Traditional Architecture

Standard Landscape Timber Sizes

As trucks, automobiles and planes replaced railroads for shipping and transport, many rail lines have been abandoned. Railroad ties were free for the taking, and lots of people began using them for retaining walls, fence posts and other landscape jobs. They were made from dense wood soaked in creosote so they wouldn’t rot. Gradually, people started to understand that things soaked in creosote weren’t so great for landscape plants and the environment, and so the demand for railroad ties declined. Meanwhile, the landscape timber, essentially a railroad tie without creosote, was developed.

Definitions of Landscape Timber

The Western Redcedar Lumber Association defines a timber as “a square member, either rough sawn or surfaced, that is larger than 5 inches by 5 inches with width not more than 2 inches greater than thickness” But home improvement stores define landscape timber as any big piece of timber which can be utilized from the landscape. Landscape timbers are wood that doesn’t rot easily (cedar or redwood) or are treated with an alkaline copper quaternary timber preservative.

Nominal vs. Actual Dimensions

Lumber is sold by nominal size. Originally, a two-by-four was close to 2 inches by 4 inches. This is referred to as a whole sawn dimension. Now two-by-fours are rough cut, then dressed or smoothed down, before they’re sold. They’re actually 1 1/2 inches by 3 1/2 inches. Full Engineered timber is the nominal size. Rough sawn timbers are 1/4 inch smaller and also dressed 1/2 inch smaller than nominal. For larger, nearly square shapes, the width and depth may be averaged.

Standard Landscape Timber Sizes

An eight-by-eight full-sawn landscape timber — 8 feet long — is really 9 inches deep, 7 inches wide and 102 inches long, so it’s close to standard railroad tie size. Landscape timbers come in a variety of sizes other than the initial railroad tie size. Three-by-three landscape timbers are available, as are four-by-four and six-by-six. An 8-foot three-by-three landscape timber is 2 1/4 inches thick, 3 1/4 inches wide and 96 inches long. A four-by-four landscape timber is 3 1/2 inches thick and wide and 96 inches long. A six-by-six is 5 1/2 by 5 1/2 inches deep and wide and 96 inches long.


Occasionally landscape timbers have square corners, and sometimes the corners are rounded. Rounded corners make them appear more like poles or logs when they’re stacked or used as fence posts. The rounded corners provide the sides a shorter dimension, but the dimension through the middle of this timber is exactly the same. Some are rounded on two corners and square on the other two. You can put either the rounded corners or the square corners in which they’re visible, giving the completed job the look you would like.

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