E76. Cross laminated timber construction with special guest Ken Slamet from The Rubix Collective

In this episode of the Building Design, Prime Time Podcast, we dive into the world of Cross-Laminated Timber (CLT)—an innovative, sustainable building material revolutionising the construction industry. In the episode we welcome special guest Ken Slamet from the Rubix Collective. Our guest explains why European spruce outperforms Australian timber, particularly in moisture control, and shares insights into how CLT delivers significant cost and time savings—reducing construction timelines by up to 30%.

Ken uncovers why CLT is rapidly gaining momentum in Australia, despite challenges such as limited local manufacturing and reliance on European imports. You'll hear how builders with no prior experience in CLT can still adopt this cutting-edge technology with the help of specialised subcontractors, making it easier to integrate sustainable practices into construction projects.

Frank and Amelia also discuss with Ken the ideal climates for CLT use, its resilience to delays and weather exposure, and how it’s transforming building processes across the globe.

If you're passionate about sustainable building, reducing construction costs, and improving timelines, this episode is a must-listen. Learn why CLT is poised to change the way we build in Australia and beyond!

Be sure to listen in each week so you don't miss an epsiode! 


About us
Prime Design is a building design company locally owned and operated in Tasmania since 2004.  Our goal is to share as much valuable information as possible about the process of building design, extensions, and more. We will talk about a different topic each week. To suggest a topic you would like us to talk about contact us at info@primedesigntas.com.au

Disclaimer
The information provided on this podcast is for educational and informational purposes only and is not intended to be a substitute for professional advice, individual circumstances, or remedy. We strongly suggest you consult a qualified professional before taking any action based on the information provided in this podcast. The views, opinions, and information provided in this podcast are those of the hosts do not necessarily reflect the official policy or position of any other agency, organisation, employer, or company. All content provided on this podcast is provided “as is” without warranty of any kind. We make no representations as to the accuracy, completeness, currentness, suitability, or validity of any information on this podcast and will not be liable for any errors, omissions, or delays in this information or any losses, or damages arising from its use. We reserve the right to change content or delete any information provided on this podcast at any time without prior notice.

Transcript

E76. Cross laminated timber construction with special guest Ken from the Rubix Collective

[INTRO] (0:09 - 0:24)

Welcome to the Building Design Primetime podcast, focused on providing valuable information for anyone looking to undertake a new build or extension project. We'll share our tips, tricks and stories from a building designers perspective.

[Frank] (0:35 - 1:13)

Hey everyone, I hope you have a great break over Christmas, New Year's. This is a continuation of the podcast at the Building Designers Association of Australia National Festival of Design at the Wrestpoint Casino Trade Night. We had Ken from The Rubix Collective talk to us about CLT, which is cross laminated timber, which is big panels of timber, Ken will explain this bit better, but he's been working on a lot of these projects.

I learned heaps from this little chat about how to incorporate this into new homes and some other really interesting electrical items that I never knew of. So I hope you really enjoy this.

[Amelia] (1:13 - 1:21)

Hello and welcome to the Building Design, Prime Time Podcast. I'm your host Amelia and once again, we're joined by Frank Geskus.

[Frank] (1:21 - 1:23)

Hey Amelia, we’re still at the trade show.

[Amelia] (1:23 - 1:27)

We're at the Building Designers Association of Australia trade show.

[Frank] (1:27 - 1:28)

We haven't left.

[Amelia] (1:28 - 1:29)

We haven't left.

[Frank] (1:29 - 1:29)

Good food.

[Amelia] (1:30 - 1:30)

Good food.

[Frank] (1:30 - 1:31)

Have you had any?

[Amelia] (1:31 - 1:32)

No, I've had lollies.

[Frank] (1:32 - 1:33)

I snuck out and got some.

[Amelia] (1:33 - 1:35)

Oh, I'm going to have to give that a crack.

[Frank] (1:35 - 1:36)

If I was polite I would have brought some back.

[Amelia] (1:37 - 1:44)

You ate it all. You did, you ate it all. 

[Frank]

I did not.

[Amelia]

Yeah, you did. Anyway, we've got a special guest here. 

[Frank]

Ken.

[Ken] (1:45 - 3:31)

I don't know about special, but thank you. 

[Frank]

Ken from the Rubix Collective. That's right.

[Ken]

Yeah, it's nice to be here. Thank you. 

[Frank]

Oh, no worries. And we're going to talk about CLT. And we're being heckled from the side. So we're in the middle of the foyer here, there’s people going past being heckled.

Anyway, all in good fun. So, CLT, Cross-Laminated Timber. 

