Skip to Content

The Root of the Problem

Infrared Scanning & Ice Dams

Article written by Jack Carr, P.E., R.S., LEED AP, Criterium Engineers
Published in Condo Media, September, 2015

 

Last winter saw an epidemic of ice dam problems for Maine condominiums, as well as all over New England. With the cold north winds not too distant in the future, boards and property managers are looking for ways to reduce this serious problem in the coming months. Infrared scanning may be one of the tools to combat ice dams and the related water damage they cause.

Sometimes unit owners do not even know they have ice dam potential problems because they have not experienced interior water damage yet. But the signs are still there. Potential ice dam problems are visible when it is noticed the snow on the roof melts un-uniformly or excessive icicles form. Sometimes brown stains can be seen on the exterior wall surface in the form of streaks.  This is the sign of ice forming in the soffit areas or other exterior components. As the ice melts and drips out of the soffit or other drain points on the siding, some of the dirt and other debris in these areas are carried away to be deposited on the siding.  

As stated in prior articles, ice dams primarily are caused by indoor conditioned air reaching the underside of the roof sheathing causing a cycle of melting snow developing an ice barrier at the drip edge of the roof. Further melting snow water will then back up under the shingles or soffits allowing water infiltration into the interior of the unit. By the time this happens snow roof raking rarely helps and chipping away at the ice dam often causes damage to the roof surface. Heating cables on the roof edge tend to reduce the life of shingles and do not address the reason the ice is forming in the first place.

To solve the problem of ice dams we must address its root cause. As stated earlier, this cause is unauthorized warm air in your attic or other roof structure related space. You may ask, why your attic ventilation system is not doing its job in removing this heated air from the attic spaces. Typically a unit’s soffit and ridge vent system (or other venting system) is designed to do just that.  Though there is a possibility this venting system is poorly installed or ventilation blockage has developed, this is unlikely. The fact that ice dams are developing provides sufficient empirical evidence the vent system is being overwhelmed with heated air from too much leakage of conditioned air into the attic space.

To determine how much and where this air leakage is occurring is where infrared scanning and other energy audit techniques come into play.  Today’s infrared camera scanning (or thermal imaging inspection as it is often called) takes colored photographs of interior or exterior building surfaces. These colors represent a gradient in temperature interpreted by a skilled infrared imaging technician to locate air leaks or even water leaks because of the sensitivity of the infrared camera. The value of these images is directly related to the quality of the camera and the image interpretation accuracy to the experience of the technician.

An infrared scan can reveal air leakage into the attic through missing or misplaced insulation; air paths through ceiling light fixtures, plumbing/ electrical penetrations; and HVAC duct seam leaks. With the current energy codes’, newer homes should have less than 4% leakage while homes older than 5 years old have been found on average to have leakage of 20%.

Newer homes required to meet the more stringent state energy codes have air seal tests performed called ‘blower door tests’ measuring the loss of pressure and the turns of indoor air per hour in the unit. If an older condo complex has been experiencing a rash of ice dams this past winter, the approach to stop their cause would be to visually inspect the unit for obvious insulation and sealing problems. Following this inspection an infrared survey of a sampling of units should be conducted to determine the location and severity of thermal leakage. To make an even more complete understanding of the air leakage, a blower test could also be conducted on selected units. The cost for a combined infrared and blower door test typically falls between $400 and $500 per unit by a number of energy auditing firms in Maine.

Often these tests can produce surprising results but more importantly they will give specific information on how to correct the air leakage problem through better insulation and the installation of air barriers.  These improvement will not only eliminate ice dams from forming but will create a more thermally efficient home thus reducing future utility costs.

Jack Carr, P.E., RS, LEED-AP, is senior vice president with Criterium-Engineers in Portland, Maine. He is a member of the Condo Mediaboard and a frequent author and speaker.