Types of Caulk and Where to Seal Leaks

Knowing where to caulk and what type of caulk to use can help seal leaks in your home.

| October/November 1991

Because as much as 80 percent of air leakage occurs in areas other than windows and doors, caulking is an absolute winter necessity. In addition to checking windows and doors, be sure to inspect the areas where:

  • the wooden sill of the home meets the foundation
  • dryer vents and fan covers pass through the wall
  • furnace vent stacks meet the exterior
  • any air leaks in the basement might lurk
  • plumbing pipes and telephone wires enter the home
  • any two different outside materials meet
  • the fireplace chimney meets the siding.

As a general rule, caulk where a permanent seal is desired, and weather-strip when doors and windows must be opened.

After determining which areas need attention, it's important to choose the right type of caulk for the job. Before buying or using a particular caulk, read each label carefully for storage and application temperatures. Check the descriptions below, and then refer to the chart to determine the best caulk for the job. While the factors may be of varying concern depending on personal preference (amount of money you're willing to spend, lengths you are willing to go to to find a certain caulk, time you wish to spend redoing the job in a few years), it is important to check the temperature resistance of any caulk if you live in a very cold climate.

Oil-Resin Base. This is often the least expensive. It is not particular durable and tends to shrink and harden. It can be painted. This material is found in most stores. It should not be used for long-term application.

Latex Base. This will bond to most surfaces. It is more durable than resin-based material, and also paintable. Some shrinkage will occur. Adequate, but not the best material available.

Butyl Rubber. This paintable material will bond to most surfaces. It is more durable than the others, but it also shrinks. This is often the best choice for use on masonry surfaces, but not on moving joints or places where two different materials meet.

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