Hey there, time traveller!
This article was published 25/10/2013 (1138 days ago), so information in it may no longer be current.
QUESTION: I just Googled a reply you gave in the Winnipeg Free Press about removing an old chimney. We are going to be doing the same, if possible.
We updated to a high-energy-efficient furnace, which goes through the side of the house. Our old chimney is brick and mortar, and runs from the opening of the living room and kitchen. I'm not sure where it runs upstairs.
How hard is this going to be to remove, if it can be removed at all?
I have recently installed a high-efficiency gas furnace and an electric hot-water tank. I am getting a new roof done with shingles. I have asked to have the chimney capped, but the contractor is saying, "Remove the chimney."
Can you please tell me if removing the chimney is the way to go? Cannot a cap just be placed on top of the chimney? Thanks in advance for your help.
ANSWER: When older furnaces are upgraded, many original brick chimneys become redundant or are simply used for natural-gas water heaters. Many homeowners don't understand that having an obsolete structure made of porous masonry materials and extending up beyond the roofline of their homes is a liability.
The first thing to address in both the homes in question is the condition and type of water heat in current use. The second homeowner has wisely upgraded to an electric water heater, which allows for a complete decommissioning of the old chimney. If that is the situation in your home in Case 1, then removing the chimney may not be too difficult, other than above the roof.
If you do have a gas water heater and it's at least five or six years old, then replacing it with an electric version will make sense before dealing with the old chimney. Changing water heaters is often a simple job as long as there is room in the electrical panel for the new circuit-breakers and the basement ceiling is open and accessible for running the wiring required for this purpose. Adapting the water-supply piping is no more work than for a gas unit, and a little more space may be gained by removal of the vent for the old tank.
Once the furnace and water heater have been upgraded, there is no valid reason to keep the chimney. Capping it at the top and bottom is certainly an acceptable practice, but it may only be a temporary measure. Because brick chimneys are held together with mortar, open and susceptible to all the worst environmental conditions, they will deteriorate over time. It's quite likely that both of these older chimneys currently have deteriorated mortar near the top, where it is not easily seen or accessible from the ground. Most older brick chimneys I see during typical inspections fall into this category.
If the old stack is still in use, then repairs will be required to prevent loose and damaged bricks or, even worse, falling debris. Since you will no longer be using this relic after mechanical upgrades are complete, removal of this potentially hazardous feature is a good idea. In most cases, taking the chimney down to just below the roofline will be sufficient to prevent falling bricks and other issues, even if it is an exterior chimney for its entirety. The last thing any homeowner wants is a loose brick falling on a family member, neighbour or letter-carrier during bad weather.
The second reason to look at chimney removal, as opposed to simple capping, is to prevent moisture intrusion. When masonry chimneys start to wear, rain and snow have a way of finding a route inside the top or through deteriorated mortar. Most chimneys of this type have a slightly sloped mortar cap or prefabricated concrete one that overhangs the bricks at the top. Both of these are subject to damage from sun, wind and especially precipitation. Even a small crack in either type of protective material can allow moisture to penetrate itself or the bricks below, which can freeze in sub-zero weather. Any moisture trapped inside the masonry will expand as it freezes, potentially causing more damage.
This cycle will continue with every change in the seasons and can cause further damage, which may not be the worst moisture issue possible.
All chimneys that have been adapted for natural gas-burning appliances should have metal liners and chimney rain caps installed. Because these are subject to corrosion and damage from flue gases and environmental conditions, rain and snow entering the chimney is likely.
Holes in the metal liner can also allow moisture in flue gases to escape before reaching the top of the chimney, which can lead to a buildup of frost or ice inside the chimney. Come spring, this will melt and run down the inside of the chimney until it finds its way into your home. Metal flashing embedded in the brick at the roof junction is subject to rusting over time.
Deterioration, holes or gaps in any of these metal components can lead to water damage in your home. Removal of the redundant chimney, rather than simply sealing it, will eliminate the possibility of ceiling and wall damage from leakage.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and president of the Canadian Association of Home & Property Inspectors-Manitoba (www.cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358, or check out his website at www.trainedeye.ca.