Heating, Cooling and HVAC

The purpose of caulking is to reduce the infiltration of air, dirt, noise, moisture, and insects into the home. Caulk is any pliable material that can be used to fill cracks and stop leaks. It is designed for areas where parts do not have to move relative to one another. Weather-stripping, on the other hand, is designed to stop air leakage in areas where parts must move, like doors and windows. Caulk is most commonly purchased in cartridges that require a caulk gun to apply, but also comes in convenient pressurized canisters, or in pre-formed rolls.

To begin a home weatherization project, examine your house for air leaks, inside and outside. Some leaks are hard to find because they are hidden behind cabinets or walls. If the home has a whole-house fan, it can help you locate leaks. Simply close up the house and turn the fan on. It will draw air out of the house, pulling air in through cracks. With the fan running, walk around the house and feel for leaks. You can use a piece of tissue paper or a feather to detect small air currents and movement. The professionals use smoke sticks.

The goal in sealing air leaks is to create an air-tight envelope around the living space. Begin on the inside, sealing every leak you can find.

Pay special attention to electrical outlets and switches. Walls are full of them and the plastic covers do little to stop air flow. Gaskets can be inserted behind the face plate and are available in hardware stores, and plastic inserts, which double as child-protection, can be inserted into the open plug openings. Also inside, areas under sinks and around doors, windows and vents should be examined carefully for leaks. Outside, look for cracks wherever two building sections meet or where dissimilar building materials come together, such as between the siding and the foundation or around windows and doors. Cracks are also likely where the building’s shell has been pierced by pipe, wire, vents, or plumbing.

For cracks larger than one quarter inch, fill them first with fiberglass, or steel wool, or spray foam insulation, then apply caulk.

Caulks come in a wide variety of types. Before purchasing one, read the label to be sure it is suitable for the material to be sealed. Some can not be painted, and others are only for inside use. An important consideration in selecting a caulk is life expectancy; some last only a few years while others last 20 years or more. Since this is probably not a job you will want to repeat regularly, buy long-life products.

Types of Caulks

There are three main categories of caulks, and their prices are directly proportional to their life expectancy. As shown here, the least expensive, oil based, has the shortest life. It works on all household surfaces, but over time, the oil seeps out and may stain surrounding materials.

Caulking Compounds Durability:-

Oil Based ————————– 2 to 3 years.
Butyl Rubber Latyex & Acrylic —— 5 to 10 years.
Silicon,Hypalon & Polysulfide ——-10 to 20 years.

Butyl rubber, latex and acrylic caulks last almost 10 times longer. Latex is restricted to indoor use unless painted and because it is water soluble, should not be used where it can become wet. Acrylic is durable and fast-curing, but can not be painted. Butyl rubber is water resistant, needs no paint, but may take over a week to cure.

Silicone caulks are usually your best choice. They last 20 years or more and can be used inside or out, however, they do not adhere well to painted surfaces.

Foam sealants like polyurethane are not true caulks but are excellent for filling large cracks. In new construction or when adding on, seal openings around pipes and wiring before the walls are sealed (which would then conceal the cracks.)

Source:Home Energy Library