Water and Masonry Chimneys

Water and masonry chimneys usually don’t work well together. Masonry chimneys are one of the most taken-for-granted parts of a home. Most people tend to ignore their chimneys, thinking they don’t need maintenance or care. However, chimneys are not as simple as they seem. Even if they appear to be working fine, neglecting them could lead to problems in the future. It’s important to understand that chimneys are not just a passive part of the house. They require attention and care like any other system.

Chimneys may look simple, but they actually do many important things. However, if they are constantly exposed to bad weather, they can become a danger to the people living in the house. When chimneys are damaged by weather, there can be problems. These issues include blocked flues or loose materials that could fall and hurt someone. Therefore, to avoid costly repairs in the future, it’s important to regularly maintain your chimney and keep it in good condition.

Water and Masonry Chimneys Explained

Water and masonry chimneys are natural enemies. A masonry chimney is made of bricks and other materials can get damaged by water intrusion. It is built using a combination of materials such as concrete, stone, steel, and cast iron, among others. Water can harm most of the materials used in building the chimney. So it’s important to take steps to prevent water from getting inside.

All masonry chimney construction materials, except stone, will suffer accelerated deterioration as a result of prolonged contact with water. Masonry materials deteriorate quickly when exposed to the freeze/thaw process, in which moisture that has penetrated the materials periodically freezes and expands causing undue stress. Water in the chimney also causes rust in steel and cast iron, weakening or destroying the metal parts.

Note: While most stone is not affected by water penetration, large amounts of mortar are required to bond the stone together properly. Therefore, a stone chimney – just like a brick chimney – should be protected from the effects of water penetration.

Water penetration can cause interior and exterior damage to your home and masonry chimney including:

• Rusted damper assemblies

• Deteriorated metal or masonry firebox assemblies

• Rusted fireplace accessories and glass doors

• Rotting adjacent wood and ruined wall coverings

• Water stained walls and ceiling

• Clogged clean out area

• Deteriorated central heating system

• Stained chimney exterior

• Decayed exterior mortar

• Cracked or deteriorated flue lining system

• Collapsed hearth support

• Tilted or collapsed chimney structure

• Chimney settlement

In addition, when water mixes with creosote in a wood-burning chimney system, it will generate a highly disagreeable odor that can permeate a home. Ultimately, water and masonry chimneys just don’t mix.

Rain covers, also known as chimney caps, are a simple and affordable solution for homeowners to keep water from seeping into their chimneys and causing damage. Chimney caps are an important safety feature that can prevent costly repairs. Underwriters Laboratories (UL) requires a chimney cap to be included in any chimney lining system that meets their testing standards.

Chimneys have one or more large openings (flues) at the top that can collect rainwater and funnel it directly to the chimney interior. A commonly-sized flue has the potential to allow large amounts of rain or snow into the chimney during just one winter when freeze/thaw cycles are common.

Chimney caps also provide other benefits. A strong, well-designed cap will prevent birds and animals from entering and nesting in the chimney. Caps also function as spark arrestors, preventing sparks from landing on the roof or other nearby combustible material.

A chimney cap should be easily removable to facilitate inspection and cleaning. For a long and effective service lifetime, a cap should be constructed of sturdy, durable, and corrosion-resistant material. Caps may be designed to cover a single flue, multiple flues, a large portion of the chimney, or the entire chimney top. A full-coverage chimney cap usually represents a larger initial investment. However, it is probably the best investment for long-term protection because of its ability to protect the entire chimney and crown.

Common Issues With Water and Masonry Chimneys

Damaged Chimney Crown Wash

The chimney crown (also referred to as the chimney crown wash or splay/wash) is the top element of a masonry chimney. It covers and seals the top of the chimney from the flue liner to the chimney edge. A crown should provide a downward slope that will direct the water from the flue to the edge of the crown. The overhanging drip edge, by directing the run-off from the crown away from the chimney, helps prevent erosion of the brick and mortar in the chimney’s vertical surfaces.

Most masonry chimneys are built with an inadequate crown constructed from a common mortar or sand mix. These types of crowns aren’t designed for years of weather abuse without cracking, chipping, or deteriorating. Therefore a proper chimney crown should be constructed of a concrete mixture, cast or formed with a minimum thickness of 2″. The crown shall also provide an overhang with a drip edge projecting beyond all sides of the chimney by a minimum of 2 1/2″ with a caulked bond beam joint. The flue liner tile should also project above the crown a minimum of two inches including an expansion joint for vertical movement.

Deteriorated Mortar Joints

When a chimney’s exterior has damaged mortar joints, it can let water in. The mortar joints should be filled in tightly and shaped in a way that moves water away from the joint. However, when the mortar is exposed to weather, it can deteriorate and absorb more water. To fix this problem, a process called repointing is often used. This involves cutting out the old mortar and filling in the joint with new mortar. The new mortar is then shaped into a surface that pushes water away from the joint. A good repointing job, using the right materials, can give the chimney a longer life and make it look better too.

Chimney Flashing Issues

The flashing is a protective layer that sits between the roof and the chimney. It’s important because it stops rainwater and melted snow from dripping down the chimney and causing damage to your home. Think of it like a flexible joint that connects two different materials – the roof and the chimney – and allows them to move without breaking the waterproof seal. This is really important because it means that your roof and chimney can expand and contract without causing any damage to your home.

Water and Masonry Chimneys - Chimney Flashing

Install a Chimney Cricket to Stop or Prevent Leaks

If the chimney is located on the low side of the roof where water run-off is directed against the chimney, the installation of a cricket will afford additional protection against water leaking into the home. A chimney cricket is a water deflector that serves to direct rainwater away from the chimney. Crickets are recommended on chimneys more than 30 inches wide and they are especially important on steep roofs.

Water and Masonry Chimneys - Chimney Cricket

Waterproof The Chimney

Most masonry materials are porous and will absorb large amounts of water. Common brick is like a sponge, absorbing water and wicking moisture to the chimney interior. Defective mortar joints or the use of improper mortar or brick can greatly increase the tendency to absorb and convey water to the interior of the masonry chimney.

Several products have been developed specifically for use as waterproofing agents on masonry chimneys. These formulas are 100% vapor permeable, which means that they allow the chimney to breathe. Therefore, water that has penetrated and the vapors produced when the chimney dries out or the water vapors produced during use are allowed to escape, while the waterproofing agent prevents water from entering from the outside. These products usually have a five- to ten-year warranty. Paint or clear sealers should never be used as a waterproofing agent because they will trap water vapors and moisture inside the chimney causing further deterioration.

Waterproofing is a preventive measure. When damage or deterioration (gaps, voids, cracks, missing mortar, etc.) already exists in a masonry structure, the chimney should be repaired before the waterproofing agent is applied. The chimney exterior should always be cleaned before the waterproofing material is applied.

Schedule Chimney Inspection and Repair

At Adams Chimney Specialist, LLC, we understand the importance of maintaining a safe and efficient chimney. That’s why we also offer comprehensive chimney sweep, inspections, and repair services to help keep your home safe and comfortable.

Our team of experts is committed to providing high-quality chimney services that meet your specific needs and budget. Whether you need a routine chimney sweep or a full inspection and repair, we have you covered.

We significantly encourage you to schedule an appointment with our team. Don’t wait until it’s too late – let us help you keep your chimney in top condition and enjoy the benefits of a well-maintained home.