Renovation & Design
Renovation & Design
Discarding chimney a common dilemma
QUESTION: I read your column every weekend and am usually quite pleased with the thoroughness of your responses. My question is about closing off or removing my chimney. In the past few years, I have had my water heater replaced with an electric water heater and my furnace upgraded to a high-efficiency model, making the chimney unnecessary. To reduce air flow around the chimney stack and improve heating efficiency, should I consider removing as much of the metal chimney stack as possible, and closing off the chimney openings on the roof and in the ceiling/attic cavity? I had water leaking around the chimney opening during a severe rain storm last summer, and wonder if I should go the extra mile and remove everything possible, and seal the openings. My 1,650-square-foot bungalow in St. Vital is 23 years old, and I have easy access to the attic and basement below the chimney.
— Duane Drayson
ANSWER: Your dilemma is one faced by many homeowners when they upgrade to a high-efficiency furnace, which doesn't require the large, metal chimney that goes from your basement through the roof. Because the new furnace is typically vented horizontally through the side of the foundation or exterior wall, the only thing that still required the large chimney was your old, gas-fired water heater. Replacing that with an unvented electric unit has offered a potential benefit, but also requires making a tricky decision.
The obvious choice you are faced with is whether to simply cap your old chimney, leaving it in place, or removing it. One of the main factors that should be considered is the condition of your roofing. If the roofing is worn and nearing time for replacement, removing the old chimney may be much more desirable. In that scenario, the chimney may be easily removed from the attic upward. The opening in the roof sheathing can be easily patched before covering it with a layer of the brand new roofing, sealing it well against the elements. If your roofing is newer, removing the total chimney may be more difficult, as matching the shingles to patch the hole can be tricky.
The other option, which you have wisely asked to explore, is the possibility of a partial removal. It is certainly possible to remove only a portion of the old stack, which is most likely a double-walled B-vent. This type of chimney is made up of several small sections that are connected together. Disconnecting enough individual sections to leave only the uppermost part will save the need for insulating and sealing the old pipe and patching the roof. If the bottom of the partially removed unit is above the ceiling, leaving the top sticking through the roof may cause no harm. Sealing the top may not even be required, as long as the rain cap is in good condition. Also, installing a metal screen near the top may be a good idea to keep insects and critters out of the attic.
It is also possible to remove only the upper sections, leaving the rest of the metal pipe installed in the walls and protruding slightly through the floor in the basement. In that case, you would definitely have to seal and insulate the bottom and top of the vent to prevent warm-air intrusion and condensation. That may be easily accomplished with a combination of a few cans of blow-in polyurethane foam and fitted metal caps. The benefit of that method is limiting the need to seal the areas around where the old pipe went through the floor and ceiling.
If you decide total removal is your best bet, attention to the transition areas between the floors of the home and attic is warranted. Patching these areas with wood or drywall sheathing will not be enough to prevent a problem. Air-sealing and insulation will also be needed, especially at the upper ceiling, which doubles as the floor of the attic. This could be done with standard 6mm polyethylene sheathing, acoustical sealant and insulation, or other materials. Covering this opening with a few layers of extruded polystyrene sheathing will ensure warm air will not leak into the attic where the old chimney used to be. Blown-in foam would also work, but would be a more costly method and may require installation in several applications to ensure enough thickness to prevent air leakage and match the insulation level of the surrounding attic.
Taking that extra step when doing upgrades is always a wise choice, but one that is not always critical. It may be less complicated to properly air-seal your home after complete removal of the entire chimney, but it is not completely necessary. Partial removal will be adequate, as long as precautions are taken in several areas. Air-sealing both the open ends of the partially removed vent and the attic floor will be necessary to prevent warm-air exfiltration and condensation. Either way, careful attention to those details will prevent a problem that didn't exist with the old furnace and chimney intact.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors -- Manitoba (cahpi.mb.ca). Questions can be emailed to trainedeye@iname.com. Marantz can be reached at 204-291-5358, or check out his website at trainedeye.ca.
Renovation & Design
Plenty of ways to get rid of pesky rabbits
QUESTION: Can you please give some advice on how to prevent rabbits from entering and eating my garden? -- Miles (Stonewall)
ANSWER: Here are some things to try:
-- If possible, construct a chicken-wire fence, roughly 60 centimetres in height. Bury the fence a few centimetres into the ground, because rabbits are more likely to climb under the fence than hop over it.
-- Surround the garden with milk jugs lined with sand. The idea is the rabbits will chew on the jugs instead of your plants.
-- Suspend aluminum pie plates around plants to keep rabbits away.
-- Sprinkle one of the following around plants or shrubs: bags of human hair (from your local hair salon), blood meal, fox urine, bone meal or Irish Spring soap shavings.
-- Add turkey manure to the soil.
-- Into a spray bottle, mix one tablespoon of baby shampoo, one tablespoon of household ammonia and one litre of water. Spray the plants every three days.
-- Soak corn cobs in vinegar for five minutes and then place them throughout the garden or under shrubs. Re-soak the corn cobs after two weeks.
-- When planting flower beds, mix thyme, spearmint, daffodils and/or eucalyptus in with flowers. Rabbits don't like the smell and often won't pass by to get to your yummy flowers.
