Chimneys are the most common way to outsource smoke from a fireplace. Unfortunately, since a chimney has to be open to the elements and are sometimes retrofitted to pre-existing roofs, chimneys often spring leaks.
Why is My Chimney Leaking?
There are many reasons why a homeowner may have a leaking chimney, including:
Flashing is a small collection of metal bonds that bridge the gap between the chimney and the roof. When a roof and chimney are first built, there is a small but significant gap between the two structures. Flashing eliminates that gap.
A proper flashing has two levels:
- Step flashing — An L-shaped piece of metal is “woven” in with the shingles next to the chimney. The step flashing is also melded to the chimney itself, creating a solid initial seal.
- Counterflashing — Another layer of protection placed within the joints of the chimney. The counterflashing also goes on top of the step flashing, providing an extra layer of security to prevent leaking.
If either one of these pieces of metal come loose, then water can seep into the house, chimney, and even the foundation.
To patch flashing, simply re-seal the problem areas using caulk or other waterproof sealants.
Improperly Covered Chimney
When rain falls, it can get into your chimney. Constant water in the shaft can weaken the internal structure of the chimney, causing small cracks that can get worse over time.
A metallic rain cap can prevent water from getting in your chimney. The cap is placed over the chimney and is elevated by metal grating. The metal grating allows the smoke to escape while the cap directs the water away from any problem areas.
Crack in the Chimney Crown
A chimney crown is a cement cap placed on the top of the chimney. The function of a chimney crown is to offer a fortified protection from invading elements such as bad weather, birds, leaves, and more.
Chimney crowns can crack for a number of reasons, including:
- Excessive precipitation
- Shifting foundation
- Natural growing and shrinking with weather conditions
- Small vermin that burrow into cement
When cracks occur in the chimney, water gets in. The water can often deepen cracks, allowing for more water to flow in.
Patching a crack in a chimney crown can be an easy fix. A patch could be as simple as adding more mortar and cement in the problem areas. If the crack becomes too large in the crown, you may have to remove all of the bricks and re-lay the chimney.
No Chimney Lining
Older chimneys may not have properly sized lining. Lining prevents dirt and other debris from building up on the side.
Do you burn gas inside of your fireplace? If so, the fumes from that gas can carry a lot of moisture. That moisture can cling onto the chimney, permeating through the bricks and keeping your masonry soaked. Since brick and mortar are porous materials, they tend to absorb water. If improperly waterproofed, they may trap and retain even more moisture. Wet bricks can affect a lot of things, including your wallpaper, foundation, and more.
If you choose to maintain the waterproofing of your bricks on your own, be careful about what kind of waterproofing materials you use so as to allow the bricks to breathe and let some water escape.
Excessive drought followed by massive rainfall can cause a foundation to shift dramatically. To adjust for shifted foundation, your house has to bend and even crack. Your chimney may fall victim to the shifting foundation, causing massive cracks in the brick of the chimney itself.
If this is the case, you may have to contact a roofing professional to assess what can be done with the roof. Problems may extend deeper than just chimney leaks.
How to Find a Leak
It is best to let qualified roofing professionals identify a chimney leak. Detecting a leak can be dangerous, involving extended periods of time on ladders and roofs. Do not perform an inspection alone.
- Identify where the leak is coming out in the house. Mark the leaking area clearly if the watermarks are subtle.
- Find the leak on a dry day. If you try to find it on a rainy day, you will not be able to see any introduced water in the problem areas.
- Cover your chimney entirely with plastic. Only the bottom portion of the flashing should be exposed afterwards.
- Station a friend with a phone or walkie talkie inside the house. Put them close to the leaking area.
- Run a hose with water up to your roof. You will be putting water through the hose, so make sure the hose works before you begin using it on your roof
- Find the lowest connection point between the chimney and the roof. Locate yourself to where the bottom-most row of visible bricks connects with a row of shingles.
- Run hose water at this connection point between 2 and 3 minutes. Keep the hose directed solely at the connection point.
- Contact your person inside of the house to ask if they spot any signs of leak
- If they do see water coming in, mark the connection point where the water was sprayed. The mark helps a roofing team find the leak quickly and repair it.
- If they do not see water coming in, aim the water one row of shingles above in the connection point. You should still be aiming close to the chimney.
Also, do not go to any other side of the chimney until you have completed a thorough assessment. Complete your check-up one side at a time.
- Repeat steps 7 through 9 on the first side until you have found the source of the leak
- If you have not found the leak on one side, extend your search to each additional side and repeat steps 7 through 9
- If no leaks are coming into the home, remove the plastic completely, then repeat steps 7 through 9 while working your way up the chimney. At this point, you have isolated the leak to something in the visible chimney.
- If you have sprayed each brick of your chimney and there is still no water leaking in, the leak must be in the chimney cap. Spray it down to confirm.
- If you still can’t pinpoint the origin of the leak, contact a roofing consultant to see if there may be issues other than water coming in from the chimney.
How much does it cost to repair a leaking chimney?
Depending on the damage, a leaking chimney repair could cost anywhere from $500 to upwards of $10,000. Identify and repair leaks as soon as they happen to reduce the cost of a leaking chimney repair.
Live in Austin and have chimney leaks?
Contact Ja-Mar Roofing & Sheet Metal today. Our team of residential and commercial roof repair teams can inspect your leaking chimney and assess what kind of work needs to be done. We can work to install or make the right kind of repair that you need.