Build a Colonial Williamsburg style picket fence (free info)

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Build a Colonial Williamsburg-style picket fence to last.

By Paul Stevens

We have tried the ready-made picket fences sold at the lumber yards, but quickly realized that the two narrow boards they use to staple them together are little more than temporary spacers to hold them together until you get them home; they are not even a full 2x4. What’s up with that? Like many, we took them home, set my post, and nailed them up, and in about a year, we had a crooked fence falling apart.

After visiting Colonial Williamsburg and admiring the white picket fences, we decided that design would be perfect for our next garden project. This design uses a strong back as the top rail; in wood-frame structures, a "strongback" is used, with another 2 x 4 or 2 x 6 turned and nailed to the side of the top rail. When you look at the fence from behind, you will see the typical top rail where the pickets attach. Now imagine another 2 x 4 laid flat and nailed across the top of the rail. This helps prevent the top rail from sagging or shifting side to side in strong winds. This is a strong back and will make a fence last for years. It is best, especially when using treated wet wood, to turn the growth rings outward so that, as the board dries, it takes a natural curvature and sheds water rather than curving inward and holding water.

The Colonial Williamsburg fences have tall corner posts with decorative tops, and then the top rails are mortised into the post with the strong back laid on top and nailed between the posts. Some use a second strong back as the bottom rail, but most use just the top, with the bottom rail mortised into the post as well. The line post is cut off so that the flat board used on top of the rail to make the strong back runs continuously across the top of the line post, or that is where the joint is made. You can 45 that joint to make it even stronger.

This type of construction does require at least the top rail to be motorized into the post as setting it on the outside would mean your top board used for the strongback would stick out 1-1/2” at each post. The bottom rail can be mortised as well, or laid flat between each post and nailed to spacer blocks. The mortise cuts are really pretty easy to do; using a skill saw set at 1-1/2” depth, I scored a few times in the mortise, and knocked out with a wood chisel. It does not have to be as precise as building furniture. I set my corner post first with the mortise cuts, then use a string to align the post holes. Once those are complete, I place strings at my top and bottom rail placement, as well as the top of the post. This way, I can plumb the post, mark it, and take it out to lay the post down, cut my mortise joints, cut the post to length, and then set it in concrete.

A larger 6 x 6 post used as the corner post and 4 x4 used for the line post make the most attractive and lasting fence. Especially when the corner post is topped with an 8” x 8” x 1-1/2” cap, followed by another smaller size to form a stepped-up cap or another ornament, and then use trim around the bottom of the cap to make it look like a porch post.

On our first project to duplicate the Williamsburg look, we used the 6 x 6 post, made our strong back rails, and hand-cut decorative pickets, then nailed them onto the rails. On our second project, I used 4 x 4 posts as the corner posts and used the ready-made picket fence sections. I left the rails that came with the fence, but mortised them into the post, then used treated 2 x 4s as the top and bottom strongbacks. Sure, this takes more material, but I’m not replacing the fence every few years either.

We go back and visit where I did the 1st project and that fence looks as good as it did when we built it over 15 years, the one we currently have around our garden in the pictures has been in place 8 years. I occasionally have to nail some of the pickets where the staples have pulled through. I also see that on the 4 x 4 corner post, the mortises on two sides do not leave much of the post left; they have not broken through, but I wish I had used the 6 x 6.

Both fences were sprayed with two coats of a good water-based primer, then two coats of white latex paint. I chose the water-based because of the high water content in the treated lumber. I could have left it to cure and used an oil-based paint, but after all this time, I’m pretty sold on the water-based products, especially the primer with the stain blocker, since knots will bleed through if you don’t prime first.

Always use galvanized nails or nails coated that will not rust. I ended up with a couple of regular nails in the nail pouch, and they rust and bleed through very quickly.