Common Problems

Moisture and Ventilation

People often wonder if new homes might not be too tight. Poor air quality is noted as a problem, as is mold and moisture. We are asked, Shouldn't a house have some air leakage to avoid these problems?

The answer is No. The solution to these problems is: "Build tight, ventilate right."

Here are the facts:

Most mold and moisture problems are caused by:

• Plumbing or roof leaks
• Poorly installed insulation that results in cold and warm spots where condensation can occur
• Poor construction

Most indoor air quality problems are caused by lack of proper ventilation, e.g., poor quality or improperly installed bath fans.

Poorly installed insulation will allow air movement through the wall, and this allows for cold or warm spots where condensation can occur. This can cause mold and moisture problems.

Weather differences can affect how a house performs. During calm weather, a "just leaky enough" house may still be too tight without good ventilation. Conversely, with a winter wind, the "just tight enough" house may experience drafts, cold spots and other comfort problems.

A properly insulated house with a good air sealing package will significantly reduce problems. Seal the wall with proper insulation, and no air moves through it: No air, no moisture.

For good indoor air quality, we recommend an appropriate method of controlled ventilation. For many homes, properly installed, good quality bath fans will remove moisture at the source. In some instances, a more sophisticated ventilation system may be needed.

The bottom line is this: The additional expense and time spent in planning and correctly insulating and ventilating your new home will reward you with lower energy bills, more comfort, and good indoor air quality.

Ice Dams

What is an ice dam?

Anatomy of an Ice Dam

Those beautiful, sparking icicles you see hanging from the gutters are symptomatic of a serious problem. A ridge of ice has formed at the edge of a roof that prevents melting snow from properly draining off the roof. Water backs up behind the dam and leaks into the house, causing damage to walls, ceilings, insulation, and other areas. What causes ice dams? Nonuniform roof surface temperatures lead to ice dams. For ice dams to form, there must be snow on the roof, and, at the same time, higher portions of the roof's outside surface must be above 32°F, while lower surfaces are below 32°F. For a portion of the roof to be below 32°F, outside temperatures must also be below 32°F. The snow on a roof surface that is above 32°F will melt. As water flows down the roof it reaches the portion of the roof that is below 32°F and freezes. Voila! - an ice dam. The dam grows as it is fed by the melting snow above it, but it will limit itself to the portions of the roof that are on the average below 32°F. Water backs up behind the ice dam and remains a liquid. This water finds cracks and openings in the exterior roof covering and flows into the attic space. From the attic, it could flow into exterior walls or through the ceiling insulation and stain the ceiling finish.

A few temporary solutions can be applied to avoid ice dams: Removing the snow from the roof before it melts, using heat tape, etc. But, these do not resolve the fundamental problem. What typically causes a roof to be warm is air from inside the house seeping into the attic. The best solution is keeping the attic cold, and that means proper insulation.

The drawback? Cost. A well insulated attic will not be inexpensive. However, on the long term, the savings in fuel and repairs to your home, as well as the inconvenience of removing snow from the roof after every winter storm, can be considerable.

Whether building or remodeling, you can rely on Duerst Insulation Technicians to help to keep your new or existing home or business free of heat and cooling related problems for many, many years.