Showing posts with label repair. Show all posts
Showing posts with label repair. Show all posts

Sunday, February 9, 2020

Masonry chimney repairs should be done in the spring

By Marge Padgitt


Badly spalling bricks on a chimney
If there are pieces of bricks or stones lying around the yard or driveway, it could be a sign that masonry repair is needed. The first place to look for damages by cold, freezing rain, and wind is the chimney since it is the area most exposed to the elements.

Signs that repairs or rebuilding is needed are missing or deteriorating mortar joints, cracked bricks or stones, or faces of masonry popped off. This is due to the penetration of water into the masonry- and when water freezes it expands, which usually results in the face of a brick or stone breaking off.

Badly spalling bricks
Unfortunately, many chimneys are built with soft type bricks rather than hard type bricks due to the cost.  Soft bricks absorb moisture more easily than hard bricks. After a few years, the soft bricks will begin to show damage, but after 30 years any type of brick or stone chimney will likely show damages of some type, if only to the mortar joints.  In some cases, masons have found completely deteriorated bricks with hard mortar left behind. In other cases, the bricks are good but the mortar is severely deteriorated or missing altogether. When this occurs it is a sign that the wrong type of mortar was used.  For this reason, the Midwest Chimney Safety Council recommends that chimneys should be built or reconstructed using hard bricks and the right type of mortar which will last many years longer than those built with soft masonry units.

Mortar deteriorated so badly that
the chimney is falling apart
Mortar sets up better when the work is done in the spring when temperatures are moderate so the curing process can complete without issue. If the temperature is too cold, the mortar can crack and take a long time to cure. If the temperature is too hot the water in the mortar may migrate to surrounding masonry and shrink. Professional masons can control some of this by adding an accelerant in cold weather or soaking bricks in water before using them in hot weather, but they much prefer working with masonry in ideal weather conditions.

Cement cap with drip edge
The cement cap (crown) should be inspected in the spring to assure that it is in good condition with no cracks, deterioration, or lifting. The cap serves as a roof for the chimney and keeps the elements out of the interior chimney chase where rain can cause damage to the interior flue, smoke chamber, damper, and firebox. Any small cracks or gaps should be filled with high temp silicone, but if large cracks, severe deterioration, or missing sections of the cap exist a new cap should be constructed.  As of 2012, the International Residential Code required a poured formed crown with a drip edge to better protect the chimney from damaging rainwater. The old-style crowns with a slope but without a drip edge actually contribute to the fast deterioration of masonry at the top part of the chimney, so this newer style is a big improvement.
________________________________________

Marge Padgitt is the CEO of HearthMasters, Inc. and HearthMasters Education in Kansas City, Missouri. Contact her at hearthmastersboss@gmail.com

Wednesday, May 24, 2017

Repair damaged chimneys quickly to avoid additional expense


Masonry chimneys should be repaired immediately following storm or chimney fire damage in order to avoid more costly repairs in the future. 

A lightning strike or tornado can open up a masonry chimney, making it vulnerable to attack by rain.  Once a cement crown or bricks have been blown out or severely cracked, the interior of the chimney is open to the elements.  Rain can wash out mortar joints, cause damage to a fireplace, damper, and any metal or masonry components.  When mixed with creosote, rain forms an acid that eats away at mortar joints and flue tiles.

Water can enter through any interior open areas in the chimney, which may include the attic or other areas of the home. This can cause damage to drywall, wood framing, lighting, or carpet. 

A chimney fire can cause expansion of the masonry, which often forms cracks along mortar joints in exterior bricks, and occasionally through the bricks themselves.  This type of damage usually occurs at or near the top of the chimney, but may happen anywhere.  Expansion breaks sometimes occur when a chimney is rapidly heated during a chimney fire.  Any cracks or breaks in masonry will allow damaging rain water to enter the interior and cause further damage to the structure. 

After a lightning strike, high wind, or chimney fire it is important to have a Level II camera inspection completed by a professional chimney sweep, who will determine if damage has occurred to the internal structure of the chimney.  If this inspection is not adequate, a Level III inspection may be necessary.  This involves demolition of parts of the chimney in order to view the interior.

Manufactured chimneys should be inspected following a chimney fire or storm in order to determine if the metal chimney, fireplace components, or exterior chase, chase top, or cap has been damaged.  Manufactured chimneys are U.L. Listed products and parts must be replaced with parts for the specific model by the manufacturer.  Parts are not interchangeable.  If left un-repaired, a damaged manufactured wood chimney chase or metal components may be further damaged by the elements.


Repairs should be completed by a qualified professional chimney contractor in order to assure that the work is done according to International Residential Code and NFPA 211 Standards.  
__________________________________________________
Marge Padgitt is the publisher of Wood-Fired Magazine, and an industry writer. She has been in the chimney industry since 1985. Websites: www.chimkc.com and www.woodfiredmag.com