Deck Board Spans
21 x 145mm Iroko decking should be installed with joists spaced at 400mm centres. When installing the boards diagonally the joists should be spaced at 300mm centres.
Deck Board Spacing
21 x 145mm Iroko decking should be installed with a 5mm gap between the boards. The space between the boards allows for air circulation and slight expansion with changes to the humidity level.
It is important to allow adequate air circulation underneath the deck to prevent cupping and warping of the boards. It is recommended that a vapour barrier is used on the ground to prevent moisture from absorbing into the underside of the deck boards.
There are a number of different options available for fastening deck boards to the joists. We recommend screwing through the face of every board using 5.0 x 60mm Countersunk Stainless Steel Screws. Fix two screws into every joist at quarter points on the deck board (36mm from each edge). We recommend that pilot holes are drilled prior to inserting the screws. This is particularly important at the ends of the boards to prevent splitting. 5.0 x 60mm Countersunk Stainless Steel Screws will flex slightly as the wood expands and contracts as the level of humidity changes with the changing of the seasons.
For a cleaner finish we suggest recessing the screws and using plugs to hide the screw heads. Plugs can be cut from off-cuts of decking using a relatively inexpensive drill attachment called a plug cutter.
There are a number of hidden fastening systems available. None of these products are as reliable as screwing through the face, and it is likely that there will be some additional movement of the deck boards when using hidden fasteners. If using a hidden fastening system it is essential to allow adequate ventilation beneath the deck and to coat the deck boards with an appropriate finish on all sides prior to installation.
The longer the deck board the greater the tendency for it to be slightly bowed. To overcome this, most professional deck installers will carry a tool called a Hardwood Wrench, or Bow wrench, which enables the user to easily straighten a bowed board single handed as it is installed. The Bow wrench is relatively inexpensive and can save a lot of time, so it’s worth buying even if you only use it for one project. It can also he hired from some tool hire stores.
Iroko decking from Silva Timber is end-sealed during the manufacturing process to help prevent splitting and checking on the ends of boards. We recommend that if the boards are cut during installation then the exposed end grain should be sealed as soon as possible. A clear, water-resistant wax such as Osmo Wax End Sealer should be used.
Cleaning and Maintenance
Your Iroko deck will benefit from regular cleaning. Brush the deck with a stiff broom to remove dirt and dead leaves, and ensure that the gaps between the boards are clear of organic debris. Clean the deck periodically with Multi Wash by Sansin® to remove grime and mildew. Iroko decking can be pressure washed, but it is important to select a low setting to prevent the wood fibres on the surface from being damaged.
If your Iroko deck is weathered it is possible to restore the natural colour with Wood Cleaner by Sansin®. This product will remove weathering, mould, algae, mildew and iron stains and prepares the surface for recoating.
If an existing finish or stain has broken down it can be removed using Paint and Stain Remover by Sansin®. This product will remove most failed oil-based or latex finishes, extreme weathering, water stains, mould and mildew and restore wood to its natural colour.
Iroko decking can be crosscut with good quality chop saw using a tungsten carbide tipped blade. Ripping can be done on a standard table saw, using a good quality, well-aligned fence and a tungsten carbide tipped blade. When drilling, always use the highest quality drill bits available. If screwing through the face, use a countersink bit with a positive stop to ensure that all the screw heads end up at a consistent depth. Screws can be lubricated to make installation easier.
Routing or planing can be done with either high speed tungsten carbide cutters. The feed speed should be fairly slow.
A dust mask and eye protection should always be worn when working with any wood. Avoid the inhalation of wood dust. We recommend a dust mask with an activated carbon filter. Some people may have an allergic reaction to hardwood dust. Remove wood splinters immediately to prevent infection.
To ensure its quality, Iroko decking from Silva is carefully manufactured, graded and inspected at source. It is inspected again during the order picking process prior to despatch. However, Iroko decking is a natural wood product and is subject to variations in weight, density, colour, grain and performance. Iroko decking is subject to dimensional changes as the moisture content in the wood fluctuates with humidity in the air. Swelling, shrinkage, checking, and other movement of individual pieces are normal occurrences in wood decking.