How to avoid the most common decking installation mistakes

Decking problems usually come from the same common installation errors. Small details around expansion gaps, joist spans, drainage, airflow and fixings can lead to movement, swelling or early failure. When installers take care with these basics, the deck stays stable for longer and call backs drop. 

Below are the most common trouble spots and the better habits that keep decks performing well. 

Gaps that restrict board movement 

Incorrect gapping is one of the main reasons boards lift or creak. When there is no room for expansion, decking reacts to moisture and heat. Tight gaps can cause cupping, buckling or edge pressure. Gaps that are too wide can break the visual line and create uneven walking surfaces. 

Setting expansion gaps with intention gives boards the room they need to move. Side and end gaps support drainage and reduce stress across the deck. Spacers or clip systems help keep spacing even. Always check the manufacturer’s installation guide, as gap requirements vary between timber and composite decking products. 

Joist spans that allow too much flex 

Joist spacing has a big impact on how solid a deck feels. When spans are too wide, boards can bounce, flex or put extra strain on screws and clips. Problems often appear when one joist spacing is used for every board size or when no allowance is made for boards laid on an angle. 

Matching joist centres to the board profile creates a more stable surface. Some boards need tighter spans due to their density or width. Closer centres on diagonal runs or high traffic zones help reduce movement. Span tables differ between manufacturers, so always follow the guidelines for the specific board you are using. 

Using low quality materials 

Low quality or untested materials can fail early in Australian conditions. Cheaper boards or products from unknown manufacturers may not be built for our heat, UV or moisture levels. These boards can fade, swell or twist much faster than expected. 

Low grade materials also make installation harder. Inconsistent sizing or density can affect spacing, fixing and alignment across the deck. 

Choosing materials that are tested for Australian conditions leads to a cleaner install and a longer lasting finish. Abbey Timber supplies decking that is consistent, reliable and designed to handle local climates, giving installers confidence in how the product will perform. 

Poor drainage and limited airflow 

Water and trapped moisture are two of the biggest threats to deck performance. Decks built flat or too close to walls often hold water around the frame. Low or boxed-in decks also trap humid air, slowing drying time and creating conditions where mould and decay can develop. 

Designing for drainage early makes a major difference. A slight fall helps water run off the surface. Openings around the deck allow water to escape from the subfloor. Good airflow under the structure helps the frame dry between weather changes. Some products have minimum fall or ventilation requirements, so always check manufacturer instructions. 

Incorrect fixings 

Fixing mistakes are common and often show up quickly. Screws too close to hardwood edges can split the timber. Over-driven screws can crush composite decking or stop it from moving along its expansion line. Using the wrong screws in wet or coastal areas can cause corrosion or weak attachment points. 

Choosing the right fixings for the material and environment helps avoid early failures. Pre-drilling hardwood provides a cleaner hold. Many composite decking boards work best with purpose-made concealed clips that allow controlled movement. Fixing methods differ between brands, so always follow the correct system for the product you are installing. 

Poor site preparation 

Many problems begin before installation starts. Boards left in direct sun can warp. Materials installed straight off the truck may move more once they adjust to local moisture conditions. Subframes that are not level or square create alignment problems across the deck. 

Allowing boards to acclimatise, storing them in shade and checking the frame for level and straightness all help create a smoother install. Sealing cut ends and confirming support points also protects the deck for the long term. 

In summary 

• Give boards enough space to move without looking untidy 
• Match joist spacing to the board type and layout 
• Choose materials suited to Australian conditions 
• Plan for water to run off and away from the deck 
• Use fixings that suit the material and environment 
• Allow airflow under the deck so it can dry out properly 
• Follow manufacturer specifications for every product you install 
  

Abbey Timber has the largest range of decking timbers, composite decking, hardware, and tools, with fast delivery and a Sydney showroom where you can see the difference for yourself.  

If you would like more advice from one of the expert trade team at Abbey Timber, call or visit the showroom or chat to us online.