Even if your deck is made of pressure-treated lumber, redwood, cedar, or some. . finish to a new pressure-treated–wood deck used to be standard procedure.
Use the water test to check your deck every few months to ensure the sealer is repelling water. If you have a brand-new deck made of treated lumber (as opposed to cedar or redwood), you should wait at least a few weeks before sealing it for the first time. This allows the wood to dry so the stain is absorbed.
There are many questions as to when a newly installed deck should be stained. Some stain manufacturers suggest you should wait 3-12 months to let the wood .
How to Seal a New Pressure Treated Wood Deck. Choose a semitransparent stain or clear sealer. Check the wood for mildew before you seal it. Clean all deck surfaces that will be stained, using a commercial deck cleaner and following the manufacturer's directions. Apply the stain or sealer with a paintbrush or sponge.
Weather wreaks havoc on unprotected wood, even pressure-treated pine,. . for some time, although new VOC regulations may limit where they can be sold.