Composite decking installation is very different from typical wood decking installation. The expansion and contraction rates of composite materials differ from those of lumber, which should be taken into account during installation to avoid expensive repairs and unsightly warping. The secret to a long-lasting, aesthetically beautiful deck is careful planning and preparation. When building composite decking, steer clear of these twelve typical blunders.
1. Not Leaving Enough Expansion Gaps Between Butt-Ends
Because composite decking boards are a combination of wood and plastic, they expand and contract more than hardwood. Boards may twist and bend if there are not enough expansion spaces between their ends. Temperature determines the proper spacing, which is normally 1 mm if the temperature is over 26°C, 3 mm between 4°C and 25°C, and 6 mm if the temperature is below 4°C. When boards are installed too closely together, they may strain against one another and buckle.
2. Insufficient Ventilation Underneath the Deck
Because it contains cellulose fibres, composite decking absorbs some moisture. Moisture buildup and decay can result from inadequate ventilation. To ensure ventilation, there must be a minimum of 35mm between the deck boards’ underside and base. This distance prevents degradation by allowing composite joists and boards to drain and dry fully.
3. Using a Low-Quality Subframe Material
Any decking project requires a sturdy substructure. Composite decking needs a strong support framework, in contrast to timber decking. Make sure an old subframe hasn’t been compromised by erosion or water damage before reusing it. Upgrade to subframes made of composite or plastic timber whenever possible, especially in regions with high water tables or floods. Plastic timber resists decay and works well in moist conditions.
4. Using an Existing Timber Subframe
A sturdy foundation is essential to the strength of your deck. Because it self-anchors, a steel subframe provides the optimum stability and longevity for a rooftop patio or balcony. Because it doesn’t decay, plastic lumber is better than wood in high-moisture environments. Make sure the wood is seasoned and fit for heavy use before utilising it.
5. Placing Joists Too Far Apart
Utilising an existing timber substructure may seem like a cost-effective solution, but many timber decks have joist centres that are 500 mm apart, which is inappropriate for composite decking. Because composite materials have a different flex than timber, joists spaced 250–350 mm apart are necessary. If joists are spaced too widely apart, the strength and longevity of the deck may be jeopardised.
6. Using Non-Compatible Decking Clips
Every composite decking company creates its clips to take into account the special qualities of its constituent materials. Using clips from a different manufacturer might have an impact on how well the deck works. Clips are made to accommodate the varied expansion and contraction of composite decking compared to wood. The boards can grow without developing problems like cracking if the right clips are used.
7. Fixing Boards Directly Without Clips
Although screwing boards together might seem like a smart idea, composite decking calls for flexibility. Because direct screw attachment limits mobility, when the boards expand and compress, fractures will form around the screw holes. The integrity of the boards is preserved with clips made especially for composite decking, which enable the boards to move naturally with temperature fluctuations.
8. Not Treating the Ends of Timber Joists
Treating the subframe’s wood on both sides—including the ends—is crucial to preventing rot. Ends are frequently disregarded since it is simpler to treat the wood after it has been placed. Untreated ends, however, are prone to deterioration and dampness, which over time may weaken the subframe.
9. Failing to Install Double Joists at Board Joins
Boards greater than 3.6 metres will need to be joined in longer decks. To guarantee the integrity of the deck and stop it from splitting or moving, double joists should be erected at these joints. By providing additional support for each board connect, you can preserve the deck’s structural integrity and stop it from moving over time.
10. Not Adhering to Brand-Specific Installation Guidelines
Every composite decking product has different installation needs and is not made equal. It’s crucial to adhere to the manufacturer’s installation instructions since doing otherwise may void your warranty. In order to ensure optimal performance, these recommendations are intended to address the particular composite material’s inherent features.
11. Neglecting to Allow for Adequate Drainage Slope
Although it may seem perfect, a perfectly level deck can result in standing water problems, which over time can lead to mould and mildew. It is advised to slope away from the house by 1% (10 mm drop per metre) to provide adequate drainage. Although it is barely obvious, this slight slope keeps the deck surface dry and lowers the risk of slippage by allowing water to drain.
12. Choosing the Wrong Type of Composite for the Setting
Not every environment is a good fit for every composite decking product. Although lightweight composite solutions are simpler to install, they might not be able to handle high foot traffic. Solid-core composite boards are a preferable option because of their increased strength and longevity in commercial or high-traffic locations. Using the incorrect product might limit the deck’s lifespan and cause structural problems.
