By Henri de Marne/Home repair: Test for radon over time
Q. I remember some time ago that you provided some information about radon testing in your column. You mentioned what kit to purchase and the time of year to do the testing. Could you educate me again?
A. The radon kit I recommend is the Alpha-track Radon Detector. It is best to test for radon in cold weather when the house is closed, regardless of the climate zone. In the summer, in areas where air conditioning is rare and we depend on open windows for ventilation, the level of radon indoors is likely to be the same as outdoors, which cannot be avoided. Because the level of radon is more likely to be higher in the winter because of the stack effect in buildings, a reading in air-conditioned buildings during the summer is not likely to be as high as a reading taken during the winter. The advantage of the Alpha-track testing is that it gives a three-month reading, whereas charcoal kits only provide the readings of the previous few days.
Because radon levels change constantly, a two-day reading is not an accurate measure of the true levels in the house. I usually suggest that you set the kit out in the late fall and send it to the designated lab in late winter, but you may still do it now if you live in the very northern part of the country, where we will still have cold weather until May.
Q. I have seen you write about shower caulking before; I guess I lost the column. Our shower needs to be re-caulked just about every year. We have a fiberglass base and ceramic wall tiles. I strip the old caulk out, scraping the area clean, and then clean it up. I rub it with alcohol to remove any residue and let it dry overnight. We use a bathroom caulk suggested by the hardware store, which is cured for at least 24 to 48 hours. As time goes by, the caulk starts to come loose and develop an orange coloring on it no matter how I clean it. We always dry the shower walls after using.
Can you suggest the proper type of caulk to use and any steps that we are not doing? This has become a frustrating job we would like to do less often.
A. Sikaflex-1a polyurethane caulk/sealant is my preferred bathtub caulk because when applied to a clean and dry surface according to directions, it stays on for a long time. I haven’t experienced a failure yet.
One word of caution: Sikaflex-1a needs to be allowed to air-dry for a week before getting wet or it will turn a yellowish pink, so it is not practical if you do not have another bathroom to use. In time, even the white Sikaflex-1a will turn a slight gray. Sikaflex-1a is a construction product used mostly in commercial and industrial projects and has not made it in the residential market, so you are unlikely to find it in local hardware and big-box stores. The national distributor is A.H. Harris, which has stores in a number of states on the East Coast. You can find a list at www.ahharris.com.
If you are adamant about wanting the caulking to remain white and are willing to accept a loss of adhesion over time, one product I have used is Dap Kwik Seal Plus Premium Kitchen & Bath Adhesive Caulk w/Microban.
Q. You recently replied to a situation where bathroom exhaust fans were drawing in make-up air from the room’s heating ducts. Your suggestion was to cut one inch from the bottom of the door so the bath negative pressure would be equalized from the hall and not the air system. That is not always the thing to do.
In many cases, the fan is located closer to the door than to the shower or tub, and the fan would pull air into the room and directly out again without taking much of the humidity with it. It would be even worse if the shower or tub were located away from both the fan and door.
That is exactly the case in my master bath. The fan is mounted on the cathedral wall directly above the door, and the shower and tub are in the middle and far end of this large room, respectively. If I were to draw air directly up from the door, little or no moist air would be exhausted. Another bathroom in the house has the fan in the ceiling at the center of the room, and the heat register is closer to the tub than is the door. Even here, I get better humidity exhaust by allowing the heat ducts to make up most of the replacement air. These fans will operate only 10 to 20 minutes usually and should not cause any serious problems with the heating/AC system. Plus, even a door with normal gap will leak and contribute to the make-up air.
A. Please read the question and answer to which you are referring again. The reader was having make-up air coming out of the air-conditioning duct while the bathroom door was closed and the system not on. Of course air coming from a heat or air-conditioning supply duct, while either is running, will do a good job. But it needs to have a return, which may be a return duct, an open door or an adequate space under the bathroom door (one inch being the accepted standard).
One of the principal laws of physics is that moisture levels seek to equalize themselves (as does water), so if your theory were correct, opening the bathroom door after showering would not dissipate the bathroom moisture because there would be no mechanical air movement. Yet opening the door clears the condensation on the mirror faster than any normal fan does. It is because of this law that we need vapor retarders on most exterior walls to prevent damage to them as the warm, moist air in our houses irresistibly flows toward the drier outside air. Without the restraining factor of the retarder, condensation could form on the inside face of the sheathing. So, regardless of the fan’s location, any drier air drawn from an adjacent area will attract the moisture molecules of the more humid air.
Q. I was so excited when I read your column about Sikaflex-1a grout for the bathtub/shower area. My problem is that I cannot find anyone who sells it. I have tried at my local Home Depot, and while it sells Sikaflex products, it does not sell this grout, and neither does Lowe’s. Can you please help me?
A. Sikaflex-1a is a one-part sealant/caulking compound -- not a grout. It is sold in A.H. Harris stores in a number of states, but unfortunately not in Pennsylvania. They have a number of stores on the East Coast, including New York and New Jersey, and can ship the product to you. Find the nearest store to you at www.ahharris.com.
Q. My story-and-a-half brick Cape Cod house just north of Pittsburgh, Pa., was apparently built in the late 1930s. Interior walls are real plaster (not drywall), and the floors are hardwood (not laminate). The original single-pane, steel-frame crank-open windows have been replaced with good thermopane-type crank-open windows that do not leak air. The house is heated with a boiler, using the original radiators, which we like. Those radiators are placed inside the exterior walls under the windows so that the face of the radiator is flush with the interior plastered wall. Why? It seems to me that in order to place the radiator inside the wall, it would mean that the only thing between the radiator and the outside air is the one-inch Homasote board and the brick. So I’m guessing much of my radiated heat is escaping the house.
I am considering re-plumbing each radiator and moving each one so that it is completely inside the house. I’m anticipating having about an inch or two of separation between the radiator and the finished interior plastered wall. I will then insulate the spot where the radiators were in the wall and plaster over that space. Before I move the radiators, I am trying to determine why they are where they are, leaking heat outside. Are they in the walls just to save space inside the house? Were they built that way to keep the original windows from icing over and never opening in the winter? Are they there to strategically heat the window/wall in some way? I don’t want to move the radiators if they are where they are for some strategic building-construction reason. Otherwise, I’m thinking I can reduce my heating bill and gain quite a bit of heat inside the house if I have each radiator moved inside the room.
A. When your house was built, we lived in a time of no concern about the use of energy, which was cheap. So wasting a lot of it to the outside was not even a consideration. The radiators were installed flush to the inside face of the exterior walls because it looked better that way and it saved a bit of interior space. Radiators, as well as baseboard radiation, are usually installed under windows to counteract the effect of cold air dropping from them to the floor and creating unpleasant drafts. The added benefit is to prevent condensation on the glass.
Your plan is a good one, but to save space, make the rooms heat more evenly and the house more appealing to future buyers, you should consider replacing the radiators with baseboard radiation. If you want to keep the radiators, consider installing a reflective shield behind them and painting them a nonmetallic color (the darker, the better) in order to get the most out of your heating dollars. If your house is built of solid masonry, as opposed to wood framing with a brick veneer, there is probably no insulation in the exterior walls.
While you are changing the radiators, would you consider adding insulation to these walls in order to save energy, make your house more comfortable and enhance its resale value? It will be expensive, but the capital investment can be recovered over time if you plan on staying in the house for many years or recouped when you sell it. If you are interested, let me know, and I will explain how you can do that.
Ÿ 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.
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