White Salt Deposits (Efflorescence)
A powdery white bloom on brick, render or skirting is efflorescence — salts left behind by evaporating moisture. It’s one of the clearest signs of rising damp.
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Where the white powder comes from
Efflorescence is the fluffy white crystalline deposit that appears when groundwater rising through a wall reaches the surface and evaporates, leaving its dissolved mineral salts behind. On Inner West brickwork you’ll see it as a chalky white bloom on the masonry, in the mortar joints, or on internal plaster and skirtings. It’s harmless to touch but it’s an unmistakable signal that moisture is moving through the wall — and because these salts are hygroscopic, they keep pulling damp from the air even after the surface is wiped clean. Efflorescence commonly appears alongside a tide mark and bubbling paint, and points to the same underlying cause a rising damp treatment resolves.
How salt reaches the surface — and how we stop it
Hit play. Watch salty groundwater climb the brick and crystallise at the surface, then see a new damp course cut off the supply so the bloom stops returning.
The wall starts dry
Press play to watch how ground moisture climbs a solid brick wall — and exactly what a new damp course changes.
What’s feeding the salt bloom
Efflorescence is the visible end of a moisture path that starts in the ground and ends at your wall surface.
Signs it’s rising-damp efflorescence
Efflorescence from rising damp usually shows two or three of these together.
Fluffy white bloom
Powdery deposits on brick, mortar or plaster.
Low on the wall
Concentrated in the lower metre of ground-floor walls.
Returns after cleaning
Wipes off, then comes back as the wall keeps drying.
Lifting finishes
Salt pushing paint and render off the surface.
On skirtings too
White residue creeping onto timber at the base.
Damp, musty feel
The affected wall feeling cool and smelling damp.
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Two problems, two solutions
Salt bloom means moisture in the wall — here’s how to confirm the right fix.
Rising damp treatment
If moisture is wicking up through the walls — tide marks, salt, bubbling plaster — you need a new damp course, not just airflow. We diagnose and install it.
Rising damp treatment →Subfloor ventilation
If the damp air is trapped under the house — musty floors, mould, condensation — you need ventilation to move it out and keep the space dry.
Subfloor ventilation →Efflorescence FAQs
Is efflorescence dangerous?
Can I just brush it off?
Is it the same as mould?
How do you treat it?
White salt on your walls? Get it diagnosed
We’ll confirm it’s rising damp, stop the moisture at the source and make good the plaster — starting with a free, fixed quote.
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