|
| Author |
Message |
Don_P
Member
|
# Posted: 20 Jan 2016 10:42pm
Reply
You'll probably be hearing more about CLT construction in the near future if you haven't already. It has been in development in Europe for about 20 years and has gotten through our regulatory hoops and into the 2015 codes as an engineered product. Mainly it's being used for large commercial presently but there is research and a few residential projects. A good way to get a strong all timber wall.
This is a good short video about how one US company is making their panels, this is a new concept within the fledgling CLT industry, using joinery rather than glue to hold the panels together.
https://www.youtube.com/watch?v=kM3APiYRswY
|
|
bldginsp
Member
|
# Posted: 21 Jan 2016 08:45am - Edited by: bldginsp
Reply
Looks interesting Don. Uses a lot of wood, which is available now but after the beetle kill is used up, if this becomes an established method, other sources will be needed and thus pressure increases on logging, or lumber price goes up. As they say in the video, wood is a renewable resource, but that's only if it's managed well, which is not a given.
Requires a crane, which is expensive, but unlike log construction that requires a crane, assembly with this should take little time, maybe one day, reducing cost for residential.
I wonder how repairs would be done when the inevitable rot occurs here and there. Insulation will be an issue in cold climes. And you don't have wall cavities for plumb and elec.
Looks nice and assembly should be fast. Complete wall in one operation, rather than the multiple steps required for stick framing. Looks quite solid and should have good lateral strength.
|
|
Don_P
Member
|
# Posted: 21 Jan 2016 10:21am - Edited by: Don_P
Reply
We have a pretty large supply of underutilized and invasives in the eastern forest that might make good core material... ailanthus or red maple or eastern hophornbeam, or... core with oak or cherry skins? I planted trees for a few winters, we were planting at a double to triple final stocking rate to account for mortality. There was to be a pre-commercial thinning at about 15 years which would be paid for as pulp. Meanwhile we have offshored pulp production and that overstocked spindly forest continues to grow. The few years prior to the beetle kill problem that was the focus of some attention. We've lost that focus but the doghair stands are still there. At some level it could be a management tool, allowing more balanced use of the forest. In a perfect world.
With the cross lamination, running 2x's vertically and horizontally, strength is built in two directions and it is stiffer when loaded out of plane, it is less likely to buckle as a wall with a load on top and wind hitting the side. There are load/span/thickness tables based on testing the panels so there are established design methods.
Good point on servicing it later, that has been one of my worries when using SIPS, lose the skin and you lose the structure of that panel. Just as with these they count on an exterior weather cladding. Insulation can be installed prior to on that face. The mass is then inside the insulated space. Without a cavity wall there is less chance of a condensation problem in those walls, solid wood does a great job of adsorbing and releasing reasonable changing moisture levels without having the moisture condense and collect. However, that is a very good point to consider. Replacing logs is a job as well. A vertical load bearing frame (that hasn't rotted!) makes replacing damaged claddings easier. I've worked on plenty of light timber and stick frames that had rotted sills or post/stud bottoms though. Detail well.
Power can run in the core as panel thickness goes up, similar to SIP or log. I suspect you noticed the surface wiring in some recent pics of a thin wall, same here, not pretty and not cheap. I have run it behind door and window trim etc, watch protection from nails though. Better to get up to a thicker panel.
I've had Superior walls, precast concrete foundation walls, installed in a day several times. Those small cranes usually walk right in to a jobsite, we have the dozer there to bring up the trucks with the panels on steep sites.
You've probably been catching wind of these in inspection circles, these are the panels being used in wood high rises. They are mostly being used on big commercial jobs right now, but that will filter down.
|
|
|
