Weight of Pressure-Treated Lumber
Roof Online Staff
Scroll to the end to see the chart.
How Much Does Pressure-Treated Lumber Weigh?
The weight of pressure-treated lumber depends on how much time has gone by since the wood was treated, as well as the size of the board or post.
Most pressure-treated lumber is made from southern yellow pine, which is a relatively heavy wood, so pressure-treated wood does tend to be heavier than most other lumber because of this alone.
But the weight that people really notice when it comes to treated lumber is the water weight that the wood picks up while being treated.
A 10-foot-long 2x6 pressure treated lumber board weighs around 40 pounds right after being treated. The same board only weighs around 23 pounds after it has had time to dry out.
About this Pressure-Treated Lumber Weight Table
The following table provides the heaviest approximate weight (dead load, self-weight) per linear foot of pressure-treated lumber.
The weights are for the wood immediately after being treated, for the wood after it has dried thoroughly, and for untreated wood with the same dimensions.
This table is intended to give you an idea as to what pressure-treated wood might weigh at its heaviest.
The values given are for the heaviest wood species, longleaf pine (southern yellow pine, longleaf), commonly used to produce pressure-treated lumber.
The “freshly treated” column in the chart shows the weight for the wood when it contains the highest amount of water commonly added to the wood during treatment (close to four gallons, or about 32 lbs., per cubic foot).
Type of Wood Used for Pressure-Treating
Around 85% of the pressure-treated wood in the US is made from southern yellow pine.
There are a few different sub-species of southern yellow pine, with different wood densities. We used the longleaf variety to calculate the values shown in the chart.
See Weight of Dimensional Lumber for the weights of other wood species commonly used for lumber.
A much more extensive list of wood densities, which includes the other varieties of southern yellow pine, can be found in "Weights of Various Woods Grown in the United States".
Wood Pressure-Treatment Process
Pressure-treated lumber is produced by using high pressure to force a solution of water and chemical preservatives deep into the wood.
Stacks of lumber are placed in a large steel cylinder in a bath of water and preservative. This tank is pressurized until the wood becomes saturated.
After the wood dries out, the preservative remains throughout the wood, protecting it from decay for years.
Weight of Water in Pressure-Treated Lumber
The noticeable extra weight of pressure-treated lumber is due to the water added during the treatment process.
Typically, close to four gallons of water (almost 32 pounds) of water is added to each cubic foot of pressure-treated wood. This means that the wood weighs over 75% more when it comes out of the tank than when it goes in.
As the wood returns to its normal air dried weight over the following weeks or months, it also returns (almost) to its pre-treated weight.
Weight of Preservative in Pressure-Treated Lumber
Once it dries, the weight difference between pressure-treated lumber and untreated lumber is entirely due to the weight of the preservative retained in the wood. This weight is minimal.
The maximum additional weight due to preservative is around 1.5% for “ground contact” designated lumber using CCA (chromated copper arsenate) or ACQ (alkaline copper quaternary) as a preservative.
For much of the pressure-treated lumber available today for residential use, the additional weight will be less. “Ground contact” lumber treated with the widely-used CA-C (copper azole, type C), for instance, will only weigh about 0.37% more than untreated wood.
Ask the Lumber Company!
The values given in the table are meant to provide a general idea of typical pressure-treated lumber weights, and should not be used if precise values are needed for critical engineering calculations.
When precision is necessary, always refer to the specification sheet for the actual, specific product you intend to use, or contact the technical department of the lumber producer.
See pressure-treated lumber at the Home Depot.* The approximate weights of the actual pieces of pressure-treated lumber for sale are usually given in the product descriptions, so this can be a good resource for calculating these weights. Home Depot also delivers to your home, by the way.
Pressure-Treated Lumber Weight Chart
For an explanation of the difference between nominal lumber dimensions and actual dimensions, see our Lumber Dimensions Table.