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Chimney Waterproofing

before chimney waterproofingBecause moisture is the biggest enemy to masonry chimneys, the experts at Hudson Valley Chimney Service, Inc. recommend chimney waterproofing. There are numerous ways in which moisture can intrude into the chimney system, and there are also many different types of damage caused by moisture. Taking a proactive approach and scheduling chimney waterproofing before any damage has occurred is an excellent strategy for slashing maintenance and repair costs.


 Vulnerable chimney materials

Bricks used to build a chimney can be as porous and absorbent as a sponge. If moisture gets inside the chimney masonry, deterioration, spalling, efflorescence, and corrosion can occur. Ultimately, if the chimney isn’t repaired, the result can be complete structural failure.

The mortar on a chimney only lasts 25 years at most, in the best of conditions. Eventually, the mortar will begin to peel and crumble, exposing the masonry to moisture intrusion and damage. Annual chimney inspections can help to identify issues such as deteriorating mortar and to address potential moisture problems before damage has occurred. It’s possible a procedure called tuckpointing can be applied, to resolve the problem. Afterwards, chimney waterproofing can help to protect the entire exterior of the chimney masonry.


If moisture gets into a brick masonry chimney, the water inside the structure will expand and contract during freezing and thawing cycles in winter. This causes corrosion of the masonry. Eventually, spalling occurs, which means that the face of the brick begins to break and pop off. A chimney rebuild may be necessary, to prevent collapse of the structure.


When staining appears on a chimney, it is evidence of efflorescence and a clear sign that moisture has entered the chimney masonry. Not all masonry is subject to staining, even if moisture gets inside. First, there must be soluble salts in the masonry, for efflorescence to occur. Secondly, there must be enough moisture in the masonry to create a soluble solution as the water mixes with the salts. Lastly, the salt solution must be able to move through the masonry, where it ultimately evaporates on the exterior, causing staining, which is usually white. The minerals in the masonry determine the color of the staining.


Without protection from moisture, bricks can begin to disintegrate and fall apart. The problem of erosion needs to be addressed as soon as the degradation begins to occur. Sometimes the issue can be helped by having a cricket added to the chimney. A cricket is also sometimes called a saddle. The purpose of a cricket is to divert water away from the chimney, to prevent erosion and other types of moisture damage.

Benefits of Waterproofing

professional chimney cap installation on chimneyStone is the only construction material used for masonry chimneys that isn’t vulnerable to deterioration as a result of prolonged contact with water. Chimney caps and various components of the chimney are supposed to help keep moisture from causing damage. The chimney crown, for instance, prevents water from entering the chimney system between the flue and the chimney exterior; but chimney crowns eventually crack.

Waterproofing the exterior of the chimney can be very effective at providing an additional line of defense against moisture. The water repellent products allow the chimney to breathe, which is referred to as being “100% vapor permeable.” Effective waterproofing agents prevent water from getting in from the outside, even though moisture inside the chimney can escape.

If you are interested in potentially saving a lot of money on repair costs, contact us at Hudson Valley Chimney today for chimney waterproofing. If any damage already exists, it needs to be repaired before water repellent is applied.

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