[Ken]

Yes. Yeah. Very interesting, very interesting concept and product.

[Frank]

Yeah.

[Ken]

Something I've had a bit of experience with lately and, yeah. Excited about the potential it has. 

[Frank]

Maybe you want to explain what it actually is to everyone.

[Ken]

Yeah, so when I have clients that I'm introducing them to, to the product or to CLT, I'll often just talk about it as plywood on steroids basically. 

[Frank]

It certainly is that, isn't it? 

[Ken]

Yeah, some people might have heard of it as mass timber construction. There's a few different terms that people refer to it as. A lot of people have seen a few episodes of Grand Designs. Where it's being used, but if you haven't seen it, it's basically big slabs of timber that's used for the floor, the walls, the roofs, wherever you can use it.

[Frank]

Staircases. 

[Ken]

Staircases, all sorts of, pretty much the whole construction of the house itself. And it's machined, so it's made and cut in a factory. Shipped to site and put up with a crane. And I say it's plywood on steroids because plywood, you've got small lamellas that go different directions. This is the same thing, but you've got 90mm, or sorry, 30mm boards on top of each other.

[Frank]

And you can get it bigger, like you can get it specked up. 

[Ken]

Yeah, you can get it very thick. You can get it, I think, as thin as about 40mm. But yeah…

[Frank]

it's pretty wild. 

[Ken]

It depends on what you need for your project really.

[Frank] (3:31 - 3:32)

Yeah, exactly.

[Ken] (3:32 - 7:29)

So yeah. 

[Frank]

And you've done a few projects. Designed a few projects.

[Ken]

Yeah, we've got a few on the run. And we've also got a few out for tender at the moment. And they just keep coming into our workflow. Because we've got no stake in the game. You know, there's no benefit to us to push CLT. But we find that we walk our clients, or potential clients, through the benefits of it. Compared to lightweight construction. I always say, when they're typically building a new house, you can go CLT or you can go the traditional route. We outline it all.

Basically 100% of the clients that we introduce CLT to end up saying, yeah, that's what I want. And that's how we're getting so many of these projects. Because we're just putting it out there as an option.

Not necessarily pushing it, but yeah. 

[Frank]

But it's a high-performing product. 

[Ken]

A very high-performing product, yeah.

[Frank]

And also, is it manufactured in Australia? 

[Ken]

There are Australian manufacturers. The probably primary Australian manufacturer is a company called XLAB. The projects that we're using, we are importing from Austria. From a company called KLH. 

[Frank]

So you're importing walls, roofs, floors from Austria to Australia.

[Ken]

It makes me sound a lot better than I really am. And a lot more organised than I really am. It's very much like, if anyone knows, if anyone's put windows in their homes before, or dealt with the build of putting windows in their homes, it works in a similar manner where you've got window fabricators who work with the profiles from a window manufacturer.

So the same thing happens. So someone's over in Austria manufacturing the CLT, but then we've got someone that's between me and Austria that is organising the import, the export, the cutting lists, the erection of the shell. So it makes my job very easy.

Because there's that liaison with the manufacturer of the CLT. 

[Frank]

But also, they do the shop drawings and the manufactured cut to such incredible tolerance. That's right, yep.

[Ken]

It's literally a 2mm tolerance, plus or minus 2mm. 

[Frank]

It's pretty wild. It's insane.

[Ken]

And it allows you then to do really cool things that would take a lot longer with traditional construction. So you could do things like angles, odd-shaped roofs that don't necessarily come together at 45 degrees. It opens up a lot of possibilities.

And I often say to my clients that we can get to the end of the design process, get everything approved. I mean, it won't be very cost-effective for them to design this late in the process, but they could decide right at the last minute whether they want traditional construction or CLT. Because there's nothing that I need to do in my work, designing it, having engineered everything, that I need to accommodate the fact that it's a CLT building.

So literally, you know, the design is done. From a design perspective, there's no limitations. And then, yeah, we send that off to our middleman, and he does all the shop drawings and organises all the pieces that need to be organised to come and fit together like a jigsaw puzzle.

And do you bring the windows over from Europe as well? There is an option there. It's funny, we can import some windows from Europe, and we have asked often if there's a possibility to put it on the same container, which it is.

We haven't yet had a client that has done that. We typically lean towards UPVC double-glazed windows. 

[Frank]

As opposed to the European...

[Ken]

As opposed to the European stuff. 

[Frank]

Is it purely from a cost point of view? 
 
 

[Ken]

It is, yeah. So UPVC windows are quite cost-effective. They're a double-glazed... 

