Above / Sweden ’ s 246-foot Sara Kulturhus is primarily made of wood grown in the regional boreal forests . Right / The cultural center houses six theater stages , the city library , two art galleries and a 205-room hotel .
of the components are manufactured off-site ,” Komp says . “ Then there ’ s our attraction to the beauty of natural materials like wood . From a consumer standpoint , there are huge benefits to utilizing mass timber .”
Natural fireproofing
Given these advantages , why has the potential of wood in large-scale construction been neglected for so long ? As Frangi points out , engineered timber is not a new material , but the association of wood with flammability has been a factor in preventing its adoption in large-scale construction .
That association , as both he and Komp stress , is based on a misguided comparison between the large beams used in mass timber construction with the thin wooden frames that make up a traditional wooden house .
“ If you think of starting a fire , you can ’ t just go straight to big logs ; you need the little pieces of kindling to get it started ,” Komp says . “ Once the large pieces of wood start to burn , they form a layer of char that insulates the inside . This means large pieces of wood can maintain their structural integrity for several hours and even selfextinguish . You can actually use wood to protect steel from fire .”
Nonetheless , regulators have historically adopted a conservative attitude when it comes to regulating the use of wood as a building material . While Switzerland used to forbid building above two stories , it has allowed wooden buildings of any size since 2015 . In the U . S ., cities and states have only started to relax their building codes more recently , following an update to the 2021 International Building Code , which now approves mass timber for use in buildings of up to 18 stories .
“ In order to get approval for building to 25 stories , we had to conduct tests to prove that the columns would survive a three-hour fire ,” Komp explains . “ There was never any doubt it was going to pass , but we didn ’ t have the data because no one has ever tested for that long before .”
As more tall timber towers are built , and stakeholders gain experience with them , Frangi believes local regulations will increasingly adapt to support their construction . “ There is huge potential here ,” he says . “ The population is growing and increasingly moving into cities . Construction is booming , but we cannot use the same resources as we have been doing . We have to find a way to meet that need for dwellings without relying on steel and concrete .” ■
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