How often should a façade be cleaned in a tropical climate?
A façade in Bangkok, Phuket or Chonburi does not age like one in Paris. Heat, humidity, the monsoon, traffic soot and sea salt each leave their mark, and they do it faster. This guide gives a realistic calendar by surface, and the signs that tell you it is time.
Short answer: in Thailand, glass on a city tower generally needs cleaning two to four times a year, shaded or north-facing cladding once or twice a year before algae sets in, stone and concrete every one to three years with a treatment, tiled and metal roofs every one to two years against moss and algae, and solar modules once or twice a year depending on dust and the inverter data. Coastal buildings in Phuket, Samui, Pattaya and Hua Hin need the shorter end of each range because of salt.
What the climate does to a building
Humidity and shade grow algae and black mould on any surface that stays damp: north faces, walls behind trees, under canopies. The monsoon washes dust off but leaves run-off streaks under every ledge and joint. The dry season lets dust and traffic soot build up for months without rain. Sea salt on the coast dries as a film on glass and corrodes metal fixings. Heat bakes dirt onto glass and makes mineral marks from tap-water cleaning harder to remove.
A calendar by surface
| Surface | City (Bangkok, Chiang Mai, EEC) | Coast (Phuket, Samui, Pattaya, Hua Hin) | Signs it is overdue |
|---|---|---|---|
| Glass curtain wall, windows | 2–4 times a year | 3–4 times a year | Haze in low sun, run-off streaks, salt film |
| Aluminium and composite cladding | 1–2 times a year | 2 times a year | Grey streaks under joints, green tint on shaded faces |
| Stone, render, concrete | Every 1–3 years, with treatment | Every 1–2 years | Black mould, green algae, dark run-off below sills |
| Tiled and metal roofs | Every 1–2 years | Every year | Moss cushions, blocked gutters, dark patches |
| Solar modules | 1–2 times a year | 2 times a year | Output drop at equal irradiance, dirt line at the lower edge |
| Glass roofs, atriums, canopies | 2–3 times a year | 3 times a year | Visible from inside: dust, leaves, bird marks |
These ranges come from our experience in France and the Thai climate data; the first pilot jobs in Thailand will refine them. They are a starting point for a maintenance plan, not a rule.
Why frequency changes the method
A façade cleaned regularly needs one pass of purified water, which is fast and cheap. A façade left for years needs a treatment pass, a dwell time and a rinse, which doubles the time. Regular cleaning with a fast method costs less per year than a rescue job every five years, and the building looks better in between. That is the economic case for the drone: it makes frequent cleaning affordable on surfaces where it used to be an event.
When to plan it
For most of Thailand, the end of the rainy season is a good time for the main clean: the dust of the dry months has not started, and the algae of the wet months is at its peak. A second clean before the hot season keeps glass clear through the months without rain. Hotels plan around occupancy; factories around shutdowns; hospitals around nothing, which is why they need a method that does not close anything.
Questions about frequency
Does the rain not clean the façade?
It removes loose dust and leaves streaks of everything else. Rain does not remove algae, soot bonded by heat, or salt.
Can CleanAlta set up a recurring contract?
Yes. In France, Saint-Gobain Recherche moved to two passes a year after the first job. Recurring contracts get the best rate because set-up is planned.
What about the burning season in the north?
Soot from agricultural burning settles on everything in Chiang Mai and the north between February and April. Glass and solar modules benefit from a clean right after it.
Investors, property groups and corporates
We present the Thai launch plan and the figures in a direct meeting, under NDA. Building owners can also apply for a documented pilot job.