What Is T-11 Siding?

T-11 is a mispronunciation of T1-11 siding. T1-11 siding is a laminated plywood panel with vertical strands running through it that give the product a rough-sawn appearance. T1-11 is a relatively inexpensive siding material.

Grades of T1-11

OSB is a type of wood composite used to make T1-11 siding.

There are two grades of T1-11 siding; plywood and OSB. Plywood is slightly more expensive than OSB but provides better performance and more finishing options.

Finishing Options

Plywood T1-11 can be stained, or primed and painted. OSB T1-11 must be primed and painted. On either product, it is important to finish the edges to prevent water from soaking in and expanding the product.


T1-11 is a panel imprinted with vertical channels that give the finished product the appearance of rough-cut siding.


Proper maintenance of T1-11 is essential to product performance. Left unfinished, the product is susceptible to water damage. Maintaining paint or stain on T1-11 will keep water from soaking into the board and causing it to expand. Stain should be re-applied every three to five years, and paint should be re-applied after about 10 years.


While it is slightly more expensive, plywood T1-11 tends to perform much better than its OSB counterpart. OSB, which consists of a series of wood flakes bonded together with resin, is much more prone to water damage than plywood.

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