Rising Salt Damp Animation

What the animation above shows

The animation shows the full mechanism of rising damp and salt attack in five stages, including a magnified view inside the brick, between the sand grains, where the damage actually happens. Here is the same content in text:

1. Water is the delivery truck

A brick is just sand grains cemented together. Ground water gets sucked up through the tiny gaps between the grains, the same way a paper towel
sucks up spilled coffee (this is called capillary suction). Dissolved in every drop: salt, sodium, chloride, sulfates, nitrates. The water is the delivery truck. The salt is the cargo.

2. Water evaporates. Salt can’t.

Part-way up the wall, the water dries off into the air as vapour — this band of wall is the evaporation zone. Salt can’t turn into vapour, so it gets dropped off and left behind, inside the brick. Delivery after delivery, year after year, the salt keeps piling up. The white powder you sometimes see on walls (efflorescence) is that salt.

3. Salt grows into crystals between the sand grains

The stranded salt grows into hard crystals in the gaps between the sand grains. Growing crystals push with enormous force — far more than brick can resist. The brick is being broken from the inside.

4. The brick face turns to powder

Every time the wall gets damp and dries again, the salt re-grows and pushes the grains further apart (the trade calls this fretting, or salt attack). The brick’s face powders, blisters and falls off. Water didn’t do this. Salt did.

5. Two problems. Two treatments.

Injection (Silonexx™ DPC) blocks the water, no new water, no new salt. But the salt already in the wall keeps working, wet cycle after wet cycle. It must be  removed with a professional salt extraction tool. Injection alone does not fix salt-damaged brick, and injecting anything into already-crumbling bricks does not strengthen them.

Common questions

Does water damage bricks?

No — salt does. Water is only the delivery truck; it dries off harmlessly. The salt it leaves behind does the damage.

Why are my bricks crumbling and turning to powder?

Salt attack (fretting): salt crystals growing in the gaps between the sand grains of the brick, re-growing with every wet/dry cycle. It is not “old age” and it is not the moisture itself.

Will DPC injection fix my crumbling bricks?

Injection blocks the supply of new water and salt. It does not remove the salt already in the wall, and it does not restore brick that has already been lost. Salt-damaged walls also need the salt removed with a professional salt extraction tool.

What is rising damp?

Ground water getting sucked up through the tiny gaps in masonry (capillary suction), typically to around a metre above ground level, then drying off from the wall surface and leaving its dissolved salts behind.

The Rising Damp Shop, 1/536A King Street Newtown — Sydney’s rising damp specialists. Free diagnosis, Silonexx™ DPC systems, trade supply.