Ask the Carpenter: Advice on freezing pipes and icicle prevention

Ask the Expert
Turning down your thermostat super low is a recipe for disaster. Paul Tessier/Shutterstock

Q. My house is 237 years old with two bathrooms, one upstairs and one downstairs. In very cold weather, the plumbing for the downstairs shower and toilet freezes until we get temps in the mid- to high 30s. If this were your house, how would you solve this problem?

TOM O’HARE, Peterborough, N.H.

A. Your solution may be some or all of the following:

■ Adding heat to the area, ensuring that it is at least 55 degrees in the space;

■ Sealing all air leaks near pipes;

■ Relocating vulnerable plumbing (water and drain lines) — anything in an exterior wall, along an uninsulated basement rim joist, or across a leaky window;

■ Insulating the basement water lines;

■ Adding more heat in the basement;

■ Insulating the rim joists near your plumbing;

■ Opening walls and adding insulation;

■ Installing regulated heat wires.


Q. I have a 50-plus-year-old house with a large overhang (1½ to 2 feet), and each winter I have huge icicles. My husband made 3-inch holes (they’re screened) in the overhang to vent the attic, but he covered them with insulation. I want to install a 2-inch-wide ventilation strip the length of the overhang (68 feet). Is this the best way to solve the problem, and do I need to cover the louvers in the gable vents at both ends of the house? Do I need to install the ventilation strip on both sides? I know I’ll have to cut back the insulation in the overhang to do this. Is it too late to add the strip now? Should I hire a carpenter to do the work? A roofer?


A. It’s not too late, but you’ll be hard-pressed to get a contractor who wants to do this in the winter. An attic with balanced ventilation has under-eave or soffit vents, which allow in fresh air. The fresh air flows up between the rafters to the ridge or gable vents, which allow it to exit. If insulation is allowed to bunch against the soffit area, air will be blocked before it can traverse the attic.

You answered your own question: Yes, install the strips. Here’s are some steps:

■ Remove all 68 feet of soffit.

■ Replace soffit material with new ⅜-inch AC plywood.

■ Install galvanized continuous 2-inch strip ventilation, about 68 feet.

■ Remove and replace the band molding (a thin strip of material used to hold objects together) in the soffit area.

■ From inside the attic, pull back the insulation so that it just overlaps the vertical exterior wall.

■ Use rafter vents to help keep a space between the insulation and the roof. Rafter vents, or proper vents, are made of extruded polystyrene foam. Place one between each roof rafter for air to flow freely up the rafters and into the attic. Insulation can then touch the proper vent.

■ Keep your gable vents in place and ensure the screens are clean and unobstructed.

Do not cover the louvers in your gable vents. You shouldn’t cover vents with anything, include insulation.


Q. I live in an old house in Cambridge where the heating and plumbing pipes run underneath the deck. The hot water heaters are malfunctioning because the pipes get iced up and the rats have removed the insulation. What do I do? Whom do I call?


A. The pipes are under your deck? No heating or plumbing lines should be outside — ever. I’m going to assume they are in a crawl space under the deck. In that case, seal all drafts, properly cover any dirt floors with concrete or a polyethylene liner, consider adding more insulation, and then introduce dehumidification and heat to the space.

Crawl spaces are difficult places to work and even more difficult to seal off. If you plan to seal off and encapsulate a crawl space, I recommend hiring a reputable company that specializes in this type of work.

Rob Robillard is a general contractor, carpenter, editor of, and principal of a carpentry and renovation business. Send your questions to or tweet them to @robertrobillard. Subscribe to our free real estate newsletter at