What is a modified roof system?
Modified bitumen roof systems can be installed with the common torch method, asphalts, or cold adhesives. A standard SBS modified bitumen roof system is a two-ply system applied in rolls that overlap the edge of the previous roll.
PROS
There are several different advantages to using a bitumen roof on
your building or home. Unlike some newer types of roofing, it has a
long, proven track record that can be counted on. Bitumen roofs are one
of the longer lasting types of flat roofing materials, easily lasting 20
years or more.
Regardless of how the material is applied (self-adhesive sheets,
hot-mopped asphalt, or cold-applied adhesives) the seams are usually
melted together which help stop leaks. Other types of membrane roofing
have seams that are left open or covered with another material that can
weaken over time, so the fact that a bitumen roof can be seamless is a
big advantage.
Bitumen roof is also very durable. They have a high-tensile strength
so they are unlikely to develop the kinds of cracks that other flat and
membrane roofs are known for. They are also rated against wind, fire,
and hail so they are unlikely to be damaged in the event of a storm.
Included in this is usually a very long manufacturer’s warranty that can
help to guarantee the roof’s longevity.
CONS
Like all roof types, a bitumen roof does have some drawbacks. The
first is their black color, which can absorb rather than reflect heat.
And while the material itself may not be damaged by heat or UV rays, if
proper insulation is not used with it, this absorption of heat can lead
to superheating of the building below.
Bitumen roofing is also available in 1, 2, or 3-ply. The 1-ply
material is not durable, and if used can pose certain problems such as
breaking down prematurely, while the 2 and 3-ply material roofs cost
significantly more to install, which can make this one of the most
costly types of flat roofing products around.
Granules need to be included as part of the installation process to
help protect the roof from the sun. If they are not included, this can
further raise the temperature of the building or damage the roof.
Unfortunately, not all types of bitumen roofs include granules as part
of the installation process.
Finally, if your roof is likely to hold a lot of water or to gather
puddles of standing water after rainstorms, this can prematurely age and
damage the bitumen roof.