We are finding T1-11 at greatly different prices from store to store ($36 at
one, $22.50 at another). All claim to be 19/32" and 8" on center. Are there
grades of T1-11? Is one company better than another? Should we just purchase
the least expensive? p.s. I notice that the exterior surface is only 1/16 inch
thick. Can we purchase T1-11 with thicker exterior surface? In other words, how
about a T1-11 course?
I’m not an expert on
T1-11, but I will tell you what I know about it and plywood in general. T1-11
or Texture 1-11 is an exterior grade of plywood with a rough, thus textured,
surface. It is often used as siding where economy is important. It is most
readily available in 4 x 8 foot sheets with the long edges milled to allow
lapping. It can also be purchased in 4 x 9 and 4 x 10 foot sheets from some
There are a variety of styles that you may find. The thicker material that you
are looking at usually has grooves cut into the surface every 4 or 8 inches.
This helps break up the large flat surface, hides the laps, and gives the
“idea” of board and batten siding. The thinner (3/8”) variety is sometimes used
with rough 1” x 2” battens nailed up on top to give an even closer resemblance
to board and batten. These thinner panels generally do not have grooves cut in
them, but sometimes are available with very shallow impressions to mimic the
grooves that would be in the thicker plywood. This material is often used in a
Yes, there are different grades of T1-11, but I don’t know what they all are.
The differences will relate to the grade of the veneers that are used in the
manufacturing process. The better grades will have fewer voids in the interior
veneers, and the finish veneer will have only patched defects. The patches in
the veneer are football shaped, and having a lot of them should make the panels
cheaper. A full service lumber yard with someone that really knows lumber and
building products can give you details on what grades are available and how
much they cost. The ones that are less frequently used will have to be special
ordered and may take a couple of days to get from the mill or distributor.
Plywood in general comes with names like CDX or ABX which tells you what the
two outside surfaces are graded and what the adhesive is rated for (X =
exterior). All of the grades (A, B, C, etc.) have rules about size and number
of defects. There are also differences in plugged or unplugged (the football
patches), number of veneers used in the sheet, “solid second layer”, and
others. Plywood used for things like cabinet making will have similar grading.
Construction grade (as in framing) plywood is rough, has many defects and few
veneer layers. Finish plywood will have fewer defects, better patches, and more
layers of veneer.
Look closely at the T1-11 that you are seeing and you will no doubt see some
differences. If you are only concerned about the looks, and don’t need the
structural strength of the plywood, make your decision based on the top veneer.
Look at the grooves that are cut in the surface, and if you see a lot of voids
in the interior veneers, you may want to look at a different yard.
Remember when you are installing the panels, that you need to use “Z-metal”
flashing between the butt joints when the 8, 9, or 10 foot panels are not long
enough to cover the wall from bottom to top. Another option is to run a trim
band along the wall that you dado a groove into. The groove fits over the top
edge to the T1-11 to keep rain water from getting in behind. If you use this
method, you will need to put the “Z-metal” flashing on top of the trim band
before adding the next set of panels.