Do You Have to Seal Composite Decking?

M. John
Do You Have to Seal Composite Decking?

Since decking is exposed to the weather, sealing the decking is important to keep the material from absorbing water or moisture. If you have wood decking in your home, you must be used to sealing the decking. But what about Ultradecking composite? Do we need to seal composite decking?

What is Composite Decking

Composite decking is a flooring material made from a combination of wood fibre, plastic and binding agents. The combination of these materials makes composite decking water-resistant. However, there is capped and uncapped composite decking. The capped decking has a higher resistance to water and moisture than the uncapped one.

Most of the composite boards in the market are capped decking. This decking has a plastic layer on its surface. The plastic layer prevents any moisture from entering the boards, making them resistant to water and moisture. Its water-resistant attribute is one of the factors that make composite decking superior to wood. Wood decking cannot repel water unless you seal the decking. Sealing timber will preserve its appearance and also extend its lifespan.

Do You Need to Seal Composite Decking?

If you have composite decking in your garden, you might be wondering whether to seal it like wood. The only reason homeowners would want to seal their composite decking is when it has no capping. But aside from that, composite decking does not require the application of sealants on its surface. The manufacturers advertised the decking material as water-resistant material.

However, the makers do not recommend sealing a composite decking since it is water-resistant. But this does not suggest that you cannot seal a composite board if you want to. It is not mandatory that you must not apply sealants on your composite decking. If you want to seal your composite decking, you can do so. Sealing a composite decking is the personal choice of every homeowner. However, it is always advisable to ask your composite decking manufacturer whether you can seal the decking.

However, applying the sealant on a composite board has its benefits. composite decking is not like wood that can’t repel water or moisture. Wood decking will warp if you don’t seal it. In the presence of moisture, lumber will expand. It will also contract when humidity is low. When this happens, the timber will surely warp.

The composite board, on the other hand, will not warp. A composite board will not absorb moisture even if you don’t apply sealants to it. Applying sealant to your composite decking will make it more resistant to mould and mildew. Bear in mind that if you seal composite decking, you will have to keep resealing the decking to maintain its appearance.

How to Seal Composite Decking

Although composite decking is water-resistant, sealing the decking will make cleaning it easier. If your composite decking manufacturer recommends sealing your composite board, here’s how to do so.

First, clear your deck surface by removing the things you place on it. Remove chairs, tables, planters and any other items you place on the decking. After clearing your decking, you can then proceed to clean it. When cleaning your composite decking, avoid using cleaners that contain bleach.

Bleach can fade the colour of a composite board; it is not a good cleaner for your decking. Use an ammonia-free liquid dishwasher to clean your composite decking. If you have a pressure washer, you can use it to clean your decking. A power washer helps in cleaning your decking faster than scrubbing. When you have finished power washing your deck, allow the decking to dry before you proceed to apply sealants.

Once the deck is dry, apply the sealants all over the decking. Homeowners can apply water-based sealants on their decking.

When applying the sealants on your decking, brush the sealants while they are wet to allow your composite decking to absorb more of them. If there is any excess on the product, wipe it off to ensure a clean appearance. Then, allow the decking to dry for at least a day or two. Once your composite decking is dry, you can start using it.


You don’t have to seal a composite decking since it is resistant to moisture. However, if you want to seal your composite decking due to personal preference, you can do so.

Tags: Seal decking

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