Asphalt shingles

Asphalt shingles are the leading choice for residential roofing, accounting for more than 75% of all roofing materials installed. Asphalt shingles have evolved considerably over the past ten years; as well as protecting the roof, new shingles boast new features that make them “greener”: improved energy performance, solar-reflective shingles that reduce the roof’s temperature in summer, and the use of recycled materials.

There are two main categories of asphalt shingles: organic and fibreglass.

Organic shingles
Organic-based shingles are the oldest type of asphalt roofing tile. The organic part of asphalt shingles is a cellular fibre substrate, often recycled paper, impregnated with asphalt and compressed under high pressure. More flexible than fibreglass shingles, they are easier to install in cold weather, more tear-resistant and able to hide imperfections on the roof’s deck. Organic shingles are heavier and therefore more resistant to strong winds. And more important in our northern climate, they are better at withstanding changes in temperature.

Fibreglass shingles
Currently more popular: asphalt shingles manufactured with a mat composed entirely of glass fibres, referred to as composition shingles. The fibreglass mat is surfaced with an asphalt coating, followed by mineral granules. Laminated or architectural shingles are somewhat thicker due to an extra layer of tabs. Fibreglass shingles are lighter than their organic counterparts, because less asphalt is used during manufacturing, and they are less expensive. They are also more heat-resistant and the “feet”, or notched ends, are less likely to lift, a problem often encountered on older roofs. An underlayment of asphalt-saturated felt should be installed over the roof structure prior to laying fibreglass shingles.

 

1- Granular surface layer
Granules constitute the superficial layer of asphalt shingles, provide colour and UV protection. This granite-like coating comes from basaltic deposits, including basalt and rhyolite, which are not only hard and durable but opaque to keep UV rays from deteriorating the asphalt. Certain granules are engineered to reflect heat and keep roof temperatures cool. They also may contain additives to prevent mould.

2- Asphalt coating
Asphalt is the waterproofing agent applied during manufacture, ensuring the roof’s protection. The thickness of the asphalt layer determines the weight of the shingle. Architectural shingles have two layers of asphalt, with the fibreglass mat constituting the centre.

3- Base, or mat
The material used for the base, or mat, differentiates the types of shingle and provides the shingle structure. The base for organic shingles is made of organic felt saturated with asphalt, whereas the fibreglass shingles are reinforced with a glass mat. This membrane acts as a frame, holding the other layers together; it must be very resistant and stable in all temperatures.

4- Adhesive tabs
Shingles come with heat-activated adhesive tabs. Never drive a nail through these adhesive tabs, which could prevent shingles from fusing or locking to the roof deck.

5- Nailing strip
Shingles must be nailed and not stapled, which makes them more vulnerable to cracks. Nail heads should be visible on the surface without being driven too deep.

Other features

Wind-resistance
The combination of adhesive and nails provide shingles with wind-resistance. The majority of shingles can resist winds more than 100 km/ h, and high-performance shingles provide protection and resistance to winds up to 220 km /h.

Solar Reflectance Index (SRI)
SRI is a measure of the roof’s ability to reject solar heat. New granule technologies have been developed making shingles more solar-reflective, and ensuring cooler roofs and attics during summer. The granular layer reflects the sun’s rays without affecting roof-colour.

 

There are many shingle models on the market, available in various colours. Each model has different features (thickness, durability, function). With the increased occurrence of major weather disruptions, such as heavy rain and strong winds, manufacturers have improved their products to make them more resistant to extreme weather conditions. Weather-Tite technology provides protection against high winds (up to 220 km/h) due to the application of sealant bands on shingles. Manufacturers also offer products more resistant to heavy rain. Warranties have been adjusted accordingly. Here are the various models:

