Asphalt and gravel
An aging system
In great loss of popularity, an asphalt and gravel roof could still be considered a relatively inexpensive alternative for small areas, if considering only the buying cost. However, considering necessary maintenance and useful life, the multi-layer roof becomes one of the least attractive choices, not only in economic terms but also and especially for its disastrous environmental record.
A multilayer roofing (or built-up roof) as its name suggests, consists of several layers of felt paper drowned in liquid asphalt.
As for the gravel, its role is to slow down the deterioration of asphalt layers that occurs with exposure to sunlight. It also minimizes the contractions and expansions of asphalt membrane due to temperature changes.
With the advent of new by-laws on reflective roofing, installers of such materials now offer white gravel, sometimes increasing the cost but certainly acting in a beneficial way to lessen the temperature changes sustained by asphalt.
Note that since January 2015, Montreal’s Rosemont Petite-Patrie and Outremont boroughs have added clause to their by-laws on roofs, banning the use of this system for new construction, and also for reroofing in Outremont, even with the use of white gravel.
Couvertures Montérégiennes, although equipped for asphalt application, has discontinued offering this system for several years, judging the quality of today’s asphalt too poor for a durable installation protected by a consequent guarantee. However, the equipment can still be used to fix roofing panels on some special applications.
Product life : About 15 years, the vast majority of insurers not offering coverage beyond that period.
Did you know ?
“Tar” Refers to an old method now banned for environmental reasons and public health. This material was however very durable compared to today’s asphalt.