There are five generic classifications of low-slope roof membranes or systems. Most low-sloping roofs have three components that protect your roof.

There are five generic classifications of low-slope roof membranes or systems.

  • Built-up roof (BUR)/ four-ply membranes
  • Modified bitumen two-ply membranes
  • Inverted
  • Single-ply membranes
    • Thermoplastic membranes (e.g., PVC, TPO)
    • Thermoset membranes (e.g., EPDM)

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Most low-slope roof membranes have three principal components:

  • Weatherproofing layer or layers — the weatherproofing component is the most important element because it keeps water from entering a roof assembly
  • Reinforcement — reinforcement adds strength, puncture resistance and dimensional stability to a membrane
  • Surfacing — surfacing is the component that protects the weatherproofing and reinforcement from sunlight and weather. Some surfacing provide other benefits such as increased fire resistance, improved traffic and hail resistance, and increased solar reflectivity

With some roof membranes, a component may perform more than one function.

There are three classifications of low-slope roof membranes/systems. Most steep-sloping roof systems are comprised of individual components.

There are three generic classifications of steep-slope roof coverings.

  • Asphalt shingles
  • Synthetic slate
  • Cedar shakes

Steep-slope roof systems typically are composed of individual pieces or components installed in shingle fashion. Steep-slope roof assemblies typically consist of three primary parts:

  • Roof deck — a roof deck is the structural substrate and usually is a wood-based material such as plywood or oriented strand board (OSB).
  • Underlayment — underlayment provides temporary protection until a roof covering is installed and provides a secondary weatherproofing barrier. Sometimes underlayment is referred to as “felt” or “paper” but can include ice and water shield, synthetic or organic felt paper type membranes.
  • Roof covering — the roof covering is the external water-shedding material


Elite Roofing services the following regions:

Halton HillsMarkhamMiltonMississaugaNewmarket
OakvillePickeringRichmond HillTorontoVaughan

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There are various reasons why roof repairs, recovery or replacement might be chosen in a certain specific situation. Some of these considerations are, as follows:

  • Cost factors – BOTH life cycle costing and immediate cost outlays need to be evaluated
  • Third party pressure by purchasers, mortgage lenders and/or CMHC as a third party mortgage insurance provider – to take specific action upon a change of ownership or re-financing of a property
  • Building use or anticipated change in use – removal and replacement of existing roofing involves more potential disruption to the building occupants as a result of dust and debris, whereas, roof recovery is less likely to generate as much dust and debris inside the premises
  • Inspection and testing – where there is evidence of extensive soiled insulation and specifically defective substrate then roof replacement becomes more worthy of consideration. It is often difficult to determine the extent, if any, of damaged substrate and complete replacement affords the best assurance that no moisture or rotten, damaged or corroded substrate will remain
  • Roof drainage – the extent of ponding water issues on a roof will sometimes dictate the type of roof system specified to allow for improved drainage. There are fewer possibilities to improve drainage during a roof recovery than with a roof replacement
  • Rental of roof space – when the roof surface will be leased to a third party for placement of solar photovoltaic (PV) systems, cellular antennas and transmitters, green roof areas and terraces or vegetative greenhouses etc., then longer term solutions might be more important due to the excessive costs and loss of income to remove the overburden during the period of time to replace the roof. Many solar PV contracts are 20 years in duration and this necessitates a longer term horizon.

There are a number of options to alleviate ponding water, as follows:

  • The “best” solution is to positively slope the roof structure to the drain locations but this is often not possible with older buildings that were constructed with flat or relatively flat structures
  • The next best option is to design a tapered roof insulation system but this can be very costly
  • A third alternative is to add roof drains at areas of ponding water
  • A fourth alternative is to install perimeter tapered insulation and/or drain sumps when considering a roof replacement
  • “Elite Advantage” – we work closely with a service plumbing contractor and can custom design a roof drainage solution for most buildings. Over the past 10 years we have installed hundreds of roof drains over finished office, commercial and residential premises.
  • We offer interior tarping or water diverter tarping services on an as-needed-basis when working over sensitive production, equipment or inventory storage areas at an additional cost.

    • These services can be arranged for off-hours to limit the interference with production schedules
    • Tarps are suspended from warehouse structural joists with bungee cords and/or nylon rope and water is discharged through hoses to disposal containers.
    • The advantage of water diverter services occurs when:
      • Leaks cannot be repaired until there is a production shut down scheduled or re-tooling period
      • Winter conditions prohibit the completion of permanent repairs
      • There is a delay between the date of roof leak assessment and approval of permanent repairs or the start of roof replacement or recovery


There are five major membrane options to choose from when deciding which roofing system is right for you. We give you expert recommendations based on our years of experience in order to reach your roofing goals. Click below for our full materials list.