Weatherboard cladding is likely to remain in good condition if properly maintained, but brick claddings may be cracked or have corroded ties, and asbestos claddings may need replacement.
Historically, older brick veneer houses have not performed well in major earthquakes. This is because the ties fixing the veneer to the timber frame were made from bent wire which corroded over time (see Corrosion), resulting in the nails or the staples fixing the wall ties to the framing to fail.
Corroded ties may also pull out of the mortar joints. Without removing and replacing the brick veneer cladding, it is impossible to assess the extent of the corrosion or replace the wall ties.
Check brick veneer for evidence of cracking or damage.
If there is cracking, the cause, and whether or not it is widening, must be determined. Cracks may occur because of:
- settlement – determine if settlement is still occurring by monitoring the width of the crack. If it remains static, a decision whether to accept the movement that has occurred and work around it, must be made. If it is increasing in size, the building should be underpinned and made stable for the extent of the settlement.
- earthquake damage – if this is the cause, damage may not get worse so cracks in joints can be repointed and cracked bricks may be able to be replaced. If cracks are widening, specialist engineering advice and design is required.
Other problems that may need to be addressed with brick veneer are:
- deterioration of the joint mortar – joints may need to be raked out and repointed
- corrosion of lintel bars
- blocked veneer drainage/ventilation
- veneer cavities that open to both the roof and subfloor spaces which allow moist air into the roof space where it can condense of the underside of metal roofing.
Horizontal timber weatherboards that have been well maintained are likely to still be in sound condition (Figure 1). Any deterioration is likely to occur at running joints in boards and at mitred corners which were more susceptible to water entry.
Vertical shiplap and board and batten cladding, while likely to still be sound, may have cupped which can allow water in.
Other problems that may need to be addressed with timber cladding are:
- corrosion of metal flashings and fixings
- timber deterioration at the bottom of the wall
- surface checking or splitting of plywood and cupping of cover battens.
See matching new to existing for information about matching new weatherboards need to existing ones.
Asbestos-cement materials will typically last about 50-60 years, so asbestos-cement wall cladding may still be sound particularly where it has been regularly painted.