Why Build-Up Roofing Has Been Used By Businesses For Over A Century

Posted on: 14 July 2023

If you have a flat or low-slope roof, you might wonder what roofing system is best for your building. One of the options you can consider is built-up roofing (BUR), which has been around for a very long time and is still trusted by businesses for over 100 years.

What is Built-Up Roofing?

Built-up roofing, also known as BUR or tar and gravel roofing, consists of three main components:

  • Ply sheets
  • Bitumen
  • Surfacing

The installation process of built-up roofing depends on the type of bitumen and surfacing used but generally follows certain steps.


The roof deck is inspected and cleaned of any debris, moisture, or defects that could affect the adhesion or performance of the BUR system. Any necessary repairs or modifications are made to ensure a smooth and level surface for the roofing materials.


A rigid foam board insulation layer is installed over the roof deck for thermal resistance and energy efficiency. The insulation is fastened to the deck with mechanical fasteners or adhesive.

The Base Sheet

A base sheet is installed over the insulation to serve as the bottom layer of waterproofing protection for the roof system and provide a surface allowing subsequent sheets to adhere with bitumen. The base sheet can be made of fiberglass, organic felt, or modified bitumen and can be self-adhered, mechanically fastened, or adhered with bitumen.

Ply Sheets

The ply sheets are installed over the base sheet in overlapping layers with bitumen applied between each layer. The bitumen can be either hot-mopped or cold-applied with a squeegee or spray gun. 


The surfacing material is applied over the final layer of bitumen to complete the BUR system. If smooth surfacing is used, a thin layer of bitumen or a reflective coating is applied with a mop, squeegee, spray gun, or roller. 

Time-Tested Technology 

BUR has been used for over a century in the U.S. and has proven its reliability and durability in various climates and conditions. BUR provides multiple layers of protection against water intrusion, weather damage, fire, and UV rays.

Low Maintenance

BUR requires minimal maintenance once installed correctly, as it resists cracking, blistering, shrinking, and puncturing. Regular inspections and repairs are recommended to ensure optimal performance and longevity. BUR is also relatively inexpensive compared to other roofing systems, especially regarding life-cycle costs. 

Built-up roofing is a traditional and popular roofing system for flat or low-slope roofs that provides excellent protection and durability at a reasonable cost. However, you should consult with a commercial roofer on which roof suits your home.

Reach out to local commercial roofing contractors to learn more.