Ask the Architect

The special challenges of winter

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Q. We came home from vacation to find water damage from frozen pipes in our new second floor, added last summer. We never expected this, but called the contractor who referred us to the plumber who, frankly, was no help. After 12 tries, the plumber responded and told us that it couldn’t be from him, even though another plumber, who did call back and looked at the problem, said the pipes froze because they’re on an outside wall, with no insulation around them. The new plumber put a foam rubber cover over the pipe, and all seems fine now. How can we prevent this from happening again?

A. Every winter I get this question numerous times, which means that the problem, which is preventable, happens continuously because there’s a gap in learning from mistakes, a denial that this could happen the next time. It starts with the question I often get in the first meeting with prospective clients — “What season is the best to build?” — to which I reply that indoor projects can be done year-round, outdoor projects in the spring, summer and fall. The problem is not remembering in those three seasons that the fourth one can bring on extremes that cause materials to react completely differently.

For example, the humidity in your home will drop from 65 to 30 percent and wood material, wallboard and furniture will literally shrink. While that is happening, the extremes of temperature meet each other inside your window frames, your ceilings and walls. The little bit of humidity is air carrying moisture that cools inside the windows and walls to form a film of moisture, which is one reason the humidity inside your home has dropped. Pipes inside your walls are also subject to moisture collection from the radiating coolness in the wall cavities. If those pipes aren’t able to get warmed up from room temperature, they’ll freeze.

It is a natural phenomenon for hot water to freeze before cool water because the molecules of hot water are farther apart, and cool air convects (moves) toward heat. That’s why the warmest place at a hockey game is right at the surface of the ice. Designing a bathroom so that fixtures are placed on an outside wall is the first problem. Unless it couldn’t be avoided, which does happen, the plumbing pipes should either be run inside the room, such as inside a vanity, or insulated so that the room side of the pipe is left un-insulated and the exterior wall side is fully insulated, or at least as much as the adjacent wall cavities. If the pipes are insulated with urethane wrap around the whole pipe, then it turns into a gamble, at your expense, whether outdoor cool air or warm room air will reach the pipe first and which temperature will have the greatest impact. When the pipes freeze, it means the outside temperature won, and you lost.

© 2015 Monte Leeper. Readers are encouraged to send questions to yourhousedr@aol.com, with “Herald question” in the subject line, or to Herald Homes, 2 Endo Blvd., Garden City, NY 11530, Attn: Monte Leeper, architect.