Risk factors for rotting balconies and decks

Watch out for potentially dangerous rotting around balconies

If you are planning on doing maintenance on your house this summer, take the opportunity to look out for signs of potentially dangerous rotting around balconies, decks, and balustrades.

If these structures collapse from water damage and rot, they could cause serious injury.

It is important to remember that balconies supported by timber framing can be prone to rotting and pose a safety risk. This is particularly so where water pools on the decking of the balcony rather than draining away.

Serious concerns about the safety of balconies, decking and balustrades on some dwellings emerged in the wake of a report into leaky buildings in 2002. Public warnings have been issued around this potential danger.

Structures that pose a risk are those that rely on timber beams for support; sometimes these beams are hidden behind cladding. Structures most at risk are on buildings with flat, lightweight claddings with plaster-type finishes, with balconies supported by untreated kiln-dried timber.

Risk factors

Consider these questions:

• Has untreated kiln-dried or low treatment timber been used for structural support of the floor or balustrade?
• Is the building clad with lightweight materials with a plaster finish?
• Does water puddle on the surface rather than drain away?
• Are there any holes or cuts in the balcony floor surface or balustrades where water might get in?
• Is it on a split-level or two- or three-storey house or a multi-storey apartment building?

Look at the balustrade:

• Is it clad with lightweight material with a plaster finish?
• Does it have a flat top where water sits?
• Does it have a railing where water is able to leak down screw holes?

Warning signs:

• Balconies that move when walked on.
• Damp spots or stains where the balcony joins the main part of the building
• Cracks, particularly near joints and corners.
• Balustrades that wobble.
• Balustrades where damp spots or stains can be seen on the cladding.
  

We strongly recommend that, if warning signs are evident or if you have any doubt, you should seek advice from a qualified expert as soon as possible.

For more information call:
BRANZ Advisory Helpline - 0900 5 90 90
New Zealand Institute of Building Surveyors - 0800 113 400

Or contact your local city or district council for further guidance.

Related topics:

• Leaky buildings.
• Dealing with mould.
• Maintaining open timber decks.
• Maintaining car decks.
• Does work on a deck or balcony require a building consent?