[Frank]

They're getting a lot better.

[Ken]

Yeah, they are. And the feel of them, they've got timber finishes, faux finishes on them, and they look fantastic. And they feel solid, which was a problem once upon a time they were tinny and thin. 

[Frank]

They look plasticky. 

[Ken]

Yeah, they look plasticky, yeah. But a double-glazed UPVC will be about the same cost as a single-glazed aluminium.

[Frank] (7:29 - 7:30)

Yeah, right.

[Ken] (7:30 - 7:54)

So that's what we're leaning to. But it's funny, we asked about, because in Europe all those windows that we would import if a client asked us to are triple-glazed windows by default. And we just out of interest said, well, could we get a price for double-glazed windows?

Because, you know... 

[Frank]

They would get you funny, wouldn't it? 

[Ken]

And yeah, I said, well, can we do double-glazed? And the quote came back, it was more expensive because they had to re-tool everything.

[Amelia] (7:55 - 7:56)

Really? Wow.

[Frank] (7:56 - 7:58)

Everything over there is triple-glazed. 

[Amelia]

So that's just standard.

[Frank] (7:59 - 8:32)

It is. Yeah, 

[Ken]

so it costs more because it was a custom job. 

[Frank]

And you don't know that until you ask.

[Ken]

Yeah, that's right, that's right. So... But yeah, sorry, just before we move on to windows, if the windows are on-site at the time that the CLT is on-site, which is what we try to organise, the whole building can go up and you've got an air-tight building, air-tight, water-tight building within five, six days for a typical house.

[Frank]

Yeah, I saw one from an architect here in Tassie and he was showing me some photos and it was gobsmacking how quickly this thing went up. 

[Ken]

Yeah, yeah, there's a couple of time-lapse videos.

[Frank] (8:32 - 8:33)

And that had the triple-glazed.

[Ken] (8:33 - 10:01)

Yeah, right, okay. They imported it from Europe. 

[Frank]

Yep, yep the whole lot. It was really impressive. 

[Ken]

Yeah, lovely. Yeah, down here at Tassie, it's probably more important than up in Newcastle City in terms of that triple-glazing. 

[Frank]

So then when you've got solid lumps of timber, what type of R rating, what type of insulation? Because you're not stuffing insulation in there.

[Ken]

Yeah, that's right. 

[Frank]

You're using the core of the timber, slabs of timber, as your insulation. 

[Ken]

Yes. So typically you get about R1 per every 100mls of CLT. Right. So the wall structure is comparable usually to just a stud wall thickness, so it's normally about 90 millimetres thick.

Yep. So you've got about R1 there, and then we insulate on the outside of the CLT. And there's a couple of different options that you can choose from there.

It won't bore everyone with different types, but you then attach that to the exterior side. And the reason why you do that is because the CLT creates a natural airtight envelope so that your insulation can stay on the outer, wetter side rather than the inside where you're getting humidity in. 

[Frank]

In a sense, it's almost reverse construction, you know that term?

[Ken]

That's right, yeah. Yeah, that's right. Which is nice because you can then leave all your CLT as exposed timber internally, and it's a beautiful finish. I mean, some people think it would look a bit like a sauna. 

[Frank]

I suppose it would. Pile of rocks in the corner.

But then you see it and it creates, you know, it's a very different feel. 

[Frank]

It's not like the VJ lining place we had in the 80s.

[Ken] (10:01 - 10:01)

No, that's right, exactly.

[Frank] (10:01 - 11:25)

That's right. 

[Ken]

So, I mean, the majority of our clients will want to leave it all exposed. As I said, there's no limitation in terms of the design, flexibility of it. So if you want it to look like a traditional house, you just line it with plasterboard. 

[Frank]

If you want, you can just paint it. 

[Ken]

Or even just do a number of different finishes on the site, whatever you want.

But, yeah, you do have to cover it from the outside and clad it from the outside. It can't be exposed. But, yeah, your internal finish could be nice.

[Frank]

Do you still put a DPC at the bottom of them? 

[Ken]

You do, yeah. So the way that it works without getting too technical is if you're going a slab on ground, what you do is your concrete slab's never going to be perfectly level because concrete is never going to get that precision.

So what we do is we put LVL bottom plates and screw those down to the slab and pack that out to make sure that's level. And that happens before the CLT comes on site. So when the CLT comes, you drop it straight in and they screw straight into those bottom plates.

[Frank]

Yeah, right. That makes a lot of sense. So, sorry, I should have said...

[Ken]

The DPC goes under there. 

