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Pressure-Treated Lumber Maintenance 101

Posted 12 October 2018 4:00 AM by ProWood Staff

Keeping up with your wood deck, railing, or fence is critical so your pressure-treated lumber remains in in tip-top shape. Know the facts and how you can protect your wood against common, naturally-occurring problems.

Wood deck with fall scene

Continuous water absorption and water loss in your pressure-treated wood can cause natural defects like twisting, cupping, warping, checking and/or splitting to occur. Application of a sealer or semi-transparent stain (made for pressure-treated wood) is key to reducing this water movement.


Whenever wood is frequently exposed to humid conditions, mildew growth will occur. To avoid unpleasant growth, you’ll need to clean the wood with a cleaner containing a mildewcide, so your pressure-treated lumber will remain bright and attractive.


If you’re looking to maintain the original color of pressure-treated wood longer, you will need to not only clean your deck periodically, but also apply a water-repellent finish with an ultraviolet stabilizer. The stabilizer will not prevent eventual discoloration, but will slow the process.


  1. Start by cleaning your wood with a cleaner/brightener that contains a mildewcide. If your wood structure is new, this step is truly preventive.
  2. Next, apply a water-repellent for surface protection. Sprinkle a few drops of water on the surface. If the wood rapidly absorbs the water, immediately apply a semi-transparent stain or water repellent sealer. If the wood does NOT readily absorb the water in 2-3 minutes, wait a few days and then test again before applying the stain.  
  3. For your pressure-treated lumber to remain in tip-top shape, we suggest maintenance every 12 months.
    1. Depending on the location of your lumber in regards to direct sun exposure, foliage coverage and moisture, you may be able to clean/brighten and recoat every two years. If you decide to wait two or more years to perform your next cleaning/brightening, you may want to use a power washer.

Note: We do not recommend the use of a conventional multicoat paint system or varnish, and we do not recommend sanding pressure-treated wood.

Maintenance on your wood deck, fence, pergola or any wooden outdoor structure is important to ensure it’ll look its best for years to come.

We know homeowners and builders prefer ProWood because it retains its natural beauty year after year and is treated to deter fungal decay and termite attack. Find a dealer near you!




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