Strong, sus­tain­able and easy to con­struct: en­gi­neered tim­ber is the ‘new con­crete’

Hun­dreds of apart­ment blocks and houses across Europe are be­ing built out of ‘cross-lam­i­nated tim­ber’. When will Ire­land get over its fear of wood?

The Irish Times - Thursday - Property - - Feature - Amanda Geard

Grow­ing up we had the quin­tes­sen­tial Aussie shack. Dad built it from the ground up with planks from a nearby mill. In­side it was lined with cut-price OSB (ori­en­tated strand board) – two decades be­fore it be­came trendy – with end­less quirky shapes from which to con­jure crea­tures. In­te­rior cloud-gaz­ing at its best.

Later I lived in a wooden cabin in Nor­way, with large pic­ture win­dows and a tiny foot­print. When we bought it, it had stood empty for 20 years. I’ll never for­get slid­ing the key into the rusted lock, jig­gling the door open and be­ing met with a resinous smell redo­lent of trekking through a pine-for­est on a warm au­tum­nal evening.

When I walk around Dublin I look for tim­ber houses. Where are they? Hid­ing be­neath con­crete? Dis­guised as pot­ting sheds? Booed out of the ur­ban en­vi­ron­ment for be­ing too pro­vin­cial?

In Ire­land we are just a lit­tle bit scared of tim­ber in our homes. Golden log cab­ins are dot­ted ever-so-spar­ingly across the coun­try­side; tiny squares of cedar creep apolo­get­i­cally into our cityscapes; tim­ber-framed houses are quickly cov­ered up with ren­der to con­form to the norm.

We have thrown tim­ber to the wind. And yet in this ma­te­rial lies a quick and eco­nom­i­cally com­pet­i­tive con­struc­tion al­ter­na­tive to our block­work and plas­ter world.

North­ern Euro­peans are quick to ex­tol the virtues of a well-built tim­ber home; they’re healthy to live in, they’re easy to con­struct, they feel cosy. Where would 2017’s most ir­ri­tat­ing word, “hygge”, be with­out a warm-pine wall in the back­ground? But hygge is cab­ins and lakes, it’s ru­ral and for­est-bound.

Ply­wood on steroids

But now Europe’s ur­ban ar­eas are giv­ing tim­ber a new place to hang out. Across the Con­ti­nent, hun­dreds of de­tached homes, apart­ment blocks and high-rises are be­ing built out of cross-lam­i­nated tim­ber (CLT).

CLT is ply­wood on steroids – built up lay­ers of planks, each strata at right an­gles to the last, providing in­di­vid­ual pan­els with ex­cep­tional di­men­sional sta­bil­ity. Widely used in Switzer­land, Scan­di­navia and Ger­many, it’s rapidly earn­ing re­spect for its high strength-to-weight ra­tio and dura­bil­ity. It’s a self-sup­port­ing con­struc­tion ma­te­rial, form­ing both the struc­ture and the skin of a build­ing.

“It is the new con­crete,” says Prof Alex de Ri­jke, co-founder and di­rec­tor at Lon­don-based ar­chi­tec­tural firm dRMM. “En­gi­neered tim­ber is the ma­te­rial of the 21st cen­tury.”

And this is a man who should know. dRMM won the 2017 Stir­ling Prize for its part-CLT re­gen­er­a­tion of Hast­ing Pier on Eng­land’s south­ern coast. The firm has been us­ing CLT since the turn of the cen­tury, working hard to bridge the gaps in knowl­edge about the ma­te­rial in the UK mar­ket. In 2006 it built its first flat­pack build­ing: Naked House. It was trans­ported to site in a con­tainer and erected in 24 hours.

“Since the fire of Lon­don we have for­got­ten how to use tim­ber,” says de Ri­jke.

It’s true the 1666 blaze hasn’t helped tim­ber ad­vo­cacy over the past 3½ cen­turies. “Peo­ple worry about fire, but with CLT the well-doc­u­mented char layer cre­ates a pro­tec­tive bar­rier.”

