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What is Chimney Flashing?

For our service area of Seattle and surrounding areas, the rainy season begins now and will continue on through spring. Between the rain and the cool temperatures coming our way this winter, your chimney is in for some work. The chimneys work constantly while fires are burning, but they work year-round to keep water and weather out.

Keep Water Out With FlashingWhat is Chimney Flashing Image - Seattle WA - Pristine Sweeps LLC

Flashing is made up of many thin layers of metal, laid in a specific pattern in order to keep water out. It is used to reinforce the area where the chimney and roof meet–the weakest part of the entire chimney system, and most susceptible to water penetration. When flashing is missing or damaged, water has a direct route into seams and cracks that lead right into the home and chimney.

Water and Winter Damage

Once water has penetrated the chimney system, it can ruin masonry from the inside out. Because masonry is constructed of materials that react poorly with water, the entire structure is affected by water, and homeowners often can’t see it until it’s too late.
Water causes damages including:

  • Rusted damper assemblies, fireplace accessories, hinges, and handles
  • Rotted and ruined wood and wall coverings
  • Deteriorated firebox assemblies and central heating system
  • Stained and decayed exterior mortar (spalling)
  • Deteriorated flue lining system
  • Collapsed hearth support and chimney structure
  • Settlement

During the winter water damage turns to winter damage. The water then enters the masonry chimney system in the home and cools, then freezes, and expands, damaging the structure. When it warms up, the water melts and moves further into the damaged area, repeating this process until serious structural damage occurs.

Hire a Professional

You can avoid water damages by hiring a professional for all of your chimney needs. Schedule chimney inspections annually, so that a professional can get a look at your chimney in the areas that are out of sight. When a certified chimney sweep sees your flashing is shifted or missing, it can be corrected before major damage occurs and any damage can be repaired.

Only a professional should install flashing because it is a meticulous process that is often done incorrectly due to lack of general knowledge and experience. The flashing is laid specifically so that no nails are visible (for water to access), and placement differs based on the slant of the roof and the roofing materials. If this isn’t done correctly, it will not last and it will leak.

If your chimney sweep finishes a flashing installation and you see nails or a covering of tar or paint, then you have a problem. Many amateurs cover the flashing with other sealers in order to prevent water penetration when they haven’t completed the job correctly.

We have a long rainy season ahead of us here in Seattle, Washington, and it’s our goal at Pristine Sweeps that every household in our service area has a safe and efficient fireplace this winter. Talk to Pristine Sweeps to ask about our flashing repairs and installation. Call 206-574-8414 or make an appointment online.

By Aaron Woodward | Tagged with: Tags: , , , | Leave a Comment

Anatomy Of A Chimney

Your chimney is more than just a stack of bricks and mortar; in fact, chimneys are surprisingly complex structures  with different parts and components that all work together to keep your fireplace burning safely and efficiently. By better understanding the anatomy of your chimney, you can begin to learn more about the purpose and function of the unique – and important – components of your chimney.

Anatomy of a Chimney - Seattle WA - Pristine Sweeps

Chimney cap

The chimney cap is a metal cover used to protect the top of the flue; chimney caps also often have mesh or wire sides as a way to keep animals and debris from getting into the flue. In addition to keeping out moisture, animals, and debris, chimney caps can also aid drafting by preventing downdrafts caused by wind.

Chimney crown

The chimney crown is the masonry or concrete slab that covers the top of the chimney; the chimney crown seals around the top of the flue pipe which the chimney cap then sits on top of. Well-designed chimney crowns will have an overhang of at least 2-2.5 inches to allow water to flow onto the roof instead of the sides of the chimney. Because they often take the most “direct hits” from the elements, chimney crowns are more prone to damage such as cracking.

Chimney chase

While the flues of masonry chimneys are surrounded by bricks and mortar, the flues of prefabricated or factory built chimneys are surrounded by the chase. The chimney chase is built around the flue to protect it as well as help make it more aesthetically pleasing; chimney chases are often made using the same siding or building materials as the rest of the home.

Chimney chase cover

If you have a prefabricated or factory built fireplace, your chimney will have a chase cover in place of a chimney crown. The chimney chase cover is a piece of metal – often a galvanized metal such as aluminum – that covers that top of the chimney chase and seals around the top of the flue. Because they are made out of metal, chimney chase covers may rust over time; staining on the sides of a chimney chase is often the first sign that the chase cover has begun to rust.


The damper is located at the top of the firebox between it and the flue and can be opened and closed using a pulley or lever when the fireplace is in use. Dampers should be opened when the fireplace is in use to allow smoke and gas to vent up the chimney; when not in use, dampers should be closed to prevent conditioned air from escaping.

Flue and flue lining

The flue is the metal pipes that create the venting system for the chimney; to protect the surrounding building materials, flues have liners made from materials such as clay tiles or stainless steel. Flues may need to be relined after damage or when a new fireplace is installed.

Learning about the anatomy of your chimney can help you understand the purpose and function of each chimney component. For more information about the anatomy of your chimney, contact Pristine Sweeps today!

By Aaron Woodward | Tagged with: Tags: , , | Leave a Comment