How To Clean & Seal A Deck

Fig 1. Decks are a great outdoor entertaining area, but they require periodic maintenance.

The majority of decking is made from treated pine because good quality treated pine may last thirty years or so, before there is any substantial decay. However, as with all timber, discoloration and splintering can begin after only a few months in harsh weather conditions. For this reason, most people take on a regular cycle of maintenance. Failure to do so won’t cause your deck to rot, but your deck will most certainly become discoloured, and the surface will become rough and prone to splinters.

Fig. 2 To tell if you need to re-seal your deck is to pour water on it and if the water beads up, the deck is waterproof, if not it’s time to re-seal

Over time, rain reduces your deck’s protective seal, turning the timber to a dark colour due to water absorption.

An easy way to tell if you need to re-seal your deck is to pour water on it and if the water beads up, the deck is waterproof, if not it’s time to re-seal (Fig 2).

Start by clearing the deck of all furniture, plants etc. Use a broom to sweep the deck keeping an eye out for damaged or loose boards and nails. Make any repairs if needed.

Fig. 3 Remove the old stain by sanding back the surface

On previously stained decks, you will need to completely remove the old stain by sanding back the surface using a drum sander (Fig 3).

Remember to always sand in the direction of the grain. Start with medium to coarse sandpaper (50-80 grit) and finish with a fine grade (150 grit).

Now that your deck is clean, it is time to choose a sealer. There are many sealers available to achieve a natural transparent finish, a semi transparent or opaque finish with stains or paint. It is important to work out how much product you need and also take into account weather conditions and timing. The type of timber and its absorbency will vary on the amount of product required, so be sure to ask Bunnings Team Member.

Applying the finish can be done with a paint brush or a pad applicator or roller. Here are some tips, but make sure to follow instructions on the finish container.

Make sure you stir thoroughly before application.

Do a section at a time, brush between boards and along the edges, coat evenly along the grain of 2 -3 boards at a time.
Keep a wet edge to avoid lap marks and double build.

Work towards natural breaks such as joins.

Don’t stop midway along a board.