A built up roof system is a popular choice for buildings with low-slope or flat roofs. Often referred to by the acronym BUR, this system has been used for 100-plus years in the U.S.

What makes BUR systems so popular?

They are known for providing excellent protection due to their redundant nature because they are made up of multiple layers of ply sheets and asphaltThese layers are then topped off by a cap sheet or a flood coat of asphalt and granules. The multiple plies provide resistance to weather and heavy-duty protection for the building.

Components of a Built Up Roof System

Built up roof systems can be constructed in a variety of ways.

Often, the built up roof system starts with a base sheet installed over the polyisocyanurate insulation or cover board, typically through the use of mechanical fasteners.

Built up roof systems can be constructed in a variety of ways.

Often, the built up roof system starts with a base sheet installed over the polyisocyanurate insulation or cover board, typically through the use of mechanical fasteners.

The base sheet serves as the bottom layer of waterproofing protection for the roof system and provides a surface that will allow subsequent sheets to be adhered with hot asphalt.

A layer of asphalt is applied over the base sheet for the installation of reinforcing felt, sometimes called a ply sheet. Many people picture kettles of hot asphalt being mopped onto the base sheet in order to install the ply sheet, but advances in manufacturing have created alternative options. For instance, contractors can choose to use cold-applied adhesive solutions instead of hot mopping asphalt and kettles.

When saturated in asphalt or cold-applied adhesive, the reinforcing felt creates a barrier that provides additional resistance to water intrusion.