2008 November Lumber Talk.com: Professional-Level information and how-to-build articles for wood, timber, and lumber professionals and users. 2008 November » Lumber Talk

Here are some options for those of you perplexed by the question of how to preserve wood posts. Whether you are trying to build a long-lasting fence or other structure or trying to extend the life of existing wood posts you have options. Without exceptions, the options are far easier before installation.

Pressure Treated Wood Posts
No additional work required – just buy wood posts treated for ground contact (usually .40pcf). Depending on the area where you are installing your pressure treated wood posts, they should last between 10 and 30 years (maybe more). 10 years if the area is pretty wet and/or has a bad termite problem and 30 years if the area is pretty dry.

Poly Coated Treated Wood Posts
poly coated wood posts from American Pole and TimberI only know of one place that offers poly coated wood posts – American Pole and Timber based in Houston, TX. The coating is a UV-resistant “poly urea” coating (look and feels like heavy vinyl) and is obviously tough as hell and will not come off of the wood. They guarantee treated poly coated posts will last 50 years. Pretty impressive. The product has only been around for about 10 years but I would put money on 50 years for treated wood coated with a thick UV-resistant vinyl. They supply any quantity but if you are outside of Texas or Louisiana, you might need to buy quite a few to justify the freight expense. You only need to have the post coated from about 6 inches above the ground line to the bottom of the post.

Plastic Coated Wood Posts
Similar to poly coated wood but I wouldn’t put my money on it. Buy treated posts and spray the bottom of the post up to about 6 inches above the ground line with spray-on plastic in a can. You can get a can of spray-on plastic for about $5 at the major big-box hardware stores. One can should easily cover the bottom 3 feet of about 10 posts. It’s cheaper than the vinyl option and should add 10 years onto any posts life.

Sealants or Stains
If you are going to seal or stain pressure treated wood, make sure it is dry first since sealing in the moisture left from the treating process will only make your posts rot faster. Sealing untreated posts will add a few years to their lives but, seriously, just get treated posts – unless you just LIKE replacing fences.

Paint is for color – not protection. Yes, it protects a little but, again, if you are going to use paint to preserve untreated wood posts just go ahead and admit that you like replacing fence posts. Want color? Paint away. Want preservation? Use treated posts.

The BEST WAY to Preserve Wood Posts
In my opinion, the absolute BEST way to preserve wood posts is with pressure treatment – whichever treatment chemical you choose – and a coating of some kind. The longest lasting wood posts will be pressure treated and coated with the vinyl coating. The most bang for your buck will probably be to use pressure treated posts and spray-on plastic.

Now you know how to preserve wood posts and which methods will work best for you. If you choose paint, don’t call me because I hate replacing posts. I will gladly lay in my hammock – supported by my vinyl coated treated posts – while you install your second set of painted posts, though. 🙂

By Chris | November 4, 2008 - 9:02 am - Posted in Decks & Fences, How To, Treated Wood

staining pressure treated lumber I regularly get questions about staining pressure treated lumber so here are some answers to as many of those questions as I can think of now. Before you read on, understand that staining or painting pressure treated lumber is just like staining untreated lumber. The main thing is that the wood needs to be clean and dry.

Can I stain pressure treated lumber?
Yes. You can stain pressure treated lumber as long as the wood is dry.

Why do I have to wait before staining pressure treated lumber?
The pressure treating process involves using a water-based solution to carry the treatment chemicals into the fibers of the lumber while under pressure. The process leaves the wood wet. If you want wood that is already dry, purchase KDAT lumber (KDAT = Kiln Dried After Treatment). KDAT is usually #1 and, yes, it costs more.

What are the consequences of staining pressure treated wood before it’s dry?
The stain or paint will probably bubble a little AND locking moisture into the wood might create a great place for fungus or rot to take hold and destroy some boards.

How long should I wait (allow the wood to dry) before staining pressure treated lumber?
It depends (of course). In a sunny, hot, and windy climate where it never rains your pressure treated lumber will probably be dry in a few weeks. In a cold and muggy climate (Seattle, for instance) it will take months for your wood to dry.

Some professionals recommend building whatever you are building and waiting about six months before staining pressure treated lumber. Then, stain the lumber after a few weeks of warm sunny weather. This is long enough for the wood to stabilize and for the water from treatment to evaporate. Remember to sweep and/or dust before applying the stain or paint.

Read further to learn about drying lumber yourself…

What kind of stain should I use for pressure treated lumber?
There are many stains and paints on the market. My favorites are based on working with lumber yards and seeing results from Consumer Reports. So, I like Cabot and Wolman brands. Many people thing Thompsons is the best because their marketing is the best. Many professionals completely disagree with the idea that Thompsons is any good at all. I am not saying anything about it – I’m just sayin’. The choice between water-based and oil-based stains is up to you. Read the backs of the cans. Back to staining pressure treated wood…

How should I stain pressure treated lumber? Or, how should I apply the stain?
Read the can because it varies with some stains but most stains can be applied with a brush, sprayer, or sponge. You will probably find a sprayer to be the easiest method.

How can I speed up the lumber drying process and stain my lumber sooner?
The best way is to buy kiln dried lumber (KDAT) in the first place. If you don’t want to do that…

You can dry lumber yourself but you need to be concerned about warping.

Ideally, you should stack the lumber on “sticks”, in the same way wood is stacked for kiln drying, and then strap the bundle to keep in straight. To do this, place a few small (1×1 or 2×2) sticks between each layer of lumber (perpendicular to the lumber and spaced about 3 feet apart) allowing for air flow between the layers. Then wrap a few straps around the lumber and make them tight. This allows air to reach all sides of the lumber while applying pressure to the lumber and minimizing the chance of warping. Warping is caused by the movement of moisture in and out of wood. You need to stabilize/support the wood while it dries. To take it to another level, point a box fan (or two) at the side of the bundle to speed up the flow of air across the lumber. If you set this up in your garage or some dry covered area your lumber will probably be adequately dry in a few weeks.

Should I stain pressure treated lumber yearly?
The answer is simple and goes something like this. If you want your deck/gazebo/arbor/whatever to look better for longer you should stain it on a yearly, or regular, basis. Of course, putting a protective stain or other coating on wood will make it last longer and look better while it lasts.

Staining pressure treated lumber is not rocket science. In fact, there is nothing remotely complicated about it but it does take time and if you don’t do it properly, you’ll mess it all up. If I did not make this point obvious enough above then let me say it again here:

Treated wood must be dry before you stain or paint it.

Enjoy your project. Wear gloves. Wear goggles. Be careful with tools. Work in ventilated areas.