Case study
Bondi Strata Garage: Two Sources, One Wall
The Property
A 1930s brown brick strata garage in Bondi, on sandy soil and close enough to the ocean to cop salt air. I was asked to look at a wall that kept deteriorating.
Strata buildings like this often have more than one thing going on, and this one did.
What I Found
On the uphill side, the external pathway sat 150 to 200mm above the garage floor for the full length of the wall. The base of that wall had efflorescence, deterioration at the downpipe and slab junction, and tree roots pushing in. Higher up, moss under a 100mm pipe and a diagonal patch line inside following the stairs pointed to a pipe leak at the ceiling junction.
The concrete slab also had corroding reinforcement, known as concrete cancer. That is a structural matter, so I noted it and referred it on rather than quoting it.
What was causing it
Two mechanisms at once. The raised pathway was bridging the wall along its full length, and the pipe was adding water higher up. Fixing only one of them would not have stopped the damage.
Options I quoted:
- The front section only, or the full wall
- Render removal along the affected wall
- A negative side membrane
- Injection through the cured membrane
- Referral to an engineer for the concrete cancer
The lesson
Committees get better value from a quote that names every source than from a cheaper one that treats a symptom. See rising damp for strata and commercial buildings.