7 Decking Fundamentals to consider for DIY Deck Renovation

The winter season can spike decking issues as it alters the moisture content of the decking, expanding the boards resulting in dire consequences.

If you’re planning to renovate your deck or build a new one this season, then go through these 7 decking fundamentals listed below. Most decking issues are a combination of more than one factor. Therefore, you should cover all the following points to ensure your deck looks healthy and lasts for years.

Timber Selection

All timber expands and contracts to the amount of moisture absorbed or released from its environment. The wood used for decking and cladding is subject to more changes in humidity from its exposure to elements like sun, rain, wind, storm, etc. Select a timber decking board that is suitable to your climate and can offer long-lasting durability. According to the timber specialist, Frank Di Stefano, a low to the ground timber deck should use a high durability Class 1 timber with a narrow board width up to 90mm and ideally a low shrinkage/ expansion rate like Merbau.


Good ventilation leads to the successful long-term performance of your deck. Ventilation should allow for an adequate crossflow of air across an enclosed space. It is this moving air that allows the sub-deck space to dry after the wet periods. Built-up humidity would be absorbed in that space, increasing the board’s moisture content causing the boards to expand and ultimately reduce the gap between the boards.

Allowance should be made to ensure air can easily service the sub-deck cavity. The usual consequence of a lack of or no ventilation is a damp sub-deck microclimate, causing the bottom of the boards to gain moisture and unsightly cupping. In the longer run, this wet sub-floor space can produce moulds leading the timber to decay.

Decking Gap

Leave a sufficient gap between the decking boards to allow expansion in the wet seasons. The wider the decking board is, the more it will expand from taking up moisture. If the gap is insufficient, the decking boards could swell to a point where they would push against each other. This pressure can cause decking screws to shear and boards to tent upwards.

Board Preparation and Finish

Apply an oil-based preservative to all surfaces prior to installation. This process acts as a sealer and helps slow down moisture loss or gain. Applying a sealer coat to cut ends when installing is particularly important as this is where most of the moisture is easily lost or gained in the decking. This oil coating penetrates through the timber providing ongoing protection while greying off if left to do so.


Properly designed decking nails and screws make your deck-building job easy. Screw fixings into treated pine joists should be 65mm long and 50mm long into hardwood joists. Predrilling and countersinking for screws are always advisable as it avoids splitting and burring.

Joist Membrane 

Use a waterproof membrane between the timber joist and the decking boards. Using a membrane will protect this joist from moisture and would maintain the holding strength of the fixings. Often early rot can be found at these junctions when water is trapped here without a shielding membrane. Using a joist membrane will help the wood to remain dry and, the joists will hold the nails and screws in place.


You must check your deck regularly for possible moulds and decaying. Early detection of the signs of degradation can help you look for a solution that will protect your deck. Without regular maintenance, the timber can rot to an irreparable extent. Seasonal cleaning and recoating would also help in maintain your deck.

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