Is Latex Paint Waterproof? (& How To Make it)

A waterproof paint refers to a finish that is formulated to be resistant to water penetration and to create a protective barrier to protect surfaces underneath from water.

Latex paint isn’t waterproof as it doesn’t have waterproofing additives in its formula. The paint offers minimal water resistance and will get washed off if exposed to constant water or rainfall.

To make latex paint waterproof, seal it with a waterproof sealer. The waterproof sealer will produce a glossy layer over the paint and protect it from water, moisture, scratches, and other elements.

Why isn’t Latex Paint Waterproof?

Is Latex Paint Water-Resistant

Latex paint isn’t waterproof as it isn’t formulated with waterproofing qualities, it doesn’t have a glossy finish and is water-based. Since latex paint is water-based and doesn’t have a protective layer, it makes its coating water-soluble.

For paint to be waterproof, its coating must repel constant water and moisture without allowing penetration, and latex paint doesn’t do that.

Latex paint has low water-resistant features, meaning it’s resistant to small amounts of water for a small amount of time. So, you can clean a latex paint finish with water without removing it, but if the finish is exposed to constant water for a long period of time it will get washed off.

Most waterproofing paints have a glossy top layer that repels (prevents) water from penetrating its coatings. The water (or moisture) slides off the glossy top layer and doesn’t penetrate into it. In comparison, latex paint has a textured top layer that doesn’t prevent water absorption.

Latex paint has a fast drying time so the paint particles don’t have enough time to harden or get compact with each other, so its finish isn’t durable (or compact) enough to prevent water from penetrating. 

How To Make Latex Paint Waterproof?

How To Make Latex Paint Waterproof

To make latex paint waterproof, seal it with a waterproof sealer. The waterproof sealer will produce a glossy waterproof coating over the paint and protect it from water, moisture, scratches, and other elements.

The sealer will act as a “shield” to the paint and prevent water penetration.

To seal latex paint do the following things.

  1. Wait for latex paint to dry
  2. Sand (scuff) the paint with fine-grit sandpaper (220-grit). 
  3. Apply 2-3 coats of waterproof sealer.
  4. Sand between coats of the waterproof sealer (except for the final coat).
  5. Let the waterproof sealer dry.

You can use exterior varnish or polycrylic as a sealer. For outdoor latex paint surfaces, use exterior sealers as they are formulated with extra additives to withstand outdoor weather elements.

You can mix latex paint with water-based polyurethane to get a water-resistant finish. The mixture will produce a colorful glossy finish that is resistant to water, moisture, and scratches.

Does Rain Affect Latex Paint?

Rain does affect latex paint especially if the paint is exposed to constant heavy rainfall. Latex paint isn’t waterproof and can’t prevent rainfall from penetrating its coating so it will get washed off within one (1) week if exposed to constant water.

Latex paint will last a few months outdoors if it’s not exposed to water, sun, or rainfall as it has minimum water-resistant qualities so it’s not affected by a small amount of water.

Rain affects (or washes off) paint finish on horizontal surfaces easier than on vertical surfaces. Horizontal surfaces, such as table tops, are exposed more as the water will stay over it for longer. On the other hand, vertical surfaces aren’t exposed to rainfall as much as the water will slide off.

So, latex paint will last longer outdoors if it’s applied on vertical surfaces and is protected from rain or constant water. To make latex paint last longer outdoors, seal it with a waterproof sealer.

Tony Adams

Tony Adams

Woodworker, Interior and Exterior Painter, Flooring Specialist

Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about.

Eral Kadrija

Eral Kadrija

Lead Editor, Home Renovator

Eral has a passion for home renovation and repair. Over the years, he has bought, renovated, and sold 7 old homes. Using his experience from different DIY projects he created DIY Geeks.

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