A timber deck is a beautiful addition to any home. However, even the best timber will need a little TLC to protect it from the elements and keep it looking great. Regularly staining or sealing your deck will help to protect it from rot, mildew and moisture damage, UV damage and general wear and tear.
What is deck sealing?
As an organic material, timber is particularly susceptible to moisture damage including rot, fungal growth, mould and mildew. Additionally, excess moisture can attract pests like termites and other wood borers.
Deck sealing involves applying a clear or transparent sealing solution to the surface of the wood. This sealer either penetrates into the wood or forms a clear film on top. This helps to lock out moisture and prevent water intruding into the timber.
By preventing moisture from entering the timber, you can significantly reduce the chance of wood rot or mould or mildew problems.
Using a deck sealer with added UV protection can also help to prevent UV damage. Prolonged exposure can lead to unprotected timber greying and fading. It can also dry up the timber’s natural oils, leading to cracking and splitting. While a deck sealer will help to retain the wood’s natural oil and prevent drying and cracking, they generally won’t help to prevent UV damage unless you use a sealer with added UV protection.
Ideally, your deck should be re-sealed once every 12 months. However, depending on the amount of foot traffic, sunlight and moisture your deck is subject to, you may benefit from re-sealing every 6-8 months.
What to do before sealing
Before applying the sealer, there are a number of things you may do to ensure the best possible results. Not all of these steps may be necessary in your particular circumstances, but they should at least be considered.
Find the right sealer
It’s worth spending some time finding the right sealer. Depending on the type of timber and your specific climatic conditions, different products may be recommended for your deck. Do your research and find the product that’s right for you.
Inspection & repairs
Applying a timber sealer to damaged timber will not improve the look or protect the wood if the damage has penetrated the surface of the timber. Before you start, be sure to replace or repair any loose or broken boards.
You should also check for any loose or raised nails, screws or fixings. These should be repaired or replaced before you commence with the sealing. Raised nails or fixings can tear and damage the brushes and applicators and prevent the smooth application of the sealer. Read the most common signs that your deck needs repairing.
Check the weather
Before preparing your deck for sealing or staining, it’s important to check the weather forecast. The sealer will need ample time to dry so you will want to ensure that you have at least 24 hours (ideally 48 hours) of clear, dry weather without rain or humidity.
It’s also important to work within the right temperature range. Too hot and the sealer will evaporate before it has a chance to be absorbed into the timber. Too cold and you may end up working on a damp or frosty deck, which could mean that timber won’t absorb the sealer, leading to an uneven, splotchy finish.
Aim for clear, dry weather, with minimal wind and a temperature range of 20℃ to 30℃.
Clean and sand the deck
The timber needs to be clean and free from existing coatings, debris and contaminants before applying the sealer. That means it’s vital that you clear and clean the deck to ensure the best possible finish.
If there is an existing coating (or remnants of an existing coat) on the timber, you may need to sand back the timber before applying the sealer. Any old coat on the surface of the timber might prevent the sealer from being absorbed into the wood.
Once the timber has been sanded back (if necessary) the deck will need to be thoroughly cleaned to remove any debris, sawdust and other surface contaminants. The easiest way to do this is with a pressure washer. Allow 24 hours for the timber to completely dry.
Apply the sealer
Now that all the prep work is complete, you can start applying the sealer.
Using the right tools (usually a brush, paint roller, or sprayer) apply the sealer in one thin coat at a time. Thinner coats dry faster and create a more even finish. You may need to use a brush to get into the corner and other tight areas to create an even coat.
It’s worth noting that sealers should be stirred before use, not shaken (shaking can cause bubbles to form in the finish).
Finally, it’s important to let the deck completely dry before anyone uses it. You should aim to allow 48 hours for the deck to completely dry. While the sealer is usually dry to the touch in a few hours, it’s best to allow plenty of time for it to completely soak into the timber.