Wet Season: What Darwin's Climate Does to a House

Buildings in the Top End age differently. It is not just that it rains hard — it is the combination of sustained humidity, intense seasonal rainfall, and salt air, working on the same structure without much of a break.

Water finds the path

Monsoonal rain does not fall gently and it does not fall straight. Wind-driven rain gets into things that cope perfectly well with vertical water: window heads, door reveals, roof penetrations, the junction between a patio roof and the house wall. A gutter or downpipe sized for average rainfall is not sized for a Darwin downpour, and once water overshoots, it goes down the wall and into the ground right against the footing.

What sustained humidity does

• Mould on ceilings, in wardrobes, behind furniture against external walls, and anywhere with poor air movement.
• Timber movement — doors and drawers that bind in the wet and free up in the dry.
• Corrosion of fixings, hinges, brackets, roof screws and gutter fasteners, accelerated hard by salt air near the coast.
• Deterioration of sealants and flashings, which are doing more work here than in a temperate climate.
• Subfloor damp, which is also an open invitation to termites.

Before the wet

The build-up is the time to do this, not the middle of a storm. Clear gutters and downpipes completely. Check that stormwater discharges well away from the building rather than into a garden bed at the base of the wall. Check roof screws and flashings. Cut back vegetation touching the roof or walls. Check that the ground still falls away from the house — it moves over time, particularly where soil has washed out.

Almost every expensive water problem we document started as a blocked downpipe or a ground level that crept up above the slab edge. Both are an afternoon's work to prevent.

After the wet

The end of the wet is the most revealing time to inspect a Top End property, because the building has just been tested. Staining that is invisible in September is obvious in April. If you are buying at the end of the wet, that is an advantage — take it.

What we look for

In a Darwin inspection, water and its consequences are the through-line: where it has got in, where it is sitting, what it has corroded, and what it has invited. We photograph and document what is visible in accessible areas. Where an area cannot be safely accessed, the report says so rather than leaving you to assume it was checked.