Seal Your Chimney Flashing Before It’s Too Late

Summer has officially come to an end, and now it is time to look ahead to the exciting change of seasons. The colorful leaves and chilly weather has everyone in the season spirit. The upcoming holidays are also on a lot of people’s minds as the end of the year approaches. This is usually a happy time of year, and no one wants to think about keeping their roofs from leaking, or even about a roof that is already leaking. However, now is the best time to take care of any roof leaks because the frigid winters in the Hudson Valley make roof conditions too dangerous to work on until spring comes around again.


Chimneys are responsible for a surprising number of water leaks into the house. Without a chimney cap, water can enter directly through the top of the chimney. If the masonry is improperly sealed, water can travel through the brick and mortar, right into the house. While these issues deserve a column of their own, leaky flashing is the topic of today.

Flashing is a covering used to stop water from leaking beneath the roof shingles. It can be found anywhere the line of the roof ends, such as around dormers or sky lights. Chimney flashing prevents water from leaking in where the chimney protrudes from the roof. Generally made of aluminum, the flashing on a chimney is much more complex than flashing on other areas of the roof. It consists of four woven layers of flashing all sealed with mortar to prevent premature decay.

While the mortar that holds the flashing together holds up longer than other materials some nonprofessionals use on their flashing, it is not indestructible. If not maintained properly, mortar will eventually deteriorate. It is a porous material, so when exposed to water, the mortar absorbs it readily. Then, around winter time, the saturated mortar expands and contracts during the freeze and thaw cycle. This inevitably results in cracks, and in turn, a leaky roof. In order to prevent a leaky roof and to maintain the integrity of the flashing, you can have your mason seal the flashing around the chimney.

Applying a sealant to your flashing keeps the aluminum and the mortar out of direct contact with the elements. The waterproof sealant prevents water from seeping into the mortar or even into your home. For the ambitious do-it-yourself types, be aware that poorly serviced flashing will not last as long as properly maintained flashing, and it could even cost you thousands of dollars in water damage repairs.

If you live in the Hudson Valley area of New York, contact All Seasons Chimney for a professional consultation. Take care of your home and chimney before it is too late.