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Chimney causes drafts in warm home

Q. I read you column every week, but have not come across this problem.

We live in a condo that is about 22 years old. We have a lot of cold air coming into our living room through our fireplace even with the flue being closed. It even feels chilly in spring and autumn. I covered the entire open space of the fireplace with an insulated board covered with fabric, which has been up since the fall and is still there. This helps but we can still feel a slight breeze.

I have been in many other end units, like ours, and there doesn't seem to be any problem with cold air coming in at all, even on the coldest days. When we've had our chimney cleaned over the years, no chimney cleaner has mentioned any problem to us.

What is going on with this fireplace?

A. It may be that the damper in your fireplace is not fitting properly.

Cold air shooting down the chimney is replacing warm interior air that escapes outdoors around windows and through any cracks and crevices it can find.

If your heating appliances (furnace, boiler, gas- or oil-fired water heater) do not have their own air supply, they contribute to the need for makeup air from the chimney. So does a dryer vented outside and any fans in kitchen and bathrooms.

This is exasperated if your chimney is masonry and on the outside of the unit, as the chimney is exposed to the cold.

Q. My husband and I would like to finish our basement in our 13-year-old home. We would like to frame the space and make a laundry room, game room, and storage/work area.

Our ongoing discussion is always about how to frame, insulate, seal and protect before we actually "finish" the space. There seems to be an array of opinions out there on how to seal and prepare basement walls prior to finishing.

Our house is on sandy soil, and we have had no issues to date of any water infiltrating into the basement from the outside. Our foundation is poured concrete. We have tested for radon, and find we are within safe limits. However we have been wondering about sealing for future mitigation. There is a product on the market called RadonSeal. It's distributed by Radon Mitigation & Concrete Waterproofing Co. Have you heard of it and do you recommend using it? We do not know of anybody who has used it and wonder how effective it is and whether the benefits outweigh the risks (such as unknown health issues down the road).

We have read about spray foam on basement walls as a way to seal for moisture. Another alternative we have read about is using foam board to both seal and insulate.

If framing is used with foam board, should a barrier of some type (such as sill seal) be used between the framing and the concrete wall?

Our contractor has suggested we use an integrated framing system - metal Z-frame with foam board insulation that attaches directly to the concrete walls. He was not planning on putting sill seal or any other material behind the framing as he believes it is not necessary, especially since it is not wood. This is a system commonly used in commercial construction sold by Trowel Trades Supply.

We don't know where to begin. Your advice would be greatly appreciated.

A. I am familiar with Radon Seal, but have had no experience with it, so I am not in a position to recommend or not recommend its use. Its application is an additional cost to your project and it may not be necessary.

Insulating a basement from top to bottom in a very cold climate must always take a number of factors into consideration.

Since your house is built on sandy soil, you already have a great advantage over those built with heavier soils. And since you haven't had any moisture problems in 13 years, you are in a good position not to experience any over time as long as you make sure that the grading around your foundation is positive (slopes gently away from it).

There are a number of ways to insulate and finish a basement; the Z-framing is one of them.

But I disagree with your contractor about sealing between the concrete walls and the floor framing. If no seal sealer was used at the time of construction, which would be unusual, I suggest that the mud sill set on the concrete walls be caulked to prevent any infiltration.

Then the band joist spaces between the floor joists should be insulated and have a vapor retarder facing. This can be done with R-19 fiberglass with an integral vapor retarder or plastic stapled to the joists, the mud sill and subfloor. Roxul can be substituted for the fiberglass.

I would not recommend spraying insulation on the walls. Not only is it expensive for such a small job, but it will end up with an irregular surface.

This is the way I would recommend finishing the basement walls:

• Brush-clean a few spots on the walls and apply walnut-size dabs of polyurethane caulking to these;

• Press 1-inch thick XPS (extruded polystyrene - blue, pink, gray or green) rigid insulation onto the caulking dabs; • Build frame walls with 2x3 or 2x4 studs set on a pressure-treated sill tightly to the foam. This will make it easy to install wiring and any other utility you may choose.

Then you have the choice of stapling fiberglass or Roxul batts between the studs for additional insulation. Apply the finish of your choice to the framing.

Q. I have a small bathroom where the previous owner put in a built-from-scratch shower stall of ugly tile board over 2-by-4s to dress the house up for sale. I realized after a few too many showers that the glass door had been installed so that the water streamed down off the door onto the step-over entrance and thence to the adjacent floor, rather than into the pan, and stopped using it.

Now I'm getting around to replacing the shower and redoing the bathroom in general. I'd appreciate your suggestions about a free-standing shower stall, to be installed in a corner, maximum dimensions about 32-by-34 inches.

I rather like the rounded glass door style, especially because the whole bathroom is only 5-by-6 feet. On the other hand, there's that functional 32-square-inch pan, which I'd like to keep, of course, but I realize that's incompatible with the curved glass doors, so I'd also appreciate advice about shower stalls designed to fit existing pans and not look too ugly.

A. Amazon sells Sterling Plumbing 62010100-0 Advantage Shower Kit, 34 inch by 32 inch by 72 inch, white. It's pricey at $660. However, it has an integral base, so it may not appeal to you.

Home Depot sells a Prime 33-inch by 33-inich by 76.75-inch corner framed sliding shower enclosure in chrome with acrylic base and back walls kit, with a round glass door for $967. It also has an integral base. So does Lowe's, but at a higher price.

Consider going to a plumbing-supply house and talking to knowledgeable customer service people and see if they can accommodate your desire to keep the existing base.

• Henri de Marne, a former remodeling contractor turned columnist and consultant, is the author of "About the House with Henri de Marne" (Upper Access Publishing). He continues to take questions from readers for this column and his website, www.henridemarne.com. Email questions to aboutthehouse@gmavt.net.

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