Is the roofspace beneath your chimney strengthened?
Problem
A collapsing brick or masonry chimney can damage or break through the roof or ceiling below. If you cannot replace the chimney, you should strengthen the roof space below to protect your house and its occupants.
To check
Check the strength of the existing rafters and ceiling joists. Is the ceiling properly supported?
Solution
If the ceiling is not properly supported, add a timber beam – sometimes called a strongback – to the roofspace.
Then, lay lengths of timber across the tops of the ceiling joists near the chimney. The timber must be close to the chimney, but it is acceptable to leave small gaps between each length.
The timber should extend roughly the same distance as the height of the chimney in all directions.
Is your gable-ended roof braced?
Problem
An unbraced gable end (a triangle-shaped area of wall at one end of the roof) which has a brick veneer attached to it may be damaged by severe earthquake shaking.
To check
- In the roof space inside your gable end, do you see diagonal pieces of timber or metal bracing your roof? The braces should either cross your rafters from the top of the gable down to the ceiling at the opposite end, or connect from the peak of the roof down to your ceiling frame through the ceiling space.
- Are the braces tightly attached at each end? If they cross your rafters, make sure they are tightly attached to each one.
- Are any gable-end braces broken or missing?
Solution
To install new gable-end braces, attach a brace from the peak of your gable end to the ceiling framing below on about a 45° angle.
- Place braces from both gable ends to create a pair.
- Add extra brace pairs down the central ridgeline.
- If you have more than one gable end, brace them all.
Are your clay and concrete roof tiles properly fastened?
Problem
Clay or concrete tiles are heavy and, if not properly secured, can damage each other and your roof in an earthquake.
To check
- In the roof space of your house, are your tiles fastened to horizontal pieces of timber in the roof? These are called battens.
- Are the fastenings on each tile in good condition and not loose, rusted or broken?
Note:
- Your tiles will likely be tied to the battens with wire, but some tiles can be fastened with clips, nails or screws.
- If your roof has underlay, you will not be able to easily see the underside of the tiles, but you should still be able to check the tie to the battens.
Solution
Replace damaged connecting ties with the same style of wire, clip, nail or screw, or install the correct new ones if they are missing.
When fastening with wire, use galvanised wire and thread the wire through the lugs on the tile, wrap it around the lower batten, and twist the wire together firmly with pliers.
Make sure you fasten at least every second tile – fastening every tile is even better.
Note:
- If you live within 500 metres of the coast, use stainless steel fastenings so they don’t rust.
- Concrete and clay roof tiles have a useful life of about 60–70 years, so if you have a house built before 1950 with original tiles, they may need replacing soon.
If you are thinking of replacing your roof, consider using lighter materials, such as sheet metal or metal tiles.