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 House Building: Engineered floor joists vs 2"X12" joists...?
topknot  [Team Member]
8/27/2005 12:43:20 PM EDT
To save money, my builder wants to use 2"X12" floor joists instead of Engineered ones.

He said that none of the spans are of critical length, where it would make a difference (longest span is about 16 feet).

Does that sound right?

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DzlBenz  [Team Member]
8/27/2005 12:46:28 PM EDT
The 2x12s will be cheaper, but you will have a springier floor in that area because the modulus of elasticity of the lumber is much, much lower than that of the engineered joists. What materials does your contract call for? Don't let the contractor cut corners.
operatorerror  [Team Member]
8/27/2005 12:47:26 PM EDT
But real lumber is so nice!
topknot  [Team Member]
8/27/2005 12:52:18 PM EDT
We will sign the contract with him next week. He will start buiding around Oct 15th.

So, should I specify that he use engineered joists even if they are at a considerably higher cost?
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K2QB3  [Member]
8/27/2005 12:53:10 PM EDT
2x12s make fine floor joists, 16' is really pushing it though if they're on 24" centers.

Stiff floors are important, otherwise you'll be able to knock stuff off shelves by jumping up and down, I've seen this in houses that met all building codes.

You'll be happier long term if you build your floors to twice the code-required working load, nice stiff floors make the house feel solid. This is often referred to as a 3 or 4 star stiffness rating.

But dimensional vs engineered isn't an issue, size is. Engineered is easier to build with, easier to wire and plumb, but not that much better/worse.
peasant  [Member]
8/27/2005 2:46:11 PM EDT
Engineered joists are definitely the way to go if you plan to stay in this house. There are no drawbacks and only plusses (other than price). Everything will be flatter, stiffer and more uniform.
inkaybee  [Member]
8/27/2005 3:15:40 PM EDT
I frame for a living. I work alot for a big tract home builder that uses TJI's always at their maximum allowable span. Two months ago I did a custom for a small time builder who wanted to use 2x12s. I thought why put a cheap spungy floor in this nice custom. But when I got the deck down I could not believe how solid the floor felt.

Now I will say these were on 16 inch centers and none of the spans were much over 12 foot. it was a better floor -- but a bigger pain in the butt to frame.

In the end it's all about the spacing and spans.
GusHasford  [Team Member]
8/27/2005 3:19:27 PM EDT
Where I use to work, we had a truck driver that delivered lumber to us. He was a fire chief until heart trouble took him out of action and into trucking.

He came in one day with our load and some engineered joists for another company. I got to talking about the joists with him. he said one thing about engineered joists is in a fire they will burn thru quicker than stock lumber.

This was just something I found interesting, never had thought about a fire situation....
beagler76  [Member]
8/27/2005 3:28:31 PM EDT

Originally Posted By inkaybee:

In the end it's all about the spacing and spans.

+ 1
brentwal  [Team Member]
8/27/2005 3:54:37 PM EDT
Engineered joists have a number of advantages as far as the contractors and sub-contractors are concerned. Any hole that's drilled into a 2x12 will weaken it, but engineered joists loss very little strength. If you can afford it, go engineered.

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