Homes with mansard roofs often attract the attention of a passersby. Also known as curb and French roofs, this style of home is characterized by steep sides and a dual pitch. While they are of notable beauty, this roof style is prone to ice dams, which can cause costly damage.
When our River Falls, WI clients had asked us for our expert opinion on ice dam remedies, it was alarming that the outside temperature was 8 degrees and a steady stream of water was exiting the roof due to how hot the home’s attic was. An attic inspection revealed an area of the roof deck that was black due to mold and mildew growth. Infrared imaging showed significant temperature discrepancies throughout the home. Further examination revealed soft wood that had been damaged by dry rot. The room directly below the area of dry rot was a bathroom that lacked both a bath fan and a vapor barrier. This meant that the bathroom’s warm, moist air had easy access to the attic. Because of all of the moisture damage to the attic and the elevated attic temperatures that allowed ice dams to form, our team needed to start from square one to increase the home’s energy efficiency, prevent mold growth, and discourage the formation of further ice dams. Here’s how we tackled the issues:
Bath Fan: In order to safely remove the moisture from the bathroom below the home’s attic, we added a Panasonic Whisper bath fan. We vented it out through the home’s roof in order to avoid introducing additional moisture to the home’s attic, which can cause frost, wet insulation, mold, and mildew. The Panasonic Whisper is an optimum choice because it is powerful, yet quiet.
Air Sealing & Insulation: Attic air sealing is the meticulous process of identifying and sealing off areas of the attic that are allowing interior air to filter in. In this home, areas of concern included the waste vent pipes, attic opening, and the areas around the recessed lighting. Once this had been done, we installed closed cell spray foam insulation which has a high R-value and is also highly resistant to moisture. After this step has been completed, we added cellulose insulation. Over time cellulose insulation develops a crust which provides additional attic air sealing. Cellulose insulation is easy to evenly distribute and is also more resistant to moisture than fiberglass insulation.
Watch the Insulation Installation:
Ventilation: When it came to the mansard roof’s ventilation, one of the most problematic issues was that there was not enough air intake in the soffits. In addition, the roof’s configuration did not allow us to install attic air chutes into the necessary areas. After the insulation portion of the project had been completed, we sealed off all of the soffit and roof vents. We then added a gable vent on the peak part of the house, so that there was an intake on one side of the house and an exhaust vent on the other. This reactive approach allows the ventilation to take into consideration the air pressure within the home and act accordingly.
These measures will prevent air from moving from the attic to the home’s living spaces, and vice versa. In addition, ice dam and condensation issues will be alleviated. Lastly, it is a certainty that the home’s energy bills will be dramatically lower.