Exterior House Paint for a Tropical Climate: What Lasts in Sun and Rain

Which exterior house paint stands up to sun and rain in Phuket?

The exterior house paint that lasts in a tropical climate is a pure acrylic water-based paint made for outdoor use, which the manufacturer states is UV-resistant, resists mould and algae, and forms a flexible film. The paint type is only half the answer. The other half is wall preparation and a primer matched to the condition of the render, because a high-grade paint applied to a dirty or damp wall peels quickly as well. This article belongs to the house painting guides from Phuket Pro Painters.

The outside walls of a home in Phuket face four things at once: strong sun for most of the year, heavy monsoon rain from roughly May to October, high humidity that lets algae take hold, and salt in the air for homes near the sea. The criteria for exterior paint are therefore much stricter than for interior paint.

What properties should exterior paint have?

When reading the label or the product data sheet of an exterior house paint, look for the properties below and compare them with the problems your own house actually has.

No single product is strongest on every point. Each manufacturer designs its ranges with different priorities. For the level of each property and the expected service life, rely on what the paint manufacturer states on the label and the product data sheet. How to read those documents is explained in the guide to comparing paint grades and reading the label.

What kinds of exterior paint are there, and how do they differ?

What is exterior acrylic emulsion?

Water-based acrylic paint for outdoor use is the standard paint for rendered masonry walls, which is how most houses and villas in Thailand are built. The paint is thinned with water, the film lets some moisture escape from inside the wall, and there are several grades. Higher grades usually contain a larger share of acrylic binder and more UV protection, so they hold colour for longer. On Thai cans, the top ranges are often described as pure acrylic or 100% acrylic.

Which walls suit a flexible-film paint?

A flexible-film paint forms a thicker film that stretches more than ordinary acrylic. This type suits rendered walls with fine hairline surface marks spread across them, because the film helps stop the small marks showing through again. A flexible paint is not a cure for cracks caused by the structure or for water entering the wall. Phuket Pro Painters does not take on waterproofing, structural crack repair or leak repair; those problems need a specialist to inspect and fix them before any painting.

Can exterior timber and steel take the same paint as the walls?

No. Outdoor timber takes a wood stain or wood paint that resists sun. Steel has to be sanded free of rust, primed with an anti-rust primer and finished with a paint made for metal. One house therefore usually needs more than one paint system, and the quotation should list the items by material.

How does colour affect how long exterior paint lasts?

Colour is the factor owners most often overlook. Dark and bright pigments show fading clearly under continuous Phuket sun, and dark walls absorb more heat, so the wall expands and contracts more each day. Pale to mid shades such as off-white, cream, light grey and beige are easier to live with over the years.

Owners who want a dark colour for its look often use the dark shade on part of the house only, such as a feature wall or the ground floor, and keep a pale colour for the main area. That is the same principle as a two-tone scheme, which is what Thai homeowners call a house painted in two colours. Examples of how to divide the tones are in the guide to two-tone grey exterior colours.

How should an exterior wall be prepared before painting?

The life of exterior house paint depends on surface preparation as much as on the quality of the paint. The usual sequence is as follows.

1. Wash the wall to remove dust, algae, mould and salt deposits, then let the wall dry completely.
2. Scrape off old paint that has blistered, flaked or peeled, back to a layer that still holds firmly.
3. Sand the surface smooth and feather the edges between old paint and bare render.
4. Fill small holes and hairline surface marks with an exterior filler.
5. Apply a primer matched to the wall: an alkali-resistant primer on new render, and a primer for old masonry on old chalky walls to bind the surface.
6. Apply the agreed number of top coats, leaving the interval between coats that the manufacturer states on the label.

Newly rendered walls must be left to dry and cure before painting, which generally takes several weeks. New render is damp and strongly alkaline, and both conditions cause patchy colour and peeling.

How often does a house exterior need repainting?

The service life of exterior paint depends on the paint grade, the direction each wall faces, the distance from the sea and the preparation done at the time of painting, so no single figure fits every house. Signs that a repaint is due include uneven fading, white powder on the hand when the wall is rubbed, algae that returns soon after washing, and paint that starts to blister or peel. Repainting when the film first begins to break down needs less preparation than waiting until the whole wall is peeling.

What makes the cost of exterior painting vary?

The cost of exterior painting depends on the measured wall area, the height of the house and whether scaffolding is needed, the amount of surface preparation, the paint grade and the hiring option. Scaffolding and surface preparation are quoted as separate lines. Estimated rates are on the painting prices in Phuket page.

How can a painter help assess the outside walls?

Looking at the real wall is the only way to tell which primer is needed and how much preparation the surface requires. Phuket Pro Painters surveys and measures the site free of charge and issues a written quotation before work starts, every time. The scope of work is described on the exterior painting service page. Owners who want the inside and outside painted together can read about whole-house painting.