Armed Polite Society
Main Forums => The Roundtable => Topic started by: MillCreek on January 22, 2020, 09:07:50 AM
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https://www.vox.com/energy-and-environment/2020/1/15/21058051/climate-change-building-materials-mass-timber-cross-laminated-clt
I know we have architects and building people here, so this may be of interest. I have read a lot about this in the local media, since the PNW and British Columbia has so much softwood timber.
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The latest season of This Old Home showed a compete reconstruction of a 1940s-era ranch into a larger Dutch Colonial-style house using almost all engineered lumber, including 2x4s and 2x6s for walls and joists, as well as a couple of large carrier beams.
They said the cost was more, but the time required was less because all of the lumber was true and straight, didn't require as much bracing, etc.
I suspect that sometime in the next 10 to 15 years we're going to be seeing a lot more laminated lumber in home stores.
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I'm an architect and a building official. I don't hear much about this from architect colleagues. The building officials (many of whom are former builders) are scared shitless by the concept. So are the fire services.
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They're not new, maybe just being rediscovered by architects. We studied laminated wood timbers in a Materials class I took in college over 30 years ago. They can be safer in a fire than steel beams (although they do add fuel) because they maintain structural integrity for a long time even as they burn. Steel rapidly loses strength in a fire -- however it doesn't add fuel.
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Laminated beams are nothing new. Para-lams and micro-lams have been around for many years.
Brad
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Some of the houses in my community that were built later (1980 or so) used engineered I-beam style joists -- wood stop and bottoms with an engineered web in the center.
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Would the glue and treatments used keep the wood dry and keep stuff like termites or carpenter bees from affecting it?
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I believe the engineered lumber is generally more water resistant, but I don't know about insects. I'd suspect that generally, though, the glues and binders are resistant to termites, and they can probably include chemicals in the matrix that will keep termites and other wood pests out.
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Glu-lams ae certainly not new ... but their use in high-rise construction is new.
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I'm an architect and a building official. I don't hear much about this from architect colleagues. The building officials (many of whom are former builders) are scared shitless by the concept. So are the fire services.
Can't be any worse than all the plastic and petroleum based products in newer construction.
I remember from my college wood products class many videos showing wood standing up better to steel in a fire situation.
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Can't be any worse than all the plastic and petroleum based products in newer construction.
I remember from my college wood products class many videos showing wood standing up better to steel in a fire situation.
I saw the same videos in an Engineering Materials class. :)
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So, fancy plywood, right?
I'm pretty sure I saw some of those "dowel laminated beams" in England in an 800 or so year old church.
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So, fancy plywood, right?
I'm pretty sure I saw some of those "dowel laminated beams" in England in an 800 or so year old church.
No, not veneer glued in alternate layers. Think of stacking long 2x4 and gluing then together, kind of like bricks.
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I was thinking about how long this material would last, but I figure if it was designed right, then it could be repaired or replaced more easily.
Many chemical plants have wooden cooling towers that require regular inspection and the wood only lasts so long. I am not certain what makes this stuff better. Maybe the glue and binders used.
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I was thinking about how long this material would last, but I figure if it was designed right, then it could be repaired or replaced more easily.
Many chemical plants have wooden cooling towers that require regular inspection and the wood only lasts so long. I am not certain what makes this stuff better. Maybe the glue and binders used.
Unless they've come up with something better recently, they use resorcinol (sp?) glue. It's a 2-part adhesive kinda like epoxy. It's not gap-filling like epoxy, but it is UV stable and epoxy is not. (I think both are waterproof) So they glue-up the timbers and then clamp them until the glue sets. I believe some marine epoxies are really resorcinol-based because of the UV thing.
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Resorcinol has been a mainstay in wooden boat building for a very long time. White oak has adhesion issues with standard epoxy but does great with resorcinol.
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I was thinking about how long this material would last, but I figure if it was designed right, then it could be repaired or replaced more easily.
I've been seeing projections of 50 years. Heck, my house is 70 years old. This stuff is the structure -- how do you replace the structure of a high-rise building?
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This is pretty interesting.
However, do the glues used give off noxious fumes?
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I've been seeing projections of 50 years. Heck, my house is 70 years old. This stuff is the structure -- how do you replace the structure of a high-rise building?
Not sure how that would be done.
I was thinking that reinforced concrete generally has a finite life as the steel reinforcement eventually gets exposed to the elements. I am curious how that compared to this bulk plywood material. On the other hand, if it is cheaper than steel, you might be able to design things so beams can be changed out without tearing things apart.
I also wonder if they would have inspection requirements for the wood support beams to make sure it is intact and not subject to rot, termites, or other problem.
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I'm sort of confused by this life span thing...
Does plywood have a lifespan?
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In high school, one odd job I had was helping a family friend with his home construction. He had some unique ideas for his home, for sure. Very unconventional building techniques.
One day, we took a flatbed truck out to the local airpark. Evidently they had demolished a hangar recently. It dated back to the 1930's.
This friend took a massive attic support beam from the demolished hangar back to his house site and cut it to length to serve as the spine of his sub-floor. The support beam was a series of true-dimension 2x12 boards that had been laminated one upon the other with glue and nails to a final dimension of 14x12, IIRC. He cut out the very little bit of dryrot in the beam, patched it with an epoxy resin, then rigged a rather nifty floor leveling system to support this thing that allowed him to adjust the floor for level as the house or concrete foundation sagged over time.
The beam survived 60-odd years of eastern Washington weather, and then building demolition, to be reused as the spine of a new home that will stand for probably another 75-100 years. It's a beautiful home today, just across the street from my old High School, a creek running through the property, he's got a waterwheel that generates power off the creek. I know it's not quite laminate like being discussed here, but old wood getting reused has a sentimentality to it, and new laminate timber beams will end up being used 100 years from now by someone much like we reused that hangar rafter beam.
