The Official Blog of The Fence Authority

When discussing problems common to wood fences, insect and rot damage take up a large portion of the spotlight. Indeed, these are serious problems, and both go hand-in-hand with moisture, which is the natural enemy of wood fences. However, another issue you may have thought about less is cracking and splitting, which can also have a major impact on the structural integrity of your fence. Some cracks are natural and normal, but many can be avoided by using high-quality wood that has already been seasoned. Let’s break down the reasons fences crack and what to do about it.

Why fence wood cracks or checks as it dries

“Check” your fence before you wreck your fence!

Checks are one of the most common types of cracks that occur in wood. Checking is a natural part of the seasoning process, which is what happens when wood dries out after being chopped. Checks form because the inside of wood dries more slowly than the outer surface. Moisture causes wood to swell, and as it dries, it shrinks, putting stress on the wood. All wood starts out “green” and needs to dry when it is freshly chopped, and the uneven drying process is natural and unavoidable in most cases, often resulting in checks.

If you get a new fence, you may notice checking during the first few weeks of your fence’s life. However, this process may not take place until summer when the hot sun dries out your fence wood. Either way, after a few weeks, your fence should stop checking, but that doesn’t mean the wood will never get wet and have to dry again, so further warping is likely over time–it’s just that cracks in already-seasoned wood aren’t called checks. Most checks are less than 4” long and 3/16” in width, and these small imperfections should not have much impact on your fence’s structural integrity. However, if cracks continue growing larger, you may have a problem, and besides, many homeowners dislike the appearance of them.

How to choose fence materials that won’t crack

Because checks appear as wood seasons, it is best to use wood that has already be seasoned if you’d like to avoid them altogether. Otherwise, the fence you install may look perfect at first, but it will begin to change when checks form. Replacing the boards using the same unseasoned wood won’t solve the problem because the new boards will be just as likely to form checks. Sealants that moisturize the wood’s surface may help it dry more evenly both during initial seasoning and as changing weather puts further stress on the wood.

Ultimately, cracks occur as a result of pressure on the wood, regardless of the cause. When your fence is first installed, it’s important to both choose a high grade of wood and ensure that installation is properly completed, either by you or your contractor. The thinner a piece of wood is, the more likely it is to split, meaning the risk is higher for panels than it is for posts. If you don’t have the budget to construct your entire fence out of the highest grade of wood, it may be safer to opt for a lower grade for posts only. Some cracks are caused by improper hardware installation rather than the quality of the wood itself, though higher grades of wood will be less susceptible to these problems.

Avoiding cracks during fence installation

Screws are a more secure method of installing fence boards than nails, but both screws and nails can cause splitting problems unless you do it right. Pointed nails are the most likely to cause splits, so although nails are not recommended, if you do use them, make sure they have been blunted. It’s also best to pre-drill holes before inserting nails or screws. While screws are superior, both nails and screws will crack boards if they have to be forced into the wood or are overdriven. Screws and nails can also cause splits when they are placed too close to the edge of the board.

If your wood keeps splitting, it may be time to split up with your fence

By properly caring for and maintaining your wood fence, you can prevent a lot of problems. However, cracking in fence boards often has more to do with wood selection and installation than what you do after your fence has already gone up. To temporarily fix cracks, you can fill them with epoxy or wood putty, but this doesn’t address the cause of the crack, so there is no guarantee you won’t continue to see problems. If one of your fence boards has severely warped and cracked, it’s likely time to replace it with a fresh one. If your fence was improperly constructed with low-quality wood that keeps cracking no matter what, it’s likely time for a brand new fence that won’t give you the same trouble!