Summer '22

MODULAR SYSTEMS
>>> Continued from page 22
process by designing a bespoke unit
that is towed behind a tractor which
efficiently slides trays off three abreast
in long, straight lines. The compost
spreader follows, evenly filling the
trays from a conveyor belt (with a little
overfill to allow for settlement) before a
levelling box passes over to gently press
the substrate down to create an even
surface ready for seeding.
Because sedum seeds are incredibly
small and even distribution into the
substrate is not easy, we’ve developed a
hydroseeding system where the seeds
are mixed with water and released with
an agricultural spinning disc dispenser.
This gives an even distribution and
helps the seeds sink a little into the
substrate to start the germination
process. The irrigated plants are then
left to grow and mature for up to 12
months, assisted by regular feeding,
weeding and close control of quality.
With no ‘hot housing’ to accelerate
growth they produce strong roots, are
fully integrated into the substrate and
hardened to the elements.
Harvesting
Because Wallbarn designed and
developed the B ROOF t(4) compliant
M-Tray system, we’ve also had to design
and build our own harvesting machines
to maintain an efficient and careful
system to lift established trays from the
field. This self-propelled machine has
specially designed wedges and spokes
to lift trays off the ground and separate
them, drawing them up a conveyor
belt ramp to a processing platform.
Operatives check the M-Trays for quality
and palletise them in the field. Trays
picked today are on site tomorrow.
Substrate science
Wallbarn is at the forefront of
developments in the green roofing
sector and has always provided
products that combine top quality
ingredients with user friendly, hassle-
Wallbarn has designed its own harvesting machines to maintain an efficient and careful system to
lift established trays from the field. The M-Trays are checked for quality and palletised in the field.
free maintenance. Each element of
M-Tray has been carefully considered,
from the design of the tray to the
scientifically developed substrate and
selection of sedum and wildflower
plants.
Working with an independent soil
specialist, we’ve developed bespoke
substrate mixes that comply with
BS 8616:2019 Specification for
performance parameters and test
methods for green roof substrates,
and with the GRO Code. They are our
own tried-and-tested recipes using raw
materials that are recycled and come
from local sources where possible.
Crucially they have been physically fire
tested and comply fully with the latest
fire safety regulations. The three key
substrate ingredients are:
• Coir, or recycled coconut fibre, which
holds moisture and nutrients and has
good drainage properties. It has high
lignin content and is relatively resistant
to slumping, providing long-term
sustenance to the plants.
• Lightweight mineral aggregate is
the main component of the substrate,
giving free drainage and improved
rooting conditions. We use a variety
of different aggregates with different
particle sizes, including Lytag and
expanded clay balls (Lecca).
• Locally sourced organic compost
which provides water absorption whilst
slowly releasing nutrients.
We do not use brick dust or building
rubble as these can form a crust within
the substrate, causing blockages and
poor rooting. Nor do we use peat or
construction waste. We are constantly
trialling and developing new mixes
to provide our customers with the
optimum substrate, including super
lightweight modular green roofs and
carbon negative mixes.
Contact Wallbarn
www.wallbarn.com
T: 020 8916 2222
@wallbarn
24 GREENSCAPE SUMMER 2022 • www.greenscapemag.co.uk