[Frank]

I should have explained DPC, damp-proof course. It’s a sheet of plastic

[Ken]

Yes, yes. So that stops your moisture from the concrete coming up so that is actually in between, that's before the CLT comes, it's between your slab and that bottom plate that gets screwed on. 

[Frank]

So you'd machine that LVL up so it matches the thickness of the wall? 

[Ken]

Yes, it's the thickness of the wall. It can be a bit thicker because you've got the insulation. Oh, you can hang it out a little bit.

[Frank] (11:25 - 11:26)

Yeah, hang it out a bit.

[Ken] (11:26 - 13:48)

But, yeah, we just put little shims underneath them to get it level. The only issue then is if you want a really nice, clean, polished concrete to CLT. 

[Frank]

Yep.

[Ken]

No skirting line. 

[Frank]

We did a job like that and that was so hard. 

[Ken]

Yeah, it is hard. A workaround that we've done is to rebate the bottom edge of the CLT walls a little bit in and then we put in a spruce piece of timber to match it. Obviously, well, not obviously, but the grain of the CLT wall will usually be running vertical. The difference is that the skirting that you put in will be running horizontal.

But we put a nice little shadow line and then it still has that nice effect of that timber and that concrete. Yeah, right, nice solution. But up on the first level, first floor, and if you're doing an elevated CLT slab, you can just screw those straight into each other and it's just this really nice, clean timber to timber, you know.

[Frank]

No skirtings. 

[Ken]

No skirtings, nothing. And that's what saves money. That's the thing that saves money. It's all these corners you can not cut, but cut out. 

[Frank]

But yeah, you don't have to put your skirtings in.

[Ken]

Yeah, plasterboards, skirtings, in painting’s, a bit cheaper. Yeah, would be. Even electrical is cheaper, which is...

[Frank]

Well, I was just about to ask that. How do you do electrical? Do you want your poer point 300ml off the floor?

[Ken]

Yeah. 

[Frank]

You're going to have to compromise on that, or... 

Yeah, so normally with power, with power points, it's typically easier to do it on the external wall. You can just drill straight through the wall and put it on the external side. If you want it on the external wall, it gets a bit trickier. You sort of have to drill up through the centre of it and that just becomes a bit messy, but it can be done. It just requires a little bit more work.

[Frank]

Being well-planned, isn't it? Yes, that's right.

[Ken]

And our projects, I like to document quite detailed and allow as little work and sight as possible. So we will actually get those holes and even the recesses cut for the PowerPoints over in Austria. So it's obvious where they go, and it's just a matter of the electrician pretty much coming in.

But a real cost-saving with electrical is the lighting and the switches. Because traditionally, with a switch on a wall, you need to get power to that switch. You then need to get wiring from the switch to the lights.

So there's a lot of work there. And on a product where you've got no cavity, it can make it a bit trickier. So what we use is quite common in Europe for quite a long time, very reliable, kinetic radio frequency switches.

And what that is...

[Amelia] (13:48 - 13:49)

I've never heard of this before.

[Ken] (13:50 - 14:15)

Yeah, so it's fascinating. 

[Frank]

What black magic is this? 

[Ken]

This should be used in almost every...in any construction, because it's cheaper than paying $50,000 for your electrician to kit out your house. What it is, is it's essentially a sticker that looks like a light switch. Maybe I'm creating the wrong visual images here.

[Frank]

I've just got this weird-looking sticker. I've peeled it off. I'm sticking it on.

[Frank] (14:15 - 14:16)

It's supposed to turn the light on.

[Ken] (14:16 - 18:23)

It's a light switch that you'd expect to see on any wall, but it's got self-adhesive tape on the back. And you stick it where you want it, and you program it to the light circuit that you want it to turn on. 

[Frank]

You program your sticker.

[Ken]

Yeah, you program your sticker, because there's no battery in it, there's no power to it. The force of your finger on that button, and that's why they're called kinetic switches, is enough of a burst of power to be able to send a very simple radio frequency to a module that's connected up to your lighting circuit. So that's why it's a sticker sensor, because it doesn't need any wiring to it, no batteries, nothing.

It's just the pressure of your finger will ping up a signal to that light, and that will turn that on and off. So all of a sudden, you've cut out a whole lot of electrical work. The electrician only needs to basically lay out the lights, and he does that through the roof, and then waterproofs it back up again, or membranes it back up again, and then basically you just get these little modules that receive the signal from the switches and wire them into the circuit.

So there's all these little tips and tricks that have been developed through decades and decades and decades of this kind of construction in Europe to make it simpler and easier to construct, and Australia's playing a bit of catch-up, but yeah, there's all these little trades and things that you can actually save on with this construction and make it essentially cheaper than lightweight construction for a much better product. 

