You can seal your composite decking by using a good water-based, decking sealer. The sealer will protect the surface texture of your composite decking from moisture and the UV rays of the sun. Sealing your plastic wood decking will ensure that you have a patio that will last longer with low maintenance. This write-up explains how you can seal your composite decking. Also, it addresses the issue of whether you should seal your plastic wood decking. Let’s commence with the latter before addressing the former.

Should I Seal My Composite Decking?

The answer to that enquiry is not straightforward. This is because composite boards are made to be durable and to last longer. Aside from that, composite decking has a capped surface. This surface has an extra layer of plastic that covers it and prevents moisture from entering the composite boards. Note that the material composition of composite decking is wood and plastic. Wood, as you know, absorbs moisture readily. 

So, since wood is part of composite decking, then the timber part can absorb moisture. But capped composite decking has plastic on its top that allows little absorption of moisture. This prevents your composite decking from swelling and warping when the wet boards dry. Some types of composite decking don’t have the extra layer of plastic on their surface. These types of plastic wood decking are referred to as the first generation decking. They absorb moisture, although not as much as wood, and they eventually become a breeding ground for mould and mildew. 

First-generation composite decking is not common these days. This is because makers of plastic wood decking have improved and are making second-generation composite decking. One thing about composite decking, whether it is first-generation or second is that you have to maintain them regularly. If you don’t and organic matters like leaves or pollen decay on it, it will become a breeding ground for mould and mildew.

 Although second-generation composite decking water-repelling attributes are good, they will still absorb a little water. This makes the wood part of your composite decking to become a breeding ground for mould. The solution to mould is for you to clean your outdoor patio regularly. If you don’t want your patio to absorb water and to breed mould, then you can seal the surface with a good decking sealer. 

How to Seal Your Composite Decking

Step One – Get All You Need

To seal your composite decking, you need a sealer. You can use any composite decking waterproofing sealer that you want. Aside from that, you need soap, a bucket, water, and a soft brush. If you have a power washer, you can bring it out.

Step Two – Clean Your Composite Decking

You have to clean your composite decking before you apply the stain to it. Note that you have to be thorough about it because sealing a composite decking is permanent. If you don’t remove dirt completely, the sealer will fix the dirt to your decking surface permanently. This will, in turn, distort the surface of your plastic wood decking. So, you have to identify dirt like mud and spray it off with a power washer.

 If you are dealing with mildew, you should mix soap with water and pour the soapy water on the spots. Then you should scrub with a brush that is not hard until you have removed the mildew completely. Also, you should wash off oil and grease stains by scrubbing with your brush after you have poured soapy water on it. After washing, please rinse your patio surface until you have removed all traces of dirt and water.

Step Three – Apply the Sealer

how to seal your outdoor decking

This is the part where you grab your sealer and open the can. Then you should pour the content in a large bucket so that dipping into it when applying the sealer will be easy. Whether you are using a brush or you are using a roller, the process is easy. Brush or roll the sealer or stain in the direction of the grain texture of your composite decking boards.

The grain texture of your composite decking is along its length. Brush or roll forward and backwards until you are satisfied. Please ensure that your composite boards absorb the sealer to get a better result. Also, ensure that you apply the sealer evenly on your patio surface so that a part will not contain more stain than other parts.

Step Four – Wait Till Your Decking Dry

Depending on the kind of sealer that you use, you will have to wait for some hours before your patio absorbs the sealer and dry completely. When your patio is dry, you can start using it for your activities.


You can seal your composite decking with the help of a water-based sealer. You should clean your patio thoroughly before you apply the stain.

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