How to waterproof exterior walls against rain
Driving rain soaks into exterior walls and shows as damp inside. Here is how to protect and decorate outside walls with SUMO Weatherguard.
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Exterior walls take wind-driven rain that soaks through porous plaster and shows as damp patches indoors. A decorative waterproof coating both seals the surface and finishes it. SUMO Weatherguard is a high-performance acrylic waterproof decorative coating for exterior walls and masonry.
This guide covers protecting and decorating an exterior wall in one system.
What you’ll need
Step by step
Clean and repair the wall
Remove dust, algae, chalking and flaking paint so the surface is sound and clean. Cut out and fill cracks with a repair mortar so they do not re-open.
Let the wall dry
Make sure the wall is dry before coating — trapping moisture under a coating causes blistering.
Apply the first coat
Brush/roller a full, even first coat of SUMO Weatherguard, working it into the surface with no misses.
Apply the second coat
Once the first coat has dried enough to over-coat, apply a second full coat for even colour and a continuous waterproof film.
Cure and inspect
Let it cure, then check coverage after the next rain. Touch up any thin or missed areas.
Care, tips & what to avoid
- !Coating a damp or dirty wallIt blisters and peels. Clean, repair and dry the wall first.
- !Ignoring cracksCracks let rain in behind the coating. Repair them before coating.
- !One thin coatThin film means poor colour and waterproofing. Apply two full coats.