[Frank]

Well, there you go. That's fascinating. 

[Amelia]

It is fascinating. 

[Frank]

So with plumbing and things like that, that's a bit different. Bathrooms, you've got to waterproof the whole thing. 

[Ken]

Yeah, we've got radio-frequency water, so you can just beam water across. I'm joking. I'm joking.

[Frank]

Amelia he’s making fun of me now. 

[Ken]

No, the bathrooms are pretty easy because you're typically lining those with tiles anyway.

[Frank]

Yeah, and you've got to chase it. 

[Ken]

That's right. So we just batten out the FC sheet or the waterproof plasterboard, and then your plumbing just runs behind there.

[Frank]

And if you want walk-in shower, do you set down paddles? 

[Ken]

Yeah, we can actually shave that CLT down with the CNC router to what we need just in that section, create a set down there anyway, provide the engineers happy with that reduced thickness. 

[Frank]

Oh, that's a question. Engineering certification. You must have an engineer who can certify this because it doesn't fit under the National Construction Code, does it? 

[Ken]

No, so we've got the middleman that I've talked about before. He has an engineer as part of his team that certifies the structure itself, so that keeps things easy for me. He provides a certificate to the certifier to say everything is fine. What we take care of from our end is basically just the footings and foundations.

We just engage an engineer to do that. 

[Frank]

Which is pretty normal. 

[Ken]

Yeah, he just gets his necessary wind loads and numbers from our CLT engineer and just makes sure that that's suitable. And then, yeah, it's quite a simple engineering process. 

[Frank]

So if you've got an airtight, how do you install your HRV system? Through the roof?

[Ken]

It depends. We... 

[Frank]

Oh, heat recovery ventilation system. Because when you make it airtight, you need to ventilate it mechanically. 

[Ken]

That's right, yeah. 

[Frank]

Otherwise it's going to get a little bit ugly.

[Ken]

You don't want to create a box that you can't breathe in. 

[Frank]

Yeah, you can't breathe in and get mould and mildew and horrible stuff. 

[Ken]

That's it. So there's two types of HRVs, centralised and decentralised. Centralised, you'll need to find a cavity in your attic space or some sort of area where you can keep that. And it's basically a ducted system where it sucks out the stale air from the house that you don't need and then replaces that with fresh air. But the heat transfer happens in that exchange. So you're not losing heat, you're just swapping air and you're pushing that back in. 

[Frank]

Great setup.

[Ken]

It is, yeah. Yeah, it's fantastic. And it's been used for a long, long time and particularly in the colder climates in Australia, it's great. But the decentralised option is what a lot of clients are going with just to save a bit of money. It's a bit more visible, which some people have got issues with.

[Frank] (18:23 - 18:23)

Because they're wall mounted.

[Ken] (18:24 - 20:10)

They're wall mounted, yeah. So you'll have a pair of them usually and they'll be in sync with each other. So one will be sucking air in on one side of the house while the other one on the other side of the house is sucking air out.

And then they'll, after a certain amount of time, they'll swap. So you've got this constant fresh air coming in and you can get HEPA filters in there, you can get all sorts of things in there to really improve your air quality. But that's how it works.

So often we'll put one in each bedroom and then in the living room, there'll be sort of one each side. 

[Frank]

And it probably ends up, what, two-thirds of the cost of a full ducted one? 

[Ken]

Yeah, I'd say about that. It's normally about $20,000 for a full ducted one and each one of these... 

[Frank]

Yeah, that's roughly I think because I'm looking to put one in my house. 

[Ken]

Yeah, right. And what are your prices that you've been covering? There was about $14,500 just for it without the install. 

[Ken]

Yeah, okay. So yeah, it's probably a bit more with the install, probably about $25,000 than with the install. But the decentralised are about $3,000 a pair. 

[Frank]

Yeah, I saw that and I thought, gee, that's ideal for retrofits.

[Ken]

Yeah, they're great for retrofits, yeah. 

[Frank]

That's a whole other topic. Yeah. But, you know, this is very cool. So you put your exterior on, you insulate, so you're basically battening, put your cladding over, still vent it. Just on the roof, because if you use a solid panel for your roof, are you still putting the impermeable membranes? Do you still put the membranes on? 

[Ken]

On the roof? 

[Frank]

Yeah.

[Ken]

Yes, we will. So we'll put... 

[Frank]

And then double-batten that to get that cavity? 

[Ken]

It really depends what insulation we use in the end anyway. If it's like an XPS, which is a hard foam. 

