> quite possibly electric heat tape.

I don't recommend using heat tape where you can't see and check it daily. Years ago, a friend of mine who was renting a half-duplex came home from a weekend trip to find smoke and water damage throughout his apartment, and the remains of the bedroom ceiling on the bed and floor. He lost a lot of personal property, and had quite a time dealing with the insurance company.

The duplex's owner had solved his freezing attic pipes problem with heat tape. After many years of use, one tape section overheated and started a fire. If the tenant in the other side of the duplex hadn't smelled smoke and called the FD, my friend would have lost a lot more property than he did. Fortunately he didn't have any pets, or they might have lost their lives.

By all means, close up your crawl space in the winter. If the pipes are already insulated and that isn't enough, I suggest adding a heat register or two in the crawl space.

All crawl spaces are not created equal. Some are more open to the outside than others. It may have more or less ground (soil) insulating it on various sides. And of course the weather plays a huge role. So it's hard to tell you what's going to happen under YOUR house. But you are right to be concerned about it. First, figure out which pipes are which, and which ones are insulated. Even drains can freeze up if it's cold long enough.

Yes, of course they will freeze if their temperature gets below 32*. Are the pipes laying exposed IN the crawl space, or buried in the dirt BELOW the crawl space?

We are in northern Michigan and have a crawl space.

We have a well and DH turns the pump off at the electrical box every time we go away for a night. He figures if a pipe breaks, only the water in the pipes will cause damage.

when we go to Florida a plumber comes in and winterizes the house. Turns off the pump and blows out the water lines.

It freezes at the cabin, I have had two occasions of pipes freezing and splitting.

If I am at the cabin when it freezes, no problems. If I am at home and leave the water on at the cabin, heat off and it freezes, there is a chance my pipes will split.

I usually drain the water when I leave, but a few times, I thought I will be back in 3 or 4 days, 2 times my pipes froze. After the last freeze (1989), I drain the water every time I leave, even if it in the summer and I plan to return in 3-4 days. I also turn off the gas heat when I leave.

Just because pipes are insulated doesn't mean that they won't freeze. All insulation does is slow the rate of heat loss. This means they won't freeze as quickly when the temperatures dip compared to if they had no insulation. A lot will depend on your crawl space, how much pipe there is, how well it is insulated, how drafty the space is, how much heat the pipe gets from the heated space, and whether the water in the pipes is stagnant or there is some flow through it at regular intervals.

I live in a location where it only gets below freezing a few days a year. Even so, last year I had a kitchen pipe freeze up overnight in an insulated, exterior wall when the temperature got down to about 25F. I opened up the sheetrock and discovered that, although the pipe was running through batt insulation, there was a gap at the base plate that was letting in cold air and there was enough of a wind that it was sucking heat from the copper pipe enough to freeze the water. I fixed the gap and put insulation only on the outer side of the pipe so that it would pick up more heat from the kitchen.

In addition to inspecting the insulation of the pipes in the crawl space and making sure it is intact, you could also consider letting a faucet drip when it is really cold as this tiny flow can will help prevent ice buildup inside the pipe.

If your heat ducts are under your house, have your heating company come and put a few small vents in them, to keep heat in there over winter. I have that at my house and our winters here are not as cold as you have. Also, make sure you shut your vents in the foundation over winter. If you dont have vent covers, make some and have them insulated. Dont forget to turn off the water to your outside faucets. I previously lived in Mn, and winters could get very cold. I used to leave the doors open under the kitchen and bathroom sinks, even at night so the heat from the house could keep those pipes warm, and we did have a basement. Please do not use heat tape. They just cannot be trusted not to catch fire. My daughter and her husband, had a mobile home when they first married and it was in a mobile home park. Heat tape was installed by the installer to protect during the winter, but, the heat tape caused a fire. They had 2 large dogs and she was home alone, but, managed to get out with the two dogs, and put them in a vehicle and moved the vehicle.

One way to reduce the chance of pipes freezing is to leave the water running when the temperature gets very cold. It needs to be a fairly steady light stream, not just a drip or trickle.

The downside is that this wastes water and the energy for warming it (you have to leave both taps on). Does it waste more than routing warm air from the heating system into the crawl space? I'll have to get back to you on that........

Heating a crawl space can waste a lot of money/energy. The only way I would do this is if I could build insulated boxes and limit the heat to those spaces.

Bad a idea to have a bathroom design or anything else involving water lines over the crawlspace.

Uhhh GN Builders, apparently, you are in an area where there are basements. That just isnt true in a lot of places. There are a few basements in my area, but, they are very few and very hard to find. Most houses in this area, have a foundation the correct depth into the ground, and a house is built on top of that foundation. There are vents in that foundation, and there is an opening, for a door of sorts into that crawl space. Some houses are really crawl, like belly crawl, some you can hunch over and walk under, and some like mine, you can crawl around on you knees, and not have a problem bumping your head, etc. Yes, the water lines are in that crawl space, and so are heating/coolng duct work. Some even have their hot water heater in the crawl space.The height of the crawl space, depends upon the land the house is built on. Some houses have a very high crawl space on one side, and by the time you get to the other side, it is a belly crawl. It is the way houses are built, and I am guessing, you have no experience with them.

My brother lives in northern Ontario Canada. His place has a very well insulated crawlspace. When he came down to Southern Ontario for Christmas last year WE had -37 degree temperatures so his were much lower. He figured his pipes would have frozen and they had. I think even if you add some direct heat ducts (expensive to heat the outdoors) into the crawlspace if (when) it gets cold enough they will freeze. I would ask your local Fire Department if there is a safe way to add some specific (safe) heaters that you can turn on when the temperature falls really low.

They make inexpensive temperature-feedback controllers these days. I got one to run a bar refrigerator when the thermostat crapped out. Comes with a temp probe and power in/out controlled by a relay. You could run a heat tape off of it - put the temp probe either in the crawlspace or inside the pipe insulation. When it gets down to 30F it turns on the heat.

For that matter there might be a ready-made system like this you could buy instead of having to wire it up yourself.

The cheap temp controllers you're talking about are made in China by no-name sweatshops and have no regulatory approvals (UL, CE, CSA, et cetera). I've used them and their humidity controller cousins, and so far they work fine, but I'd never put one where I couldn't keep an eye on it.

Good point, yes the one I bought was a cheap Asian made one. Has worked for a year or two. One could mount the thing where it was visible and run the wires to wherever the controlled heater is located. That makes it easy to monitor the pipe or crawlspace temperature from the comfort of a heated space. Probably a project more suited to a DIYer like myself, but I just thought I'd mention it.

Thanks all for the wonderful advice, suggestions, and solutions! The pipes are exposed under my crawl space.

Sometimes due to crawl space is somewhat exposed in brief cold spells can freeze water in the pipes. A better remedy would be to insulate the pipe using foam wrap made for this purpose and close the perimeter vents during the cold seasons.

I assumed the pipes were already insulated, but if not, definitely good advice.