Why your roof is melting from the inside out
In short: Ice dams aren't just a winter nuisance; they are a structural threat. When internal heat escapes into your attic, it melts snow that refreezes at the eaves, creating a reservoir of water. This trapped moisture can seep under shingles, rotting your roof decking and interior walls.
The fundamental cause of an ice dam is a failure in the home's thermal envelope. Heat from the living spaces rises into the attic, warming the roof surface. This causes snow to melt, but because the eaves remain unheated, the water refreezes as it travels outward. This creates a physical dam that forces meltwater to back up under the shingles. To stop this, homeowners must address the source of the heat loss rather than simply clearing the ice.
Home technology expert Ross Trethewey suggests two primary architectural solutions: vented and unvented roof systems. A vented system maintains the attic as a buffer zone, using soffit, ridge, and gable vents to exhaust air while keeping the 'conditioned envelope' below the ceiling. Conversely, an unvented system—often achieved using spray foam insulation—incorporates the entire triangular attic space into the home's heated interior. This method involves applying foam to the rafters on both sides of the roof's peak to seal the space entirely.
To ensure these repairs work, experts utilize precision diagnostics. This includes a blower door test to depressurize the house and a manometer to perform zonal pressure diagnostics, identifying exactly where air is escaping. Thermal imaging cameras are also used to pinpoint leaks from the attic to the main floor. By sealing these leaks and optimizing insulation, homeowners can prevent structural damage while simultaneously increasing the overall energy efficiency of the building.
Opens the Intellect+ feed with this card first. Swipe up for the next one.
Sources
- Summary by Intellect · source: Fixing Ice Dams on a Roof | Ask This Old House
To cite this card, link to https://intellectplus.co.uk/app/society-fixing-ice-dams-on-a-roof-ask-this-old-house.
How we source, check and correct cards: Editorial standards.
General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.
Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?
Related
More in Home & housekeeping · More in Society · Latest · A–Z · All topics
