Structural Repair near you

The Housing Provisions set the amount of subfloor ventilation by climate, and the numbers show how much air the Code expects. Table 6.2.1a requires minimum aggregate ventilation openings of 2000 square millimetres per metre of wall in Zone A, 4000 in Zone B and 6000 in Zone C where no membrane is laid on the ground, halving to 1000, 2000 and 3000 respectively where a membrane is used. Where the ground or subfloor space is excessively damp or subject to frequent flooding, Clause 6.2.1 requires that ventilation to be increased by 50 per cent as one of the compliance options.

Clearance to the ground is set the same way. Table 6.2.1b gives a minimum of 150 millimetres where termite inspection is not required, and 400 millimetres where a termite management system requiring inspection is installed. The larger figure exists so a person can get under the house and look, which is the entire preventive mechanism for a timber-framed floor in a country with subterranean termites.

Almost every Australian subfloor repair traces back to one of those two numbers being lost after the house was finished. Ground levels rise as gardens are topped up, paths and paving are poured against the wall, a deck or a carport slab covers half the vents, and a subfloor that was designed to breathe stops breathing. The repair replaces the timber; only fixing the ventilation and the ground stops it happening again.

Isolated damage is worth isolated repair. A single stump that has rotted at ground level under an otherwise sound floor, or one joist end that got wet under a leaking shower, can be spliced or replaced without disturbing the rest, and doing more than that is spending money on timber that is fine.

The point at which a whole run should go is when the cause was general rather than local. If the ventilation was blocked for years, every member in that bay has been sitting in the same damp air, and replacing the three that failed first buys you a repeat visit. Ask the contractor to sound and probe the members either side of the damage and to show you what they found, rather than accepting a scope drawn from the worst three metres.

A full restump is usually argued on levelling rather than on decay. Once a floor has moved enough that doors, skirtings and wall junctions all need correcting, doing the stumps in stages leaves the house sitting on two different reference levels, and the internal finishing work costs more than the extra stumps would have. That is a judgement to make with the person who will have to finish the walls afterwards, not only with the person putting the stumps in.

Structural repair sits on the regulated side of the line almost everywhere. Victoria's position, as the City of Monash states it, is that underpinning, re-stumping or otherwise altering the footing of a building is a structural alteration and requires a building permit. Other states reach the same place by their own route, with approval issued by a council, a private certifier or a registered building surveyor depending on the jurisdiction.

Because building regulation in Australia is a state responsibility, the licence class that covers structural repair also differs by border, and the honest instruction is the same everywhere: ask which class of licence or registration covers the specific work, then check the number yourself on your own state regulator's public register rather than on a business card or a website.

Keep the approval, the engineering documentation and any inspection records together. Structural work that was done without approval is a problem that surfaces at sale, at the next insurance claim, or when the next owner's building inspector asks what happened under the floor and there is no paperwork to answer with.