must seal out water
Today's "enviro-friendly" pressure treatment is nowhere near as long lasting as the older pressure treated wood. My dock was done with the "new" PT wood and I'm replacing boards all the time from splits and rot and that started when the deck was about 5 years old. It is now 14 years old. Two years ago I decided I was either going to redeck the dock with one of the better synthetic decking boards or pressure wash and seal and try to extend the existing boards. The dock was black and many boards starting to split but I replaced all the marginal boards and pressure-washed and sealed the whole thing with Thompsons Waterseal. The whole dock went from black and old looking to like-new and has stayed that way for 2 years now, but may need a touch-up in some heavy traffic areas.
We had sealed our house deck with this product when it was new 15 years ago and the boards have never split nor rotted and still look like new today. The key is to seal the wood from water penetration as others have said. Newer PT lumber is going to not last otherwise. Whether Thompson's is the best product to use, not sure. It seems to do the trick, but if the wood is not dry when applied, it can flake off. Also, it's pretty odd when applying as it looks like milky coffee when putting it on, but dries clear, and water will bead off it nicely for quite a while.
|