If you’ve ever had a roof leak, you know how frustrating it can be. And when it happens around your chimney, it’s even worse. You don’t want to get up on the roof and fix the problem only to have water leak right past your repair and into your house again!
But don’t worry—we’ve got you covered. There are a few things you should do and a few things you should absolutely not do when fixing a roof leak around a chimney.
Table of contents
What should you do when you have a chimney leak?
If you have a chimney leak, it’s important to address it promptly to prevent further damage to your home. Here are some steps you can take:
- Inspect the chimney: Check the chimney for any obvious signs of damage or deterioration, such as cracked or missing bricks, damaged mortar joints, or rusted flashing. Also, look for water stains on the walls and ceiling around the chimney.
- Determine the source of the leak: Try to identify where the water is coming from. It could be from the chimney cap, the flashing, the chimney crown, or the flue liner.
- Fix the chimney cap: If the chimney cap is damaged or missing, replace it with a new one. The cap helps prevent water from entering the chimney.
- Repair the flashing: The flashing is the metal sheet that covers the joint between the chimney and the roof. If the flashing is damaged or corroded, it can allow water to seep into the chimney. Repair or replace the flashing as needed.
- Seal the chimney crown: The chimney crown is the concrete or metal slab at the top of the chimney. If it’s cracked or damaged, water can enter the chimney. Apply a waterproof sealant to the crown to prevent further leaks.
- Install a chimney liner: If the flue liner is damaged or missing, install a new one. A chimney liner helps protect the chimney from heat and corrosion, and also helps prevent water from entering the chimney.
Steps for how to fix a roof leak around a chimney
Step 1: Safety first
Before you start working, make sure to wear appropriate safety gear, including a safety harness, safety glasses, and non-slip shoes. Set up your ladder securely and make sure it is stable.
Step 2: Inspect the chimney
Flashing Climb onto the roof and inspect the chimney flashing for any damage or wear. Check the base flashing, counter flashing, and cricket (if present). Look for any signs of rust, cracks, or breaks.
Step 3: Remove old flashing
Using a pry bar, carefully remove the old flashing and sealant around the chimney. Be careful not to damage the roof or the chimney while removing the flashing.
Step 4: Cut new flashing
Cut new metal flashing to size with tin snips. The flashing should be long enough to wrap around the chimney and extend several inches beyond the chimney on all sides.
Step 5: Install base flashing
Install the base flashing onto the roof deck with roofing nails, making sure it is properly aligned and level with the roof surface. Nail it down securely, but do not overdrive the nails, as this can damage the flashing.
Step 6: Install counter flashing
Install the counter flashing over the base flashing, tucking it securely into the mortar joints of the chimney. Use roofing nails to secure the counterflashing to the chimney, making sure it is snug against the chimney.
Step 7: Apply sealant
Use a lot of roofing cement to make a watertight seal around the edges of the flashing and chimney. Use a caulk gun to apply sealant in the areas where the flashing and chimney meet.
Step 8: Check for proper drainage
Check that the flashing is properly sloped and that water will not pool around the chimney. If necessary, adjust the slope by adding more sealant or shimming the flashing.
Step 9: Test for leaks
Wait for the sealant to dry, then use a hose to spray water on the roof and chimney to test for leaks. Check inside the attic for any signs of water damage.
Step 10: Maintenance
Regularly inspect the flashing for signs of wear or damage and reapply sealant as needed. Keep gutters clean and make sure they are not allowing water to enter the gutter system.
How do you waterproof a chimney?
- Clean the chimney: Use a stiff brush or pressure washer to remove dirt, debris, and loose mortar from the chimney’s exterior. Make sure the surface is clean and dry before proceeding.
- Apply the sealant: Choose a waterproofing sealant that is specifically designed for chimneys. Apply the sealant using a brush or sprayer, starting at the top of the chimney and working your way down. Make sure to cover the entire surface of the chimney, including any cracks or gaps.
- Let it dry: Allow the sealant to dry completely according to the manufacturer’s instructions. This may take several hours or days, depending on the type of sealant used and the weather conditions.
- Inspect the seal: Once the sealant is dry, inspect the chimney to make sure there are no gaps or cracks that were missed. If necessary, apply a second coat of sealant.
- Maintain the seal: Regularly inspect the chimney for signs of wear or damage, and reapply the sealant as needed to maintain a watertight seal.
How common are chimney leaks?
Chimney leaks are relatively common and can occur for a variety of reasons, such as damaged flashing, cracks in the chimney crown or cap, deteriorated mortar joints, and damaged chimney liners.
It was estimated that one out of every 30 homes will experience chimney leaks throughout the year. Water can penetrate the chimney and cause damage to the structure as well as to the surrounding roof and walls.
Leaks around chimneys can be hard to find and fix because water can travel a long way before it can be seen.
Therefore, it is important to inspect your chimney regularly for any signs of damage or water intrusion and to address any issues promptly to prevent further damage.
What causes roof leaks around a chimney?