[Frank]

But you might put that directly above the ceiling anyway? 

[Ken]

Yes. So we put that on the... Because we do a lot of flat roofs and ballast roofs as well.

[Frank] (20:10 - 20:10)

Oh, right.

[Ken] (20:10 - 21:03)

So sometimes we'll just put ballasts, like pebbles on your roof. Sometimes we'll do that because... 

[Frank]

Yeah, I was thinking just normal, like, you know, gable roof. 

[Ken]

Yeah, if it's a gable roof, yeah, it would just be insulation, then your permeable membrane on that just so that it can, you know, if it does get some moisture in there. I know that moisture isn't coming from inside because you've got the air tightness there, but just, you know, it's just a good idea just to be able to let that breathe anyway, we find. 

[Frank]

It's a really fascinating construction, you know?

[Ken]

It's a bit backwards, but it certainly works. 

[Frank]

Well, yeah, like, we've done one project with it, as I've spoken to you about, and not one straight wall on the thing. But it was the only way I thought we could do it with CLT because it wasn't a straight wall. No roof angle was the same on this thing. It was a little bit ape shit. But that's the shape they wanted to achieve with the polished concrete.

[Ken]

Yeah, right.

[Frank] (21:04 - 21:05)

Yeah, it was. It was a detailing challenge. But anyway, it's being built right now.

[Ken] (21:06 - 21:44)

Oh, great.

[Frank]

But these panels came from Wynyard in Tasmania. 

[Ken]

Yeah, right, okay. 

[Frank]

Yeah, so...

[Ken]

And what brand were they? 

[Frank]

Oh, I can't remember the brand. They're only a new company up at Wynyard.

[Ken]

Yeah, interesting. 

[Frank]

Out of hardwood. 

[Ken]

Oh, great. Oh, hardwood. Okay. 
 
 

[Frank]

I'm pretty sure it's hardwood because it was out of all the hardwood forests that were done for the pulp mill that never went ahead.

[Ken]

Yeah, right. 

[Frank]

So you've got so many hundred thousand hectares of regrowth. 

[Ken]

I'd be interested to get some details about that.

[Frank] (21:45 - 21:46)

They're doing all this research of hardwood LVLs and all sorts of stuff. Pretty exciting.

[Ken]  (21:46 - 23:07)

Because without going on too much of a tangent, what we've found, I don't mean to shoot down anyone in particular, but what we've found is with the Australian softwoods, we can't get those dried enough to maintain a comfortable relative humidity when you build an airtight box out of them. 

[Frank]

Yeah. So... I just heard this recently with another builder. He bought all these packs of timber. You know, they're all wrapped in plastic. He cracked one open after a couple of years. Disintegrated. 

[Ken]  

Yeah, right.

[Frank]

Because the pine is what it is. It wasn't dry.

[Ken]  

It retains a lot of moisture.

[Frank]

And it stayed in its glad wrap. And it just rotted itself to pieces. 

[Ken]

Even the cell structure of pine, because it's such a fast...Our pine here is such a fast-growing pine. It's almost impossible without, you know, thermally modifying the timber to get that out of the cells. Whereas the European spruce that we use is a much slower-growing timber. It's still sustainable. 

[Frank]

We're just impatient here in Australia. Yeah.

[Ken]

But we can get that down to about 40% moisture content, which means that it's about... Sorry, about 12% moisture content, which means that when you build a box out of it, you get about 40% relative humidity inside, which is really comfortable. So it's one of the preferences that we have of the Austrian one over the Australian one.

[Frank]

Yeah, that makes all the difference. Yeah, right. So the Australian guy's got to really look at what they're doing there.

[Ken]

But the hardwood should be...

[Frank] (23:07 - 23:09)

Oh, it should be... That'd be a game-changer, I reckon.

[Ken] (23:09 - 24:06)

Yeah, I'd be keen to do a bit more research on that. 

[Frank]

There was a six-storey office building built in Launceston. Yeah. And a lot of the timber came... I'm pretty sure it came from Austria as well. 

[Ken]

OK.

[Frank]

But a couple of the floors, they used the hardwood. 

[Ken]

Yeah, right. Yeah. That'd be a nice contrast. 

[Frank]

Yeah, I haven't been in there. It's really cool, this building, what they've done. And, gee, it went up fast. 

[Ken]

Yeah, yeah. We...I'm from Newcastle. And, yeah, the university there has used a couple of... Yeah.

...done a couple of CLT buildings now. 

[Frank]

So universities seem to have the money to do this too. Yeah.

