Everything you need to know about ...Painting exterior walls

ONE WAY TO tell if your exterior paintwork is due for a touch up - apart from the tell-tale signs of cracking and peeling - is to stand on the street and look at it critically as if you were a potential buyer. If the house looks tired and outdated, or simply unappealing, then a fresh look might be in order.

Repainting a whole house can be a major job. Unlike individual rooms that can be redecorated one by one, the exterior requires total commitment. Apart from the time and expense involved, it is important to choose a colour you can live with because, if you do the job properly the first time, it can last for up to 10 years.

The state of the exterior will give you an idea of the size of the task. If the old paint is peeling, you will have to resign yourself to the tedious business of scraping it off with a wire brush, or blasting it away with a pressure hose before applying the new look.

It is common in Hong Kong, because of the humid climate, to find spots of mildew, green mould or moss on your masonry walls. It is vital to find these spots and scrub them clean, then treat the area with a fungicidal solution or bleach. If you don't kill the fungus, it will soon reappear to spoil the new paintwork. Some people use ordinary household bleach, but solutions sold at paint shops are stronger, costing up to about $45 for a litre.

Because the weather in Hong Kong makes exterior walls flaky, Fanny Lui of Yuen Fat Ho paint shop on Hollywood Road recommends using a base coat of waterproof primer or stabilising solution. If the surface is not too chalky, a primer will do, but if it is powdery you will need to remove the old layers and put on some stabilising solution, otherwise your new paint will soon flake off.

Check for structural cracks that should be filled with a rubber or elasticated filler that expands and contracts with the movement of the building. Do not use regular plaster, of the type you would use inside, because it will only crack again.