Knowledge is Power: Know Your Roof – Chimney

Part III: Your Chimney – Leaks and Other Problems

In the first article of this series, we introduced you to the parts and pieces of your roof. Next, we explained the importance of a healthy ventilation system.  Now let’s discuss the chimney and how they relate to issues with your roof. We will explain the chimney’s structure and look at common leaks and other problems associated with a stack.

The diagram in the photo above shows the major structural parts of a chimney stack.


Cap and Crowncounter-flashing-diagram

No, your chimney is not graduating, but it must maintain a passing grade.


Chimneys without caps get a lot of rain falling straight down into them. Not only do caps keep the rain out: they also keep birds, animals, and debris from entering the flue.


Without a proper chimney crown — or if you have a cracked one — rain water seeps into your chimney’s bricks and mortar. This water continually freezes and thaws during the winter. When water freezes, it expands by about 10 percent, enlarging cracks and causing the bricks to peel and the mortar to deteriorate.

You should get your chimney inspected whenever you suspect water damage. What might appear to be minor damage may only take one more season of wet weather to ruin your chimney.


What is Chimney Flashing?

Do not worry; it isn’t anything for which you’ll be arrested.

The chimney structure comes through the roof, leaving a large gap between thechimney-flashing-zbar8 chimney material and the roof deck. Flashing keeps the water from entering that space and must be fully sealed.

Flashing is typically made from lead but can also be aluminum, steel or copper. It is placed in between a couple of bricks and bends to lay on a section of shingles. The second layer of shingles positioned on top of the flashing creates a layered effect, which makes it difficult for moisture to enter unwanted areas of your roof.


Why Do I Have a Leak?

Homewise Inspection, an A+ rated Better Business Bureau roof inspection company, lists their top six high probabilities for roof leaks:


As time passes roofing materials lose their ability to maintain a weather-tight system. Asphalt shingles can curl and shrink. Built-up roofing (multiple layers of roofing material on a roof deck) dries out and cracks. It is important to remember that although it’s possible for a new roof to leak, it’s much more likely for an old roof to have problems.

Faulty Installation

When improperly installed, a roofing system is highly likely to fail. Installation defects include abnormal nailing patterns, exposed fasteners, poor alignment of materials, incorrect materials, and too many layers of roofing.


Manufacturing Defects

Defective materials can cause problems with the performance of the roofing system. Look out for cracking or premature aging of the materials and for cosmetic flaws such as color variations.



Flashings, which cover seams or other interruptions in a roof,  are its most vulnerable and complicated elements.Water, snow, or ice are most likely to create problems in these vulnerable areas.


Complex Designs

Roofs with varying slopes, angles and penetrations are more liable to develop problems than a steep, simple roof. A low-pitch design combined with a large roof overhang will make the roof more prone to ice damming, for example.



Weather is the most unpredictable factor in predicting leakage. Often, even a new, perfectly installed roof will leak under certain conditions. Wind-driven rain coming from an atypical direction or a heavy snow followed by warmer temperatures and rain can create problems with a new roof.


Have Your Chimney’ Health Evaluated


Clean your chimney at least once a year, and perhaps even twice, depending the type of wood burned and how often. Have a professional chimney sweep check the chimney for leaks, cracks, missing bricks, compromised flashing or mortar.

A chimney sweep will inspect the inside of the chimney, checking for flue damage, a malfunctioning damper and excess soot.



Your chimney is part of your roof system, as a roofing contractor, we will refer you to a mason if you have specific concerns about your chimney that are beyond our skill set or expertise.

While re-roofing a building, it is common practice for a roofing contractor to evaluate the health and structural integrity of the stack and make repair or replacement suggestions before they start work.

Horch Roofing can inspect your chimney and flashing for potential leak areas for integrity, and we’ll guide you in the right direction.

Call 207-273-1111 or visit our website and complete an inquiry form.