What are the standard dimensions for a sheet of T-1-11?

The most common size is 4 feet wide by 8 feet tall (48 inches by 96 inches). However, it is also sold in 4x9 and 4x10 foot sheets for taller walls.

How thick is T-1-11 siding?

T-1-11 is commonly sold in two nominal thicknesses: 3/8-inch and 5/8-inch. The actual thickness of 5/8-inch T-1-11 is usually 19/32-inch.

What does 4-inch or 8-inch O.C. mean on T-1-11?

O.C. stands for 'On Center'. It refers to the distance between the vertical grooves cut into the face of the siding. 4-inch and 8-inch are the industry standards.

How much does a sheet of T-1-11 siding weigh?

A standard 4x8 sheet of 5/8-inch (19/32-inch) T-1-11 plywood weighs approximately 70 pounds, while OSB versions can be slightly heavier.

Is T-1-11 exactly 48 inches wide?

Yes, the overall width is 48 inches, but because of the shiplap edge, the actual coverage area when installed is closer to 47-3/8 inches per sheet.

T-1-11 Siding Sheet Sizes & Dimensions Guide

Whether you're shopping at Home Depot, Lowe's, or a local lumberyard, understanding the true dimensions, thicknesses, and groove spacing of T-1-11 siding is critical for a weather-tight build.

Plan Your Sheets

Standard Lengths and Widths

T-1-11 (Textured 1-11) is designed to act as both sheathing and siding in a single step. To minimize horizontal seams (which require ugly metal Z-flashing to prevent water intrusion), manufacturers produce it in multiple heights to match common wall framing dimensions.

All sheets have a standard nominal width of 48 inches. The standard heights are:

4×8 (48" × 96"): The industry standard. Fits perfectly on a standard 8-foot wall framed at 16" or 24" on-center.
4×9 (48" × 108"): Often used when the siding needs to span an 8-foot wall plus drop down to cover the floor joist rim board.
4×10 (48" × 120"): Ideal for barns, garages, and homes with 9-foot or 10-foot ceilings.

Note for AU/NZ builders: The equivalent product in Australia and New Zealand is often referred to as Shadowclad, which shares similar dimensions but is typically manufactured in metric (e.g., 2440mm × 1200mm).

Actual vs. Nominal Thickness

Like almost all lumber and sheet goods in the US building code, what you ask for isn't exactly what you get. T-1-11 is available in two main structural thicknesses:

3/8-inch (Nominal): Often measuring exactly 3/8" or slightly less (11/32"). This thinner material is generally used for sheds or applied directly over existing structural sheathing.
5/8-inch (Nominal): The heavy-duty standard. The actual thickness is strictly regulated as 19/32-inch. This thickness is structural, meaning it can be attached directly to the studs without OSB sheathing underneath (check local building codes).

Groove Spacing (O.C.) Explained

The defining visual feature of T-1-11 is the vertical grooves cut into the face, designed to mimic individual vertical boards. You will see labels indicating "4-inch O.C." or "8-inch O.C." at the hardware store.

O.C. stands for "On Center", indicating the distance from the center of one groove to the center of the next. 8-inch O.C. is generally the most popular for residential siding, while 4-inch O.C. offers a busier, more textured look often seen on sheds and accent walls.

Frequently Asked Questions

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Now that you know the sizes, find out exactly how many sheets your project requires.

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Other Resources: 8x4 Sheet Calculator | Sheet Optimizer