Air-Tight Construction

It has only been in about the last ten years that home builders have recognized the importance of building tight and ventilating right.

Houses built in the early to the mid 1900's generally were not insulated and had a high rate of air exchange in the building. Owners of these older houses, particularly those in colder climates, experienced problems such as cold drafts, discomfort, dry air, and high heating bills.

Driven by the rising cost of energy and consumer demand for more comfortable and efficient homes, builders began insulating homes, reducing the high rate of air exchange. Improved insulation, along with the introduction of new building materials such as plywood sheathing, thermopane windows and plastic vapor barriers, resulted in homes becoming more airtight, creating a need for mechanical ventilation. The newer, well-insulated homes can have different problems such as poor indoor air quality, condensation on windows, wet insulation, moisture damage and wet basements. This is where the term "build tight and ventilate right" comes into play.

The new Minnesota Energy Code now addresses the importance of whole house ventilation and sealing the interior of the home to prevent structural damage that can eventually lead to mold and mildew.

One of the most cost-effective, energy-saving details in an energy- efficient home is maintaining a continuous seal between the heated and unheated areas. In the winter months, warm moist inside air is trying to migrate to the outside through the walls and ceilings. Indirect or hidden paths and openings where warm, moist air can leak through the structure are called bypasses. Examples are wire, pipe and plumbing holes that penetrate exterior walls and attics, spaces around chimneys, soffits and attic hatch doors, gaps around recessed lights and other areas where warm, moisture-laden air can leak into the homes structure.

Careful attention to sealing these gaps and spaces will eliminate condensation problems that can cause mold, woodrot and other structural damage to your home. You will also be building into your home durability and longevity.

For as little as $500 to $1,000, depending on the size of the home, you can seal all of the bypasses. The cost includes both labor and materials. Sealants can be various types of acoustical caulks, spray foams and tape. It makes sense to purchase high quality sealants that will remain pliable. If the sealant completely dries out, it will break up and expose the original space or gap.

Ventilation

As a home becomes tighter and tighter, it is imperative to provide for indoor ventilation - the exchange of air inside the home. It's separate from attic or roof ventilation and has a very different purpose. It has two essential functions: to exhaust pollutants, moisture and odors from inside the house to the outside, and to bring in outdoor air to mix with the indoor air. It's a necessity for controlling the air quality in an energy efficient home. New energy code rules have recently been implemented as part of Minnesota's building code regulations requiring mechanical ventilation in all newly constructed homes.