A secure and well-maintained roof means more than just your physical comfort. It symbolizes the entire concept of domestic shelter and psychological well-being. One of life’s basic necessities, along with food and clothing, is “a roof over one’s head”.

Yet most homeowners pay little or no attention to their roof—until it leaks. Even then, repairs are often put off until the problem is too great to be ignored.

Roof leaks, though, are more than just annoyances that must be remedied. They can be the cause of severe internal structural damage which is more difficult—and more costly—to repair.


All roofs have five basic components:

  • Roof structure: the rafters and trusses constructed to support the sheathing;
  • Sheathing: the boards or sheet material which are fastened to the roof rafters to cover the house;
  • Roof covering: shingles, tiles or sheets which protect the sheathing from the weather;
  • Drainage: the features of the roof’s design, such as shape, slope, layout, etc., which affect its ability to shed water;
  • Flashing: sheet metal or other material laid into the various joints and valleys of the roof to prevent water seepage

Roofs have not one, but many enemies in nature:

Sun: The warmth and ultra violet rays of the sun cause roofing materials to dry out, overheat and deteriorate. The sides of a roof with southern or southwesterly exposure, therefore, often wear out faster than those facing the north or east, especially if they are dark in colour  since they absorb more of the sun’s rays.

Rain: When rainwater finds its way through the interior of the roof structure, it sets up a moisture condition that is conducive to mildew and rot. It can destroy drywall, render insulation useless and jeopardize a home’s electrical system.

Wind: A strong wind can actually lift shingles off a building, as well as drive rain water under the edges of roof shingles. It can also knock tree branches down onto the roof’s surface, thereby scraping or even puncturing it.

Snow/Ice: Melting snow often refreezes at a roof’s overhang, forming an ice dam and blocking proper drainage into the gutter. Instead, the water backs up under the shingles and seeps into the interior. In the early melt stages, gutters and downspouts can be the first to fill with ice and be damaged beyond repair, or torn off the house.

Moss: Wood and built-up roofs are particularly susceptible to the decaying effects of moss. Its root systems serve as conduits for moisture to penetrate the roof surface. On built-up low slope or flat roofs, moss impedes the runoff of water. It also rusts nails, causing shingles to loosen and blow off.

Another important aspect of roofing structure is the extent of a roof’s steepness or incline. Referred to either by its slope, pitch or angle, this factor determines the type of roofing material that may or may not properly be used.

A roof with little or no slope is called a low slope or flat roof. Often these are bituminous material (such as asphalt) and gravel or, more technically, built-up roofs, and present the homeowner with a specific set of circumstances. Water tends to lie in ponds, and debris accumulates on flat roofs because of their lack of run-off. Clogged drains running through the building may leak and result in internal damage.

Since water expands 700 times in volume from the liquid state to the vapour state, any moisture penetration into the felt layers of a built-up roof can cause bubbles, ripples and delamination of the system. This often results from the flat roof’s accumulation and longer retention of rainwater, ice and  snow.

Flat roofs also chronically suffer from poor ventilation. As a result of condensation, or in the event of leaks through the bituminous coating of the built-up roof, poor ventilation can lead to decay or delamination of the plywood sheathing.

As a result of these many problems, architects now call for some slope, and for the drainage system to be located along the outside perimeter rather than through the  building.

The Truth About Leaks

The truth is that while many roof leaks are easy to repair, their sources are often difficult to find. Water dripping from a ceiling may not be from a leak directly above, but from a leak many feet away that runs down the rafter or across the ceiling before coming in. It could also be caused by the condensation of moisture rising from a bathroom or kitchen, collecting on the roof sheathing and then dripping through to the floor below. It might just as easily be from a plumbing leak situated in a wall or ceiling, and incorrectly attributed to a roof leak.

The best way to start tracking a roof leak is to become familiar with the many possible causes. Then, by carefully examining the roof and using the process of elimination, you should be able to locate its source.

The most frequent causes of roof leaks  are:

  • Improper flashing, sealing or worn-through flashing around projections through the roof such as plumbing stacks (vent pipes), chimneys, skylights, antennas, dormers,
  • Missing, broken or pierced shingles, caused by stones, hail, broken branches or walking on the
  • Tears in roof valleys, created by expanding and contracting metal or by someone walking in the Also, debris can build up in the valley and block run-off.
  • Exposed nails, nails in the wrong places or nails not set flush with the underlying
  • Wind driven rain: through an attic window or louvre, into the chimney brick or mortar or under shingles, through the siding and behind the step flashing where a lower roof joins the vertical side of the main
  • Ice dams, which prevent proper run-off and force water to back up under the
  • Improperly hung gutters or drip
  • Improperly installed roofing, or a roofing type which is incorrect for the slope
  • Cracking and blistering of roof mastic on rolled asphalt or on built-up
  • Ponds of water, created when flat or low-sloped roofs
  • Clogged roof
  • Cracked or disintegrating chimney

Points to Remember On Maintenance:

By heeding the following points on maintenance, you will do much to lengthen the life of your roof:

  • Cut off or trim tree branches that overhang the roof and gutters. This will prevent debris and moss from clogging the valleys and gutters and from keeping everything wet or damp. It will also eliminate the problem of branches scraping and damaging the roof surface when the wind
  • Run downspouts (leaders) to the ground onto splashblocks slanting away from the foundation, or directly to another gutter below, never onto a lower roof
  • Never try to change the colour of roofing by painting the The paint and the granules will come off.
  • Don’t exceed your local building code limit on the number of layers of shingles that can be applied. The additional weight can cause structural problems, and the increased thickness may prevent nails from penetrating the roof sheathing. And while nail-over replacement roof coverings are less expensive than tear-off re-roofing jobs, they may only last 65-75 % as Too many layers also increase the difficulty of fighting fires.
  • Never nail in valleys or in places where nails will be exposed between shingles, such as in the slots or shadow lines. Follow the manufacturer’s instructions printed on each bale of shingles. Keep nailing well concealed on cedar
  • In order to prevent corrosion, don’t allow different metals to come in contact with each other, such as galvanized nails and copper flashing, or adjoining strips of aluminum and copper
  • Clean filters and downspouts (underground drains, too) in the Spring and Fall