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Articles by Chimney Doctors

Finding Your Water Leak

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Cracked Concrete

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Finding a water problem is not easy, and is always a process of elimination. Water may be coming in from more than just one area. We suggest not doing any drywall repairs until you are positive that you have found the water entry points.

To help in finding leaks entering into your home, it is suggested that you start with outside controlled water testing starting at the lowest possible point of logical water entry.  Do water testing only on dry days so that you can create a very controlled artificial rain situation.

Instead of soaking the entire chimney, only apply water on a specific area of the ground or chimney. We recommend that you journal your soaking times, such as 20-30 minutes, 1 hour, etc.  Think which way the down spout water is flowing into the storm drains, or the curb cut at the street. It is important to list the locations where the water was tested on the ground, chimney or shingles.

A couple of hints we have found that may help you are to lightly sprinkle white talcum powder on any wood or concrete areas that you can, in hopes of discovering which direction the water is traveling to or from. (Such as: water around a fireplace, in the basement, or traveling down on a wood roof rafter or sheeting in the attic.) Also, marking the outline of the tear drop water marks with a pencil and dating them to see if the problem is growing might be helpful.

Another form of testing the brick mortar joints is using what is called a Matt tube. These Matt tubes are about 3” to 4” L shaped glass tubes that are attached to the brick chimney with putty. The tubes are positioned at the intersection of a mortar joint on a brick surface. The tubes are then filled with water to verify how long it takes to drain.

Ground-level Water

Ground level water could be coming in from broken connector pipes underground used for the down spouting.  By filling just the down spouts this may help isolate the problem.  Ground shrinkage from hot, dry summers cause a lot of foundation crack problems. Often a break or a separation appears where the horizontal footer meets the vertical foundation wall under the ground.

Corbel Slopes

Corbel slopes or the shoulders can allow water into your home. You can check from the roof top or use a step ladder to check these areas. Many times we find the brick have exposed brick holes where the mortar has eroded or was just never applied.

Dripping Water

Many water problems that we see are what we refer to as water torture problems. These may be caused by water dripping from the high side of the roof where the chimney meets the roof edge onto the brick sloped corbel area below. These corbelled area are often marked with water soaked grayed mortar joints or green mold stains and may be accompanied by signs of cracked, spalling, and damaged brick.

Gutter Issues

It is also a good idea to check to see if the gutters are filled with leaves or pitched to fall back to the chimney instead of out to the down spout where they can drain properly. Gaps at the roofline where the gutters meet the chimney can allow a lot of unwanted water to constantly drip onto the corbelling slope shoulders.

Chimney Flashing

Chimney Flashing may also be a contributor to leaking problems. We find that most of the time the original flashing has never been maintained after the original installation. Wire brushing, painting, soldering , silicone and sealing the flashing is recommended . Flashing is usually made up of two metal panel parts, the first piece of metal is called the step or base flashing and is installed under the shingle and is bent up onto the brick chimney. Cracks and holes in the metal are often found in this step flashing. The second piece of metal is called a counter flashing  The counter flashing is bent down over the step flashing piece and is cut back into the mortar joint at the top and seals or caps off the top of the base flashing .

A cricket is roofing term for a triangle shaped dog house that is built behind the chimney, where it meets the roofline. Roof flashing systems are made up of a lot small of metal pieces that over time could have moved with the heating and expansion of roofing.  

Ice Damming

What is called Ice Damming can also occur. This is when snow melts, then refreezes and will then backs up under the shingling. Many times this happens at the gutter and flashing valleys.

Metal Chimney Chase Covers: 

In a manufactured fireplace, or what is called a prefab fireplace, water problems are often accompanied by the sound of water pinging onto the fireplace during rain or as snow is melting. The common construction of the chase covers at the top where the flue pipe exit was rough cut in the field.  We find that these chase covers are very thin and are not ridged enough to support the weight of conditions they are exposed to. The original chase covers can belly down over time and hold pooling water. Another problem we also is that the collar that was put on around where the metal chimney flue pipe exits, was not fastened on, but was only sealed on with silicone that may have deteriorated .  Replacement covers should only be made in a metal fabrication shop. We suggest that any new chase cover is be made of Stainless Steel for a life time warranty.

