What Happens to Chimneys Over the Winter

By Marge Padgitt

Winter is rough on any type of chimney- especially brick or stone chimneys. During the winter months, moisture penetrates the bricks, then freezes. When water freezes it expands and often causes part of the brick or stone to break off.  This is called "Spalling." The constant freeze/thaw cycles over winter can wreak havoc on masonry. Chimneys built with soft type brick are more susceptible to moisture penetration and spalling. 

Check the ground and roof for pieces of brick. This is the first indication that there is a problem. The area most affected will be the portion of the chimney above the roof line since that area is the most exposed.If you see spalling bricks or stones, call an expert to do an inspection and provide a solution. 

If the damage is not too severe, bad bricks can be removed and replaced, then an application of a professional water repellent sealer is recommended to reduce penetration of water. 

If the damage is widespread, the only solution is partial or complete tear down and rebuilding of the chimney. 

WATER is the primary problem when it comes to chimney damages! 

Rain water not only causes damage to bricks, but causes deterioration of the cement cap/crown. The cement cap is what keeps rain water out of the chimney interior where it can cause even more problems such as washing out mortar joints in the interior chimney and tile flue liners, deterioration of the smoke chamber and fireplace, and rusting of the damper.  

Hint: Do NOT paint or stucco over masonry chimneys - this only traps moisture inside the bricks and causes them to fail more quickly. 

FLASHING

Flashing that is poorly done, missing, or in need of repair can cause water leakage into the home and damage to rafters, joists, ceilings, and walls. Flashing should be checked each spring, and especially right after a roof repair or replacement is completed. 

The best way to avoid costly water damage is to keep it out and off of a chimney! 

Tips: 

• Have chimneys checked in the spring by a professional chimney sweep/mason
• Put a heavy duty stainless steel chimney cover on all flues to keep most of the rain out of the interior flues
• Repair or replace bad cement crowns/caps with a code required 2" drip edge to keep water off of the masonry below the crown where the most damage is usually found
• Have a professional water repellent masonry sealer applied
• Make sure J and Counter flashing is in good shape and sealed completely

____________________________

Marge Padgitt is the CEO of HearthMasters Masonry School and HearthMasters Restoration in Kansas City, Missouri. 

To Vent or Not to Vent- that is the question

Excalibur gas fireplace

Many of our customers have asked us to take out their vent-free products due to a horrible smell, water running down the windows and walls, stains on walls, soot on walls, baseboards, and ceilings, mold and mildew issues, headaches, and being ill while in the house and using the logs.

When burning gas several by-products of combustion are produced: Carbon Monoxide, Carbon Dioxide, Nitrogen Dioxide, Formaldehyde, and Water.

Manufacturer instructions say to use non-venting gas logs four or less hours per day and to operate the logs with a window open. Since these are listed as heating appliances and most customers purchase the logs as a heating source, this seems impractical in the middle of winter. The American Gas Association Research Division (AGARD) recommendations for proper usage of a vent-free appliance include that the appliance is not to be used as a sole source of heat or in confined spaces or bedrooms. What happens when there is a power outage? Homeowners are tempted to use the logs continuously.

During the combustion process moisture is created. When a 40,000 BTU vent-free appliance is used to heat it can produce over six gallons of water a day. If the homeowner notices condensation on windows and walls the vent-free appliance may be the cause. We call these appliances “Room Vented” for this reason. The condensation will be absorbed by the drywall, wood flooring & furniture, and may cause structural damage to the home. The excessive moisture may cause mold and mildew which creates problems for people with allergies, asthma, and other respiratory problems, or create new health problems. 


The situation is worsened in tightly constructed homes without adequate make-up air to provide air for the appliances, and for people to breathe. Visit www.plusaireusa.com for more information on make-up air.

Carbon Monoxide is a very real issue. CO is always produced during combustion, and with room-vented heaters it is vented into the room at so called “acceptable' levels. Even at low levels, CO can be dangerous to children, pregnant women and their unborn babies, small children, the elderly, animals, birds, and people with upper respiratory conditions. See Dr. David Penny's website at www.coheadquarters.com for more information on CO.



Regency direct vent fireplace
 

Instead we suggest using a direct-vent gas log insert or fireplace. These types of appliances are vented through the wall or up an existing chimney. They are sealed systems which use outside air for combustion, thereby increasing the efficiency of the appliance and eliminating the need for opening windows while the appliance is in use. No by-products of combustion are vented into the room, so toxic gasses and water are vented directly to the outdoors. Direct-vent is a much better choice.

Vent-Free VS Direct-Vent	Vent-Free	Direct-Vent
Must operate with window open	Yes	No
Has its own combustion air supply	No	Yes
Is a High-efficiency appliance	Yes	Yes
Toxic gasses vented into the room	Yes	No
Moisture/water vented into the room	Yes	No
Can produce bad smells	Yes	No
Should have an annual service check-up and cleaning	Yes	Yes
Can be used in a masonry chimney	Yes	Yes
Can be used in a manufactured fireplace	No	Yes

 

Spalling brick a sign of severe moisture damage

When chimneys spall, it is a sign of severe moisture penetration of the masonry bricks or stone. Spalling is the flaking off of a brick or stone surface, and is evident when the face of the masonry is missing. Pieces of bricks or stones may be found on the ground or on the roof, which is an indication that there is a problem. This is a common issue in the Kansas City and Midwest area.

Spalling is caused when the masonry absorbs too much moisture from rain and is subjected to freeze/thaw cycles. Damages can be exacerbated by condensation of flue gasses in improperly sized flue liners and gaps or cracks in mortar joints on the interior of the chimney, and by moisture entering the interior of the chimney chase from the top at the cement crown area where cracks or gaps allow water to enter.   If the cement crown is not built with a poured crown with 2” overhand and drip edge per code, damages to the top of the chimney structure will occur more quickly. However, builders seldom build poured crowns due to the added time and expense involved.

Soft type brick is more susceptible to moisture penetration than hard type bricks, but builders often use soft brick because they are less expensive. When building a new home, homeowners should request that hard bricks be used in all construction so they will last many years.

Chimneys usually show damages more extensively because they are more exposed to the elements than the rest of the house. The top portion of the chimney will show the first signs of moisture problems. By the time bricks or stones spall, the damage is done. Spalled bricks or stones cannot be repaired and must be replaced. It may be tempting to save money by replacing spalled bricks and doing partial rebuilding of a chimney, but keep in mind that the entire chimney will need to be rebuilt at some point, so any partial repair is a temporary fix.

Painting chimneys is never a good idea. This servies to temporarily cover up the problem, but will speed up the deterioration process since the bricks can't breathe.  Buyer beware if you see a painted chimney.

The application of masonry water repellant sealer can help stop further penetration of moisture, but bricks that already have interior damage will continue to spall. Masonry water repellant should be applied every year to every five years, depending on when it loses its ability to shed water off the bricks. Professional chimney contractors prefer to use Chimney Saver brand water repellant.

To find a qualified chimney restoration contractor in the greater Kansas City area visit the Midwest Chimney Safety Council or the Masonry Heater Association of North America website.