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I'm sort of confused by this life span thing...
Does plywood have a lifespan?
In today's disposable culture it will likely outlast many of the structures it is used in.
How often do you see some commercial or civil building that is only 30 or so years old getting razed because it's obsolete or insufficient maintenance was done and it's cheaper to knock it down and start over?
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In high school, one odd job I had was helping a family friend with his home construction. He had some unique ideas for his home, for sure. Very unconventional building techniques.
One day, we took a flatbed truck out to the local airpark. Evidently they had demolished a hangar recently. It dated back to the 1930's.
This friend took a massive attic support beam from the demolished hangar back to his house site and cut it to length to serve as the spine of his sub-floor. The support beam was a series of true-dimension 2x12 boards that had been laminated one upon the other with glue and nails to a final dimension of 14x12, IIRC. He cut out the very little bit of dryrot in the beam, patched it with an epoxy resin, then rigged a rather nifty floor leveling system to support this thing that allowed him to adjust the floor for level as the house or concrete foundation sagged over time.
The beam survived 60-odd years of eastern Washington weather, and then building demolition, to be reused as the spine of a new home that will stand for probably another 75-100 years. It's a beautiful home today, just across the street from my old High School, a creek running through the property, he's got a waterwheel that generates power off the creek. I know it's not quite laminate like being discussed here, but old wood getting reused has a sentimentality to it, and new laminate timber beams will end up being used 100 years from now by someone much like we reused that hangar rafter beam.
We framed up our house and shop with recycled 8"x12" timbers from am old lumber mill. They were roof trusses originally. Solid cut Doug fir. Also used a bunch of 6"x12"s that were stack laminated from 2x6 material. They must be going on 50 years at least.
That waterwheel sounds really interesting- a good way to charge a battery bank. Got any details on it, design of the wheel/turbine ,how far away the stream is from house, etc?
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We framed up our house and shop with recycled 8"x12" timbers from am old lumber mill. They were roof trusses originally. Solid cut Doug fir. Also used a bunch of 6"x12"s that were stack laminated from 2x6 material. They must be going on 50 years at least.
That waterwheel sounds really interesting- a good way to charge a battery bank. Got any details on it, design of the wheel/turbine ,how far away the stream is from house, etc?
It was 25 years ago, I definitely don't have any design data on it. The wheel dips into Yellowhawk Creek, just north of Walla Walla High School in Walla Walla, WA. The property is off Fern Ave, if you google-map the high school it's the L-shaped house off Fern with a roundabout driveway. The stream is within 50 feet of the house. I'd guess it produces somewhere around 300-500 watts, nearly 24x7 as long as the creek has water, and I don't remember it ever running dry or even low during my time at high school. He didn't wire a battery bank into it or inverter, I remember him telling me it was wired so the power company would reimburse him for contributions to the grid if he had a surplus. Then again, this was the mid-90's before the solar panel revolution made power companies revisit that policy. The wheel was good-sized, and he poured a nice foundation for the wheelhouse that would have protected it from any flood erosion during high flow periods. The wheel was probably 8-10 feet in diameter if I remember correctly. It's a really pretty installation. He always overbuilt everything. :-)
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I'd guess it produces somewhere around 300-500 watts, nearly 24x7 as long as the creek has water, and I don't remember it ever running dry or even low during my time at high school. He didn't wire a battery bank into it or inverter, I remember him telling me it was wired so the power company would reimburse him for contributions to the grid if he had a surplus.
A surplus? From a wheel generating 300 to 500 watts? That's basically two or three light bulbs. Did you mean kilowatts, perhaps?
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In this day and age given EPA and Army Corps strictures, could you even get away with altering the banks of a flowing stream to put in a water wheel?
"That's basically two or three light bulbs. Did you mean kilowatts, perhaps?"
If it were generating 300 watts an hour, and managed to run 24 hours non stop, that would generate around 7.2 KhHr a day of power, or just shy of 2,700 KwHr a year.
If it were generating 300 KwHr an hour?
No chance of that happening.
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A surplus? From a wheel generating 300 to 500 watts? That's basically two or three light bulbs. Did you mean kilowatts, perhaps?
He never expected it to generate a surplus unless he somehow didn't use any power at all for a month, like if the family took a long vacation somewhere.
I rather doubt it was in the kilowatt range. I have some concept of watts/volts/amps from my own solar installation in a camping trailer I've built. Pretty certain of the numbers I said, but I'm working off a 25 year old memory.
In this day and age given EPA and Army Corps strictures, could you even get away with altering the banks of a flowing stream to put in a water wheel?
"That's basically two or three light bulbs. Did you mean kilowatts, perhaps?"
If it were generating 300 watts an hour, and managed to run 24 hours non stop, that would generate around 7.2 KhHr a day of power, or just shy of 2,700 KwHr a year.
If it were generating 300 KwHr an hour?
No chance of that happening.
Eastern Washington, tiny stream that goes through hundreds of private property parcels in a rural setting. Lots of similar tiny streams all over. No bend to the stream on his property segment where the wheel is installed. It's installed, so obviously he got away with it back in the 90's.
In prime spring/fall temperatures when no heating and no cooling is needed, it probably did result in a net 0 to the property's electric consumption if all that was running was lights, fridge, and some intermittent TV and such. But he has a large 2-car separate workshop, aside from the 3-car garage. He's a tinkerer and owns an auto body shop (not on property). Plenty of power consumption going on to make sure that probably never happened.
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I'm sort of confused by this life span thing...
Does plywood have a lifespan?
I was thinking about inspection requirements and lifespan in bigger buildings. It would probably last long enough. Plywood usually isn't a structural wood, but things change all the time.