Top 3 Flat Roof Systems

Nowadays, houses and cottages can be quickly built with a second and/or third floor — without needing an attic — to add an additional area. Thanks to the growing technologies and better building materials, this type of construction is also energy-efficient, allows flat roofs to endure the test of time, and reduces residential house building costs considerably.

The main advantages of flat roofs include their low-cost, time-saving project, reliability, and durability. For instance, if the cost of arranging a pitched roof it’s about 20%-50% of the total cost, then investments in flat roof materials will be determined by the costs of strengthening the upper floor.

Flat Roof Types: Single-Ply, Built-Up Roof, Modified Bitumen

Property owners can choose among different types of flat roofs: Single-Ply (EPDM / TPO / PVC), Built-Up Roof (BUR), and Modified Bitumen (MOD-BIT).

Let’s dive into what they are and what the pros and cons they have:

#1 Single-Ply (EPDM / TPO / PVC)

Ethylene Propylene Diene Monomer (EPDM) is a true rubber. The polymer membrane has become increasingly used in roofs thanks to their high reliability, rich color palette, adaptability to different temperatures (low or high), and durability (life span of up to 50 years). What’s more, the EPDM rubber covering is made from environmentally-friendly materials. It can be mechanically anchored with fasteners, ballasted with stone, or glued. In addition to a rubber base, composite flat roof replacement materials are also available. Their upper layers are traditionally rubber, while the lower layer is flexible bitumen-polymer.

Pros:

The coating is resistant to any weather conditions.
EPDM roofing is durable (life span is 30 to 50 years).
It differs from other membranes with increased elasticity (about 400%) and lower cost.
Leaks are easy to patch.
The material’s relatively light yet highly resistant to scuffs and tears.
Easy to install and lower maintenance costs.

Cons:

The standard black material tends to absorb rather than reflect heat, and light-colored coatings (recommended in warm climates) add 30% or more to the cost.
It’s more vulnerable to punctures than other flat roof systems.

Thermoplastic Polyolefin (TPO) is becoming one of the preferred materials for flat roofs. This rubber membrane type is usually a blend of polypropylene and ethylene-propylene rubber. It has three layers bonded together: a thermoplastic polyolefin base layer, a polyester-reinforced layer (aka scrim), and a thermoplastic polyolefin top layer.

It has become popular due to its cost (it’s one of the least expensive roofing materials available) and its superior performance. And thanks to its popularity, there are different kinds of TPO available. While white has been the color that is used most commonly, you can find membranes in gray or black (this is not only for design considerations but also for how much the roof will contribute to the structural energy efficiency). Different manufacturers produce TPO in various thicknesses and widths to suit the roofing project’s needs. Commercial-grade roofing TPO is typically thicker but more narrow, and residential-grade roofing TPO is thinner but often longer and wider.

Pros:

It reflects heat and is energy efficient.
It can be installed on both residential and commercial properties.
It’s flexible and light, allowing easy installation and maintenance.
Generally, roofing experts estimate a TPO roof will last 10 to 20 years.

Cons:

You can find different quality variations at the same price.
Less costly TPO roofs are known to develop surface cracks rather quickly.
The seams are often areas where the membranes become loosened, leading to water leaks in the roof.

Polyvinyl Vynil Chloride (PVC) roofing is a single-ply roofing membrane that has been used on flat roofs, besides low-sloped roofs, for more than 50 years. It’s a commonly used polymer that finds applications in a variety of products due to its excellent properties and low cost.

A PVC roof consists of two layers: polyester is added between the layers to serve as support. These layers have additives that give the roofing material flexibility and other benefits. Also, PVC membranes are innovative waterproofing flat roof materials.

Pros:

Strong and long-lasting (longer than 20 years).
Resistant to chemicals and other hazards.
It’s sturdy and elastic, making it an excellent option for rough and deformed surfaces/
PVC membranes meet all fire safety requirements.
Reduces the main structure load thanks to its lightness.
A single-ply membrane simplifies the process of covering.
Ease of installation makes it possible to conduct the repair in almost any weather condition.
High vapor permeability eliminates the possibility of condensate moisture stagnation.

Cons:

Requires complete removal of the old roof.
Problems occur with age and climate.

#2 Built-Up Roof (BUR)

Built-up roofs have been known for solving the low-pitch roof problem for ages — a challenge that asphalt shingles could never handle.

A built-up roof comprises three (or more) layers of waterproof material, alternated with hot tar and ballasted by a layer of smooth river stone on top to protect the built-up roof assembly from UV light and weather. Also, these roofs gradually use more advanced materials, such as fiberglass membranes. Depending on the climate and the specific materials used, built-up roofing has a life span of 15 to 30 years (it tends to fare better in warmer temperatures than in cold regions).

Pros:

A life span of 15 to 30 years.
Durability due to gravel use.
Several types of built-up roofing for any demand: smooth and ballast asphalt, cold layer, etc.
Protection against water, ultraviolet rays, fire retardant, and adverse weather conditions.

Cons:

Extremely heavy.
Installation takes a lot of time.
Joists sometimes have to be strengthened.
Challenging to repair.
Gravel can clog gutters and scuppers.

#3 Modified Bitumen (MOD-BIT)

Modified Bitumen Roof (MOD-BIT) roof systems are a single-ply material with a mineral-based outer surface. Initially, these systems required heating the adhesive with a torch as the material was unrolled, but nowadays, newer peel-and-stick options are more manageable and safer.

MOD-BIT roofs are an evolved version of asphalt roofing. This modified version creates a better seal than asphalt and comes in self-adhering forms requiring no sealing heat. They are also moderately priced and energy efficient, as their light color reflects heat.

Pros:

Its light-colored mineral surface reflects heat and cuts energy bills.
Its price is affordable.
They are applied in overlapping reels to create large seamless areas.
Available in a variety of easy application methods.
Requires low maintenance due to its durability.
It provides better elasticity and flexibility at low temperatures.
It provides better durability than BUR, with the same ease of installation as EPDM.

Cons:

Some application methods require an open flame/burner, which requires special safety measures.
Overlapping seams must be properly glued to prevent possible water leakage.

What is the Best Material to Use for Flat Roofs?

EPDM is one of the most popular materials for flat roofs. It’s one of the most affordable materials and has long-last durability (up to 50 years). Since it uses polymer and synthetic rubber, it provides the roof with excellent flexibility and elasticity. TPO is another popular material for flat roofs, thanks to its affordability, easy-to-install method, and white color that helps improve a property’s energy efficiency.

What is the Longest-Lasting Flat Roof Material?

There’s no doubt that EPDM is known as a long-lasting flat roof material. It’s designed to withstand a flat roof’s most extreme weather conditions. Thanks to its permanently flexible and highly resistant to UV and infrared light and acids from rainwater, its durability can help it last at least 30 to 50 years.

What Is the Best Flat Roofing System?

Choosing the right flat roofing system for your property depends on various factors, such as its design aesthetics, budget, location-specific environment, local building codes, and more. Compared to traditional roofing materials (like asphalt shingles or metal walls roofing), flat roofing is often unfamiliar to homeowners or business owners.

Flat roofing decisions usually require the assistance of a roof services corporation and a professional roofer to explore the options that will provide the most benefit for the most affordable cost. The proper experience and knowledge to install and maintain a flat roof are crucial to ensure it performs well.