Rising damp questions, answered

Because that is what the tool can honestly establish. A building inspector uses a surface meter, which measures how well the wall conducts electricity. Old salt in a wall conducts even when the wall is dry, so a salty dry wall reads as wet. The inspector is not being vague. They are reporting exactly what their method can show, and a proper diagnosis needs a different test.

It takes up to two hours. Moisture is measured at intervals up the wall, not at one spot, because rising damp makes a curve that is wettest at the base. A sample is drilled from the mortar behind the plaster and tested for its real moisture content. The outside is checked too: ground levels, paving, garden beds, reticulation and weep holes. You get a written finding that names the cause.

No. That is the assessment and the written diagnosis only. Any treatment is quoted separately after we have seen the wall, and the written diagnosis is yours to keep whatever you decide. The assessment is charged for because an inspection you do not pay for is paid for by a sale, and that is the wrong incentive when four of the five likely answers are cheap.

It can be. Houspect WA, a building inspection firm, wrote in 2019 that lateral damp, not rising damp, is the predominant finding in its WA water-ingress investigations. Sand soil and double brick let water travel from a sprinkler, a raised garden bed or a path straight through to the inside wall. It looks identical. The fix is usually far cheaper.

It usually makes it worse. Sealing the face does not stop water entering the wall, it stops it leaving. The moisture then rises higher or moves along to find somewhere to evaporate, and the salt builds up behind the coating until the render lets go. Undoing a sealed wall is real work, and it is billed.

Limestone is porous and some older Perth and Fremantle walls were built with no damp course at all. It takes up groundwater readily and it takes injection differently to brick, usually needing more of it. A cement render on limestone traps the moisture and the stone decays behind it, so the render often has to come off before anything else is worth doing.

No. It stops water climbing. A wall that has been wet for years holds a lot of water and it leaves slowly, over months. It also does not remove the salt already in the masonry, and salt is what blows the render and stops paint holding. A proper specification deals with the render separately, and that is often the bigger half of the bill.

Usually not. Home policies can exclude gradual deterioration, and rising damp is gradual by definition. A sudden burst pipe that soaked a wall is a different matter. Read your own policy or ask your insurer, because we cannot tell you what your cover says.

We do. One damp specialist takes the job from the assessment to the finish, on time and without handing it around. WA has no damp proofing licence, so the written diagnosis is what to judge us on: it names the cause before any treatment is quoted.

No. It is a false alarm worth ruling out first. Bore water leaves an orange or brown iron stain on walls, paths and fences, usually in a spray pattern from a sprinkler. It sits on the surface. Rising damp leaves a level tide line low on the wall with salt below it. It is worst in late winter and can look healed by late summer, though the cause is still there.

Not if the cause was found and fixed. That is the whole reason the assessment comes before the quote. An injected damp course in a wall whose real problem was a paved garden bed will fail, because nothing about the wall changed. Fix the cause first and the barrier lasts.

Persistent damp encourages mould, and mould can affect people with asthma or allergies. We are not medical people and we do not give health advice. If someone in the house is unwell, speak to a doctor. What the assessment can do is find out why the wall is wet.

Salt draws moisture out of humid air. A wall carrying salt from both the ground and the sea air can darken on a dry day. That is a sign the salt needs removing, not that a treatment has failed.

Not before someone establishes what is already under the existing coat. A hard render over old masonry can be the cause rather than the cure, and rendering again seals the same problem in for another decade.

Height and pattern. Rising damp climbs to a level and stops. Lateral damp follows the ground line where soil sits against the wall. They need different work, so the distinction is worth making before a quote, not after.

It can bridge a damp course that was working perfectly well. If the outside level sits above the course, wet ground is in contact with masonry above the barrier and the barrier is irrelevant. Lowering the level is sometimes the whole fix.

Because something is holding water against the wall that would otherwise have drained: a slab, paving, fill or a buried footing. On sand the useful question is what has been built against the house and when.

It limits what can be cut, drilled or rendered on the facade, which pushes the work toward injected courses and lime finishes. That is generally the better technical answer anyway. Approvals belong in the timeline and in the quote.

Aspect is one possible reason. A wall that gets no sun stays cold and wet through winter while the others dry between rains. A path, garden bed or downpipe against that one wall is another, so check those too.

Both properties', in practice. Moisture crosses the boundary, and treating one side alone can push it to the other. It is worth raising with the neighbour before booking any work.

Not usually, but the diagnosis should come before linings go back on. Closing a wall up over untreated damp turns one job into two, and the second one is more expensive than the first.

Probably not. A wall that dries out over summer can be wet again by the next winter. Look at it again in August before you decide that anything has worked.

Possibly both. Flooding saturates a wall through its full height and leaves salt behind; rising damp arrives from below and stops at a level. An assessment tells the two apart before any work is priced.

It can be, where a newer building sits close to an older one and its drainage runs against the old wall. Worth establishing first, because fixing the drainage may be most of the fix.

Yes. Fill holds water differently to natural sand and varies between properties, so what is under the wall matters as much as the wall. A specification written without that is a guess.

A great deal. Wet rooms added against original external walls, and outside levels raised for new paving, both work against a wall that was coping. The conversion history is the most useful thing you can bring to a diagnosis.

Not the treatment — the arrangements. Body-corporate approval, after-hours access, and whether the wall is common property or inside the lot. The body corporate usually needs to know before anyone is booked.

Evenness points away from a leak. A level band the length of a wall is moisture arriving uniformly from below; patches spreading from a point are usually a leak or a bridged spot. It is a useful thing to photograph before anyone attends.

Not necessarily. Newer houses next door are likely to be on slabs with a membrane and cannot get rising damp at all, so their being dry says nothing. Ruling a leak out is still cheap and worth doing, but the pattern can answer it first.

It can be. Salt crystallising inside the pores breaks masonry apart from within, and that damage can be well advanced before anyone calls it damp. Expect the repair to cover both the moisture path and the damaged material.

Probably not. On a mixed street an older solid-masonry cottage and a later house on a slab are different buildings with different problems, even side by side.

Where hard surfaces shed water toward a wall, surface water leaves a very similar mark. Check the falls of paving and garden beds toward the wall first; an injected course cannot stop water that arrives from outside.