Built-Up Roofing (BUR)


Built-Up Roofing, or BUR, is one of the oldest roofing systems available — invented over 100 years ago. It is the most common roofing material used on low-slope roofs. It can also be known as “tar and gravel”, coal tar, or asphalt and gravel. It is the preferred system for low-slope or “flat” roofs because it will create a continuous sealed surface. 

Built-Up Roofing: Quick Summary

  • Extremely durable roofing system, due to the multiple layers used, offering high protection
  • BUR lifespan lasts a long time
  • One of the most cost-effective roofing systems available today
  • Exceptional performance during varying Canadian Climate
  • Low maintenance and easy to repair
  • Energy efficient
  • Most popular choice to use on low-sloped, flat roofs
  • Provides outstanding waterproofing and protection against UV rays

What is a built-up roof (BUR)?

Coal tar is a byproduct of the coal manufacturing process, and it makes a great water and oil resistant material. In warm temperatures, this material can soften and “heal” itself. The warmer the temperature, the easier it is for the coal tar membrane to adjust to changing conditions and seal any minor rupture or abrasions. This helps keep it resistant to leaks.

Built-up roofing systems offer added protection of multiple layers that perform well in all types of weather. It is composed of alternating layers of reinforcing fabric and bitumen (asphalt), and is finished with a top layer of aggregate, like stone or gravel. 

The special fabric used with BUR is typically reinforced with fibreglass or organic materials. Each of these ply sheets is laid over hot or cold bitumen to bond to the roof. 

After those layers are complete, surfacing materials will form the top layer. These might consist of small stones or fine gravel. This layer helps to provide the finished look and protect the layers beneath from UV rays and damage from debris. It also serves the purpose of making the roof safe to walk on.  

Why Choose Built-up Roofing?

The main factor that makes built-up roofing so attractive is that once installed properly; it provides a hassle-free roofing solution. A reliable and durable roof that should last you 20+ years if properly maintained. Additionally, the maintenance and life cycle cost of BUR is low.

It’s important to hire professionals who will do detailed work, as the application process requires it. A professional will pay attention to details such as curbs, walls, flashings and other projections that interrupt the membrane. This will help to achieve quality, efficient, long-lasting roofing for your commercial building.

While many other roofing systems are available, many commercial building owners still go with built-up roofs because it is the most tried and true option.

Types of Built-up Roofing: Cold vs. Hot

While BUR has been around for years, its installation and its materials have evolved during its time. These days, built-up products integrate an insulation layer for improved energy efficiency. 

The bitumen used during the installation can either be “hot” or “cold.” “Hot” means that the bitumen has been heated so that it is liquified during installation. Or it can be “cold,” meaning that it is more of an adhesive while installing. Cold built-up roofing is sprayed or applied with a squeegee, and it will not give off toxic fumes during application and is not dependent on the weather. Cold built-up roofing also offers better performance than hot built-up roofing. 

Advantages of Built-up Roofing

Guaranteed Performance

BUR has been used for a long time, and it is still the preferred option compared to newer types of systems. It has proven its reliability and trustworthiness as a roofing system.

Durability & High Tensile Strength

Due to its layered structure, it can handle stress and does not become easily damaged under pressure. It is also resistant to abrasion, all thanks to its self-healing properties.

Weather Resistant

BUR can be modified to suit different climates. It can be made available as wind, fire and hail resistant, making it suitable for all weather conditions.

Low Maintenance

Because BUR has high durability, it does not require high maintenance. Annual inspections are enough upkeep.


While initial costs of installing are high, BUR ends up being more cost-efficient in the long run because of the lower maintenance costs and repairs. 

Variety of Finishing Options

BURs has various options for surfacing, for example, gravel finish or smooth, coloured finish. Many people go for lighter shades because of their energy-saving ability.

Disadvantages of Built-up Roofing

  • Has a slower installation process.
  • Has a higher initial cost for installation.
  • If going with the “hot” application method, there will be fumes during the installation.
  • Requires a larger set-up area during construction.

Basic repairs of Built-up Roofing

If your BUR undergoes any damage, it is vital that you get it repaired right away to prevent further damage to the roofing and construction materials below. Most of these common problems have relatively simple repairs. 

  • Open Joints – To repair open joints or seams that have separated, cement is added under the abrasion to adhere to the substrate. 
  • Blisters – Small blisters can be repaired by cutting them open with a knife and letting them dry out. Then, the felt layer and asphalt can be replaced.
  • Undulations or Waves – These are repaired by simply adding a layer on top of the area to level it.
  • Cracks – Cracks on the asphalt surface are an easy fix. Apply a few coats of asphalt and roofing felt to the area and cover with a layer of gravel on top of cement.

Contact Aimed Group for Your Commercial Roofing Services

If you live in Toronto or the Greater Toronto Area and are interested in Built-up Roofing (BUR) installation services, call us at 905-505-0162 or contact us here

We strive to provide sustainable commercial roofing solutions to the Toronto area. As a local company, we want the commercial roofing we install to last for generations and be safe and durable for our friends and neighbours to enjoy for life.


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