A ‘SYSTEM’ SOLUTION

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According to Rothoblaas Engineer Ernesto Callegari, the ground connection continues to be one of the most critical points of a timber building and can be solved in an innovative way.

Ground connection is one of the most critical points of the building, as it consists of a discontinuity of materials, a geometric discontinuity and where timber can potentially come into contact with water from different sources.

In recent decades, buildings have become increasingly complex, so it is no longer sufficient to apply a few simple rules to ensure the required performance – this is particularly evident in the ground connection of timber buildings. Our modern buildings have become complex systems to which we are demanding increasingly higher performance – and complex systems cannot be treated with simple solutions.

Ensure passive protection

The possibility to raise the entire ground floor, is not necessarily the only possibility: for example, it is possible to align internal and external floors, but creating a ventilated cavity on the external side of the wall, using a floating floor. In this case, the water run-off surface is moved to a lower level than the timber wall, while still ensuring the continuity of the floors.

Another very common method is the reinforced concrete curb: the timber walls are installed on top of a small reinforced concrete elevation, raising the installation surface. Personally, I have used this method extensively in my design experience, but I have recognised all its limitations, especially from the point of view of the construction site. Let me explain: the pre-cut timber structure and in-situ concrete are two worlds in terms of installation tolerances. Although for reinforced concrete an installation tolerance of 1-2cm is perfectly acceptable, in the case of a CNC pre-cut timber structure, those same 1-2cm can be a serious problem, resulting in extra costs for the customer.

Evolving ground connection technology

In recent years, pre-engineered systems using ‘metal curbs’ have been developed, they can be a good opportunity to manage in-situ tolerance, creating a separation between concrete and timber. However, it is important not to consider these products as a miraculous solution which, on its own, solves all the problems: the correct design of the ground connection requires a ‘system’ solution, in which different materials and different technologies are involved to reconcile the necessary requirement of durability with the need for rapid and troublefree installation. Metal profiles can greatly contribute to this. We are very proud to have been the first to produce ALUSTART a single profile with CE marking according to ETA, capable of ensuring durability and at the same time transferring all the stresses of a timber building to the ground. Based on this premise, I will highlight how various problems can be solved using an innovative metal profile system:

• Construction site problems: an interposed metal profile can act as a

‘compensator’ between the execution tolerance of the reinforced concrete casting and the timber wall, acting as a ‘template’ for marking out the plan and levelling the walls. • Static problems: the metal curb does not merely transfer the weight of the wall to the ground but is very well suited to being used as a ‘single’ connection system, both for seismic or wind shear and tensile stress and for wind action perpendicular to the wall. The advantage is that all other connections (angle brackets and hold-down) can be eliminated. • Thermo-hygrometric problems: it is important that the metal profile does not introduce a thermal bridge; for this reason, the use of an optimised geometry of the profile, able to avoid air movement by convection in the lightening chambers, can be of great help. • Regulatory issues: EU and UK legislation prescribe precise procedures for the certification and

CE/UKCA marking of construction products. A pre-engineered and certificated metal profile can solve this issue, providing the designer with all the information needed to carry out the structural verifications of the metal profile. Remember – prevention is better than a cure – and prevention means accurate planning, trusting in expert builders and using materials and technologies that are certified and produced by reliable companies.

www.rothoblass.com

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01. As buildings have become more complex so has the technology involved in their construction

TIMBER MACHINERY

DEMONSTRATIONS

Leading machinery distributor Daltons Wadkin is holding its annual Wood & Panel Machinery Show at its Nottingham premises from 4-6 October 2022. What will visitors be able to see?

This year’s focus will be on crosscutting technology with the complete Salvador range of automatic crosscut saws on demonstration, as well as a selection of manual radial arm saws from SCM, Graule and Wadkin.

Salvador – in partnership with Daltons Wadkin – have a proven track record in revolutionising timber frame manufacturing through the installation of automatic and semi-automatic crosscut saws that increase yield, reduce skilled labour, and boost productivity. From the high speed SuperPush 250 model with chain infeed and automatic outfeed system to the all-new range of semi-automatic SuperUp saws, the show will be an ideal destination for anyone looking to boost their straight or angled crosscutting production.

The Wood & Panel Machinery Show will also include working demonstrations on other key brands and product types for processing a wide range of materials including solid wood and wood-based panels, composites, plastics, metals and more. Visitors can see Elcon vertical panel saws, SCM classical machinery, Altendorf sliding table saws, Stenner band resaws, Kimla CNC fiber laser and CNC-router technology amongst others. 01

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For more information visit: www.daltonswadkin.com/oh22/ or email: info@daltonswadkin.com

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01-02. The Wood & Panel Machinery Show will include demonstrations for those working with many wood-based products