Checking compatibility before recoating masonry

Why rigid and flexible systems clash

Some older masonry paints are relatively rigid, while many modern acrylic and silicone systems flex slightly with the substrate's natural movement. A flexible coating over a rigid one, or the other way round, can crack along the boundary between the two as they move at different rates.

• Existing coating type identified before any new system is proposed
• Flexibility and rigidity of old and new products compared
• A test area recoated and left to assess before the full elevation proceeds

Testing rather than assuming

A small test patch, coated and left for a period before committing the whole elevation, is the honest way to catch an incompatibility before it becomes an expensive full-wall failure. We would rather lose a few days to a test area than commit a whole house to a mismatch.

Chalking and powdery existing coatings

Old, degraded masonry paint often chalks — a powdery residue that comes off on a hand rubbed over the wall — and this needs stabilising with a proper primer before anything new is applied, or the new coat simply bonds to loose powder rather than the wall itself.

When stripping back is the honest recommendation

Where the existing coating is badly failed, of unknown type, or clearly incompatible with a sensible modern system, full removal back to sound substrate is sometimes the only reliable answer, even though it costs more upfront than recoating over the top.

• Full removal considered where compatibility cannot be established confidently
• Cost and time implications explained honestly before deciding
• Removal method chosen to avoid damaging sound substrate underneath