Tips on winterizing a home

Q. I leave my house in the winter and have had two methods of winterizing. I used both, which partially failed. The first was leaving my hot water system on and set at about fifty degrees. The furnace quit when the temperature outside was 26 degrees below and furnace repairs were over $800. This past winter I had a licensed plumber drain all the water out of the house and left the furnace off. None of the pipes burst, but when I returned in the spring and turned the water on, three pipes separated because of expansion and contraction during the winter and flooded the basement before I noticed the condition. Next winter I am thinking of leaving the furnace on, set at approximately 55 degrees, and having at least two electric heaters around the house set below the furnace temperature as backups. Give me your opinion on this please.

A. Do you know why your boiler shut off? Was there a power interruption, which is often the cause? If not, I hope you had an HVAC contractor inspect the boiler to determine what caused it to shut off.

It is preferable to keep the heat on at a low thermostat setting as you did rather than having the domestic water drained and the hydronic heat protected with antifreeze. It's healthier for your house, furniture and other possessions.

In order to protect yourself from a repeat event, consider having one of the many available alarm systems installed to warn someone if such a power failure or other complication occurs again in the winter in your absence. If the temperature in the house gets below the selected setting, the alarm is triggered.

These alarm systems range from a simple battery-operated red light in a window visible from the street, if you can have a neighbor accept the responsibility of checking it daily, to a fancier system that rings several phone numbers to alert family, friends or a maintenance person who have agreed to be on call and have access to the house.

Google "freeze alarm systems" to see what is available.

Q. I had a driveway reinstalled in December (timing was probably poor).

The contractor promised two inches of blacktop over a stone base (he later mentioned that he used crushed concrete for the base). Water runs across the driveway in a few places. It does not sit for more than one day. In each of the places where the water runs over, there is a white, chalky-looking sediment on the driveway. This started the first day after installation. My guess is it is lime from the crushed concrete coming to the surface. The blacktop appears to be a little coarse to me.

Do you think there is a solution to the problem? I was considering having the driveway sealed in hopes that it would cover the stains and protect it.

I have phoned the contractor but he still has not looked at the problem, and I am not sure he is going to be able to help. Thank you for any help.

A. White, chalky residue on an asphalt driveway is not uncommon. It is likely to be calcium carbonate, common in soil and gravel, brought to the surface by water that penetrated the asphalt.

In your case, it is also possible that it is the efflorescence from salts in the concrete base the contractor used. This should eventually disappear on its own with time.

It is much too soon to have the driveway sealed; it could make maters worse by sealing the source of the problem instead of letting time take care of it.

Asphalt driveways should not be sealed for a couple of years, even longer, until the oils in the asphalt have evaporated fully and the driveway has turned a light gray. Sealers should be applied in very thin layers and during hot weather, and they should not be reapplied until the previous coat has worn out.

Q. We have an unheated 10-by-16-foot closed-in porch attached to the house. Do you see any problem with installing 2-inch rigid insulation in contact with the plywood? Obviously, there is no venting.

Even though it's unheated we go in and out of the house (via the porch) and we get snow melt/ice dams in the winter on the porch. My hope would be to alleviate this issue.

A. You haven't given me much information. Am I to assume that the porch is enclosed on all sides with plywood? If this is your question, I don't see what adding rigid insulation to the plywood walls would do to improve the situation.

If you mean installing the rigid insulation onto the plywood ceiling of an unheated porch (you mention "no venting," which tells me that may be what you have in mind), again I don't see the advantage. That is unless a considerable amount of the house's heat escapes during your comings and goings (and they would have to be very frequent) to cause any snow on the porch roof to melt and develop into ice dams, in which case adding rigid insulation to the plywood ceiling may help.

My guess is that it is more likely that the snow melting comes from the house's roof and freezes as it comes in contact with the porch's cold roof. In that case, it may be worthwhile to look into improving the insulation of the house's attic, if there is one, or of the roof.

Q. Our poor old cat had some accidents on our wood floor. Now she is gone and there are three planks that are black. Is there any way we can refinish those planks?

A. Try this: Remove the floor finish and apply the following solution with a paintbrush.

Get oxalic acid crystals from a paint or hardware store. Using a plastic or glass container - never metal of any kind with oxalic acid, mix the crystals in hot water to saturation (when some crystals can no longer be absorbed).

Oxalic acid is very caustic, so wear appropriate skin and eye protection.

It may take several applications, and even then, you may never be able to remove all the dark stains.

Oxalic acid is a very potent bleaching agent, so be careful not to overdo it and end up with the treated area lighter than the rest of the floor.

When you judge the results satisfactory, wipe the treated floor boards with a clean cloth dampened with white vinegar.

Allow to dry thoroughly and refinish the floor.

• 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.