Making improvements as part of a renovation
If you’re thinking about renovating your home, then it’s the perfect time to improve resilience to natural hazards. Making upgrades as part of a planned renovation, rather than separately, could save you money, time and effort.
Some key things to talk about with your builder or engineer while they’re onsite:
Hazardous chimneys
Thousands of chimneys have collapsed in past New Zealand earthquakes, causing damage and injuries. The most hazardous chimney types are those that extend above the roofline and are constructed from unreinforced brick or concrete masonry. These are most commonly found on homes built before the 1970s. Chimneys that are twisting, leaning or showing signs of cracking, may require immediate attention.
There are different options available for making chimneys safer. Read more on Chimneys.
Heavy roofing materials
A single roof tile can weigh up to 4.5kg – that can do a fair amount of damage if it falls off or through your roof. If your heavy clay or slate roof needs replacing, consider lighter weight options such as corrugated iron or metal tiles. You can get some metal roofs that look very similar to clay tiles. Otherwise, ensure that heavy tiles are well secured to the roof framing beneath.
Brick gable-ended roofs
Brick gable-ended roofs are vulnerable to damage during an earthquake. This is due to a lack of bracing that is particularly common in older homes with framed roofs, and unreinforced masonry’s inherent weakness in dealing with tension and movement from events like earthquakes.
Brick gable-ended roofs can be strengthened by adding secured diagonal braces. Read more about this in Strengthening brick gable-ended roofs from BRANZ Build magazine.
Find out more on Roofs and Walls.
Foundation connections
Many Kiwi homes built prior to the current Building Code era do not have connections between the timber framing and foundation system. This practice came from a time when the seismic risk associated with homes was not well understood. Now, because of experience from earthquakes, we are aware of the risk of building movement off its foundations.
When a dwelling subfloor is accessible, appropriate connections can be added to the foundation system, bringing it up to current Building Code standards.
Foundation bracing
Sloping sites or hillside sections can be prone to dwelling foundation movement during earthquakes. Adding lateral bracing in the subfloor can significantly improve foundation performance. Diagonal timber bracing installed between piles, or piles and bearers, where ground clearance is above 600 mm, is particularly beneficial.
Find out more on Foundations.
House walls
If your house was built before 1950 there’s a chance any external brick (such as double brick) and concrete block masonry walls are not reinforced. These are at risk of being damaged in an earthquake. If your home has brick veneer this can come away from timber framing if ties have corroded or fixings have weakened. The best time to check the ties or fixings is when you have the wall open for renovations.
Houses built before the 1930s often have ‘lath and plaster’ wall linings. These are closely spaced horizontal thin timber strips covered with plaster. These types of wall linings are not intended to provide bracing in an earthquake. Removing wall linings provides an opportunity to upgrade lining materials and add bracing to improve performance.
Find out more on Roofs and Walls.
Retaining walls
Ensuring retaining walls are in good condition is important to reduce the risk of a landslip, or the wall failing because of heavy rain, flooding or an earthquake. Older walls may have been built before there were Building Code requirements, so while you have a builder or engineer onsite, ask them to check for any immediate issues and to say whether they think your retaining walls are fit-for-purpose.
Find out more on Slopes and Retaining Walls.