you’d offer your two cents. From what I can tell the savings with solid joists are canceled out in the long run of building a house. I installed ceramic in my kitchen and the open web joists are stiff enough that I’m not worried about anything cracking. Thanks for your thoughts.

By: Todd

Todd — Tue, 03 Jun 2008 20:40:12 +0000

Ethan,

Every new home we build uses some type of composite floor beam system. There are so many advantages to use them that the cost never really plays into the decision. The big deal really is span and deflections. Typically floor sizing isn’t governed by load condition. The size of a beam that works for code governed loads typically isn’t as large as a beam sized to produce minimal deflections and vibrations. Now that people are installing beautiful tile floors and granite counter tops the floors need to deflect less. The stiffness of a 2×12 regular floor joist can be less than half the stiffness of a 11.25″ deep TJI. The fire issue is certainly a problem but we find that most people are finishing basements today so a layer of drywall will certainly improve the fire rating drastically. Great post!