Green Algae on outside walls Brickwork, drystone walling, render are a few subjects covered here. Click here to post questions and get answers

[roger crouch]

I need to paint the walls of two basement courtyards built of Bath stone being north facing they receive no sunlight, consequently the walls are covered with green algae what is the best treament to use to eliminate the algae and what would be the best paint to use for the walls, at the moment they are painted with white emulsion.

[thedoctor]

Go to our damp or mould project and read through. The company in there, Lectros, make all sorts of products to keep the walls free of mould etc. For paint you need an external masonry paint with bacteria prohibiting properties and you can try contacting Property Repair Systems via our DPC injection (small jobs) project. They give free, no obligation advice.