Model	Features	Brands	Colours available	Warranty
	Economical and popular; Appropriate for roofs with slopes between 4:12 and 2:12); Effective for all low-sloping roofs	Rampart; Dakota; Mirage; Yukon; Superglass Ultra	Up to16 colours available depending on the brand and manufacturer.	Three quality levels associated with three warrantees (20, 25 or 30 years)
	Have become increasingly popular; Two thicknesses provide texture to the roof; Attractive; Cannot cover the crest and ridges; requires three-tab shingles in a compatible colour. Not compatible with a roof with a slope less than 4:12.	Mystique; Everest; Harmony; Eclipse.	Up to 16 colours available depending on the brand and manufacturer.	Manufacturers offer a Lifetime Limited Warranty
	Attractive; Different designs available; Certain models are resistant to strong winds, other imitate slate and natural-wood shingles.	Designs available: - Rustic (ex.: Roofmaster); - Textured (ex.: Mirage, with the illusion of a raised design); - Slate-look (ex; Europa, with a slate imitation); - Interlocking (ex.: Tite-lok, also wind-resistant).	Up to 12 colours available depending on the brand and manufacturer.	Solid 15-year protection; Many manufacturers have begun to offer a Lifetime Limited Warranty. This includes better protection against damages caused by strong winds (up to 220 km/h)
	Shingles designed for the ridges and crest of the roof. Available in one, two or three thicknesses.		Up to 7 colours available depending on the brand and manufacturer.	Manufacturers offer the same warranty for these shingles as for laminated shingles
	Shingle half the size as a regular shingle (approx. 8"), designed to begin installation

 The slope or pitch of a roof dictates the type of shingles you should install. For a low-slope roof such as 4:12 (a ratio of 4 inches of rise to 12 inches of roof) to 2:12 (a ratio of 2 inches of rise to 12 inches of roof), three-tap shingles are preferable. Low-slope roofs are more susceptible to ice and water problems such as ice dams, so that more attention must be paid to water-resistance. 

For an average-slope roof (more than 6:12) or high-slope roof (8:12 to 12:12), architectural shingles are recommended.

Asphalt shingles should never be installed on roofs with a slope less than 2:12 (8.5°).

For a roof with two slopes, add the surface area of the two slopes plus 10% to cover the crest of the roof. This 10% also enables you to cover any losses. The percentage is higher in the case of a roof with several slopes with ridges, verges and valleys. The manufacturer or retailer is a good resource-person to estimate the exact quantity you’ll require. 

For laminated shingles, the calculations are different. You need to add the surface of the two slopes plus only 5 to 7%. This excess consists of three-tab shingles, needed to cover the crest of the roof. Remember that with laminated shingles you need three-tab shingles to cover the crest and ridges. To help you with your calculations: each package of three-tab shingles covers 30 linear feet. 

Installing shingles on a simple roof with two slopes is fairly straightforward and can be done by home-owners. When a roof is composed of several slopes, with valleys, ridges and verges, the work should be entrusted to professionals.

If you are installing shingles on an existing house, make sure the sheathing (decking), underlayment and eaves protection sheet are all sound, or if possible, new. Flashings and drip edges should also be replaced and installed using the plastic cement for this purpose.

Installation sequence of materials

1. Perimeter drip edge
2. Eaves protection sheet and underlayment
3. Valley and chimney flashings; gable drip edge
4. Shingles and vents

To begin installation, you need to establish the first row at the bottom of the roof, on the drip edge. Pre-cut starter shingles sold by the manufacturer are fine, or, you can cut the shingle by approximately half of its width. Take care to install the first row in a straight line. On the crest and ridges, shingles are installed perpendicularly. If you are installing laminated shingles, use three-tab shingles for the crest and ridges. For more detailed explanations, consult the step-by-step installation guide.

Measuring tools:

• Tape measure
• Chalk line
• Square

Cutting tools:

• Utility knife to trim the underlayment, protection sheet and shingles
• Metal snips for shingles and flashings

Installation tools:

• Hammer or pneumatic nailer
• Caulking gun
• Trowel
• Gloves

Safety equipment:

• Safety harness with snap link
• Strong nylon rope attached to the snap link
• Cap
• Ladder, secured to the roof top and on the ground

If you first need to remove old shingles and flashings from the roof decking, use a square roofer’s shovel (with teeth and a bent handle) and crowbar.
 

New programmes have been introduced to collect and use old and discarded asphalt shingles, primarily for road resurfacing work. Asphalt shingles contain a great deal of bituminous concrete used for asphalt production. Recycled shingles are used as additives to asphalt pavement.

• Inspect your roof every two or three years, though not more often since every time you walk on the roof you cause some dammage;
• Inspect the attic. Check that the insulating wool is dry, as well as the wood. Humidity may be due to inadequate attic ventilation.
• Check that the plastic cement under the flashings is in good repair.
• If you see cracks or a joint without caulk, use a caulking gun with a tube of plastic glue to do the necessary waterproofing.