Timber iQ October - November 2019 // Issue:46 | Page 32

INTERNATIONAL PROJECT
A first for CLT structures
in the US
By IKD
Yugon Kim and Tomomi Itakura, from Boston and San Francisco
based architectural design firm IKD, completed the first hardwood-
cross-laminated timber structure (hardwood CLT) in the US – The
Conversation Plinth.
T
he structure was unveiled at Exhibit Columbus in
midwestern modern art and architecture mecca,
Columbus, Indiana. Its form takes cues from the
conversation pit in the living room of the Miller House, as
well as the plinths that elevate the important landmarks
immediately surrounding the site – the library designed by I.
M. Pei, the First Christian Church designed by Saarinen
church, and the Large Arch by Henry Moore.
USING HARDWOOD CLT FOR CONSTRUCTION
The Conversation Plinth was constructed from the first-ever
commercial pressing of hardwood CLT in the US, developed
by IKD and team partners. Although softwood CLT already
existed in the US, hardwood CLT did not.
9m x 3m hardwood CLT panel set in place amongst site bollards.
The hardwood CLT was derived from combined species of low
value grade 3 common hardwoods. Hardwood CLT is harder
and heavier than traditional softwood CLT. This created
challenges during the project because of the impact on
processing and fabrication timelines. In addition, there was
also an increase in transportation costs. The project took ten
days to be completed on site and a boom crane was used to
assemble certain tiers of the Conversation Plinth. The
installation is made of a high-tech engineered cross
laminated timber.
IKD was awarded a 2017 Wood Innovation grant by the
United States Forest Service to develop this material
innovation for the installation and for product certification
that could potentially lead to mass production.
Using the Conversation Plinth as a demonstration project,
the IKD team hopes the installation can be a catalyst for a
new timber industry by upcycling low-value hardwood sawn
logs that are extracted from regional forests in Indiana and
the mid-west. Indiana’s largest cash crop is hardwood, but
over 55% of each log processed is of low value. The idea is
that low-value hardwood, such as grade 3 common oak,
maple, and ash, can be used to create high-value HCLT, which
can then be used in commercial applications.
BENEFITS OF HCLT
The hardwood CLT panels are used for floor, stair and
balustrade.
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OCTOBER / NOVEMBER 2019 //
HCLT offers numerous benefits over softwood, including
superior mechanical properties, material volume savings,
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