Patio Cleaning in Caterham

Patio Cleaning for homes and businesses in Caterham

The white chalky bloom that appears on new-ish paving is the problem most often made worse by the products sold to cure it. It is efflorescence: mineral salt from inside the slab, carried to the surface by moisture and left behind as the water evaporates. The single most useful thing to know about it is that it goes invisible whenever the paving is wet, because the salts turn temporarily transparent, and comes back as the surface dries.

What actually helps, and what makes it worse

Brushing helps. Regular dry brushing, a rinse with clean water and another brush is the approach the trade recommends, because it lifts the deposit off and can speed up the point at which the slab finally runs out of salts to give up. It costs nothing and it is worth doing between visits.

What backfires is chemistry and force. Proprietary efflorescence removers tend to be a temporary fix and can make the problem worse by un-plugging the capillaries in the slab, giving the salts a clearer route out. Acid risks bleaching the pigment. Pressure washing looks dramatic on the day and does the same un-plugging over time, as well as putting the surface itself at risk.

Cast slabs have a face worth protecting

Most pressed concrete paving is made in two layers: a cheap structural backing mix, with a thin facing mix laid on top that carries the dyes and the selected fine aggregates. That facing layer is only a few millimetres thick and it is the entire appearance of the slab. Underneath it, the concrete is a different colour and a much coarser texture.

A close lance will cut through that face in seconds and leave a pale scoured patch, which is a permanent fault where the efflorescence was a temporary one. It is the same reason pattern-imprinted drives get ruined by people trying to clean them harder, and it is why cast paving takes an even, moderate pass and nothing more.

How we work

1. 1
   Free quote and stone identification

   The single most important step. Indian sandstone, limestone, porcelain, Yorkstone, concrete slab and clay pavers all behave differently under a washer, and getting this wrong is what causes the damage you see on badly cleaned patios.

2. 2
   Protect the borders and check the pointing

   Furniture and pots moved, nearby planting protected, and a look at the pointing. Slurry-pointed joints and loose mortar will lift under pressure, so we find that first and tell you instead of discovering it halfway through.

3. 3
   Set the pressure to the softest thing on the patio

   We work to whatever is most delicate, not whatever is toughest. Soft sandstone gets a gentler pass than the concrete edging next to it, even though both are getting cleaned in the same visit.

4. 4
   Treat black spot and lichen with chemistry, not force

   Black spot lichen roots into the stone. You cannot blast it off without taking the surface with it, so it needs a treatment and time to work. How much will shift, and how much may need a second visit, gets said before the job starts.

5. 5
   Rinse down, sweep and walk it with you

   Everything rinsed off, the silt cleared, furniture back, and a walk round so you can see the result and hear what we found while we were in there.

Black spot lichen roots into the stone, so it needs a treatment and time rather than more pressure. How much is likely to shift can be judged on the slabs themselves.

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Patio Cleaning near Caterham