One of the possible problems of having a deck is swelling. If you have a deck or planning to install one, you may have encountered this problem. The question is, how do you fix swollen composite decking boards? And why do they swell in the first place? And do composite decking boards swell?

Why Do Decking Boards Become Swollen?

Decking boards become swollen because of moisture and temperature. The boards absorb the moisture, causing it to swell. Wooden decks are the most susceptible to swelling. When the expansion of the board is too much, it can warp the board. After swelling, most decking boards will contract after the moisture leaves out of the boards.

Why is this an issue? The movement of the boards can damage the deck. If the deck absorbs too much moisture, the decking boards can warp and bend. The constant contraction and expansion also loosen fasteners over time. Nails are more prone than screws. 

Do Composite Decking Boards Swell?

As previously mentioned, wooden decking boards are the most prone to constant expansion and contraction. But how about composite decking boards. Do they become swollen?

Composites or more accurately wooden-plastic composites do swell. However, the amount of moisture they absorb compared to wooden decking boards are far less. Because of their construction, they are more resistant to swelling. But that doesn’t mean that they don’t expand.

Because composite decking boards do have wooden fibres, these fibres absorb moisture. And because the fibres are mixed with the plastics, the swelling of composites are uniformed. 

So to summarize, using composite decking is an excellent choice if you’re planning to build a deck and you’re concerned about swelling. However, you should remember that not all composites are the same. Some are more resistant than others. 

The best composites will absorb only about 5% of moisture even when submerged in water for a month. Others may absorb twice or thrice that amount. For best results, you may want to use capped composite decking boards for extra protection. 

How to Fix Swollen Boards

swollen boards

The only way to fix swollen wood or composite boards is by air-drying them. Moisture will leave out of the boards and will return it to its original size. However, there is not much you can do if the wooden deck boards are warped beyond repair. 

The best thing to do is to replace this with new boards. As for composites, some of them are resistant to warping and bending. They will return to their original size eventually. You may also need to re-attach some nails or screwdrivers that became loose due to the movement of the boards. 

Swelling is a huge problem for deck owners. As mentioned, there is very little you can do to fix boards that are too affected by the swelling. If that’s the case, the only way to fix it is to remove the boards and replace the new ones. However, there are many ways to prevent this problem from occurring. Doing so will save you time and materials.

For wood, you will need to purchase a sealant. It is applied to wood to prevent moisture from entering the boards. You will need to re-apply sealants every few years since they do come off over time. However, if you are using composite decking boards to build a deck, you don’t need to do anything to the boards. As previously mentioned, while they swell, they are resistant to warping, especially capped composites.

During the installation, there are also things that you can do to minimize the damage done by swelling. For both composites and wood, you would need to air-dry them first, so that they’ll return to their original size before you install them. 

You will also need to consider proper deck spacing. If you install the boards too close to each other, the boards may swell and create friction. On the other hand, if you installed the boards too close to each other, it can be quite dangerous. The amount of space you’ll be needing will depend on the materials that you’ll be using. To know the exact details on board spacing, you can read the manuals or ask the manufacturers.