Hi. Is it common or uncommon for Home Depot and Lowe's to stock 4 x 12
lumber? I wanted to use a 4 x 12 for a header, but was unable to find it at
HD, and didn't know if it was this particular store, if it has to be special
ordered, etc. Thanks.
On Wed, 17 Aug 2005 08:04:59 GMT, "Eric and Megan Swope"
4X12 is a common size, but you won't find it at any Home Depot or
Lowes I've ever frequented. To find sizes like this you have to find a
real lumber yard, not the silly, poorly stocked and over priced "Home
I was recently in an 84 Lumber just up the street, which is a real
lumber yard, and they had 4X12 rough cedar beams, as well as other
For a header, that isn't exposed so it doesn't matter what it looks
like, I would laminate one up for myself. I would probably build it in
place because it would be a bit heavy once assembled. Use 1/2" CDX
plywood glued between two 2X12 boards and you will have a 4X12. And it
will be stronger than a solid piece of lumber would be. Gang nail or
bolt it together, or both. If I wanted this exposed, I would probably
still build it like this and then dress it up on the outside with
whatever grade wood I wanted.
(Remove the Primes before e-mailing me)
On Wed, 17 Aug 2005 13:32:42 -0400, "CL (dnoyeB) Gilbert"
Depending on where you live, you can often find rural sawmills where
they can make any size timber a tree will allow. Of course they will
be rough sawn, and you will have to rely on the type of wood they
have, or supply your own tree.
I agree that nailing two 2X12's together is stronger than a single
A composite beam may be stronger because the defects and local weakness will
not likely coincide.
There is another factor, the tendency to twist and buckle under load may be
improved by the fact that the pieces have different twist in the fibers.
We are talking about wood, here. Not aluminum beams like in an airplane
Those are some hypothetical maybes that sometimes might, sometimes might
not actually help...
I still don't believe an engineering load test of two nailed 2x12's
would beat a 3x12 in load on average of several trials of same species
and grade material...
Tomorrow if I have time I'll see if I can find anything on the US
Forestry site specific to the questin...
You say same species and grade, and add averaging over several specimens.
This imply uniformity. The more we assign importance to uniformity the more
we make wood an homogeneous material, which is not.
Clearly there is no reason why a composite should be stronger that a single
piece of equal crossection IF the material are homogeneous. Wood is less
dependable than a steel beam
in the sense that a higher safety margin must be applied for wood.
In construction you consider the lowest of all possible breaking loads and
stay below that.
With wood the ratio between lowest breaking load and typical is a smaller
fraction than with steel.
To make a silly extreme case a knot hole at one third of the span in a
single beam is worst than two knots symmetrically placed on a composite
In other words the issue is about homogeneity or lack thereof. If you
select 2 perfectly grained flawless board and compare it to the same perfect
single piece there is no difference.
That's exactly my point--that <on average> (which is all one can deal
with w/ timber since, as you say, it's an inconsistent material),
there's no difference between a composite built of 2-tubaX's and a solid
beam of the same actual dimensions.
I don't believe there's any code based on the difference between the
combination outlined above based on the assumption of defects cancelling
on the composite beam.
Engineered and laminated material is something else entirely...
There are counteracting forces. Take a thin strip of wood and bend it. Now
take two thin pieces of wood, bend them, glue them together, clamp, dry, and
they remain bent. Why do you think that is? Laminations for curved
materials are often made that way.
Nick was quick to chime in with a one word answer, perhaps he will take the
time to talk about the molecular flow of this so everyone can easily
understand what happens with laminations when you are pushing one while
pulling the other. .
On Wed, 17 Aug 2005 15:34:52 -0400, "CL (dnoyeB) Gilbert"
No, the tube is *stiffer* than the solid rod of the same material.
Our Strength of Materials teacher in 3nd year engineering went through
the math/physics for the proof and I remember being stunned by it. But
it was clearly correct as I recall.
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