How to carpet over basement slab

Q. We would like to finish our basement and need your expertise on how to go about it, especially the slab floor. With excellent gravel soil and perimeter footing drain on our 5-year-old house, the basement is very dry, and a dehumidifier is run in the summer months. We will insulate the interior walls, but not the exterior. We plan to use one-inch extruded polystyrene foam board glued to the interior of the poured concrete walls studded with two-by-fours. How do we finish the slab floor? We would like to cover the slab with 6-mil poly and put the pad and the carpet over it. Or do we need some kind of a subfloor built before we place the carpet?

A. Your plan is very sound, and I assume you mean that you will insulate the interior face of the exterior walls. If you know that the concrete slab was poured over a stone base and either a plastic vapor retarder or 2-inch thick extruded polystyrene (XPS) foam placed over the stones, there is no need for applying plastic over the slab. Just lay a synthetic pad, and carpet over it. But if neither plastic nor XPS was placed under the slab, and if the slab was poured directly over the sand without a stone bed under it, lay a sheet of reinforced plastic under the pad. You should be able to buy reinforced plastic from a building-supply company.

Q. The 89-year-old woman who was going to fix her concrete driveway inspired me. Can you give me the steps, so I can do this project from start to finish? The concrete driveway was never sealed and is showing signs of wear in some areas.

A. Clean the driveway with a pressure washer or a garden hose. Remove any oil stains by sprinkling TSPPF crystals onto them and sprinkling hot water over the crystals. Let stand for 20 to 30 minutes, and scrub with a stiff brush. Buy a clear concrete sealer in a construction specialty store and spray it with a garden sprayer, following the directions on the container.

Q. We just installed a new vanity in our bathroom only to find out the walls are not straight. The base fits nicely; it's the top where you notice a gap, about 3/8 of an inch at its widest point. It's a new contemporary top, which doesn't have back or side splashes. How do I hide the gap?

A. You should be able to find a flexible vinyl molding with a slight crease in the middle at hardware stores. It can be applied with an adhesive that the store can also sell you.

Q. I enjoy reading your column every week. I am planning on using travertine marble for my tub surround and bathroom floor. Can you recommend a sealer that you think is best? Also, how do you take care of and clean travertine marble to get rid of soap scum and dirt? Is special care needed to take care of a granite counter? Can I use the same spray cleaners that I used before?

A. I checked with my longtime friend, the foremost tile expert in the United States, and here is his answer: #8220;I do not recommend travertine in wet areas because it is porous and requires frequent application of sealers.#8221; As for your granite countertops, not knowing what cleaners you used before, and what kind of granite you have, you will have to ask your granite dealer if the spray cleaners you have been using will be compatible with your granite tops.

Q. We have just replaced a pressure well tank along with a new brass check valve, pressure valve and copper piping. Every time the tank refills and the well pump shuts off, it makes a loud bang/clunk noise. The tank is only a month old; we tried replacing with a new check valve, but we still have the banging noise. Do you have any ideas as to what could be the problem?

A. Two possibilities come to mind. Did you install a swing check valve instead of a spring-loaded check valve? The former closes with a bang while the latter closes softly. The other possibility is that the factory left the pressure switch shut-off setting at the maximum. It should be set five to 10 pounds lower to leave an air cushion to absorb the pump shut-off.

Q. The timing was perfect in the question about a whole-house fan, as I just had an energy audit and I was told the same thing. They recommend covering the opening in the ceiling instead of removing the entire fan and then boxing in the fan in the attic and insulating around it. How difficult would it be to remove the fan compared to simply covering the opening?

A. It should not be difficult to remove the fan. You will need to make sure that the circuit breaker to it is turned off and that, once the fan is removed, the junction box has a proper cover and is left accessible, as required by the National Electric Code. It must not be covered by insulation or hidden behind other construction. It is safest to have a licensed electrician handle that part of the job.

Q. We have a mound system that is in the unmowed portion of our yard. A friend said he thought that the top of a mound system was supposed to be kept mowed. Is this true?

A. Not at all. Many mound systems are planted with evergreen trees and shrubs. This is especially so in evapotranspiration systems developed by the late Dr. Alfred Bernhart, so that effluent is absorbed by the vegetation year around.

