Sealing a Deck with Deck Sealant

How to Seal a Deck Properly with a Clear Deck Sealant

By Mark J. Donovan

A deck is an extension of your home. It is a living space that enables us to enjoy the outdoors without having to be literally standing or sitting in the yard. It is the ideal space to have a barbeque or just sit back, relax, and read a book and enjoy the comfortable outside temperatures on a warm summer day.

A deck takes a lot of abuse from nature’s elements, however. Rain, snow, ice, extreme hot and cold temperatures, and ultra-violet light from the sun can destroy a deck in less time than you think, if it is not maintained properly and regularly.

One of the chief ways to protect a deck from all of nature’s elements is to seal your deck every one or two years. Sealing a deck not only protects it from the elements, it also helps to preserve’s the natural beauty associated with any wood deck.

Described below are instructions on sealing a deck so that your wood deck will last for years to come.

Best Time to Seal a Deck

In order to maintain the natural beauty of my wood deck I typically seal it every year or two. Also, because I live in New England, I find sealing the deck in late summer or early fall also makes the most sense. By sealing it during this time of the year I prepare it for the upcoming winter months which are the most severe and detrimental to wood decking. Snow sitting on a wood deck can slowly eat away at the wood due to the acidity of the water content in the snow.

 Sand your deck and restore it to looking like new!

Thus by sealing the deck just prior to winter I’m giving the wood decking a layer of protection to combat against the acidic snow and water.

If you live in a warmer climate, then I recommend sealing your deck in late spring to protect it from the intense heat and ultra-violet sunlight of the summer months.

Preparing Deck for Sealing

The first step in sealing a deck is to remove all the furniture and other objects from it and give it a thorough cleaning. You can clean the deck with any of the commercially available deck cleaners and/or you can clean the deck with a power washer. However, if you choose to use a power washer take great care not to destroy the wood decking with it. The wood can be severely and irreparably damaged by a power washer. If you decide to use a pressure washer to clean your deck, use the lowest pressure nozzle setting and keep the nozzle head at least a foot away from the wood decking and railings while washing with it.

Deck Installation Bid Sheet

If there is pine pitch on your deck then you may also need to use a stiff bristle brush to loosen it up and remove it.

After the deck has been cleaned allow it to thoroughly dry for 24 to 48 hours. Do not seal a deck with the wood still damp. If you do, the deck sealant won’t absorb well into the wood and will end up flaking off and overall making your deck look like an ugly mess.

Just prior to sealing your deck give it a once over with a broom or leaf blower to ensure it is free of any dirt or debris.

Sealing your Deck

Seal your deck when the temperatures are above 50oF and there is no sign of rain in the forecast for at least the next 24 hours. If it rains just after sealing the deck, again the sealant won’t absorb properly into the wood, and you’ll have a peeling mess that will only be able to be removed by sanding the entire deck.

If you have a relatively small deck, apply the sealer with a brush. If you have a large deck, use a roller to initially apply the deck sealer. However, I find that the sealing penetrates best when applied with a brush. Thus, if you do use a roller to apply the deck sealer to the decking boards, apply it in small sections and follow right behind with a brush to work the deck sealer into the wood for maximum penetration.

Typically only one coast of deck sealant is necessary. After applying the deck sealer wait 24 to 48 hours to walk on the deck and return the furniture to it. If the humidity is high I recommend waiting 48 hours to ensure it is fully dry. If the deck is tacky at all, wait another 24 hours before using it.

For help on building a deck, see’s Deck Installation Bid Sheet. The Deck Installation Bid Sheet will teach your how to hire the right deck contractor, and help to ensure that your deck project is completed on time and budget.

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