How Much Does Pressure Treated Wood Shrink

While the chemicals in pressure treated lumber prevent rot and ward off insects they don t prevent moisture from seeping into the wood.

How much does pressure treated wood shrink. Why does pressure treated lumber need to be sealed. Pressure treated wood has been around for nearly 70 years yet most of us still know very little about this popular outdoor building material to start pressure treated wood is softwood lumber. Values over 30 mc will be. Measure the board s width.

Remember pressure treated wood is often sold wet meaning it has not yet tried out from the chemical treatment it received. Wood shrinkage calculator width. Do not enter decimals or fractions and do not enter the percentage sign after the value. The amount a piece of wood will shrink lengthwise called longitudinal shrinkage is so small typically about 0 1 to 0 2 that it is usually inconsequential to the volumetric shrinkage however plywood greatly benefits from the low longitudinal shrinkage of wood layers of wood veneer are glued together with the grain direction of each ply oriented perpendicular to the adjacent ply.

Enter the initial moisture content mc. Here s how to find them. Know that wider boards expand and contract more than narrower ones. As they dry in the sun they ll shrink.

So how much does it shrink. Wood movement can ruin a seemingly well constructed project. As the lumber gives up this moisture the change in size can be dramatic. Pressure treated wood shrinkage how much shrinkage depends on the moisture content of the wood when you bought it and the normal moisture content of wood in your area after it dries.

Shrinkage of pressure treated lumber it s delivered sopping wet with moisture forced in under pressure. This happens because almost all wood except for the densest species is. Once installed treated wood will dry out for a few months which will cause it to shrink. On a deck that s going to be directly exposed to rain water can seep into the boards and cause them to swell.

Experts clarify the situation. The greatest amount of shrinkage occurs across the face of the grain. Luckily getting ahead of the material and calculating wood shrinkage and expansion is fairly easy all you need to do is multiply three numbers together. But it s important to know that a standard piece of lumber does not shrink the same amount along all of its dimensions.

Enter the actual measured width of the lumber in inches and fractions of an inch centimeters if metric. The people where i have my wood treated say they do not know the moisture.