And Arup For
The American Hardwood Export Council (AHEC)
has collaborated with Alison Brooks Architects,
Arup and the London Design Festival to present
a cross-laminated tulipwood structure, ‘The
Smile’ at the Chelsea College of Art Rootstein
Hopkins Parade Ground from 17 September
until 12 October.
The Smile is one of the Festival’s Landmark
Projects, which can be inhabited and explored
by the public. The spectacular, curved, tubular
timber structure measures 3.5 m high, 4.5 m
wide and 34 m long and is effectively a beam
curving up at both ends.
Showcasing the structural and spatial poten-
tial of cross-laminated American tulipwood,
Alison Brooks’ concept is the first ever ‘me-
ga-tube’ made with construction-sized panels
of hardwood CLT.
Cross-laminated timber (CLT) is an engineered timber
that can be used to make the walls and floors of entire
buildings. It has a layered construction with the wood
fibres turned at right angles in each successive layer,
creating a panel with equal strength in both directions,
just like plywood. Weight for weight, CLT is stronger than
concrete and it can also be machined to incredibly high
This makes it ideal for prefabrication and rapid as-
sembly, reducing construction times by up to 30%.
CLT is usually made of a softwood called spruce, bet-
ter known as the Christmas tree. Together with Arup,
AHEC has started a process of experimenting with CLT
made from fast-grown North American tulipwood.
Testing has shown that the tulipwood is considerably
stronger than spruce; it also has a superior
The Smile is the first project in the world to use large
hardwood CLT panels, in fact the entire structure is made
from just 12 huge tulipwood panels, each up to 14 m
long and 4.5 m wide.
Fabricating these panels in a real CLT production plant
has been an important step forward, showcasing how
the material can be used for commercial projects.
•The American Hardwood Export Council (AHEC)
Contractors World UK Ireland Vol 6 No 2