[Ken]

Yeah, that's right. Well, I mean, that being said, we've had estimates done and the builders come back and our estimators are saying, you know, we'll get a quote back for, you know, a million-dollar build or a $1.5 million build. And the builders will say or the estimator will say this would be a $2.1 million build under standard construction. So it's about 30% cost-saving. And when you consider the benefits of it...

[Frank] (24:06 - 24:07)

Yeah, exactly.

[Ken] (24:07 - 24:34)

...it just blows you away. And this is why we've got all our clients, anyone that we give it to as an option, they take it up. 

[Frank]

Makes a lot of sense.

[Ken]

It does, yeah. Yeah, it does. Especially when labour's so expensive in Australia.

[Frank]

Oh, and it keeps going up. 

[Ken]

You'd be cutting out nine months of carpentry... 

[Frank]

Yep.

[Ken]

...with a couple of blokes on site. And to compare with, you know, you're paying a lot for a crane but that's just for four or five days. That's just one operator.

[Frank]

Yeah, four days. Yeah. Exactly right.

[Ken]

And it's, yeah. 

[Frank]

Yeah, so you've built the whole walls. 

[Ken]

Yeah.

[Frank]

Sounds awesome.

[Amelia] (24:35 - 24:37)

So why is it not more widely used?

[Ken] (24:37 - 24:53)

Well, it is in Europe and more increasingly in the States. It's just taken us a little while to get there. I mean, we've sort of been a bit behind the eight ball in terms of the passive house movement and, you know, that's now sort of...

[Frank]

But this doesn't have to be passive house.

[Ken] (24:53 - 24:53)

It doesn't have to be.

[Ken] (24:54 - 25:03)

But it's a good way to achieve it. Yeah, yeah. But I think it piggybacks off that movement. Also, it's probably not suitable for all climates in Australia.

[Amelia] (25:03 - 25:03)

Okay.

[Ken] (25:04 - 25:37)

It's typically zone four and up, which, you know, if you don't understand that, it's not great for tropics and sort of hotter, more humid climates. 

[Frank]

High humidity climates, yeah. Yeah, yeah.

[Ken]

But, you know, Sydney, Newcastle, I've done one in Congarene. 

[Frank]

Where's that? 

[Ken]

Which is about an hour south of Coffs Harbour near Maxfield.

[Frank]

Okay.

[Ken]

That's probably as high as you'd want to go. He was keen on doing it, so he went ahead with that. But, yeah, it's originally used in the Swiss Alps where it's freezing.

[Amelia] (25:37 - 25:38)

Yeah, where it's cold.

[Ken] (25:38 - 29:17)

That's not to say that it can't be used in, you know, in a more temperate climate. 

[Frank]

It could be ideal here for Tassie. Yeah.

[Ken]

And the other thing that's slowed it down is that there hasn't been many Australian manufacturers of it. So KLH were the first on the ground, and they've been building awareness of it for a couple of years. 

[Frank]

But also getting it from Europe, which is, you know, they're experts at it. We're limited by a container size too. 

[Ken]

That's right. And you need to know the people here in Australia that can get it from Europe for you. Like I said, I'm not the one ringing up Austria. So unless you've got those connections, it's a big limiter in terms of how fast the industry can adopt it. But once you've made those connections, which we're lucky enough to have done now, then, you know, it opens up all this possibility.

And it is starting to get a lot of momentum. Like, as I said, there's government buildings going up. There's a lot of residential buildings going up.

And, yeah, and when it comes to builders, because I guess builders, I think, you know, whenever an innovative technology comes, that, oh, you know, I'm not trained for that, I don't know how to do that, it will be adopted quite quickly because the builder doesn't necessarily need experience and CLT to do one of these things because it's done by this, the actual erection and handover is done, essentially by a subcontractor, which is this middleman that comes and puts it all up for us. 

[Frank]

So would you say that subcontractor, so if you order this in your house, they'll come down and erect it? 

[Ken]

Yeah, that's right. So they'll organise the, as I said, the shop drawings, the import, it lands in a shipping container and then they'll ship it to site and they'll organise traffic control, cranes, put it up. What they say is they don't need a builder on site that has had any experience in CLT before to help them. They just want someone that's passionate about building sustainably and is excited about the building process.

And if they've got that, then they say, yeah, that's the perfect combination, that's the perfect team and they direct the builder as to what to do while that's going up. And as long as they're on hand, they're there to almost be labourers in a way. But yeah, once you've got that shell, a locked up shell with windows, doors and the frame there, then you can let the builder run loose.

He'll just start with the insulation, the battens, the wraps, all the stuff he's used to, but this time he's not doing the whole framing, he's got a house basically just to fit out. 

