There are certain circumstances where, upon inspection, it’s clear that a flat roof is too damaged to be repaired or re-covered. Damages that would lead to flat roof replacement include cracks, blisters, water entrapment, wet insulation and rotted decking. When these circumstances arise, the only option you have is to replace your roof.

Here are some reasons to consider flat roof replacement:

  • 25% or more of the roof is damaged
  • Insulation is not up to par or is wet
  • The building owner is looking for a long-term solution and wants to utilize the latest technologies


  • Replacing a roof is the best option if an owner plans on keeping the building for the long-term
  • Lower maintenance costs
  • Least likely to have problems going forward
  • Energy savings

Most buildings may never need to replace their roof over the lifespan of a building. The need to replace a roof usually occurs after owners either having less expensive repairs performed to save money, or delay fixing problems until the issue is so bad that a new roof is needed. This especially occurs when the roof has leaks. When water comes in contact with insulation, the insulation absorbs water like a sponge. This moisture will then likely cause the decking to rot out.


If you need to replace your flat roof, your roofing options include:

Built-Up Roof (BUR)

Built up roof membranes (BUR), have been in use in the U.S. for more than 100 years. These roof systems are commonly referred to as “tar and gravel” roofs. BUR systems are generally composed of alternating layers of bitumen and reinforcing fabrics that create a finished membrane.

The number of plies in a cross section is the number of plies on a roof: The term “four plies” denotes a four ply roof membrane construction. Sometimes, a base sheet, used as the bottom ply, is mechanically fastened. Built up roofs generally are considered to be fully adhered if applied directly to roof decks or insulation.

The reinforcing fabrics also are called roofing felts or ply sheets. Roofing felts are reinforced with either glass-fiber mats or organic mats. Felts are produced in a standard width of 36 inches and metric width of about one meter.

Surfacing for built up roof systems include aggregate (such as gravel, slag or mineral granules), glass-fiber or mineral surfaced cap sheets, hot asphalt mopped over the entire surface, aluminum coatings or elastomeric coatings.

Modified Bitumen Roof

This type of roofing is an evolution of asphalt roofing. It is made from asphalt and a variety of rubber modifiers and solvents. There are several ways of connecting pieces of this material. In a heat application process the seams are heated to melt the asphalt together and create a seal. There is also hot-mopped application, similar to how conventional built-up roofs are installed. Cold-applied adhesives and self-adhesive membranes are two of the more recent options. This material is also referred to as APP, SBS, and SEBS.

Single-Ply Roof

Single-ply membranes are factory-manufactured sheet membranes. They generally are categorized as either thermoplastic or thermoset. Thermoplastic materials can be repeatedly softened when heated and hardened when cooled. Thermoset materials solidify, or “set,” irreversibly after heating. Single ply membranes commonly are TPO, PVC or EPDM.

A finished sheet’s thickness typically is referred to as mil thickness; 1 mil equals 0.001 inch. Common mil thicknesses for these sheet membranes range from 30 mils, 60 mils and 80 mils.

Single-ply membranes can be installed fully adhered or mechanically attached down. Most single-ply roof systems do not receive surfacings.

In many instances, a combination of attachment methods are used to secure a roof system. For instance, an insulation may be mechanically attached to the substrate with the roof membrane fully adhered to the insulation.

If you need a flat roof replacement, the experts at Dolphin Roofing will help you find the right new roofing solution for you. Contact us today for a free estimate!