Wooden fences do a great job of protecting our privacy, controlling our pets, and defining our yard. However, wooden fences can fall into disrepair fairly quickly if regular maintenance is not performed, like sealing the wood. Almost all wooden fences are built from moisture and insect resistant wood, like pressured treated, cedar, and poplar. To maximize the life of a wooden fence, it is important to seal the grain to prevent splitting and cracking of the pickets. Today we will discuss the subject of sealing a wooden fence and how to get started.

Why Would I Seal My Wooden Fence?

The vast majority of wooden fences are built with pressure treated lumber, although cedar, farm grown redwood and poplar are also commonly used. Pressure treated pickets (the vertical boards between the posts) are usually made from rough hewn 5/8” x 6” lumber, and can have any number of profiles on the top. Some are dog-eared, some are 45 degree angles, while others are rounded over.

These boards are prone to splitting and warping because they are cut from a single log and are wider than they are thick. Sealing these boards greatly reduces this effect by preventing the wood from remaining porous. Sealers do a great job of sealing the pores within the wood grain, preventing it from soaking up moisture. Wood that is protected from this constant expansion and contraction is much less likely to crack.

The posts and rails that hold the pickets are also usually pressure treated. This chemical treatment is very useful to prevent water and insects from damaging the fence over time. Posts are not as prone to warping and splitting as the pickets, but they are prone to twisting. Sealing the posts deter this twisting, preventing the rails from bowing as well.

How Do I Seal My Wooden Fence?

1. Pressure Wash First

Pressure washing a wooden fence before sealing it is strongly recommended as this will remove and loose debris and raise the grain of the wood. Allow the fence to dry completely, as this will allow the fence to soak up the most sealer.

Be careful using a pressure washer however, as the pickets are quite thin. Especially if the pickets are bone dry, the force created by a pressure washer can damage the pickets. Most pros use either a white or yellow tip to prevent blasting a hole through a picket.

2. Allow the Fence to Dry Completely

Drying is critical, so allow plenty of drying time. Often the smartest strategy is to wait until the warmest, driest time of the year, as this ensures the fence is as dry as possible before applying sealer. This step is important, because as the wood dries it makes space within the grain for the sealer.

3. Apply the Sealer

Applying the sealer with a sprayer is the easiest, fastest method, but it can be applied with a brush or roller as well. The first coat will often require as much as 50% more sealer than the subsequent coats, because the first coat does most of the sealing. The additional sealer will be absorbed into the wood, protecting it from the inside out. After the first coat has dried, additional thin coats are applied, and so on until the desired thickness is reached. In most situations, two or three coats are recommended.

Seal Your Wooden Fence For Years Of Use

If you use pressure treated lumber for your fence, you’ll want to wait about a year or so before sealing it unless your lumber has been kiln dried. This is because the chemicals used during pressure treating will leach out as the lumber slowly dries. Usually a couple of warm summers is long enough to dry out the pressure treated lumber enough to allow it to accept a sealer.

If your fence is built from naturally rot resistant lumber, you’ll probably want to seal it immediately. Consult your lumber dealer for specifics, but most natural lumber will not be treated prior, so it’s a good idea to seal your fence before it gets wet. It’s not the end of the world if you wait, but your fence will likely have fewer checks, cracks, and twists if your natural lumber is sealed sooner rather than later.