All About Residential Roofs

Are you building a house or hoping to replace your existing roof? Choosing just the right type of roof is super important. That goes without saying, I mean, it’s the part of the structure that protects against humidity and regulates heat transfer, while also limiting convection between the air and the rooftop. Although there are a lot of choices, three elements will help you narrow down your options:

• Type of roof (flat or pitched)

• Preferred aesthetic

• Your financial means

This article will mainly focus on those aspects. 

Types of Roofs

There are different types of roofing materials, and these largely depend on the roof’s primary function. And, essentially, there are three different types of roofs: dome, gable (pitched), or flat residential roofs.

Amongst these residential roofs, few roofing companies actually offer the possibility of building a dome-style roof. This type of architectural design is extremely rare in Quebec and seems to be from another time period. That being said, we’ll focus on flat roofs as well as pitched/gable roofs. 

Pros and Cons of Pitched Roofs

The pitched roof design leaves nothing to chance. During the winter, it allows snow to easily slide right off and also avoids any damage to the framework. Furthermore, the roof’s slope facilitates rainwater collection systems throughout the rest of the year. 

However, its steep slope makes any roof work harder and more hazardous. A single misstep can lead to a fall. Therefore, installation and maintenance cost very much function according to their pitch. 

Inevitably, a pitched roof renders a loss of space, which can only be recovered by converting the attic into a living space or by building dormers. 

Pros and Cons of Flat Roofs

The flat roof’s best feature is its space optimization aspect. As a matter of fact, that’s why most administrative buildings are built like so. And, these rooftops can be vegetated or easily accommodated by solar panels, which are wise choices.

Nonetheless, flat roofs have two major flaws: drainage issues and snow build-up. Again, it’s no wonder flat roofs are traditionally preferred in southern countries. 

In Quebec, heavy and frequent rainfall makes flat roofs a secondary concept. Moreover, snow must be manually removed to steer clear of possible roof collapses. 

Also, humidity is the main reason why flat roofs must be equipped with a specifically made cover, composed of the following three elements:

• Structural support

• Insulation material 

• Waterproofing membrane

The waterproofing membrane has to be inserted between the asphalt, elastomeric, or polymeric layers. That’s why this type of roof cannot be fitted with just any covering material. 

Source: Wolfgang Eckert - Pixabay 

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The Different Types of Roof Coverings

Residential roofs and the materials from which these are made are offered in numerous styles. However, first and foremost, your roof type (flat or pitched) is the deciding factor when it comes to roofing covers. 

Therefore, for flat roofs, we recommend:

• EPDM or TPO membrane

• Green residential roof

• Asphalt and gravel residential roof

• Elastomeric or bitumen membrane

For pitched roofs, we recommend: 

• Steel/metal residential roof

• Plastic residential roof panels

• Asphalt shingle residential roof

• Wood shingle residential roof

EPDM or TPO Membrane 

EPDM stands for Ethylene, Propylene, Diene, and Monomer, which are all synthetic elastomers. This amalgam forms a single-layer membrane that serves as residential roof covers, and that since the 1960s. Visually, it very much resembles synthetic rubber. 

EPDM has many advantages, such as its resistance to oxidizing agents, ozone, and adverse weather conditions. All the more, EPDM is thermally stable and lasts over 50 years.

TPO, which stands for Thermoplastic Polyolefins, is another type of roof covering material. Its inception is rather more recent than that of EPDM, and is a single-layer polymer, which happens to be UV- and heat-resistant. It’s a hot-air welded roofing system, so it does have similar attributes to EPDM and PVC membranes. 

EPDM and TPO membranes aren’t more expensive than aluminum roofing. Account for about $7 to $12 per sq. ft. For a product with 50-year-plus durability, it’s a pretty decent price point. 

Green Roof

Source: Flickr

The residential green roof has numerous advantages and allows to:

• Fight against urban heat islands 

• Limit rainfall surface runoff 

• Filter rainwater of heavy metals and nitrogen

• Improve air quality

• Encourage biodiversity

• Soundproof

Green roofs are perfectly adapted to flat roofs. This super environmentally responsible roofing concept is becoming increasingly frequent in Quebec and throughout the rest of Canada. 

Yet, as a substrate is placed on a protective watertight layer, it has the same drawbacks as any other flat roof: water-draining difficulties. However, in the case of a vegetated roof, identifying cracks is made more difficult by the thickness of this micro-biotope. The durability of a green roof is directly linked to the quality, and regularity, of maintenance.  

However, architects have highlighted that roof vegetation enhances membrane durability by 40 years. That said, vegetated roofs are indeed worthwhile, even that of the blue roof, a type of rooftop that is often equipped with leak detectors. 

A green roof costs between $8 and $15 per square foot. To that, one has to account for the strengthening of the roof structure, since it has to bear the weight of the vegetation.

Asphalt and Gravel Roof 

Asphalt and gravel roofing is almost exclusively used for flat, residential roofs. And the reason for this is that asphalt has a relatively high Sd value. This is the value that determines the degree to which a material is waterproof. Gravel is added on top of the asphalt to protect it from external elements like UV rays.

The durability of this roofing material is between 15 and 25 years. In terms of costs, account for $8 to $10 per square foot. However, costs can vary depending on the province and the price of the oil barrel at the time.

Modified Bitumen or Elastomeric Membrane Roof

Modified bitumen usually comes as bands that will be hot air welded to the roof. Roofers use torches to perform the installation. The initial risk of fire is greater, therefore, it’s important to choose an experienced residential roofer that also has professional liability insurance. 

