24 x 36 cabin flloor beams

[robojo]

Im in the planning stage and was looking at building my support beams with 3- 2x's glued and nailed together to make 24ft 6x's, the cabin is 24x36x1 1/2 floors can I use 2x8 boards or 2x10 to make the beams any advise would be appreciated.

[MountainDon]

Lots of variables to consider from snow loads to bearing capacity of the soil and are there special wind or seismic considerations. As well what the local building codes will or will not accept for a foundation can influence how you build. If there is no local inspection process all those things still need to be determined in order to design and build a structure that will be safe.

[rocking23nf]

I would do 2x10, little price different for a less bouncy floor.

I like to overbuild.

[rocking23nf]

Sorry i misread, that wont make your floor less bouncy, i thought you were talking joists.

I would still use 2x10 for beams also.

[Squirl]

It depends on span, roof load, type of root etc. You said 24ft?  Are you not running the beams down the 36 ft side? Here a guide on how to read the code chart.

http://countryplans.com/smf/index.php?topic=10511.0

A lot more information would be needed to determine the size.

[Erin]

I must be reading jo wrong....
I didn't think he was asking to size the beams so much as asking if it was kosher to sandwich multiple pieces of 2x together to make the full sized beam.

Which, btw, (if that is indeed the question) is perfectly acceptable.  Somewhere around here is a page that shows how to do this, as well as including plywood in the "sandwich."

[MountainDon]

You are correct Erin, the question was really was it okay to build up a beam, and you are right in that it is okay.

But the way I see the question there are simply too many other unknowns the way the question was asked to say, sure do this....  I figure when I don't know the other variables that come into a full answer I should either, (A) ask for more data, or (B) ignore the whole question and hope someone else comes along.   With a sufficient number of properly place piers, for example a beam could be constructed from two 2x4's. 

FYI, the plywood in a beam sandwich is just there to make the beam width work out to a size that can be readily used with metal brackets (usually sized for 3.5 and 5.5 actual dimension. The beam and girder tables in the IRC and Southern Pine information do not consider the plywood as a structural element and neither should us DIY builders. If there is any strength gain just think of it as a hidden bonus.

For my money I'd venture as far as to say that one could build a built up beam from, say three layers of 2x material and only use plywood "plates" at the brackets and piers to flesh out the beam width to fit those brackets. I'm not an engineer, but that would seem to be a safe choice, IMOpinion.

[Erin]

For my money I'd venture as far as to say that one could build a built up beam from, say three layers of 2x material and only use plywood "plates" at the brackets and piers to flesh out the beam width to fit those brackets.

I am SO glad you said this, Don.

We're actually at this same point and I've been pondering how I might do this.  I have a tripled 2x12 which, obviously, is only 4.5" thick.  Yet the 6x6 post it's going to be sitting on is another inch wider.  So I've been trying to picture how to get them to marry up over the posts for the connections.  I was going to flesh the entire thing out with ply, but just adding ply at the brackets would still serve the purpose and be SOOOO much easier!


PS, for jo:  This is the page I was thinking of that includes the ply in the "sandwich."  http://www.countryplans.com/builtupbeam.html

And Mt.Don posted a pic in this thread:  http://countryplans.com/smf/index.php?topic=7959.0
showing a built up beam, sans ply, from Southern Pine.