Acrylic Waterproofing for Exterior Walls with Moisture: What the Film Solves and What Requires Fixing the Cause

An exterior wall with moisture can have more than one origin, and the acrylic waterproofing paint solves part of them. Separating what the film does from what depends on correcting the source of the water is what decides whether the paint will last or peel again.

What the water-repellent film solves

Coral Proteção Sol & Chuva Pintura Impermeabilizante (waterproofing paint) forms a rubberised, flexible and water-repellent film with Power Flex technology. This film repels rainwater and prevents water from entering from outside in, prevents cracks and infiltration, fights algae and mould and keeps the wall clean for longer. For rain hitting the facade and infiltration coming from the external side, the film acts directly on the surface.

The flexibility has a specific function: the film follows the movements of expansion and contraction of the wall caused by temperature changes, which helps prevent cracks from reopening a path for water.

What requires treating the cause first

When the water does not come from rain on the surface, the paint alone does not solve it. Moisture from a pipe leak, rising damp that climbs through the base of the wall or infiltration from an untreated structural crack have an origin that must be corrected before waterproofing. The documented guidance is to resolve the cause of the moisture before starting the painting; otherwise, the protection does not stay effective. Where the acrylic paint fits among the other waterproofing approaches is set out in the guide on types of wall and facade waterproofing and when to use an acrylic waterproofing paint.

Preparing the wall with moisture

The surface must be dry at the moment of application. Walls with mould are washed with water and bleach in equal parts, with a wait of 6 hours, rinsing and full drying. New plaster is a particular case: with the antisaltpeter action, the paint can go on dry new plaster, covered in the guide on waterproofing new plaster without waiting for the full cure.

Application

Thinning is 10% (ten parts of product to one of potable water). There are 3 coats, with a low-pile wool roller, brush or paintbrush, and drying of 30 minutes to the touch, 4 hours between coats and 24 hours for final drying. Finished coverage reaches up to 85 m² in the 18 L can. Avoid application on rainy days, with temperatures below 10 ºC or above 40 ºC and relative humidity above 85%. For the full line and its criteria, see the Coral Proteção Sol & Chuva waterproof exterior paint guide.

Frequently asked questions

Does the waterproofing paint solve moisture rising through the base of the wall?

Not directly. Rising damp originates at the base of the wall and must be treated at the cause; the film acts on the water coming from rain and from infiltration from outside in.

Can an exterior wall still damp be painted?

The surface must be dry at the moment of application. Painting over a damp wall compromises adhesion and protection.

Does the water-repellent film fight mould?

The same film prevents and fights algae and mould, with the purpose of preserving the durability and the aesthetic properties of the dry paint. Existing mould must be removed in preparation before painting.

How many coats does an exterior wall need?

3 coats as a reference, which may vary with the type and condition of the surface and the chosen colour.