Parts of a Roof and Its Trusses

If you drive around Edmonton and its surrounding area including Sherwood Park, Leduc, Stony Plain and Spruce Grove, you may be surprised to see many different roof designs.

Not only that, Edmonton roofs feature a varied array of roof coverings, including clay and slate tiles, traditional wooden shingles that have been popular in Canada for hundreds of years, and contemporary shingles that look like wood but are made from coated steel.


But the fact is that all these very different roofs have a lot in common!


Whether you’re building a new home or considering a re-roofing job, it pays to understand the roofing terminology your roofing contractor will use.


Generic Roof Types

Generally, roofs are either flat or pitched. This in itself is confusing, because flat roofs aren’t always flat: many are what we call low-pitch roofs, which could be constructed with as little as a 3- to 5-degree slope. Confusingly, roofs that slope less than 15 degrees are commonly termed flat roofs.


While some flat roofs really are flat, the reason for incorporating a slope of some sort is primarily for drainage – to create runoff for rainwater. After all, we need roofs on our houses to keep us dry and protected from the elements.


If there is no slope, the roof design will usually incorporate an inner drain or scuppers that allow the water to drain through the walls. For these systems to work, it is essential they are correctly designed and installed.


Ultimately, if water can’t drain off the roof it will puddle and pool, and likely damage the basic roof structure.


Edmonton boasts a relatively mild climate – most of the year. But while it normally rains in summer, the winters are usually very cold, with lots of snow that eventually melts and also needs to drain off roofs. For this reason, pitched roofs are the most popular type in Edmonton, Stony Plain, Leduc, and various neighboring suburbs.


Pitched roofs sometimes slope in one direction, but more often in two directions, particularly when the slope is steep. Those that slope only one way are called mono-pitched roofs, and many are constructed as low-pitch roofs.


That said, larger houses often have a number of sections that result in considerably more than two sloping sections, and sometimes also with a part that is low-pitch or flat.


The degree of the pitch itself will depend on the design of the trusses that form the basic framework of any roof structure. Even though a homeowner, unless trained as an architect, engineer, or roofing specialist, won’t design the roof structure of his or her house, it’s important to realize that both the span of the structure it will support (essentially the size of the house), as well as the type of roof covering to be used, are critical factors in roof design.


More importantly (especially for the layman who has no technical knowledge or experience), the design of the roof structure is fundamental in terms of the visual character of the house. These are three common pitched roof types:

  • Gabled – The gable ends of a house are formed when the roof is pitched to form a triangular shape. The ridge beam of the roof is at the top and runs between the two gable ends.
  • Hipped – The end of the roof, rather than the walls, form a triangular shape. There may be several hips in one complex roof design.
  • Shed – A mono-pitched roof that slopes in only one direction. Commonly used for lean-to structures.


Basic Roof Structure

The primary parts of a roof structure include the trusses, rafters, wall plates, and various other roofing elements including battens or roofing laths for roof tiles, and purlins, which are horizontal beams utilized when roof sheeting is used as a cover.


There are various different types of traditional roof trusses including the king post truss, queen post truss, Howe truss, Fink truss, fan truss, scissors truss for a vaulted ceiling, and attic truss that can accommodate dormer windows in the roof and in this way add to living space.


Most are made with wooden rafters, tie beams, posts and struts, but some, including the fan truss, may be made out of steel. The choice will be dependent on the area the roof must span as well as visual impression.


Trusses are commonly designed by professionals and assembled before being delivered to the building site. Alternatively, the framework for the roof may be assembled on site with individual lengths of lumber, following the approved house plans.


Trusses are usually held together with special nail plates, which are advanced connectors for lumber that are easily hammered into place. The rafters are the sloping beams that are used to form hips where the roof slopes on all sides, and valleys where two parts of a roof meet.


The entire roof structure rests on wall plates, which are planks of wood fixed to the inside of the top of the walls of the house.


Apart from the basic framework of the roof, there are additional elements that are used to neaten and finish off the roof structure. For instance, the eaves, which are that part of the roof structure that overhang the house itself, are often closed with soffits that are usually wood, vinyl, or cement fiber.

Fascia board is fixed to the ends of the rafters, not only to neaten the ends but also to provide a surface onto which gutters may be attached. Fascia may be made from various materials including wood, cement fibre, PVC, and even aluminum. Bargeboard used to neaten the appearance of the roof at the gable ends, is made from the same materials as fascia board.


Edmonton Roofs
Even though there have been substantial advances in materials used for roofing, particularly types of fixings and roof coverings, the basic structure of Edmonton, Leduc, and Stony Plain roofing really hasn’t changed much in the last century, perhaps even longer. The structure of roofs in the newer Spruce Grove and Sherwood Park areas shows minimal evidence of change.


Whether you want a new roof or are looking for a residential re-roof, Silverline Roofing can help. You’ll be sure of a professional job at a competitive price, so if you live in Edmonton or the surrounding areas, contact us today for a free quote. You won’t be sorry.