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Other engineered woods such as plywood and MDF are around 10% adhesive (glue), often urea-formaldehyde, which can produce hazardous chemicals during recycling or incineration. CLT, however, is below 1% adhesive, and typically uses a bio-based polyurethane. The planks are bonded together under heat and pressure to fuse that small amount of adhesive using the moisture of the wood. To look at, smell and touch, it’s as pure wood as a child’s tree house – knots and all.
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In any case, there are already quite a few buildings that use this so, I'd say this is a non-issue.
There is also CLT without glue. Check https://www.youtube.com/watch?v=4j_UjIshzMc where Matt Risinger is visiting a Swiss factory where they use wooden (berch?) nails and dowel pins in stead of glue. And by using more layers they also need no insulation. Gives R=24...
Some adhesives use formaldehyde, but you can also get formaldehyde free adhesives. It's no different than plywood or OSB which is greatly used in the construction of most wooden stick framed houses where that's common (i.e. North America).
It's the same chemicals used in the production of plywood (glue), only there's a lot less of it. It basically is plywood, just with fewer and thicker layers so a lot less glue is needed.
" Other engineered woods such as plywood and MDF are around 10% adhesive (glue), often urea-formaldehyde, which can produce hazardous chemicals during recycling or incineration. CLT, however, is below 1% adhesive, and typically uses a bio-based polyurethane. The planks are bonded together under heat and pressure to fuse that small amount of adhesive using the moisture of the wood. To look at, smell and touch, it’s as pure wood as a child’s tree house – knots and all. "
In any case, there are already quite a few buildings that use this so, I'd say this is a non-issue.