TECHNICAL & RESEARCH
membranes provide high tensile strength, excellent 
weather resistance, and ease of installation compared 
to older systems. Their adaptability to various 
climates and compatibility with different substrates 
make them a preferred choice for contractors and 
building owners worldwide. Unlike BUR systems, MB 
membranes come in roll form, making transportation 
and installation more efficient.
This article explores the history, global adoption, 
modern applications, and sustainability aspects of 
modified bitumen membranes. It also examines 
their advantages over other roofing systems and 
their expanding use in waterproofing applications 
beyond roofing. Additionally, the economic impact 
of MB roofing systems, including cost-effectiveness 
and lifecycle benefits, is analyzed to provide a 
comprehensive view of their role in the construction 
industry.
Origins of Modified Bitumen Roofing
Imper Italia, which began manufacturing APP-modified 
bitumen membranes in 1967 with its pioneering 
Paralon product, played a crucial role in the 
development of MB membranes. By the early 1970s, 
these formulations were commercialized and began 
gaining traction in the European roofing industry. The 
superior performance of MB membranes compared 
to traditional BUR systems led to increased adoption. 
Additionally, as MB membranes were refined, they 
became more cost-effective, increasing their appeal to 
a broader market.
Two major polymer additives were introduced: Atactic 
Polypropylene (APP) and Styrene-Butadiene-Styrene 
(SBS), each providing unique performance benefits. 
APP-modified bitumen was developed to improve 
UV resistance and thermal stability, making it 
primarily suitable for warm climates where elevated 
temperatures could degrade conventional bitumen. 
SBS-modified bitumen, on the other hand, was 
designed to enhance elasticity and crack resistance, 
making it ideal for cold-weather applications where 
flexibility was crucial.
Germany faced a shortage of natural rubber 
and developed synthetic alternatives, including 
styrene-butadiene rubber (SBR), to meet military 
and industrial demands. The development of SBR, 
also known as Buna-S, was led by Dr. Walter Bock, 
a German chemist working for I.G. Farben in the 
1930s. His work on polymerizing butadiene with 
styrene resulted in a synthetic rubber that could 
replace natural rubber, which was in short supply 
during World War II (Feldman & Barbalata, ‘Synthetic 
Polymers: Technology and Applications’, 1996).
This research laid the foundation for later 
advancements in elastomeric polymers. In the 
post-war era, Shell Chemical Company built upon 
these earlier innovations and developed Styrene-
Butadiene-Styrene (SBS), a block copolymer 
that combined the elasticity of rubber with the 
processability of thermoplastics. Initially intended 
for use in adhesives and industrial applications, 
SBS was later adapted for construction materials, 
including modified bitumen roofing.
Shell researchers pioneered the integration of 
SBS into bitumen, creating a highly elastic and 
durable roofing material. SBS-modified bitumen 
offered superior flexibility, even at low temperatures, 
significantly reducing the risk of cracking and 
extending the lifespan of roofing membranes. By the 
1970s, SBS-modified bitumen membranes had been 
widely adopted across Europe, paving the way for 
their introduction to the North American market.
Dissemination and Global Adoption
The success of modified bitumen roofing systems 
in Europe soon influenced markets in North 
BITEC Photo
Continued on page 34

View this content as a flipbook by clicking here.