Facade Stains on Your Office Building: Causes, Cleaning and Prevention

Quick answer: most facade stains on office buildings come from water that runs where it should not, from blocked or overflowing gutters, leaking downpipes or sills without a drip edge. Cleaning removes the marks, but they come back unless the water source is fixed. Facade cleaning at height is specialist work and should come with a risk assessment and method statement.

For facilities managers, a stained facade is one of the first things tenants and visitors notice, and one of the easiest to put off. Here is what causes the stains and how to deal with them properly.

What causes facade stains

• Overflowing gutters. Leaves and silt block gutters, and rainwater spills over the edge and runs down the wall.
• Leaking downpipes and joints. Water escapes at joints and leaves a dark streak below.
• Sills and ledges. Without a drip edge, dirty water runs off sills and down the facade.
• Algae and green growth. Damp, shaded walls on the north side grow algae, especially on render.
• Rust. Metal fixings, railings and brackets leave orange streaks.

Cleaning by surface

Different materials need different methods:

• Render. Usually a low-pressure soft wash with a suitable cleaner and biocide for algae. High pressure can damage render and drive water into it.
• Brick. Brick and mortar can be damaged by high pressure; a controlled clean with the right product is safer.
• Cladding and metal panels. Follow the manufacturer’s guidance, as coatings can be damaged by strong chemicals.
• Stone and concrete. Often suits a careful pressure clean, tested first on a small area.

Safety at height

Facade cleaning usually means working at height, from access equipment, a cherry picker or rope access. It should only be done by a team with the right training and equipment, with a risk assessment and method statement (RAMS) agreed before work starts, and with the area below protected for staff and the public.

Fix the source, or the stains come back

Cleaning without fixing the water problem only buys a few months. Before or alongside a facade clean:

• Clear and check gutters at least once a year, more often near trees
• Repair leaking joints in downpipes
• Check sills, copings and flashings
• Treat algae with a biocide that keeps working after the clean

How Premier can help

Gutter cleaning and external window cleaning can be added to an office cleaning contract, quoted separately and agreed in writing. Keeping gutters clear is the simplest way to prevent most facade staining. For larger facade restoration, we can advise on what the building needs.

See our office cleaning service in Dublin, or book a free site survey of your building.