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Homeowners often don’t look closely at their roof and, in most cases, do not know about their roof and the roofing systems implemented to protect their home.
Usually, most people underestimate the intricacies of a roof and what products and expertise are needed to put together a long-lasting weather-resistant roof.
We will now look at the layers of a roof by looking at a typical, modern shingle roof installation. The example used will replicate standard practices in Calgary, Alberta.
We will look at each layer, starting from the attics insulation and then from the decking to the shingles exposed to the elements.
Although not a direct layer on your roof, attic insulation is critical to an efficient roofing system. Because of this, we decided to include insulation as an essential layer. Why?
When we look at the framing of the home, we also have to consider the overall design. For our example, we will have a classic sloped roof with a vented attic from an atypical light wood-frame home in North America.
The main factor of the frame of the roof is to hold up everything you're putting on it. Most framed roofing designs allow the roof to withstand a lot of weight; however, this weight can vary and should be considered, especially for heaver roofing products such as slate. Furthermore, remember that we can get heavy snowfall in Alberta, Canada; the additional weight of snow in your region needs to factor into the total required weight for the structure.
The roof deck is installed directly on top of the framing. A good roof deck will provide a foundation for the additional layers and help stick the layers together by providing a fastening material (Roofing Nails, for example).
The decking is typically made out of materials like plywood or OBS; however other material types are used in certain instances.
One critical part of the roofing system that you can’t often see is called underlayment.
Underlayment provides a layer of protection that the shingles on top cant do by themselves. The extra layer helps defend against moisture damage and other inclement weather from penetrating the roofs deck and the rest of your home.
Special underlayment or ice barriers are used in areas such as the home’s valleys, eaves, protrusions and surfaces with low slopes.
Three primary types of underlayment:
Asphalt shingle strip (or modified shingles) placed on the roof’s edge around the rake edges and eave of the roof. This extra layer helps protect the roof’s edges from high winds and lifting shingles where the effect is most common.
The star of the roofing system is the one that gets the most attention, and that being the one layer you can see at the top, Shingles.
Shingles take the brunt of all the forces your roof experiences and are considered an essential part of your roofing system. However, the other layers and parts are often just as important. Also, improperly installed or faulty materials will make your costly shingles useless without the proper layers underneath. An example of not considering the previous layers is when people place shingles over shingles.
We have just gone over many of the roof layers, but other parts are just as important. They include eavestroughs (gutters), Ventilation, and other weather protection components. To learn more about these parts of your roof and the terminology, check out our post!