There are several common decking problems outlined below. They are, in our experience the most common, but the list should not be considered exhaustive.
Sagging and Bounce
Timbers used in decks must satisfy the span requirements and minimum size requirements set out in the Building Code and Australian Standards. Complying with these ensures that the timber is unaffected by a negative structural effect (bounce or sag) These are legally binding and should your deck sag a sa result of unsuitable timber span or dimension then defective building work is implied.
Premature Deterioration
Pine is commonly used in timber deck construction. It is readily available and easy to work with. Pine must be treated, depending on the application for external use.
If in contact with the ground pine must be at least H4 treated. If the minimum treatment has not been achieved (the ends of timbers are marked with a tag specifying the grade) they can tend to rot.
Cupping / twisting of boards.
High moisture content, framing members too close to the ground and inadequate ventilation are common causes of cupping or twisting of decking boards. Decks must be constructed with sufficient ground clearance, drainage and ventilation to prevent such damage.
Another common cause is not sealing boards with a suitable agent. Commonly decking oil is applied to prevent moisture from entering the timber, the protective coating ensures that moisture is unable to come in contact with wood.
Honourable Mentions
decking boards are often installed reeded side up as opposed to reeded side down. It is a common misconception that reeded decking should be installed upwards facing for aesthetics, or grip. The reeding is actually designed to allow moisture to bead on the underside of the timber and fall with gravity. Moisture forms on the ridges of the reeded decking at the unsealed, underside of the boards, especially at joist connections, preventing moisture from penetrating into the timber as a result of soil in close proximity, lack of ventilation and rainfall. Installing reeded decking with the reeded side down combined with adequate clearance, suitable fixings and adequate sealing of timbers is expected to prevent cupping of boards.
