Recently I posted on OSB, or oriented strand board, which is so often found as siding on manufactured homes. In fact, it is found on lots of different homes, however the vertical panel style (not lap) is what I am concerned about in this post and that tends to be on manufactured homes.
If, as a realtor, you want to be able to tell the difference between OSB or a common veneer, like T1-11, here is a tip. The OSB is made by grinding wood into flakes, then basically gluing it all back together with a very weatherproof glue, or so we hope. Another siding called hardboard is different but a similar process and has similar weathering issues. With the T1-11, however, it is made like plywood, where several thin layers of wood are glued flat to one another. With the T1-11, since it is considered to be a good grade of exterior plywood, they will remove the knots and insert "plugs" -- the oval kind you will see in plywood. So, without getting into too much detail, look at the photos below. One is T1-11. The other is OSB on a mobile. You can see that they have a similar look. The oval plugs in the top photo make it clear which is the T1-11. If you look hard enough at a home, you should find them in T1, but not in the OSB, although they do put a grain on it. Rule of thumb, with these panel sidings, is the T1 will more often be found on a home, and the OSB panels will be found on manufactured homes or mobiles. However, you cannot count on that for sure as various people change things around or do it themselves. I have seen homes with T1-11, but then one sheet of a similar OSB was in place somewhere else, put in by a homeowner as a replacement.
Thanks for dropping by,
Steven L. Smith
Bellingham WA home inspector
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Steve -
A few years ago we had a house sided with T1-11. On thing I discovered is that the bottom grain and the first two or three feet of the back side should be primed to prevent water problems due to backsplash. Now this was in florida where the torrential thunderstorm rains can be almost horizontal.
Judi, the T1-11 is better. Fred, that's a good idea, and properly installed T1-11 has a specially designed Z flashing at the bottom. This prevents the wicking problems.
Steve, You probably know this, but another ID clue on grooved panel siding is that the OSB groove is obviously molded in and the T1-11 groove is cut; you can actually see the plies in the groove if you look closely.
David,
Yes, I drug, dragged, whatever it is you do with the mouse and made the pictures bigger and that point you made is something people can probably see pretty clearly.