Algae and moss on exterior walls: cleaning and follow-up

Identify areas where staining returns

Photograph the whole facade and mark where stains reappear. Explain whether they are near vegetation, in a recess, beside a downpipe or beneath a projecting feature. Location helps prepare the inspection; it does not prove the cause of the stain on its own.

If the wall has been cleaned before, find the date and method used. “Washed last year” is a starting point. Knowing the product, contractor and appearance after cleaning makes the discussion about recurrence and further checks more useful.

You can supplement this record with the observations for damp exterior walls before painting.

Practical example

Check the cleaning method on a small area

A brush is working on a small area with green deposits. The visible action helps explain the value of a limited trial, followed by assessment after drying, before extending the method to the whole facade.

How to approach this situation

1. Have the coating, vulnerable areas and places where water remains checked. Green colouring alone does not describe the whole problem.
2. Agree on a compatible method and a discreet trial, following the product instructions and precautions for nearby surfaces.
3. Assess the surface after cleaning and drying, distinguishing removed deposits, residual marks and defects requiring another type of work.

What determines the decision

Painting becomes a separate task if the surface needs it. It should not be added automatically to maintenance cleaning.

What to check at the end

Compare views under similar conditions and plan to observe exposed areas. A one-off treatment cannot justify a promise that staining will never return.

Explore the service : Facade cleaning Technical documentation (PT) — Weber — weberantimousse

Renovation ideas

The same facade. A cleaner appearance.

Before After

Cleaning does not simply mean higher pressure

Ask which method is proposed for your substrate and whether a discreet trial area will be used. Define the objective: removing dirt, treating plant growth and preparing for a new finish are different tasks that the word “washing” alone does not explain.

Weber identifies weberantimousse as a cleaning agent for moss and plant residues. Its specific documentation distinguishes that use from a finishing paint and should be read alongside the safety instructions. This is not a universal product recommendation for your home. Weber — weberantimousse, Portuguese documentation.

What the proposal should clarify

1. The surfaces to be cleaned and the condition of the existing coating.
2. Any trial or inspection before work on the full area.
3. Protection for windows, paving, plants and equipment.
4. Responsibility for collecting and disposing of work residues.
5. Assessment before deciding whether repainting is necessary.

Also ask what cleaning is expected to improve and which marks may have another cause. This avoids paying for cleaning while expecting a repair that the quotation does not include.

Record the result with comparable photographs

After the work, keep photographs from the same viewpoints and the intervention description. If marks return, it becomes easier to communicate the difference and see whether recurrence is concentrated in one place. A folder for each elevation with dates and short observations is usually enough.

The maintenance plan should suit the coating and the installed system’s guidance. Avoid assuming a universal interval between cleaning visits. What matters is having clear reasons to inspect again and request an assessment when the appearance changes.

If the facade has external insulation

Mention capoto or ETICS at the first enquiry. Its assessment must consider the existing system and available documentation. Before accepting washing or repainting described as identical for every facade, consult the inspection and maintenance guide.

To prepare an assessment of your property, consult facade painting in the Aveiro region and specify the location and the purpose of the work.

For cleaning work, see the facade cleaning service and cleaning planning guide. The quote should distinguish maintenance, preparation for painting and problems needing further assessment.