After renovation work is underway you can discover some nasty surprises. We look at common problems discovered behind walls, ceilings and under floors.

Problems exposed

Depending on the age of your house, it's when you start removing wallboards and other sections of the house that you discover the true state of things, for example:

  • Wiring - people commonly discover they need to rewire because the electrical wiring and fittings have become unsafe. This is particularly true for wiring in black or white rubber-like sheathing (pre-1960 houses), timber conduit (pre-1950 houses) or steel conduit (pre-1940 houses).
  • Plumbing – corrosion of water pipes, particularly old galvanised pipes, can sometimes be so bad that the whole house needs new plumbing, hot water reticulation is likely to be low pressure, or disconnected waste pipes may be emptying into the subfloor.
  • Carpentry – a rotten weatherboard can reveal rotten framing when the board is removed, floors out of level, and serious borer. Corrosion under flashings and under the bottom edge of the laps of galvanised steel roofing.
  • Glazing – in older homes it is often thin, can break easily and is a safety hazard. Asbestos, which could present a [safety risk], may be discovered in some materials such as roofing, sprayed ceilings, cement sheeting, and some floor coverings.
  • Unstable brick chimneys.
  • Lack of sub-floor ventilation.
  • No insulation in the walls or ceiling.
  • Floor and framing too close to the ground.
  • Foundation settlement.
  • Insufficient lateral support (bracing) in the sub-floor structure.

It can be difficult to budget a set figure because so much of the work is unseen before you start. Your alterations may have to go on hold to deal with more urgent repair work.

A note about glazing

If you are replacing glass, it must be replaced with glass that complies with the Building Code. Acceptable Solution F2/AS1 requires glazing that people may fall against to comply with NZS 4223 Code of Practice for Glazing in Buildings.

A skilled tradesperson should be knowledgeable about Building Code requirements. But when you are renovating make sure that in areas where slips are more likely – such as in bathrooms and kitchen, or where windows are close to the floor or at the end of stairwells - that the right grade of glass is used. For more information about different types of glass see Materials and features.