T-1-11 Siding Calculator

T-1-11 plywood and OSB siding is a staple in US construction, heavily stocked at hardware stores like Home Depot and Lowe's. At upwards of $40 to $60 per sheet depending on the grade and thickness (like standard 19/32" or 5/8" nominal), buying too many sheets destroys your project budget. Buying too few means halting your weekend project for another lumber run.

Calculating T-1-11 coverage isn't as simple as dividing total square footage by 32 (the square footage of a 4×8 sheet). You have to factor in gables, window cutouts, door headers, and crucial groove alignment. Because T-1-11 features vertical grooves (usually 4" or 8" on center) and a shiplap edge, you can't always just flip an offcut and use it elsewhere—the grooves must line up continuously across your wall framing.

Using a dedicated sheet cutting optimizer ensures you map out every angle, accounting for kerf and ensuring the groove patterns run perfectly plumb.

When calculating plywood or OSB siding, the waste factor depends heavily on the geometry of your building:

• Standard Box Walls (No windows): Add a 5% waste factor.
• Walls with Windows/Doors: Add 10% waste. While you remove the area of the window, you often can't reuse the cutout because it's too small or the grooves don't align.
• Gable Ends (Triangles): Add 15% to 20% waste. Angled rooflines create awkward triangular offcuts that are rarely reusable unless your pitch is exactly symmetrical and the grooves happen to line up perfectly.