Condensation Water Problems:

  1. A chimney flue from an abandoned hot water or furnace flue is a prime candidate for water leaking problems.  For every 100,000 BTU of natural gas that is burned in an appliance it will produce about one gallon of water. This water must be vented up the chimney flue. If the flue is blocked or not sized properly, this water can drip back into the ceiling and walls.  Another symptom that shows up is a white chalky or powdery substance on the brick surface. This is called efflorescence.  Usually this is not damaging to the masonry as much as it is a symptom of an interior water problem. This white efflorescence chalking happens when the salts are breaking down coming out of the brick or mortar and will often show up on a sunny side of the house. It goes without saying but every chimney also needs a chimney cap to prevent water from coming down the flue year after year and causing needless damage to the inside of your chimney.
  2. Blocked flue vents may be caused by animal and bird nesting materials.  Broken flue tile liners can also block a chimney.
  3. Attic condensation problems: Air vents in the attic that are blocked up with insulation can cause water condensation. This is what we referred to as attic rain clouding. This often shows up in drywall tape peeling off the ceiling or wet blackened roof sheeting in the attic space. Too often this is perceived as a chimney related problem and in reality it is an insulation installation problem. A good rule of thumb for proper attic venting is that you need 1sq. ft. of unobstructed venting for every 300 Sq. ft. of foot print of your home.
  4. A hollow chimney chase: We run into this with prefab chimneys and fireplaces.  This is the cave-like effect with warm air inside and cool air outside; the opposite is true in the summer with hot temperatures outside and air-conditioned temperatures inside causing sweating and odor problems.

Chimney Crown Problems:  

Cracked Concrete Chimney Cap

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A chimney usually has five sides to it.  It is built from the ground up and deteriorates from the top of the chimney crown down.  Most crown failures were due to the original mason’s bad craftsmanship of constructing the crown out of simple brick mortar and not installing cement or a concrete crown. The purpose of the crown is to shed rain water from the top of the chimney and to keep it from entering into the chimney chase.  A cement crown wash is the most widely used crown for chimneys today.   It consists of cement that is applied to the top of the finished brick chimney concrete crown – or what is often referred to as a drip edge crown or cast in place concrete crown are used less than the cement crown washes, but are still seen.  A drip edge crown is installed by building a form over the top of the finished brick masonry of the chimney and filling it with concrete. It too is slightly tapered to shed water and usually extends approx. 1” – 2” beyond the side of the masonry to form a drip edge.  This style of concrete crown is not suggested or stated in the NFPA 2:11 building code.  Most building code recommendation requires a flexible expansion joint around each chimney flue tile that protrudes out of the top of the chimney crown.   A trumpet shape design at the top of a chimney will help shed water from the brick.  It is our opinion that shape alone of a chimney will not protect the masonry as well as an application of a good high quality water repellent. Never use a cheap sealer on brick, only use good quality water repellents.

Damaged shingles and bricks also cause of many water problems. 

Your shingling may even have roofing nails that are popping out of the shingles, and your shingle may have been damaged or cut from tree branches rubbing against the roof. Also, look for signs of raccoon and squirrel entry around gutters and evens areas of your home.  Masonry problems such as open gaps or cracks between flue tiles located on the top of the crown wash can allow lot water to entry into the chimney.  Missing mortar on the chimney that needs to be tuck pointed will also allow water entry..  Many homes are constructed of used brick that are very porous brick so they are prone to hold rain water and break down.  This is referred to as powdering.  When this happen the damaged used brick need to be replaced and tuck pointed back in properly and water repellent applied to help arrest the problem.

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