Watch this video from This Old House to learn how to prevent frozen pipes.
1. Seal air-leaking holes and cracks around home with expanding foam sealant or silicone caulk.
2. Use foam-rubber pipe insulation to protect exposed pipes from cold.
3. Slip foam-rubber insulation over pipe, peel away backing strips, then press the adhesive surfaces together.
4. At pipe corners, miter-cut the ends of the foam-rubber insulation with scissors, then secure the corner joint with foam tape.
5. Before attempting to thaw a frozen pipe, open the faucet.
6. Locate ice blockage, then use heat gun or blow dryer to thaw frozen pipe; don't use propane torch or other open flame.
7. If the frozen section of pipe is inaccessible, use an electric pipe-thawing machine.
8. Find the exposed ends of the pipe, then place one clamp from the machine onto each pipe; the machine will warm the pipe and eventually melt the blockage.