Decks, Balconies, Verandahs, Patios and Stairs
Australians love outdoor living and entertainment areas, but they can be costly to maintain.
When made of timber and exposed to the weather, outdoor structures are high maintenance. To add to this, a poorly maintained structure is a safety hazard. Some timber floors need to be coated in oil or water-based acrylic paint every year.
Start by inspecting decking and framing timbers for any signs of fungal decay (rot). Decay is usually at the edges of the structure and at the tops of joists where they are more exposed to the weather. Unroofed timber structures deteriorate at a much faster rate as they are exposed directly to the weather. Decayed sections weaken the timber and can cause it to collapse. This is a potential safety hazard and decaying timber should be promptly replaced. When you walk on the floor of the deck or balcony it should not have excessive spring. If the floor is bouncy then the timbers may be undersized.
Check the steelwork on the structure, including bolts and brackets, for evidence of rust. Surface rust can be easily treated but more significant rust weakens the steel and can cause it to fail. Again, this is a potential safety hazard and rusted steel components need to be repaired or replaced quickly.
Inspect balustrades (horizontal handrails) to make sure they are strong and stable. There should be no excessive movement. The top rail should be at least 1 metre above the height of the deck floor. Gaps between the balusters (the upright posts) should not exceed 125mm. Balusters should not be vertical if the deck is more than 4 metres above ground level.
A balustrade is required if the structure is more than 1 metre off the ground. Although, I would recommend putting a balustrade on anything that is more than 190mm off the ground.
You should refer all outdoor timber structures, such as decks, stairs, walkways, ramps, verandahs and the like, to your building inspector for further assessment.
Outdoor timber structures should be checked annually by a building inspector or structural engineer to ensure they are structurally safe and sound. The older the structure, the higher the risk of unsafe structural issues.
In Queensland in 2009, a deck collapsed killing a woman and badly wounding about 30 other women attending a party at the house. All the women were mothers. It was an end of school year celebration. I read the coroner’s report and other reports from various inspectors, engineers and timber experts. It appears that the cause of the collapse was inadequate end bearing of the floor joists that flexed and collapsed when placed under load. This was a very tragic accident, and a vivid reminder that decks need to be built to code and properly maintained otherwise they can be a major safety hazard.
Where there is an exterior tiled deck or balcony over a timber floor, the risk of this floor having a fault in the waterproofing system that allows water penetration and subsequent damage is very high. Generally, these floors will eventually leak and are usually very expensive to rectify properly.
External timber stairs are very prone to damage from structural decay. Annual inspection and maintenance by a building inspector or licensed carpenter is recommended as structural decay can occur within a matter of months. Any decay found must be repaired immediately. It is preferable to replace the affected timber. I recommend using only highly durable timber for external stairs and to avoid using softwoods and engineered timber altogether.
Steel sections of stairs are prone to rust and require regular maintenance to prevent structural rust from occurring. Surface rust can be treated, while structural rust needs to be promptly replaced.
Concrete stair treads are commonly used in external stairs with steel stringers. Concrete treads often crack when moisture gets into the steel reinforcement inside the tread and causes corrosion. Be sure to check the underside of concrete treads for cracks. Often the damage is not visible from the top side. Replacement of any cracked treads should be carried out without delay.
The sides of stairs should have sturdy handrails that are 865mm above the stair nosings and have gaps that do not exceed 125mm.