I am building a deck using pressure treated wood. I want to ensure the longest possible life of my new deck. So, I am going to completely (all sides and ends) seal every piece of wood I use with wood sealant.

Now someone has told me "No, don't do that. If you completely seal the wood it will cause rot and premature failure because the wood won't be able to breathe".

What do I do? Even if it is over-kill is it OK to seal up all my wood...or not?

First of all let's look at treated lumber... the most common treatments are cca & acq

CCA stands for Chromated Copper Arsenate, a wood preservative formulation containing copper, chromium and arsenic. The copper acts as the main fungicide and also provides some protection against termites. Arsenic provides protection against termites and copper-tolerant decay fungi. Chromium helps to bond and "fix" the chemical components to the wood.

ACQ stands for Alkaline Copper Quat, a wood preservative formulation that contains copper and quaternary ammonium compound (quat) as active ingredients. Copper is a very cost-effective fungicide protecting against decay. It also provides some protection against termite attack. The Quat provides protection against termites and certain types of fungi that are tolerant of copper.

Wood has been used for centuries as a building material due to its availability, structural properties, versatility and appearance. A renewable resource, wood continues to make sense in our modern world as an economical and environmentally sound choice in building materials.

Treatment of wood with a range of technology options improves its properties and performance characteristics, expanding its use to a variety of applications. Making wood last longer and perform better saves trees and optimizes the use of the world's most valuable renewable resource, our forests.

For cut ends of treated lumber, it is recommended you use a brush-on copper naphthenate formulation available from home centers, lumber dealers and hardware stores.

Second of all, YES , you can stain or paint treated wood. Also, you can coat treated wood with a water repellent; in fact, (wolmanized & Chemical Specialties, Inc.) highly recommend it. The best way to tackle these jobs depends on the wood you have, its exposure, and the coating you plan to use.

When wood is pressure-treated, it is saturated with a liquid solution of preservative diluted in water. In a typical situation, the wood you buy is still somewhat damp.

PAINT . Do not apply paint until the wood is dry, both on the surface and internally. Otherwise, as the wood dries out, escaping moisture will cause blisters and poor adhesion in the paint. Once the wood is dry, the procedure for painting treated wood is no different from that for painting untreated wood. (It is recommended against using paint on deck flooring because frequently used pathways, such as from the steps to the door, will become worn.)

STAIN . Some stains are heavily pigmented and form a film, just as paint does. The recommendations for their application are the same as those for paint, including our advice against using them for the floor of a deck. Most stains, however, are more transparent and do not block moisture movement. There are other differences, though. Stains may be oil-based or water-based. Some formulations can be used immediately; others perform best when the wood is allowed to dry for a while. Best advice: follow the stain manufacturer's instructions.

WATER REPELLENT . Most brands say that it is okay to apply a water repellent without delay, which is ideal timing. For other brands, a slight delay is recommended. Again, it is best to follow the manufacturer's instructions.

Sources: http://www.wolmanizedwood.com/ http://www.treatedwood.com/

Alter Eagle Construction & Design

That's a lot good info! Very helpful. Thank you.

In addition the the first post there is a product from the Flood Company called Seasonite that is good to use on a newly installed deck. Check out their web site for more information.

You do not ever want to paint a deck with with a porch and deck enamel as it will peel off even if you let the wood dry out as moisture will enter the wood from the back side.

I feel that the best products to use on a deck are the sealer types because they don't peel and just have to be washed and redone every so often. The ones with some pigment will last the longest but don't get to much as it will wear off in high traffic areas.

I also feel that people need to remember that it is a deck and not a piece of furniture.