[Frank]

And one last question, do you get the whole box up? 

[Ken]

I’ve talked too much, sorry.

[Frank]

No, no, no, no, it's all good. But I'm saying I think practically, you know, and it's been the same in Europe, that you get the box up, bang, then the builder comes and does his bit. How long can this structure sit in the weather for?

[Ken]

Yeah, good question. 

[Frank]

The reality is delays, whatever, and your box is exposed. It's no different when you build a normal stick frame for a house, see they're exposed and there is a limitation there because you start getting mould growing on the timber.

And most people don't know, don't care because it's behind the plaster and you've got black mould in there. 

[Ken]

Yes, yeah. The good thing about this is there were mould to grow, it's on the outside.

[Frank]

Yeah, you know, you're 100% right, until you get the windows in, you know. That's right. But it's always more than people think.

[Ken]

So there's an anecdote or story that my CLT guy says where they erected a structure, there was a parapet wall right around the roof and something happened to the client, I can't remember what, but he had to go overseas or whatever and it became a literal swimming pool. It stayed a swimming pool for three months and after three months they soaked it out and just dried it up and just carried on. So typically the general advice is get it covered.

[Frank]

ASAP. 

[Ken] (29:17 - 29:18)

ASAP. 

[Frank]

Like any structure.

[Ken] (29:18 - 29:21)

12 weeks is what they say.

[Frank] (29:21 - 29:21)

Really?

[Ken] (29:21 - 29:23)

And you should be able to more than organise the equipment.

[Frank] (29:23 - 29:24)

Well, that's interesting. Yeah, because I would have thought being exposed.

[Ken] (29:24 - 29:30)

Yeah, well, it's, I mean, I guess it's such a solid thing.

[Frank] (29:31 - 29:33)

I'd just give it a paint job straight away.

[Speaker 1] (29:33 - 29:59)

Well, if you're putting an insulation on it, we often do rockwall, it's hydrophobic, and then you're putting a permeable membrane on that, there is still a bit of surface moisture sunk into the outside of the CLT, it's going to come out. But yeah, if you can get a Pro Clima UV stabilised wrap or something on there, which is the best thing, they've got a six-month warranty exposed on there as well. So you've got plenty of time its not like we’ve got up, gotta rush and cover this thing, you get to it when you get to it. 
 
 

[Frank]

Yeah sure

[Ken]

The building is built in a way that moisture can sort itself out and dry up. 
 
 

[Frank]

Yeah, there you go. 

[Amelia]

Very cool  

[Frank]

Are you better educated now?

[Amelia]

I am. I’m curious yeah. because it’s not really something I’ve heard much about. 

[Ken]

No, no and a lot of clients that come to us haven’t, but it will be something that you’ll start to hear more about in the future.  I’ve often looked towards not just future proofing the business but also just out of interest seeing what the next thing is and I research you know 3D printed buildings, CLT and SIPS and all these types of construction methods and this is  the one that we’ve really landed on as being you know what we think is the future of the construction industry

[Frank]

Yeah

[Amelia]

Very cool. 

[Frank]

Watch this space. 

[Amelia]

Yeah it will be interesting to find out what happens. 

[Frank]

Yeah it’s awesome

[Amelia]

Alright well we might start wrapping up. Are there any resources available for anyone to learn more about cross laminated timber? It sounds like its kind of very niched and sort of not really well known in Australia is it?

[Frank]

Not in Australia but there’s a lot of European influence

[Ken]

There’s a lot of content, If you’re just early stage researching then yeah there’s plenty of content online as I said you could even look at a few grand design episodes just if you’re after the aesthetic quality of it but if you’re after more technical information then yeah there’s things on YouTube there’s you know, you can contact me at the Rubix Collective and ask me any questions if you want but yeah you should be able to find a lot of content online on CLT and even companies if you’re starting to get into the technical side of it or if you’re a tradie that’s listening to this podcast even companies like Gripset waterproofing are now doing data sheets on how to waterproof CLT 

[Frank]

Wow

[Ken]

so the industry is catching on, the products manufacturers are catching on and are starting to give specific advice on that too so yeah. 

[Frank]

There you go

[Amelia]

Well thank you so much for coming in today Ken and chatting to us. 

[Ken]

That was fun, thank you very much for inviting me

[Amelia]

Enjoy the rest of the trade show and the rest of the night 

[Ken]

Thank you. Cheers.

[Amelia]

Thanks for listening to the Building Design, Prime Time Podcast.  

[Frank]

Catch ya’s later

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