Silane Siloxane sealers are the most common type of concrete sealer to use on a block wall. They are penetrating, breathable sealers designed to reduce damage and deterioration caused by water absorption. They will also help to reduce mold and mildew growth, and efflorescence. They won’t change the look or color of the block, and will last for up to 10 years.

Silane Siloxane sealers are very easy to apply. They can be applied with a 3/8-1/2″ roller, but on a vertical application you will get better coverage with a high volume, low pressure pump sprayer. With a sprayer, you get better coverage and more consistent coverage.

Sealing your concrete block wall can be done in a few easy steps:

1. Make sure the block wall is clean, and free of anything that could prevent proper penetration and absorption.
2. Once the block wall has been cleaned, allow it at least 24-36 hours to dry. While the block may look dry on the surface, water can remain in the pores for up to 24-36 hours later.
3. Once the block is dry, seal with a roller or sprayer. Two coats are always suggested, but follow the directions and guidelines of the manufacturer.
4. Let the material dry, and keep the block dry for at least 24 hours after application. The Silane Siloxane sealer can take up to 72 hours to fully cure before you will notice water start to repel.

Other Types of Block Wall Sealers

There are two other types of sealers that can be used on block walls, but they don’t offer the same type of benefits that a Silane Siloxane sealer does. The other types of sealers are silicate densifiers and acrylic sealers.

• Silicate densifiers are used to increase the strength and density of the block. They help to reduce dusting and deterioration caused by surface strength. While they can help to strengthen the block, they can’t help deterioration caused by water from rain, melting snow, ice, sea water, pool water, or irrigation systems. If a silicate sealer is used, a Silane Siloxane sealer should be used over it. One other thing to keep in mind with silicates is that if you over apply a silicate to a porous surface, such as block, white crystals that would normally form in the pores can form on the surface. These crystals are permanent and can’t be removed.
• Acrylic sealers enhance the block with a wet look, low gloss, high gloss, or colored gloss finish. They are great sealers for stand alone block, or block that doesn’t have any issues with hydrostatic pressure or moisture. When an acrylic is applied to below-grade block walls, or block walls with hydrostatic pressure or moisture issues, the acrylic sealer can delaminate. If you are considering the use of an acrylic sealer, apply it to a test area first.