http://hometips.gregvan.com/siding.htm I recommend watching this video before you even consider these I mean a building with horizontal T-1 11 plywood siding. If you don’t install the product correctly you could end up with water seeping into the building. Last but not least, I don’t know if the manufacturer recommends T-1 11 siding to be installed horizontally, because most of the time it’s installed vertically. You should also check with your structural engineer before using this method. Don’t forget to watch more of our helpful construction, home repair and remodeling videos.