HPH320 : Precision-cut timber frames – with Antoine Costantini from Kithurst Homes
Antoine Costantini explains how Kithurst Homes has embraced modern cutting technology to increase efficiency and minimise waste.
Interview with Antoine Costantini
With a background in physics and trouble-shooting in the construction industry, Antoine has always loved working with timber. He explains that engineered timber is a great way of using the material responsibly and with less waste.
There are 4 main types of engineered timber that Kithurst Homes use
- Laminated Veneer Lumber (LVL) – “Like a plywood on steroids”
- KVH – Finger-jointed soft wood
- Cross Laminated Timber (CLT) – A cross lamination of timber in opposing directions
- Glulam – Soft wood glued together
Automating the process is faster and produces less waste
Previously they would use a large chop saw to cut frames by hand, which meant manually changing the direction each time a different angle was needed. This would get repetitive and there was the risk of human error so they looked for a way of automating the process.
The Hundegger machine they now use is a five axis saw which enables them to make cuts at any angle and inclination. It has also reduced the time it takes to cut, mark and pack a 200 square metre frame from two and a half weeks, down to three hours! On top of this there's now only 3% wastage.
The Hundegger software reads and cuts from various file types
One of Kithurst's customers is Passivhaus Homes with their PH15 method of construction. They send over their completed BVX file of the timber frame design, which gives the machine all the information it needs.
Get access to our in-depth video case study of Buckinghamshire Passivhaus, a PH15 build, in The Hub
Kithurst Homes also work from DWGs or can convert a hand drawing into a 3D image that the saw will then read.
The machine software creates a picking list
This will tell the operator the amount of I-joists, glulams and LVL that will be needed. These are then manually placed in order of size and fed into the machine.
The machine is clever enough to recognise the material that is being fed in, and will alert the user if the geometry of the material doesn't match with what it has been asked to cut.
Using I-joists is an efficient way of building
They use less timber than a traditional stick frame approach, and also reduce cold bridges because of their size and geometry. They arrive at the factory in 13 metre lengths, with Antoine estimating that an average frame would use around one kilometre of I-joists.
The combination of the web of the I-joist with incredible shear strength and the lamination of the flange gives the I joist its strength and load bearing capacity. The regularity of the timber makes it predictable, and that is a good thing in engineering. They know how it will react on strength, density, bending, modulus, and shear.
If it's not compostable or recyclable they won't use it
Once the timber has been cut, numbered and marked, it is packed together by wall. Steel bands are used to secure them, as these can then be recycled whereas the plastic alternatives can't. They are then stacked and transported to site by curtain sided trucks. Once on-site there is no need for a skip, as everything fits and there is no wastage. This complies with the company ethos of trying to preserve the environment as much as possible, and not using PU or polystyrene foams for example.
It just takes common sense and DIY skills to put it together!
Kithurst Homes will always provide training, whether that be on site or at their factory, in how to construct the frame. With everything being marked, it's a case of needing to be bound together, and Kithurst Homes provide all the fixings, the screws, the staples, the membranes, the plywood.
Antoine says that anyone with good DIY skills can put together their flat pack systems. Some of the parts can be heavy so may need extra pairs of hands, but generally because the I-joists use so much less timber they can be quite manageable.
Their full wall systems however require craning in and a team of carpenters to put together.
All their timber is PEFC certified
The timber comes from two or three manufacturers, with Steico in Germany being where they get their wood fibre insulation, LVL and I joists. It is fully certified to European regulations and Kithurst know their suppliers are using the timber properly, with everything on the tree being used and documented.
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