Aethos advice
Before painting sandstone or harled walls
Stone, harling and later render do not all manage moisture in the same way. The first job is to identify the surface, the existing coating and the reason it now needs attention.
By Aethos Studio · Published
Identify what is actually on the wall
A wall described as stone may include exposed sandstone, lime joints, cement repairs, harling, later render and several generations of coating. Record the changes by elevation. A finish that suits one area may be wrong for another, so age or appearance alone is not enough to choose the next system.
Read failure before removing it
Flaking, hollow render, powdering, algae and local staining are observations, not a complete diagnosis. Note where failure gathers: below sills, beside downpipes, near ground level or on the most exposed face. Active water entry, unstable render or failed joints should be addressed before decoration is treated as the solution.
Cleaning must suit the substrate
Aggressive pressure washing can damage weak joints, erode soft material and drive water into defects. The cleaning method should be tested, controlled and allowed to dry. Biological growth may also indicate persistent wetting that needs investigation rather than a stronger topcoat.
Compatibility matters more than a label
A mineral paint or limewash can suit some traditional walls. Other surfaces may take a compatible modern masonry system. Check the existing coatings, condition and moisture before deciding. A finish that allows water vapour through cannot make a wall breathable if an impermeable layer remains beneath it.
Read modern paint or breathable paint?Repairs need time and definition
Loose material, open cracks and defective joints should be repaired with materials appropriate to the wall and given suitable time before coating. Structural cracking, persistent saturation or widespread detachment needs a building professional or relevant specialist, not a decorating allowance.
Specify elevation by elevation
A useful quotation records preparation, repairs within scope, access, primer and finish by surface. It should also state what is excluded, particularly scaffolding, extensive masonry repair and defects that cannot be assessed from the ground.
See how Aethos prices exterior work