- Damaged flashing: Flashing is a material that seals the area where the chimney meets the roof. Over time, flashing can become damaged due to weathering, rust, or improper installation.
- Cracked chimney crown: The chimney crown is the top of the chimney, and if it’s cracked or damaged, it can allow water to seep in.
- Missing mortar: The mortar between the bricks or stones of the chimney can deteriorate over time, leaving gaps that allow water to penetrate.
- Poorly installed or damaged shingles: If the shingles around the chimney are not installed properly or are damaged, they can allow water to seep in.
- Clogged gutters: Gutters that are clogged with debris can cause water to back up and overflow onto the roof, leading to leaks.
- Condensation: In some cases, water leaks around a chimney can be caused by condensation forming on the inside of the chimney and then dripping down into the roof.
- Faulty flashing installation: Improper installation of the flashing system is one of the most common causes of chimney leaks. If the flashing is not installed correctly, water can penetrate through the gaps and enter your attic space, causing water damage.
- Chimney cap damage: A chimney cap is a protective covering that sits on top of your chimney and prevents debris, animals, and rainwater from entering your home. If the cap is damaged or missing, water can easily enter the chimney and leak into your home.
- Damaged masonry: If the masonry on your chimney is damaged or cracked, water can enter through the cracks and gaps. Water that enters through the masonry can cause the brick or stone to deteriorate and weaken, leading to further water damage.
How do you identify a chimney leak?
- Water stains: Check the walls and ceiling around the chimney for water stains or discoloration. This is often the first sign of a leak.
- Dampness or mold: If you notice dampness or mold around the chimney or in the attic, this could be a sign of a leak.
- Rust: Look for rust on metal parts such as the chimney cap, chimney crown, or flashing. This could indicate water damage.
- Loose or missing mortar: Check the mortar joints between the bricks or stones on the chimney. If you notice any gaps or missing mortar, water can seep in and cause damage.
- Damaged bricks or stones: Cracked or missing bricks or stones can also allow water to penetrate the chimney and cause leaks.
- Damaged flashing: Check the flashing around the chimney for signs of damage, such as rust or cracks. Flashing that is loose, missing or improperly installed can also cause leaks.
- Chimney cap or crown damage: The chimney cap and crown are designed to keep water out of the chimney. If they are damaged, water can enter and cause leaks.
- Condensation: Condensation can form on the inside of the chimney and cause moisture problems. This can be caused by poor insulation or improper ventilation.
What to consider when fixing a roof leak around a chimney
- Consultation with a professional: Before attempting any repairs, it’s always a good idea to consult with a professional roofer or chimney specialist. They can help you assess the extent of the damage and determine the best course of action.
- Consider cost and sustainability: When choosing materials and repair methods, it’s important to consider both the cost and sustainability of the options available. Cheaper materials may not be as durable, while more expensive options may not be within your budget.
- Make sure the repair is strong: A proper repair should be strong enough to withstand the elements and prevent future leaks. This may involve reinforcing the flashing, repairing the chimney cap or crown, or replacing damaged bricks.
- Repairing the leak: Depending on the cause of the leak, the repair may involve sealing cracks in the chimney or replacing damaged flashing. In some cases, a more extensive repair may be necessary.
- Use the right materials: The right materials are essential for a long-lasting repair. This may include sealants, flashing, and mortar.
- Make sure the repair is waterproof: The repair should be waterproof to prevent future leaks. This may involve applying a waterproof sealant or installing a new flashing system.
- Make sure the repair is safe: Safety is paramount when working on a roof. Be sure to use appropriate safety equipment, such as a harness and hardhat, and follow all safety guidelines and regulations.
- Follow safety precautions when working on the roof: Working on a roof can be dangerous. Be sure to follow all safety precautions, such as using a ladder that is properly secured and stable.
- Have a professional check the finished work: Once the repair is complete, it’s always a good idea to have a professional check the work to ensure that everything has been done correctly and that there are no additional issues that need to be addressed.
Tips for preventing roof leaks around chimneys
Clean chimney regularly
Regular cleaning of the chimney helps to prevent debris and other materials from accumulating, which can cause blockages and lead to leaks.
Make sure the chimney is properly maintained
Regular maintenance of the chimney is essential for preventing leaks. This includes checking for cracks, loose bricks, and other damage.
Check for defects in the chimney
Any defects in the chimney can cause leaks. It’s important to check for any damage and repair it as soon as possible.
Check for leaks around the chimney
Look for any signs of water damage, such as water stains or mold, around the chimney. This can be an indication of a leak.
Install a chimney liner
A chimney liner helps prevent leaks by providing a barrier between the chimney and the flue.
Make sure the flashing is secure
The flashing around the chimney should be checked regularly to ensure that it is secure and in good condition. Damaged or loose flashing can allow water to enter the roof and cause leaks.
Make sure there are no cracks in the roof
Check the roof for any cracks or damage that could allow water to enter. Repair any damage as soon as possible.
