| Nominal
lumber is a typical choice that has been used for years and years and..
you get the picture. A standard 2x12 #2 or better spaced at 24" on
center can span a distance of 15'8" at 40 psf but only 13'11"
at 60 psf. Why do you care? Let's say you have one room with a lot of
antique wood furniture where a lot of people will be admiring it. You
would probably choose to only span the 13'11" at a maximum. What
if we decide to use TJI's with the same depth? We could span up to 20',
which is quite a difference.
What good does this do us? It allows
us to optimize the size and number of joists, bearing points, and work
that we perform. The fewer pieces we have to handle the better. What other
advantages/disadvantages to using TJI's are there? Some of the advantages
are ease of installation, less work, and quality of material. The one
disadvantage is that they are typically longer and can be hard to handle.
A minor disadvantage in my opinion.
Whatever you choose for your joist
material most lumber stores will provide engineering for your floor framing
package if provided with a floor plan. You should come away with number
of joists, rim joists, lengths of each joist, and a framing plan.
Now that we've got what we're framing
with and a plan to do so we will want to get the material delivered. One
thing to remember with deliveries is put them where they are not going
to be in the way of other deliveries or other work being performed.
The first step of framing, as in
most home construction activities, is to lay out where everything is going
to go. This should mostly be taken care of for you from the plan received
with your framing package. For this article I'm going to assume you are
using 1-1/2" inch joist material and they will be placed at 24"
on center.
I like
to layout the rim joists before I begin handling any joists. There are
two conditions that you will encounter with rim joists - running perpendicular
to the joists and running parallel to the joists. Where the rim joist
is perpendicular you will have a joist every 24" that will support
the exterior wall above it. On the parallel side you will need to add
a joist 5 1/2" away from the rim joist to support the exterior wall. See
image below (Top drawing depicts a parallel condition).
To begin the layout we will make
sure that the near edge of the first joist is 24" to the center of
the joist. Therefore, the first edge mark will be 23-1/4" from the
end of the rim joist - they will then run at 24" to the edge of each
joist from the first mark. This will put your 8' piece of plywood at the
center of the 4th joist.
Now you will need to continue on with the layout
as dictated by your floor framing plans (hopefully your designer has included
these)
Continue on to - Floor Sheathing |
