Wooden decks are subject to weathering from Mother Nature. Older decks show signs of aging on the surface. Have you ever noticed that older wooden fixtures are covered in cracks? Your deck is no exception. You can tell a lot about a deck based on the cracked deck boards. In this blog we explore the nature of cracked wood on your deck.
What You’ll Learn in this Blog:
Types of Cracks
Causes of Cracking
How to Repair Deck Cracks
Types of Cracks
We separate deck cracking into two main categories: Shake and checks. Shake divides the wood along the grain. These splits are most typically found on the posts creating a separation between the rings of grain. Checks are splits in the wood through or across the grain. They develop as the wood dries over time. Posts typically have natural checks running up and down the surface.
What home owners see most often are shake and checks on the surface of the handrails and floor boards. These separations occur over time as the wood suffers repeated moisture and sun damage.
Causes of Cracking
Not all cracks result from aging. Some cracks occur in the tree, before the lumber is cut and dried. Trees experience ruptures based on a number of factors such as growth stress, microorganisms, and conditions in their environment. Processing lumber also creates splits in the wood. Both machine and drying processes can cause splits. Of course, best practices include inspecting lumber before you purchase for these types of pre-installation cracks. Another major cause of cracking happens post-installation as the wood bakes in the sun. This type of splitting is tension-based cracking.
Did you know that trees are about 50% water? In addition to natural moisture, pressure treated lumber receives a treatment of chemicals mixed with water. This lumber continues to ‘bake’ even after being installed. The sun causes the wood to shrink as the moisture dries. The tension of drying is responsible for the shrinking that leads to checking cracks. While at first the cracks are thin and small, without proper sealing, they continue to grow.
For more on Cracked Treated Wood, Ask The Builder.
Why Cracks are a Problem
Cracks on the wood are far from attractive. They affect the appearance of a deck and the smoothness of the surface. Not only are they unattractive, they’re also harmful to the health of the wood. Cracks allow water and moisture to seep into the wood’s core. As this water dries from the sun, the tension cracking continues, causing the cracks to grow. Unsealed cracks perpetuate the problem. Eventually the wood becomes so cracked that it needs replacing. Cracks running deep and long compromise the strength of the board.
Now that you can identify the different types of cracks, how can you repair them? Cracks found in 4×4 posts and along the band board wrapping around the deck floor are unfortunately not repairable. However, we have a solution for cracked deck boards on the floor as well as the hand rails. Besides, these are the parts exposed to direct sunlight, and usually suffering the most from splitting. The key is to seal your deck as soon as possible. Proper sealing prevents water from seeping into the wood. You’ll notice on a sealed deck that moisture beads up on the surface, as opposed to being absorbed. The best option for protection is an oil based solid color stain. For a step by step of how to seal your deck, read our Professional Guide to Staining your Deck.
To repair your existing cracks, use an epoxy polymer and generously fill in gaps. This step precedes the staining. For best results, sand the cracked deck boards down first to create a clean surface and access the cracks easily. The epoxy polymer requires mixing. It also hardens quickly so expect some trial and error. Once the cracks are sealed, sand the excess epoxy polymer, once again creating a smooth surface. Sealing the the splits is crucial to effectively protecting your deck from future damage.
Get a step by step guide for How to Refinish Your Deck.