Said membrane is the underlayment used to waterproof flat, vegetated roofs. Its main feature, besides being waterproof, is that it's used for roof repairs; it’s often enough to just affix a new elastomeric membrane on the old one, and there you, you’re all set.

Also, a simple visual inspection is all that’s really required to determine the presence of cracks or wear. This roofing material lasts between 20 to 25 years and costs $9 per sq. ft. Thus, settling this roofing membrane somewhere roughly in the middle range of materials dedicated to flat roofs.

Metal Roof

Source: Flickr

In Quebec, this type of residential roof is nothing new, and there are three design styles:

• Corrugated metal panels

• Modular panels

• Standing-seam panels

And four different materials: 

• Copper

• Metal

• Steel

• Aluminum

A metal residential roof can last up to about 50 years, maybe even 100 for those made of steel. To extend durability, apply a coating of paint adapted to the material's expansion.

However, it’s quite expensive: the cost is about five times as much as shingles, depending on the roof’s pitch and the type of metal used, making metal roofing a long-term investment. 

Every material has a unique price:

• Copper: $14 to $30$ per sq. ft.

• Metal and steel: $5 to $12 per sq. ft.

• Aluminum: $8 to $12 per sq. ft.

Plastic Roof Panels

This entails a PVC residential roofing method that, as seen among the benefits of TPO, can be hot-air welded. However, this isn’t its only advantage. Plastic roof panels are impermeable, sturdy, light, and cheap. 

Even though it’s a cost-effective solution, its durability is nothing to boast about; it really depends on the quality of the PVC, and the material tends to fade and lose its impermeability over time. Also, bear in mind that the thermal insulation and soundproofing qualities are near zero. 

Asphalt Shingle Roof

Asphalt shingles are roofing materials that will be nailed to the rooftop. These offer superior impermeability and are available in various models and colours. 

Notwithstanding, the average lifespan of asphalt shingles is between 10 to 30 years. This 20-year gap is a direct result of the shingle manufacturing process. As a matter of fact, each and every shingle undergoes oxidation; too much air will make the shingle brittle, while too little air will make it limp. By that, the quality of the shingle will absolutely reflect its durability. 

$3.50 to $7 per sq. ft. Asphalt shingles are one of the cheapest materials out there, without having to compromise much in regard to quality. 

Wood Shingle Roof 

Source: Flickr

In Quebec, wood shingles are in a way the predecessor of asphalt shingles. First used in the 17th century, they’ve fallen out of use. Although more expensive and time-consuming to install, wood shingles have the added benefit of lasting anywhere between 30 to 120 years.

Fir, pine, or cedar shingles tend to last up to 30 years, while those made from larch or chestnut wood last up to 120 years.

The switch to asphalt shingle roofing isn't only due to its cost and quick installation process. Wood shingle roofs have numerous disadvantages; wood shingles are often prone to knots, tendrils, irregularities, or warping caused by excess moisture. All of which lead to waterproofing problems.

This is especially true since the manufacturing technique which consists of cutting the shingles along the wood grain is no longer used. Today, manufacturers prefer to saw shingles. This mere distinction causes the wood to rot. Then, the installation method comes into play; some residential roofers nail the shingles directly to the roof to save time. However, the lack of battens prevents the shingles from being properly ventilated, thus accelerating the rotting process.

When it comes to this type of residential roofing, qualified roofers, who use the right tools and efficient products, are harder than ever to find. Moreover, very few roofers offer this service. 

In regard to pricing, generally, you’re looking at anywhere from $17,000 to $30,00 for a multi-storey home. For a bungalow, prices vary between $15,000 and $26,000.

Source: Flickr

Three units of measurement are used to determine the protection capacity of materials against weather conditions: 

• Thermal effusivity

• Thermal diffusivity

• Thermal conductivity

Thermal effusivity determines the absorption and restitution capacity of a material’s thermal energy.

Then, thermal diffusivity measures the rate of temperature transmission through materials.

And, on the other hand, thermal conductivity determines whether the material transmits heat based on its width and temperature.

To these three notions, we add the speed of transfer of outside temperatures by materials.

Moss, fungi, and lichen are among the vegetation that will inevitably grow on residential roofs. To tackle this problem head-on, there really aren’t that many solutions. You’ll have to climb onto your roof and use either a brush or biocide. 

However, note that biocide products are harmful to the environment. Most contain benzalkonium, a toxic plant chemical that will inevitably drizzle off roofs along with rainwater.

The Kärcher (electric pressure washer) is a solution which is often brought to the forefront. However, it poses significant threats to the roof. Depending on the type of roof you have, using a pressure washer can make the roofing material porous, therefore brittle. This is especially true for clay or slate roofing. Another problem with the Kärcher is that it doesn't actually thoroughly clean the sprayed surface. So your roof will look good and clean once sprayed, but it’s only a temporary fix. 

Using a cleaning brush is a more effective, eco-friendly solution, but it’s much more time-consuming and demands more effort. A stiff cleaning brush paired with a bucket of soapy water is all you need. Proceed by gently scraping the moss to remove it, and then give it a rinse. 

If you don't want it to come to that, you'll need to maintain your roof from the get-go by doing simple things such as removing dead leaves from its surface. Dead leaves cause moss and fungi to grow since it either feeds or spreads the vegetation. So don’t let the leaves the pill up!

Another problem that’s directly linked to leaves: they clog gutters rendering water drainage near impossible. This isn’t as much of an issue with pitched roofs, however, it’s downright lethal for flat roofs. Clogged gutters often lead to rainwater pooling on the roof’s surface, and stagnant water results in the erosion of the roof, which in turn leads to water infiltration.

To ensure your roof is adequately installed, make sure you’re dealing with certified professionals.