If your brick chimney is in perfect condition, and there are no issues with deterioration or leaking, then sealing your brick chimney is fairly easy. The best sealer to use to seal a brick chimney is a Silane-Siloxane water repellent sealer. Silane-Siloxane water repellent sealers penetrate into the surface of the brick where they chemically react to form a hydrophobic barrier within the pores. When water hits the brick, it will roll right off instead of penetrating through. Silane-Siloxane concrete sealers can be used to seal the brick, the grout, and the crown (if the crown is concrete).
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If your chimney is not in perfect condition and has issues with deterioration, cracking, moving, or leaking, you may need more than just a chimney sealer. A chimney is made up of a few different parts, and each part should be analyzes separately:
- Flashing: The flashing can be found at the bottom of the chimney where the chimney and the roof leak. This is the number one source of water penetration. If there is no flashing, or if the flashing needs to be repaired, water will slip right past the flashing and into the home. Make sure the flashing is in tact and properly functioning before applying a sealer.
- Chimney Crown: Chimney crowns are usually made of a hard material, like metal or concrete. Make sure the chimney crown is in good working condition. If there is no crown, or if the crown is in need or repair, repair the crown before painting or sealing it.
- Brick and Grout: Some chimneys are build well and last forever, while other chimneys need to be repaired every 10-20 years. Make sure the bricks and the grout are in tact before sealing. If your chimney needs to be re-pointed, or if grout needs to be repaired, make sure that is done before sealing the brick.
- Chimney Cap: The cap goes over the opening of the chimney. It helps to reduce water and snow from going down your chimney into your fire place or furnace. If you don’t have a cap, you risk your fireplace or furnace filling up with water, and you risk having your chimney deteriorate from the inside. A cap is never a bad a idea.