8 Important Benefits of Roofing Underlay

In this article, you will learn:
1. What is Roofing Underlay?
2. The 3 Main Types of Roofing Underlay
3. 8 Important Benefits of Roofing Underlay

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A strong and reliable roof is one of the most important features of your home.

As the primary defense against the outdoor elements, animals and pests – your roof is made up of a system of structures that work together in keeping your home comfortable, dry and secure.

While the advancement of modern roofing has helped Canadian homeowners optimize the safety of their homes, there are a variety of roofing parts that many people are not as familiar with – such as the roofing underlay!

At T. Simpson Roofing Ltd, we encourage product education to help our clients get the most out of their roofing structures.

The following sections will help you understand the purpose of roofing underlay, the 3 main types of materials used, and the 8 important benefits they can provide to your home.

What is Roofing Underlay?

Roofing underlay is the protective barrier installed between the framing materials and the top layer of shingles.

Also referred to as “shingle underlay”, the key purpose is to prevent the risk of leaks, mold and water damage from entering your home.

For over 25 years, major organizations such as the National Roofing Contractors Association (NRCA) and the Canadian Asphalt Shingle Manufacturers Association (CASMA) have encouraged the use of roofing underlays to meet the needs of residential waterproofing and building code requirements.

Traditionally, roofing underlayments were made of heavy black felt with an adhesive layer of asphalt to bond to the shingles.

Today, modern technology has introduced a variety of alternatives to optimize protection based on specific weather conditions.

At T. Simpson Roofing, we pride ourselves on matching homeowners to roofing solutions that will extend the overall lifespan of their roof, and minimize the need for maintenance and repairs. With a variety of options to choose from, it’s important to consult a roofing professional to ensure your home will be protected well into the future.

The 3 Main Types of Roofing Underlay:

In today’s market, there are a variety of underlayment materials to choose from.

While each option has its own set of pros and cons, most available products are often divided into three main categories: asphalt-saturated felt, rubberized asphalt, and non-bitumen synthetics:

1. Asphalt-Saturated Felt Underlay

Asphalt-saturated felt underlay is the longest-standing and most affordable option on the market.

Also referred to as “felt paper” or “tar paper”, roofing felt is often made from various combinations of asphalt, natural plant fibers, polyester, bitumen, and fiberglass to enhance strength and water-resistance while still allowing the structure to breathe.

Available in 15- or 30-pound variations, the felt is often fastened with staples or attached to high-wind areas using plastic caps.

It is important to note, however, that while felt underlay may be water-resistant, it is not waterproof.

An excellent option for steeply sloped roofs where the water can drain, felt underlays are not ideal for flat surfaces where water can seep in, infiltrate and damage your roofing structure.

– Budget-friendly
– Water resistant
– Ideal for sloped roofs

– Not completely waterproof
– Not ideal for flat roofs
– Asphalt can wear down over time, or with direct UV exposure
2. Rubberized Asphalt Underlay

Rubberized asphalt is one of the newer, more enhanced underlay options on the market.

While the name is misleading, many modern manufacturers have opted to exclude the use of asphalt, turning instead to various combinations of recycled rubber, polyethylene, polyester and even fiberglass for extra reinforcement.

Applied in large panels, rubberized asphalt is heat-fused into one seamless membrane that is able to fill in cracks and create an air-tight seal around staples and nails.

With rubber-like flexibility, rubberized asphalt is considered to be an ideal choice for climates with extreme temperatures as they are waterproof, self-adhesive, resistant to UV rays and easy to customize for oddly-shaped roofing sections.

Although these waterproof materials make them one of the more expensive options on the market, they are very easy to install and repair, which helps to keep professional installation and maintenance expenses low.

– Durable and waterproof
– Self-Adhesive
– Low installation and maintenance expenses

– Can be expensive
– Not all are resistant to fire

3. Non-Bitumen Synthetic Underlay

In recent years, non-bitumen synthetics have become one of the top choices for Canadian roof replacements.

Made from thermoplastics such as polyethylene or polypropylene, non-bitumen synthetic underlays are known for being highly waterproof, flexible, mold-resistant and strong.

Although they might seem similar to rubberized asphalt underlay, the major difference is the use of synthetic materials which make them extremely lightweight, long-lasting and resistant to fungus and UV exposure.

While non-bitumen synthetic underlays receive higher performance ratings than their alternatives, they are not completely without flaw.

With the use of synthetic materials during the manufacturing process, this highly effective underlay material is more expensive and less budget-friendly than its alternatives.

– Waterproof
– Lightweight and long lasting
– Resistant to fungus and UV exposure
– Non-skid

– Manufacturing materials can be expensive

8 Important Benefits of Roofing Underlay:

Adding a layer of protection between your structural roof frame and roofing shingles has proven to not only improve the lifespan and durability of your roofing structure, but it can also improve your quality of living.

While underlays are often the silent heroes of residential roofing, here are the top 8 important benefits they provide to your home:

1. Curb Appeal:

While your roofing structure might not sit completely flat on its own, roofing underlay can create an even, uniform surface to install your roofing shingles.

With a clean aesthetic, your roofing underlay can support your property’s overall curb appeal.

2. Fire Safety:

In order for shingles to meet their Class A fire requirements, it is important to choose underlayments that are approved by industry-standard compliances such as the Canadian Standards Association (CSA).

If you are unsure, be sure to speak with a roofing professional before renovating your roof. 

3. Weather Protection:

While your shingles are often the first line of defense against the outside elements, your underlay functions as a backup layer to protect your roofing structure as well as the inside of your home.

In the case where your shingles start to deteriorate, this extra layer of protection will save you from water damage, mold, and unnecessary repairs.

4. Moisture Barrier:

While not all underlay materials are waterproof, most of them are at least extremely water-resistant.

When choosing the best underlay option for your home, it is important to consider the shape, slope and local climate to ensure your roof is effectively protected.

5. Energy-Efficiency:

While shingles can crack, break and deteriorate over time, your roofing underlay can add an extra layer of insulation that prevents air from entering or escaping your home.

As a result, this extra line of defense can also save you unnecessary energy expenses in the long run.

6. Protection from Ice and Water Damage:

With harsh Canadian winters, excess snow, rain and ice formations can put a strain on your roof.

While this extra weight would typically lead to leaks, mold and water damage, this water-resistant membrane will seal around the frame to prevent water from entering and damaging your home.

7. Protects the Roof Deck:

Much like a tarp or saran wrap, roofing underlay fits perfectly over the roofing frame to prevent the risk of water or air infiltration.

By protecting the roof deck, the roofing underlay can protect the wood from the elements, mold, and damage.

8. Increases Peace of Mind

With harsh winds, rain, and snow – it is not uncommon for Canadian homeowners to worry about their roof during extreme weather.

By having your underlayment installed with a certified professional, you and your family can rest assured that your roof will remain strong and reliable for many years to come.

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If you are interested in learning more about your roof replacement options, our professionals at T. Simpson Roofing Ltd. offer the largest GAF Certified Roof Replacement Services in Canada!

Click here or call 1-800-925-3044 for more information.

T. Simpson

Originally founded by a 16-year-old Tony Simpson as a way of acquiring funds to help pay his way through university, T. Simpson Roofing, propelled by Tony’s strong work ethic and commitment to delivering quality work and unbeatable customer service, quickly grew into a thriving business.

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