Green Algae Growth on Exterior Walls in Swindon
Green or black film on north-facing render, under gutters, behind planting, and in shaded corners of the property.
Swindon spans Victorian railway terraces in Old Town, interwar semis around Rodbourne and Park North, and large modern estates at Wichelstowe and Tadpole Garden Village. Solid-wall terraces and fast-built modern plaster fail in completely different ways, so the right remedy depends heavily on which era of Swindon housing you are standing in.
Why algae on walls happens
Persistent surface dampness combined with low sunlight. Overhanging planting and leaking gutters keep the wall wet enough for growth to establish.
It sits between Marlborough (about 12 miles S), Highworth (about 6 miles NE) and Royal Wootton Bassett (about 6 miles W).
How we diagnose it on site
- 1
Note which elevations are affected — algae concentrates where sun and airflow are lowest.
- 2
Check gutters and downpipes above the growth for overflow or splashing.
- 3
Look at planting proximity; shrubs against a wall keep it permanently damp.
The repair process we use in Swindon
- 1
Cut back planting and fix any gutter or downpipe overflow first.
- 2
Apply a fungicidal wash and allow the full dwell time rather than jet-washing it off immediately.
- 3
Rinse and let the wall dry thoroughly before any coating.
- 4
Apply masonry paint with a fungicidal element, or reseal render as appropriate.
Products we specify
- Exterior fungicidal wash applied per manufacturer instructions
- Dulux Weathershield masonry paint with fungicidal protection
- Breathable mineral masonry paint on older, solid-wall properties
How long it takes
Washing and treating alone is often one day; a full elevation repaint takes three to five days including drying.
How we price it
Treatment without repainting is a much smaller job, and we are happy to quote it on its own.
Stopping it coming back
Keep gutters clear, trim planting back from the wall, and rewash shaded elevations periodically rather than waiting years.
directly on the M4 with the A419 linking north to Cirencester and the A420 east to Oxford
Recent work near Swindon
Algae on walls in Swindon — FAQs
Does jet washing remove algae permanently?
It removes the visible growth but not the spores, so it typically returns within a season without a fungicidal treatment.
Will painting stop algae coming back?
Masonry paint with fungicidal protection slows it considerably, but shade and moisture are the real drivers.
Is algae damaging the wall?
It is mostly cosmetic on sound render, but it is a signal that the wall stays wet, which is worth investigating.
Related problems we fix in Swindon
Algae on walls in other towns we cover
Get algae on walls looked at properly in Swindon
We survey the cause before quoting the fix — no painting over problems. NVQ Level 3, reviewed on Checkatrade, professional.