Inspecting Modern Flat / Low Slope
Roof Coverings
When I first started conducting home inspections many of the
flat or low slope roofs were covered with roll asphalt for residential
applications or built up roofing for commercial. Although some people may still
use roll roofing, and it may have its place; most modern flat roof coverings
are made from newer, more durable, and more waterproof materials. Some of the
materials that are commonly used for flat roofs are IRMA – Inverted Roof
Membrane Assembly which is widely used for commercial applications. Normally
you would not see this on a residence. IMRA incorporate insulation in the
assembly and have a protective coating that may contain gravel. Modified /
Polymer Bitumen which can be Atactic Polypropylene or Styrene Butadiene Styrene
is a rubber like compound that is installed in sheets. Elastomeric or EPDM are
sometimes called rubber roofing. PVC or plastic roofing materials are also
available. These types of materials are most common for modern flat roofs. Some
bitumen coverings may be prone to damage from the sun’s rays unless they are
coated with ultraviolet protection. Bitumen materials can also be reinforced
with fiberglass. Flat roof covering materials can be applied by heating (torch
down), peel and stick, or glued down. It will be difficult for a home inspector
to identify the different types and specific materials of bitumen. We normally
refer to these types of coverings in our reports as a “Single Ply Membrane.”
Here are some of the things home inspectors should be looking for when
inspecting single ply membranes on flat roofs:
·
Seams facing the wrong direction which could
cause water entry
·
Cracking or splits in the membrane
·
Blisters / wrinkling
·
Any areas that have been repaired or patched
·
Seams that are not overlapped at least 3 inches
·
Areas that have “bubbled” or are not properly
attached to the substrate
·
Ponding / standing water
·
Any puncture or tear in the material
·
Side & end laps should be staggered
·
Flash points especially around air conditioning
systems due to vibration
·
Flashing around parapets
·
Flashing around skylights
·
Flashing around any roof drains
·
Examine any drains that travel through the
interior from underneath if possible
·
Ensure the water is draining properly including
the drainage system / gutters
