diene monomer). “Depending on
which particular membrane you’re
using, you have different degrees
of chemical resistance,” Graham
explains. “Single plies have the
ability to be just about any color
and could give you reflectivity.”
Modified bitumen: These roof-
ing materials combine a bitumen
(usually asphalt) with a polymer
modifier and a reinforcement layer.
They sometimes come with gran-
ules or foil laminates on the sur-
face to provide extra protection.
Built-up roofing: Often abbreviated as BUR, built-up roofs are
created by alternating layers of
bitumen (most commonly, asphalt
or coal tar) and reinforcing fabric.
“Built-ups and modifieds are gen-
erally more durable because there
are more layers to them,” says
Graham. “If you have a lot of foot
traffic on a roof, that could be the
best way to go.”
Metal panel systems:
Architectural metal panels are
used for residential roofing, but
commercial buildings are more
likely to use a structural metal
panel roof system. They’re strong
and can be crafted in nearly any
color, Graham notes. It’s also rela-
ROOF TYPE WHAT TO CONSIDER
Built-up roofing (BUR) Tough and puncture-resistant because of the multiple plies used.
Creates a continuous layer.
Some asphalt products have to be heated for application. Hot-applied BUR shouldn’t
be installed in cold or wet weather.
Some installation processes involve fumes, which could pose a problem for occupied
Asphalt is normally dark-colored – if you need a cool roof, look into coatings,
membranes or light-colored ballast.
Single-ply membranes Many types of membranes that include different substances to achieve certain
Usually installed in one layer.
Flexible and UV-resistant.
Normally not compatible with other roofing systems.
Modified bitumen Several layers, including base sheets or plies, modified bitumen membranes and
Durable and flexible.
Some types require welding with a torch, which can pose a fire risk. Flame- and VOC-
free versions are available.
Often black, but surfacing may be available in cool/reflective colors.
Metal panels Long lifetime.
Available in virtually any color.
Designed to allow thermal movement when metal expands and contracts.
High seams provide watertightness and wind uplift.
Spray polyurethane foam Combines a layer of spray foam insulation with a protective coating or membrane.
Punctures typically don’t penetrate the full thickness of the foam.
Can fill gaps in the existing roof/substrate.
Application requires a professional who understands the chemical reaction that
produces the foam.
Don’t install during cold, windy or rainy weather.