Q. I live in a middle unit of a condo building. Our den (and sometimes the adjacent living room) smells moldy. The units are on slabs, and I'm afraid that moisture is somehow coming into our home through the wood flooring. I am especially distressed, as both of my cats have been wheezing and coughing and I think this may be the source of their problems. I'm not sure where to start with all of this. I just e-mailed our property manager and am waiting to hear from her also.

A. You should consider contacting an environmental engineer to assess the situation. Mold is never good, and it can get out of hand if not controlled before it gets too advanced. You may wish to contact Bryan Schultz of KD Associates in South Burlington, Vt. His phone number is (802) 862-7490.

Q. I read in your column a while back about a product made of zinc plates to control mold and mildew on roofs, but lost track of the article. Would you please e-mail me the name of the manufacturer, phone number or e-mail address?

A. There are a number of firms that sell zinc-coated strips or rolls to be applied just below the ridge-cap shingles to kill and control the growth of mold, algae, moss and lichen on various types of roofs. The one I have mentioned before is the Stainhandler (www.stainhandler.com).

Q. I have an older house with a stone foundation. The front wall is bowing in. What options do I have, and who would do this type of work? I also noticed a sinkhole outside the foundation near the sewer pipes leading out of the house. What is causing this? Thanks for any response or direction you could provide.

A. Call in a stonemason, especially one who has experience with foundations suffering from the same problem you have. The bowing of your foundation is probably due to fluid soil pressure caused by poor grading and saturation of the soil in contact with your foundation. To prevent further damage, this condition must be corrected. The sinkhole could be caused by settlement of the backfill (if work was done on the sewer line recently), a leak in the sewer line or by a rotting tree stump that had been covered with soil a long time ago. The mason can investigate, recommend a fix, and add soil to fill the hole. But if the sinkhole is due to a sewer-line leak, the town or a licensed plumbing contractor needs to take care of it.

Q. The mold in my attic is in the right-hand corner of the roof on the plywood. It covers about a quarter of the attic ceiling. Should I be concerned, and what is my next step? There is no visible moisture. Thank you.

A. If the moisture is severe and ice builds up in winter, and if you begin to notice fungus growing (white or colored growth), it is of concern. For such a significant area to be affected, there must be some convective losses from the living quarters below it. An energy auditor or an experienced home inspector should be able to determine the cause and offer a solution. Your utility may offer energy audits, and you can find a competent home inspector by going to the ASHI website at www.ashi.org.

A great product recommendation from a reader: #8220;As an inveterate do-it-yourselfer, I decided to re-roof my 50-year-old house last summer. I wanted to add a ridge vent, but as you often pointed out, the ridge vent is not effective without accompanying soffit vents and I have no eaves overhang.

Research led me to a company that makes an eaves-vent product that works perfectly for a roof with no eaves overhang. DCI's SmartVent provides a 3/4-inch fiberglass fabric screened, continuous vent when used under the first course of shingles at the eaves. The 3/4-inch eaves edge tapers down to 1/8-inch, one foot in from the eaves, making the vent virtually unnoticeable.

For the venting to work, a one-inch-wide continuous slit is cut into the roof sheathing six inches up from the eaves before applying the SmartVent. The slit ends within one foot of the rake ends, any interior wall framing, dormer or other obstruction. A weatherguard layer, if required to combat ice damming, is applied over the SmartVent. A drip edge is applied along the eaves before installing the SmartVent.

My house (without air conditioning) was noticeably cooler this summer. Also, the huge snow load this past winter and massive ice dams resulted in no water infiltration or damage for me, whereas many neighbors had ice-dam damage or even had gutters torn from the house. See www.DCIProducts.com for complete details.

Dear reader: Thank you for sending this information on a great product idea, and one much needed for houses without eaves overhang. The results obtained are proof of the effectiveness of the proper combination of soffit and ridge venting. Is it possible to add insulation to your attic to reduce snow melting and ice dams?

Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via e-mail at henridemarne@gmavt.net.

© 2010, United Feature Syndicate Inc.