The chimney is one of the most taken-for-granted parts of a home in New Jersey. Why you need chimney repair? Typically it tends to receive neither the attention nor the concern usually accorded other household service systems. The fact that chimneys may do their job reasonably well, even when abused or neglected, contributes to this atmosphere of indifference. Chimneys are far from the passive black holes that most people assume them to be. They perform several vital functions, and their simple appearance misrepresents their complex construction and performance requirements. A chimney deteriorated by constant exposure to the weather can be a potential safety hazard. Weather-damaged lining systems, flue obstructions and loose masonry materials all present a threat to residents. Regular chimney maintenance is essential to prevent damage, deterioration and future high-cost chimney repair.
A masonry chimney is constructed of a variety of masonry and metal materials, including brick, mortar, concrete, concrete block, stone, flue tile, steel and cast iron. All masonry chimneys contain combinations of, or possibly all of, these materials, most of which are adversely affected by direct contact with water or water penetration. Water Penetration (highlightthis and add picture from waterproofing picture attached) 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:
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.
Chimney caps, also called rain covers, are probably the most inexpensive preventive measure that a homeowner can employ to prevent water penetration and damage to the chimney. Chimney caps have long been recognized as an important chimney safety and damage prevention component. Underwriters Laboratories (UL) specifies that any chimney lining system that is to be listed to their test standard must include a chimney cap.
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 crown.
The chimney crown (also referred to as the chimney 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. The 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.
Deteriorated mortar joints on the chimneys exterior are entry spots for water. Proper mortar joints have no gaps or missing mortar and are shaped in a way that directs water out of the joint. When mortar deteriorates from exposure to weather, it becomes much more absorbent. A common repair for deteriorated mortar joints is called repointing. In this process, the existing mortar joint is cut to an appropriate depth and the joint is repacked with new mortar. The joint is then cut to form a concave surface that will direct water out of the joint. A good repointing job, using proper materials, will give the chimney a much longer life span, and often will enhance its appearance.
Flashing is the seal between the roofing material and the chimney. Flashing prevents rainwater or snow melt from running down the chimney into living spaces where it can damage ceilings and walls and cause rot in rafters. The flashing is the expansion joint between two dissimilar materials. It is designed to allow both the roof and the chimney to expand and contract at their own rates without breaking the waterproof seal in either area.
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 may also need to be cleaned before the waterproofing material is applied.
The primary culprit for chimney breakdown is the acidic moisture that comes from condensed flue gases. This acidic moisture attacks the chimney from the inside. Years of normal use with hot and cold cycles and seasonal weather conditions all take their toll on a chimney.
Many chimneys venting gas or oil furnaces or hot water heaters may appear to be in fine condition on the outside. That is why a chimney may look good from the outside, but the inside can be totally different story! Yesterday's chimneys were not designed for venting today's more energy efficient appliances. Inside of the chimney is where most of the problems are!
A look at the inside of this same chimney shows how acid-laden residue from the furnace attacks the flue. The original clay liner erodes away and pieces of it start falling. (Old chimneys might not even have a liner.) While the mortar, bricks and/or clay lining is loose and falling, moisture has leeched through to the home's interior walls. With continued use, more erosion will take place, possibly leading to leaks in the flue, complete flue blockage, or possibly even carbon monoxide poisoning of the home's occupants.
The advent of high efficiency furnaces have helped conserve the use of earth’s natural resources, and has also meant lower heating bills for the homeowners. New furnaces extract more heat from a given amount of fuel than the older furnaces. The combustion process is more thorough and less heat is lost up the chimney. Since less heat is sent up the chimney, the flue has seldom opportunity to “dry out” as less efficient furnaces of the past have allowed. Once flue gases drop to 120 degrees F, condensation begins. Herein lies the side effect of high efficiency furnaces – excessive moisture in the flue. Traditionally built chimneys with clay liners will not last under this moisture assault.
It happens thousands of times each year. Damaged chimneys resulting in disaster. Carbon Monoxide leaks through cracks in flue lining and into your home. Even small amounts can make you and your family sick. There is also the risk of a chimney fire into a house fire. Highly combustible creosote can leak through even small cracks in the clay lining. Once ignited, a creosote fire can find its way though cracks, and dangerously increase chimney heat. Or the flames can simply penetrate cracks in the mortar and lining and ignite a home. In severe cases, the chimney erosion will lead to partial or complete internal collapse, blocking the flue and sending these poisonous gases into the home. A few cracked flue tiles is serious business!
But fortunately, the problems of a deteriorating gas or oil furnace flue can be corrected without completely rebuilding your chimney.
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