-- Some people have had success with burying fabric softener sheets around plants.
-- Bury a collar cut out of a milk carton or jug around newly planted vegetables to protect each plant.
-- Fill mason jars three-quarters full with water, and add a drop of dish soap to each jar. Line jars along the garden and place them on top of foil pie plates. The water reflects the sun off the jar and the foil, and scares rabbits.
-- Ultrasonic repellers send a high-pitched noise humans are unable to hear but is uncomfortable for animals such as dogs, cats, deer, rabbits, raccoons, opossums, armadillos, skunks, bats and squirrels. Adjust the unit frequency so the sound doesn't hurt animals in the area. Study the best unit for your yard -- some are not effective.
Nerbas enjoys your questions and tips; keep them coming. Check out reena.ca. Every user assumes all risks of injury or damage resulting from the implementation of any suggestions in this column. Test all products on an inconspicuous area first.
Renovation & Design
Basement floor a job best left for professionals
QUESTION: My Wolseley home was built in the 1920s, and my basement has gone through some heaving.
Now I'm faced with removing the cracked basement slab and replacing it. I have read similar articles to yours, in regards to this type of project, and I think I can just isolate one area and replace the damaged concrete. While I'm at it, I was thinking of replacing the cast iron plumbing underneath the slab as well. My goal is to finish the basement with a half bath. I've never had an issue with moisture or sewer backup, but I will also be installing a sump pump during the project. But, before I embark on such a journey, there are a couple things that I am concerned about.
When removing the slab, and whatever else that may lay underneath, I'm worried about structural issues. I certainly don't want to tax the strength of my foundation by removing any support. My foundation walls have no visible horizontal cracks, just some thin vertical ones that run from my basement and I believe the walls are around 16 inches thick.
Also, after I remove the slab, how much crushed stone is required before I pour new concrete and how thick must the concrete slab be? I've heard of some basements being finished with only a vapour barrier and sub-floor over either dirt or crushed stone. Is this even an option?
Many, many thanks in advance for your time and most appreciated expertise.
Regards, Wyeth Krauchi
ANSWER: Removing and replacing a basement floor slab is a difficult and very messy project, which may be beyond your skill set as a home handyman.
A partial removal, as you suggest, will be much simpler but may not be sufficient for the plumbing upgrades you desire.
I am a little confused by your request as to the amount of your damaged basement floor slab you are planning on removing. In one sentence you state you will only remove a portion of the floor, but you also desire to install a bathroom, sump pit and pump, and replace the older cast iron drains beneath the slab. All of these items are not necessarily possible by only removing a small section of the concrete. You are further muddying the waters with your questions about an air/vapour barrier below the new concrete. That would be very desirable, but only really effective if most of the older floor is removed. Despite these discrepancies, I will endeavour to provide whatever insight I can.
Your first concern with possible effects on the foundation may only be valid if you are planning on removing most or all of the basement floor slab. The concrete floor does provide a structural function in preventing inward movement of the bottom of the foundation walls, due to excess soil pressure. Since your slab is already damaged and heaving, some of this function may be compromised, but it has to be severely buckled to lose all of this function. By removing the entire slab, you will be subjecting the foundation to the possibility of cracking or inward bowing, but that would depend largely on the amount of time the slab is missing and the amount of rainfall. Removing and replacing a few small sections of the floor may only serve to improve the strength and help prevent further problems of this nature.
The answer to your last question about the possibility of removing the entire floor and leaving only stone and a polyethylene air/vapour barrier should be common sense. Firstly, my previous concern about inward foundation movement would be multiplied enormously. Secondly, the thin plastic sheathing installed over the soil or stone would easily become damaged, over time, and rendered all but ineffective in preventing moisture or soil gas intrusion. It would also allow moisture to be trapped beneath, with potential for mould growth. Finally, how would you have a practical bathroom in a basement without a proper floor for the base? If you are talking about only removing small portions of the concrete, patching these openings with concrete after your upgrades should not be that difficult, even for a do-it-yourself-er.
It is admirable to endeavour to repair your damaged concrete basement floor slab, especially in an effort to upgrade older plumbing drains and protect your home from sewer back-up with a backwater valve, sump pit and pump. Unfortunately, this type of work, especially replacing the old drains and installation of the rough-in for the new bathroom, is very specialized work. I would not attempt this, unless you have extensive expertise in plumbing. The portion of the work that you may be able to tackle is breaking up and hauling away the old concrete and clay soil. Filling in the voids around the new drains and sump with pea gravel or smooth stone, would also fall under this category. Finally, mixing, pouring and finishing four or five inches of new concrete where the old damaged floor is removed may also be within your power, to keep costs down and satisfy your desire to be involved in the renovation.
While it is always a good idea to ask the types of questions you have posed before embarking on any renovation, the fact these have to be asked should alert you to the likelihood you are in over your head. I would initially consult a licensed plumber to come to your home and ensure your plans are practical or even possible before embarking on removing sections of your basement floor. Then you can decide how to proceed and how much of the floor removal and repair you are willing and capable of tackling yourself.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home and Property Inspectors -- Manitoba (cahpi.mb.ca). Questions can be emailed to trainedeye@iname.com. Marantz can be reached at 204-291-5358. Check out his website at
trainedeye.ca.