Roof Types
Published On:  March 29, 2022
Residential Flat Roof

There are 3 different types of commercial or flat roofing:


1. Built-up Roofing

 Built-up roofing, also called BUR, has been since around the 1840s.  It is made up of alternating layers of reinforcing fabric and bitumen.  It is used in low slope      roofing such as commercial flat roofing.  There is also generally an aggregate layer on top such as stone or gravel.  This type of roofing has good waterproofing and also is protected from the elements such as UV due to its aggregate layer.

It can last between 15 – 30 years and may even last up to 40 years if well maintained.


2. Modified Bitumen Roof

Modified Bitumen was the next advance from Built-Up Roofing and first appeared in commercial roofing around the 1960s.   These membranes are composed of asphalt that is combined with a rubber or plastic membrane.   There are two main varieties APP and SBS.   Modified Bitumen has several advantages over Built-up roofing.  It isn’t as heavy and is easier to repair.  It also has a reasonable life expectancy that can be increased with regular roof maintenance.

Modified bitumen membranes usually come in rolls that are either heat welded or cold-adhered and can sometimes be mechanically attached as well.

Two Types:    SBS and APP

SBS and APP roofs can last between 20-40 years with regular roof maintenance.


3.  Rubber Membrane Roof 

There are 3 main types of rubber roof membranes:

  • EPDM or Ethylene propylene diene monomer is a rubber roofing membrane that usually comes in black.  It can be fully adhered, ballasted, or mechanically attached.  It stands up well to UV radiation and harsh temperatures.    It comes in various thicknesses ranging from .045″ to 0.90″.  EPDM roof membranes can last up to 50 years if properly installed and maintained. Because it is made of rubber, it provides an excellent water proof barrier.

  • TPO or Thermoplastic Polyolefin is a single ply rubber roofing membrane that can be ballasted, mechanically fastened, or chemically adhered.  TPO comes in 10, 12, and 20 foot wide sheets. TPO is generally white but does come in other colors usually at an increased cost.  TPO reflects UV rays and is impact and weather resistant. The seams are hot air welded.   TPO roofs can last up to 30 years if well maintained.

  • PVC or Polyvinyl chloride is a synthetic polymer of plastic.  PVC is a single ply roof membrane that is very strong and durable.  PVC can be installed by heat welding the seams.  It is impervious to chemical and water leaks and provides UV protection.  PVC roofs can last up to 30 years and are relatively easy to repair.


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