Open-plan de­sign

In 2013, dRMM col­lab­o­rated on the first all-tim­ber home to be built in cen­tral Lon­don since the fire. Wood­Block House, nes­tled be­tween brick and con­crete, fea­tures a south-fac­ing l i vi ng area with an open-plan de­sign rem­i­nis­cent of that Ir­ish icon – the Der­mot Ban­non ex­ten­sion. But with car­bon cre­den­tials.

“CLT is a car­bon se­quester,” says De Ri­jke. While a tonne of ce­ment emits its equal weight in car­bon, the process of grow­ing a tonne of tim­ber will re­move up to 2 tonnes of car­bon from the at­mos­phere.

“One of the most ob­vi­ous rea­sons to start us­ing tim­ber rather than con­crete is that it’s com­monly grown, and there­fore an ex­cep­tion­ally re­new­able build­ing mate- rial that we have avail­able to us,” says de Ri­jke.

This is a fact that should pique the in­ter­est of Ire­land’s bur­geon­ing bioe­con­omy. With Coillte plan­ning to dou­ble pro­duc­tion and Brexit loom­ing omi­nously over the near-term tim­ber trade with the UK, we may need an in­ter­nal mar­ket for this ever-grow­ing re­source. Or even look to pro­vide the ex­pand­ing Euro­pean de­mand.

In 2003, just 2,000 cu­bic me­tres of CLT were pro­duced glob­ally. In 2018 that fig­ure will top 1 mil­lion cu­bic me­tres. In­creased pro­duc­tion will mean de­creased costs; a much wel­come boost for a grow­ing in­dus­try.

The down­side, of course, and De Ri­jke ad­mits it, is that the raw ma­te­rial cost of CLT build­ings is gen­er­ally higher than that of tra­di­tional block­work equiv­a­lents.

“How­ever, what we do is so much quicker. It re­quires less peo­ple and sig­nif­i­cantly fewer pro­cesses. Huge sav­ings can be made over stan­dard build­ing projects. That way it’s pos­si­ble to get prices down to

It is the new con­crete. En­gi­neered tim­ber is the ma­te­rial of the 21st cen­tury ‘‘ While a tonne of ce­ment emits its equal weight in car­bon, the process of grow­ing a tonne of tim­ber will re­move up to 2 tonnes of car­bon from the at­mos­phere

some­thing com­pa­ra­ble.”

Pre­ci­sion en­gi­neer­ing and pre-fab­ri­ca­tion means that a struc­ture built from CLT can of­ten be com­pleted in less than half the time of a tra­di­tional build. Rig­or­ous en­gi­neer­ing also makes for trou­ble-free air-tight­ness test­ing. There’s no need for scaf­fold­ing and ev­ery­thing is qual­ity con­trolled on-site.

“Dis­tri­bu­tion, trans­port and stor­age; they’re all quicker and eas­ier,” says de Ri­jke, adding that a CLT build will re­quire a fifth of the de­liv­er­ies of a tra­di­tional build.

‘Calmer’ process

“There’s a low skill re­quire­ment, ev­ery­thing is put to­gether with hand tools,” says De Ri­jke. This makes the process qui­eter, calmer and rel­a­tively dust-free. “Con­trac­tors are happy, neigh­bours are happy.”

And, ca­su­ally, he drops the W-bomb. “Of course, with tra­di­tional con­struc­tion the time­line of­ten be­comes wish­ful think­ing be­cause the real Achilles’ heel is the weather. With CLT build­ings, even if it’s pour­ing rain, a roof can be rapidly in­stalled.”

As I look out the win­dow at the end­less spring down­pour, I won­der what we’re wait­ing for. A build­ing ma­te­rial that is sus­tain­able and durable, quick to erect, quiet to work with, and could, one day, en­sure the fu­ture of Ire­land’s bioe­con­omy. Surely there’s some­thing in this tim­ber revo­lu­tion that we can learn from?


WoodBlock House in Lon­don: the first all-tim­ber house to be built in the city since the great fire of 1666; and (right) ar­chi­tec­tural firm dRMM’s Naked House which was erected in 24 hours.

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