Framing construction question


Hi all,
I am not clear which type of wood is stronger for building a home, garage for rafter. I used 2x12 for my garage and currently I have the same on the house, now I need to rebuild the house, now the question is the structural rafters which is make of 2x4 vs. OSB rafters used with two 2x4 in the shape of I beams vs. regular 2x12 which one is better, of course 2x12 got to be more expensive and less tree friendly. Thanks Max
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wrote:

It's not about which is "stronger". It's about which is suitable for a given span. You speak of two products... standard framing lumber and engineered lumber. Both come with span tables.
Having been a framer for several years, I've had experience with both and I can offer a few comments...
The use of engineered members is normally specified when the span required is greater than that which normal lumber can span. In other words, due to a greater cost, use it only if you need it. There is the claim of labor savings in floor applications, but from my experience, the savings are minimal.
In applications where normal framing lumber would be used, engineered members can offer greater stiffness... if you're willing to pay the added cost. (We're talking floors here.)
In my experience, the lion's share of engineered members were used in floor applications rather than pitched roof applications. The few instances where they were used in a roof assembly were in homes with monsterous open spaces and high vaulted ceilings... and even then, normal lumber was used in less demanding roof areas.
From the carpenter's perspective, engineered members are a little more difficult to work with... and that goes double for using them as rafters.
And I think your notion of "tree friendly" has no usefulness in the discussion. If you're really interested in being tree friendly, build the home using steel framing. Then again, if you did that, it might not be so "strip mining" friendly. You could always build a home from excess brush you find in the woods ;-) But then it would be a fire hazzard. Options are running thin here.
Joe Barta
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rammed earthen walls? lotsa dirt around.
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Thanks Joe for grate comments, now here which type if engeneerd lumber you are referring to? the one made of OSB with two 2x4 or all made of 2X4 or they are some other type out there you are talking about. The floor will span about 40 feet which with regular lumber I need to use 3 14 feet or so, where I assume I can order engeneered lumber in 40 feet, I hope.
Thanks Max
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wrote:

Yes, the most widely used engineered member in residential construction (other than laminated headers) are Trus-Joists... http://www.trusjoist.com/ These are the ones that have something like a 2x2 or 2x4 on top and bottom with something like OSB in the middle.

You mean you hope it won't break the bank. 40 ft is a LONG way for standard wood frame construction to span... even with engineered rafters.
Methinks your plan needs a rethink.
Also, try alt.building.construction. Lots of knowlegable construction folks there. Tell them Joe Barta says "wazzup y'all!"
Joe Barta
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Hopefully he has some beams under the 40 ft span. Anyway, to the op, 40 ft trusjoist are easy to get and easy to work with (but you can't span 40 ft. free with them).
Ken Muldrew snipped-for-privacy@ucalgazry.ca (remove all letters after y in the alphabet)
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I really like the BCI beams for floor joists. I've never heard of them being used for rafters. Besides being a "greener" material using less lumber more effectively, it retains its strength even when you punch big holes through it for utilities and wiring. And it's a lot easier to do than in dimensional lumber.
snipped-for-privacy@gmail.com wrote:

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An engineered joist can be manufactured to span larger areas than normal dimensional lumber. Say you are going to span an distance of 30' (floor). The engineered joist can be made in several configurations and set on different centers. Dimensional lumber would be much more expensive for the same span and options for size and centers are more limited.
For flooring and commercial roof applications, an engineered joist is generally preferred for cost savings and configurability.
Dave
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snipped-for-privacy@gmail.com wrote:

I really don't mean to sound like a jerk, but........
After reading your post, it doesn't seem like you have enough grip on the situation to be doing it yourself. For the type of spans your must have if your considering engineered joists for rafters, I would think you would want the advice of some lind of professional (Architect, engineer or a framing buddy). I have been a carpenter for 11 years (4 framing) and have never seen I-joists used for rafters. I've done some pretty big jobs too (Not saying it isn't done or that it isn't an option sometimes).
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the manufacturer here http://www.trusjoist.com/ showes they are used for roof as rafters, however I was more concidering for the first and second floor, for roof I would go with pre build constructional 2x4 material, the only drowback is then I would not have a usable space under the roof. If not that then I would rather go with 2x8 douglas fire wood, which I used for my garage, but the max length I fould was only 20 feet which will be short for a 40 feet spanned floor. Even they have the same material for studs.
So any how I can ask my architect to drow the plan base on these engeneered material and he kind of figures out the load capacity and other required information for the permit, I just got to find out first if they are better and second if the price will be lower that regular wood. Thanks Max
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snipped-for-privacy@gmail.com wrote:

you tell the architect that you want a building of such and such a style for a given site within a given budget and suitable for a given purpose. you let the architect design it. then the architect sends the design to the engineer for structural review. you don't tell the architect what kind of joists and rafters you want used. they go to school for a long time to learn how to design buildings- it's their job to figure that part out.
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I agree with you in sime degree, not all. Good ideas is every where, architechts design what they learned, the diffrent between a architecht and normal person is they can bring on the paper what they think but normal people can just think and see thinks in the head, that's why you go to architect to pring your idea on the paper so the vilage or city can review them for permit. My 30 and some year experienced architecht drew the blue print of my garage with lots of input and ideas from me, of cource he did had lots of ideas I did not know anything about it at all, when the cancreat contractor was looking on the job for estimate, he did corrected, or better improved what architecht designed for me. by end of the project I did added some new items to the garage wich made the garage most unique in the neiborhood. The lumber supplier did fixed some weack design as well. So what I am saying I do not rely 100% on some one only because he/she went to school, some time you learn a good think from a little kid. So I am affraid to tell architect what I want or how I want. that's may be just me. Thanks for advice anyhow Max
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