Install a rainproof chimney cap
A rainproof chimney cap can help prevent rainwater from entering the chimney and causing leaks.
Use correct chimney construction material
When constructing a chimney, it’s important to use the correct materials to prevent leaks. The materials should be durable and able to withstand weather conditions.
The tools and materials needed to fix a chimney leak may vary depending on the extent and nature of the leak, but generally, some of the commonly used tools and materials include:
Tools
- Ladder or scaffolding to access the roof and chimney
- Hammer and nails or screwdriver and screws
- Pry bar
- Caulk gun
- Chisel and hammer or angle grinder
- Wire brush or sandpaper
- Flashing material (e.g., aluminum, copper, or lead)
- Chimney sealant
- Roofing cement or tar
- Roofing nails or screws
- Safety harness and ropes (for steep roofs)
Materials
- Replacement shingles
- Chimney cap
- Chimney liner
- Metal flashing
- Mortar or sealant
- Waterproofing membrane
- Roofing tape or sealant strip
How much does a leaky chimney cost to fix?
Hiring a roofer to fix a leaky chimney can cost anywhere from $350 to $750 or more to fix and repair flashing on a chimney. In some cases, if the damage is more extensive, it may cost $1500 to $3500 to rebuild a chimney.
You can also do it yourself. If it’s a minor leak, you may only need to purchase some sealant or flashing tape, which could cost anywhere from $10 to $50. However, if the leak is more serious and requires replacement of flashing or other materials, the cost could be a few hundred dollars higher.
The exact cost will depend on the extent of the damage, the materials used, and the cost of labor in your area.
Will my insurance policy cover a leaky chimney?
The coverage for a leaky chimney may depend on your insurance policy and the cause of the leak.
Some insurance policies may cover damage caused by a sudden or accidental event, such as a storm or fire, while others may not cover damage caused by wear and tear or a lack of maintenance.
If you do find out that insurance does cover these damages, you’ll next have to decide whether it’s worth it to have them cover the repair because you’ll almost certainly have to pay a deductible for the repair request.
Depending on how much the deductible is and how much the repair alone will cost, you might be better off paying for the repair without getting insurance involved.
It’s important to review your insurance policy and contact your insurance provider to understand the coverage and any exclusions related to a leaky chimney.
How often should you inspect your chimney for leaks?
It is recommended to inspect your chimney for leaks at least once a year. It’s best to do this inspection before the rainy season or winter months, when your chimney will be used more frequently.
However, if you live in an area with heavy rainfall, strong winds, or other severe weather conditions, you may want to consider more frequent inspections. It’s important to keep in mind that regular maintenance and inspections can prevent more costly repairs in the future.
What should you look for when inspecting your chimney for leaks?
When doing an annual or regular inspection of your chimney for leaks, you should look for the following:
- Loose or missing flashing: Check for any visible gaps or areas where the flashing is not properly sealed against the chimney.
- Cracks or damage in the chimney crown: Inspect the top of the chimney for any visible cracks or signs of damage that may allow water to penetrate.
- Damaged or missing chimney cap: Look for any visible damage to the chimney cap or if it’s missing altogether.
- Deteriorating or missing mortar: Inspect the chimney for any loose or missing mortar between the bricks.
- Water stains: Check for any water stains on the walls or ceiling around the chimney area, which can indicate water is leaking into the house.
- Rusty or damaged chimney pipe: Look for any signs of rust or damage to the chimney pipe, which can also indicate water is leaking into the house.
- Vegetation growth: Check for any vegetation growth around the chimney, which can indicate water is penetrating the structure.
What you shouldn’t do when repairing a chimney leak
Use straight flashing
It may seem like a quick fix, but straight flashing is only temporary and can lead to more serious issues down the line.
Use caulk around the chimney
Caulk may seem like an easy way to fill gaps around the chimney, but it is not a permanent solution and will eventually crack and fail. Instead, use proper flashing and sealant materials.
Ignore the root cause of the leak
If you only patch the visible leak without addressing the underlying issue, the leak will likely recur. It’s important to identify and fix the root cause of the leak to prevent further damage.
Attempt repairs without proper safety equipment
Repairing a chimney leak can be dangerous work, especially if you are not comfortable with heights. Always use proper safety equipment, such as harnesses and ladders, to ensure your safety while working on the roof.
Attempt repairs without proper knowledge and experience
Chimney leaks can be tricky to diagnose and repair, so it’s important to have the right knowledge and experience to properly fix the problem. If you are unsure about the repair process, it’s best to consult with a professional.
Other interesting articles:
- How to Fix a Leak from Flashing (7 Steps to Secure and Prevent Leaks)
- What is Roofing Lead? (It’s Uses in Roofing and Potential Health Concerns)
- The Complete Guide to When Your Roof Is Leaking (7 Things to Do When You See a Leak)
- Are Roof Leaks Covered By Insurance? (Solutions to Common Issues Everyone Runs Into)
Author: Logan
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