Your roof relies on flashing, shingles, fasteners, and many other components all working together to keep moisture outside. Chimney flashing plays a key role in waterproofing, but is often one of the last things homeowners think about. When it starts leaking, however, flashing issues are among the most common causes of roof leaks.
Chimney flashing creates a watertight seal where the chimney intersects with the roof. Because chimneys disrupt the normal flow of water runoff on a roof, they require special installation and materials. Proper chimney flashing allows water to flow freely down your roof while preventing leaks into your roof, attic, insulation, and home.
If you know how to spot poorly installed flashing, you may be able to fix the problem before it leads to costly roof damage.
What Is Chimney Flashing?
When homeowners think of flashing, chimneys are usually the first thing that comes to mind. Chimney flashing is usually made of metal and installed around the base of the chimney where it meets the roof. It redirects water away from the seams between the chimney and roof materials.
Typically, flashing will include:
- Step flashing
- Counter flashing
- Base flashing
- Back flashing or cricket flashing
All the pieces work together to form layers that overlap and direct water away from the roof.
Chimneys expand when hot and contract when cool. Your roof also shifts slightly over time. Flashing installation must account for these movements to avoid breaking the seal.
Does the Flashing Look Neat and Secure?
Appearance can be one of the most important indicators of proper flashing installation. A trained professional should make the finished flashing look neat and seamless.
Check to see if the flashing:
- Has rounded edges that lay flat against the roof
- Is securely fastened
- Has properly installed counter flashing that is sealed to the chimney
Bad flashing often looks messy or patched up. Telltale signs of poor installation include:
- Jagged, bent flashing
- Glue or tar
- Visible gaps or holes
- Flashing that is not securely fastened
- Poorly installed counter flashing that isn’t sealing to the chimney
Keep in mind that chimney flashing is not meant to be decorative. However, poor workmanship usually stands out.
Is the Flashing Properly Layered With the Shingles?
Another important step in chimney flashing installation is correct layering. Roofs are designed so that water rolls downhill. Flashing must be layered to effectively redirect water.
Step flashing should be installed between each row of shingles on the sides of the chimney. By overlapping the next lower piece, water will continue to flow down your roof and off of the flashing.
Incorrect flashing can appear as large strips of metal on top of your roof, without weaving between the shingles.
Some contractors try to save time by using roofing tar or caulk as a substitute for step flashing. Sealants can be used to strengthen flashing, but should never replace proper flashing.
Are there Signs of Water Leaks in Your Home?
Do you notice water stains on your ceilings near your chimney? Water damage on your interior walls or paint bubbling near your chimney are also signs that your flashing is failing.
If your flashing is not functioning properly, you will likely see water leaks inside of your home.
Water damage can start small and become more noticeable with each rainstorm. At first, you may only notice leaks during large storms when rain blows in under the flashing. As your flashing continues to fail, you may notice leaks every time it rains.
Keep in mind that exterior damage can occur over time, even if you do not spot water damage inside of your home.
Leaks can cause major damage to roofing materials, insulation, ceilings, and walls. Flashing that isn’t installed correctly can lead to a decayed roof deck and even mold growth in your home.
Was Counter Flashing Installed?
Counter flashing is the part of your chimney flashing that goes inside your chimney. This covers the edges of the step flashing.
Counter flashing should always:
- Weave in between each row of brick/chimney
- Be installed into the chimney, NOT on top of the chimney
- Be filled with caulking and sealed
Notice how counter flashing should always be embedded into your chimney’s mortar joints. Flashing that is glued or caulked on the face of your chimney will become loose over time.
Temperature changes cause your chimney to expand and contract. Surface-mounted flashing is more prone to being dislodged.
The picture above clearly shows lots of caulk on the outside of this house. This is not always bad, but it could indicate that homeowners know there is a flashing problem. Caulk is not meant to be a permanent solution to leaky flashing.
Is there Rust or Corrosion?
Chimney flashing is made to last for years without rusting or fading. Stains or corroded material may indicate that your flashing is beginning to fail.
Three types of metal are used for chimney flashing:
- Aluminum
- Galvanized Steel
- Copper
If you notice rust stains running down your roof from your chimney, your flashing is likely rusting. Not only will rust make your flashing look bad, but it could create holes that allow water to penetrate your roof.
Check to see if any nails or flashing pieces are sticking up or have been rubbed bare by the elements. Exposed nails can also cause leaks.
Does Your Chimney Have a Cricket?
Not all chimneys have a cricket, but it’s typically installed on larger chimneys. A cricket is a small peaked structure that diverts water around the chimney.
Water can pool behind the chimney without a cricket. This allows water to trickle down behind the chimney, creating leaks and damage. In northern climates, ice dams and heavy snow can accumulate behind the chimney as well.
If your chimney is wider than it is tall, ask your roofing contractor whether you should install a cricket.
Should You Schedule Your Roof for Inspection?
Issues like improper overlapping, rust, and missing shingles can be hard to spot from the ground. Roof inspections can reveal hidden issues before they become costly.
During an inspection, your roofing contractor should look for:
- Missing flashing
- Improper flashing overlaps
- Sealant failure
- Missing or deteriorated shingles around the chimney
You should have your roof inspected yearly, after severe storms, and as your roof starts to age. Flashing problems can also develop as your roof ages.
If you recently moved into a new home, have your roof inspected to ensure there aren’t any underlying problems. Aging roofs might have flashing that was installed incorrectly or has begun to fail.
Why Proper Chimney Flashing is Important
Installing flashing incorrectly can decrease the lifespan of your roof. Not only will water leak into your attic or roof and cause damage, but water loves to travel.
Water typically spreads into the surrounding framing, insulation, ceiling, and walls. Because roofing leaks can go unnoticed for years, many homeowners don’t understand how damaging failed flashing can be.
Waterproof flashing can help protect:
- Roofing Materials
- Roof Decking
- Attic Space
- Inside of your ceilings
- Wall Framing
- Insulation
High-quality flashing is key to preventing roof leaks and reducing your risk for water damage.
Final Thoughts
Knowing how to spot poorly installed flashing can help homeowners avoid some common roofing issues. Some things to remember are that flashing:
- Should look secure
- Should overlap shingles
- Should not have any signs of rust
- Should not allow water into your home
If you suspect your chimney flashing was installed incorrectly, contact a professional roofing contractor right away. The longer you wait, the more damage could happen to your roof.
For professional chimney flashing inspections, roofing repairs, and more, contact Atlas Roofing & Siding today to learn how we can help protect your roof from expensive leaks.
