Flat Roofing Systems Overview

Flat roofing systems come in many different types, colors, and thicknesses. But what is the difference between them? The 5 most common types of roof systems are below. Click on the tabs to get more information on each system.

 

TPO (Thermoplastic PolyOlefin)

Finished TPO Complex

Years Used as Roofing Product Over 30 Years
Base Product Polyolefins (Polypropylene,Polyethylene) / Plastics
Color White, Gray, Tan + Pallet of colors over 100,000 Square Feet
Temperature Impact on Roof Cools Roof
Seaming technology Heat Welded
Thicknesses .045 to .080
Reinforced Always Reinforced
Puncture Resistance Good to excellent, depending on thickness
Chemical Resistance Good
Environmental Impact Excellent
Slippery With Moisture Yes
Known Problems Effective welding requires experience.

EPDM “Rubber” (Ethylene Propylene Diene Monomer)

EPDM Membrane CoverPhoto

Years Used as Roofing Product Over 50 Years
Base Product Synthetic Rubber
Color Black, White (At price premium)
Temperature Impact on Roof Heats roof (Unless white)
Seaming technology Since 1980, 3” or 6” Seam Tape.
Before 1980, liquid adhesives
Thicknesses .045 to .090
Reinforced Reinforced or Non-Reinforced
Puncture Resistance Good to excellent, depending on thickness
Chemical Resistance Poor
Environmental Impact Moderate
Slippery With Moisture Yes – Moderate
Known Problems
  • Seams come apart over time.
  • Grease and other chemicals deteriorate product.
  • Creates hot environments for rooftop equipment.

PVC “Vinyl” (Polyvinyl Chloride)

PVC Coverphoto

Years Used as Roofing Product Over 50 Years, but formula has changed dramatically over time
Base Product Vinyl / Plastics
Color White, Gray, Tan
Temperature Impact on Roof Cools Roof
Seaming technology Heat Welded, with earlier systems using solvent welded seams
Thicknesses .036 to .090
Reinforced Always Reinforced (Older non-reinforced systems could shatter)
Puncture Resistance OK to Good, depending on thickness and manufacturer
Chemical Resistance Excellent
Environmental Impact Poor – is actually banned in some countries
Slippery With Moisture Yes -Very
Known Problems
  • Older products shattered under colder conditions.
  • Newer products still shatter, but reinforcement contains it to smaller areas.
  • Shrinks over time causing numerous issues.
  • Expensive compared to other single ply products.
  • Many concerns with fire resistance and fumes emitted when burned.
  • Effective welding requires experience.

Modified Bitumen (Mod-Bit)

Completed Modified

Years Used as Roofing Product Over 50 Years
Base Product Asphalt with modifiers (APP and SBS)
Color Wide variety of colors readily available
Temperature Impact on Roof Dependent on color used
Seaming technology Depends on Installation Method. Typically adhered with hot asphalt or cold adhesives.
Thicknesses 2-5 plys
Reinforced N/A
Puncture Resistance Outstanding
Chemical Resistance Good
Environmental Impact Moderate
Slippery With Moisture No
Known Problems
  • Very Expensive
  • Cracks and pulls apart without granules or other protection from sun
  • Some application methods, like torch down, are extremely hazardous and unsafe

 

Built Up Roof (BUR)

BUR Roof Overview

Years Used as Roofing Product Over 150 Years
Base Product Asphalt or Coal Tar Pitch
Color Black, Often Graveled
Temperature Impact on Roof Heats Roof
Seaming technology Mopped down with hot asphalt
Thicknesses 2-5 plys
Reinforced N/A
Puncture Resistance Outstanding
Chemical Resistance Good
Environmental Impact Moderate
Slippery With Moisture No
Known Problems
  • Incredibly high cost
  • Cracks and pulls apart without protection from sun
  • Mopped down installation method is very unsafe
  • Asphalt products don’t last as long as they used to