Chimney Liner

Have you looked at your masonry chimney lately? If so you have probably noticed some discoloration throughout the chimney brick or stone, particularly in the upper portion of the structure.

This is a sure sign of excessive water infiltration into the chimney shell and if not taken care of can lead to costly damage with premature deterioration.

Excessive water in a chimney shell can manifest in three ways: efflorescence, mold growth and spalling. One or two of these symptoms could be visible on your chimney or all three depending on the severity of the problem.

Let’s take a look at each of these symptoms and the recommended solutions, so that you can protect your chimney from un-wanted damage.

Efflorescence - Efflorescence is a white power that is visible on the surface of the brick or stone (masonry) of your chimney shell. Water that is inside of a chimney will dissolve soluble salts in the brick and mortars.

As the water migrates to the outside surface of the chimney by wicking action it carries these soluble salts with it and then deposits them on the surface of the masonry during evaporation.

Solution: As with any water problem you must stop the water from entering at the source. Most water entering a chimney comes in through the top of the chimney or the chimney crown. Cracks allow water in during each rain so all cracks must be filled and sealed to prevent them from leaking.

The crown should be inspected annually and necessary repairs done to keep it from leaking. You may remove the efflorescence with a stiff brush while applying a neutralizer made of 1 cup of household bleach mixed with five gallons of cold water. Several applications may be necessary.

Mold - Mold can be but not usually, seen directly. It manifest by a slight darkening the masonry on the chimney shell. Since most of the water entering a chimney comes in through the top, most of the mold will be present there and you will notice a definite difference in the masonry tonal color range from the top of the chimney to the bottom.

Solution: An application of a heavy degreaser or detergent as purchased from a pressure washing supply company will usually do the trick in removal of most surface molds. Soak the chimney with a hose before applying the detergent then let set for approx. fifteen minutes. Then use a pressure washer to remove the detergent and the mold.

Spalling - Spalling is the action of the de-lamination of the face of brick or stone masonry unit. It is caused by excessive water within the pores of the unit freezing and thawing over hundreds of cycles. The constant freezing action breaks the pores of the brick apart and causes the face to fall off.

Solution: If only a few bricks are spalled you may get by with re-surfacing the brick face or removal and replacement. If the damage is wide spread, particularly in the upper portion of the chimney then removal of the damaged portion of the chimney will be required. Again the chimney crown must be waterproof in order to prevent this damage from occurring.

Remember though, once a brick has spalled it has basically lived its’ useful life and will begin to act like a sponge by absorbing more water so replacement and rebuilding is the preferred long term repair method.

All three of these problems can be prevented by the installation of a quality chimney crown. Talk to your chimney professional for additional information.

Michael Olding is tradesman and consultant in the field of restorations and repairs and currently operates a restoration and repair business in Cincinnati, Ohio. He is also a Master in the field of masonry construction, restorations and repairs.

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In addition he is a writer and speaker as well as a marketing, training and business consultant for the contracting industry. If you interested in his services he may be contacted by visiting http://www.cincihomepro.com

The metal alloys that are used in Chimney liners go from 316TI to AL-29-4C. You might be wondering what all this means.

There are different kinds of stainless steel and they will have differences in the alloys. These numbers have nothing to do with the thickness of the steel. Here we will begin to explain the many choices you have when you are selecting the metal used in your chimney liner.

There are different alloys that should be used in certain circumstances and you will need to know the correct metal alloy for the liner for you.

Stainless steel gets its name from the fact that the steel does not rust or stain very easily unlike other steel. It is the name that is applied to steel grades that have more than ten percent chromium whether there are or are not other elements.

316TI Stainless Steel

This type of stainless steel is made up of stainless steel alloy that has titanium added in a small amount. The combination of this alloy will allow the steel to resist acids and the problems caused by the stresses of hot temperature and cold temperature.

It is best used when used with wood, gas and oil fuels. It is able to handle temperatures of 2100 degrees.

316L Stainless Steel

This type of metal is typically found in thick flexible liners and also stiff liners. It is the same as the other alloy but it does not contain titanium. It is used on coal, gas, oil or wood heating systems.

304L Stainless Steel

This type of steel alloy should only be used on chimneys that are venting for a wood burning system. It is most typically found in a rigid liner.

This type of stainless steel is the most common and is more than half of all the stainless steel that is produced around the world. This particular grade of stainless steel will hold up well against corrosion and is usually used in food processing. It can also resist many chemicals, if not most.

AI29-4C Stainless Steel

This alloy is most commonly used on liners that are used in a clay lined chimney or masonry chimney. These chimneys are usually venting a gas or oil furnace system.

This alloy is resistant to being effected by corrosion. It will be used in flues where the gasses that are in the flues may be filled with very corrosive elements. The temperatures in the flue tend to be relatively low because the heat is typically routed into the home.

If the temperature in the flue is kept low it will keep the moisture that is contained in the flue gas from evaporating into the flue. The combination of moisture and other chemicals that may be taken up into the flue can make the composition in the flue very corrosive.

This particular metal alloy is designed to resist these corrosive elements for a very long time.

Chimney liners are most often made from series 304 or 316 stainless steel. It is typically non magnetic. Rigid pipe generally comes in sections. The sections are round and one to two feet long. They can also be five to ten inches across the diameter.

This is very different from flexible liners. The thickness gauge of these sections is usually 24 or 22 gauge stainless.

The factory will seal the section along a seam that runs down the length of the piece. These sections are then joined with the crimped part facing down. The joints will be secured with rivets.

The manufacturer recommends pop rivets be used to ensure a more secure hold. If screws are used they may become loose over a period of time.

The liner will expand and contract which could loosen screws.

The bottom of the chimney is where they are usually supported. They can also be supported in the thimble area.

In the areas where cleaning will take place, a stainless steel tee will be used. It is possible for a rigid liner to expand up to several inches when it faces higher temperatures.

To make up for the expansion of the liner it will be allowed to move up and down at the top end of the chimney.

To keep moisture out of the chimney a storm collar will be placed over this sleeve. At the top of the chimney where the sleeve is located a plate made of stainless or concrete pad will be used to seal the area.

Rain caps are highly recommended for use with stainless steel lined chimneys. The highest efficient venting is necessary.

It is more efficient to use a smooth rigid liner for venting because it will have less turbulence. It will have the ability to be shaped to accommodate the entire length and give the most amount of draft.

The chimney liner can be made into a rectangle, square or oval shape.