Corrosion Resistance

There are two things you should never do in life. The 1st being, doing everything opposite your wife tells you to do; the 2nd is applying white aluminum to pressure treated wood. As you can see when you mix the two bad things happen. Pressure treated wood used to be treated with chromated copper arsenate, but I believe this was phased out in 2005. This house was built in 2005 so not sure which type of lumber was used. Now treated wood is treated with alkaline copper quaternary and copper azole. This contains much more copper than previous applications. When aluminum flashing contacts this type of wood the two metals collide and corrodes the aluminum. This flashing is only 10 years old and you can see the damage. Our last build we used pressure treated as a base and then painted over it. If you do it this way you'll have to repaint every 5 or so years. With flashing you'll have to replace every 10 years. Paint is about $20 for a gallon and flashing replacement with paid professional install is $400. You be the judge. Of course there are many ways to wrap a post but in my opinion if you are building complete custom posts wrap it in Hardie board and then paint. You'll still need to paint every 5 years but there will be fewer warps and fewer calk applications to apply. Of course we did it all wrong and re-wrapped with aluminum so you'll catch us 10 years later trying to figure out what our wives told us not to do.....Oh, and if you need help with any flashing or vinyl work call my buddy Paul at 850-624-9625