Is mortar waterproof? No, but you can make it waterproof

Mortar is not waterproof. It’s made of a mix of cement, sand, and water, and it is porous which means that water can seep through if the pressure is high enough.

However, mortar isn’t rapidly damaged by water. If the mortar layer is thick enough, and the water pressure is not too high, mortar can successfully prevent water from seeping through.

For instance, if you spray a garden hose at a brick wall for 5 minutes, water won’t pass through.

But if you spray it for 3-5 hours, the wall will start to absorb moisture at a very slow rate. Mortar has a dense makeup that successfully slows down water absorption.

The good news is that your brick wall will dry out during intervening dry periods.

Other structures may behave differently under high water pressure conditions.

For example, if the water table raises too high, your concrete slab may fail to prevent groundwater from getting into your basement.

While mortar is not impervious to water, it can be made water-resistant by adding a waterproofing agent to the mix.

How to make mortar waterproof

You can add special waterproofing additives and sealers to make mortar impervious to water penetration.

You can add a latex-based liquid or a silicone-based sealer to the mix. This will prevent moisture from penetrating the structure.

Other waterproofing agents that you can add to your mortar mix to make it waterproof include acrylic, epoxy, and urethane-based coatings.

However, not all these waterproofing agents, additives, and sealers are suitable for all types of mortar. Their effectiveness varies.

If you don’t add the right amount of waterproofing agent to your mortar mix, or you fail to apply it properly, water can seep through.

Always consult with a professional before attempting to waterproof mortar, especially if you don’t have any previous experience.

Contract a building professional to get the job done and guarantee the results.

If you still want to follow a DIY approach, here’s a general guide on how to make mortar waterproof.

Steps to make mortar waterproof

1. Select your waterproofing agent

Decide on the waterproofing agent you want to add to the mix to make your mortar waterproof. The agents you’ll use depend on the type of mortar you’re using, and the moisture conditions.

2. Mix the mortar with the waterproofing agent

Prepare your mortar mixture. Once it’s ready, add the waterproofing agent. Mix everything thoroughly until it is fully blended and you get the consistency you want.

3. Prepare the surface and apply the mortar

Now that you have your mortar ready, prepare the surface. Remove dust, debris, and any loose material.

Apply the mortar mixture to the surface using a pointing tool. Spread it evenly making sure it covers the surface completely.

5. Let the mortar dry

The process should take a few days depending on the weather conditions.

Make sure to regularly inspect the structure for signs of damage. Repair any cracks or signs of damage as soon as possible.

Mortar takes a long time to degrade. Even if you don’t make it waterproof, it will still perform well as dampness doesn’t affect its effectiveness.