Sympathetic locally-sourced materials, technical
expertise and market-leading guarantees led Vale of Glamorgan Council to choose
BMI Redland and BMI Icopal materials when re-roofing an early 20th century primary school.
“We chose BMI because it could offer us 15-year
guarantees on the products; the roof slate was made from locally-sourced
materials and because the pitched and flat products could work in conjunction
on the details,” says Paul Hynam, Consultant Building Surveyor to the project.
Built in 1905, Cogan Primary School suffered from a
roof that continually leaked despite being patched with various types of slate
over the years. The roof’s deterioration was accelerated by thieves stripping
lead flashings and it had the complexity of there being a 100m2 flat roof right in the centre of the school.
“The interface between pitched and flat roof can
sometimes cause an issue, so it was a concern. If you have two companies
responsible for each, then one can blame the other for any faults,” Paul
explains.
“We’d worked with BMI before using its SpecMaster
service for pitched roofs and knew that it would oversee the job closely.
However, as BMI supply both pitched and flat roofing solutions, we also knew
that we could rely on them for all parts of the roof and they would make sure
that the detailing between the two roofing systems was sufficiently robust.”
Acting for Vale of Glamorgan Council, Paul set several
challenges for the new roof: it should look like the existing roof, not require
any maintenance, and should be sourced locally to reduce the carbon footprint
and its environmental impact. It also needed to be installed quickly to reduced
health and safety issues and completed during the school holidays, avoiding
risk to the school’s pupils.
To reduce the risk of theft, the council also wanted
to use a lead alternative and needed a secure interface between the flat and
pitched roofs.
For the pitched roof the solution was BMI Redland
Cambrian Slate, an interlocking slate manufactured from recycled waste slate in
nearby Merthyr Tydfil, a dry-fix system to cut down maintenance, and fixings on
the ridge and hip system to mimic the previous roof.
Some of the details on the side abutments were leaking
because there was only a secret gutter rather than a cover flashing, so cover
flashings made from a lead alternative were installed under the coping, a
difficult task because the coping stones were very large.
In addition, standard eaves vents could not be used
because there was lath, plaster, and tar between the rafters at eaves level.
Installing eaves vents would have damaged the vaulted ceiling, so vent tiles
were used for venting instead.
For the flat roof, BMI’s Area Technical Manager
specified BMI Icopal’s Firesmart SBS modified reinforced bitumen membranes,
accredited by the Loss Prevention Certification Board (LPCB).
Where robust details were needed, the BMI
specified specific installation methods, particularly where the pitched
roof met the flat roof. BMI’s solution was to carry the waterproofing under the
Cambrian Slate and up to the top of the eaves batten. This detail and others
were monitored by the Area Technical Manager during installation.
The school’s roof now provides the Vale of Glamorgan
Council and school the security and reliability it needs – with
guarantees it can rely on of up to 20 years, quality products specified and
installed, a pitched and flat roof that collaborate on the details and
locally-sourced materials. Sounds like a winning combination.
