Wood is increasingly recognized by the construction sector as an essential and innovative choice of material. On an international scale, wood has been gaining popularity for prefabrication of wall, roof, and floor elements. The building envelope plays a key role for a comfortable, durable, and energy efficient building. The design of a building envelope consisting of solid wood or engineered wood products differs from that of traditional light wood-frame buildings and requires special attention because of the unique characteristics of the product. This workshop will discuss the design and construction of building envelope assemblies based on mass timber products, with a focus on protecting the structure from moisture and environmental elements, separating the indoors from the outdoor environment, and ensuring thermally efficiency. Construction moisture management will also be covered. Knowledge and experiences learned from the recent developments of mass timber buildings in various countries will be shared.
Moderator: Jieying Wang, FPInnovations, Canada
Prefabrication of volymetric modules: timber as high quality product
Speaker: Toni Kekki, Rakennuskonsultointi T Kekki, Finland
In Europe’s northern regions, volumetric modules are gaining popularity. Because of lengthy winters, on-site work is often done in harsh conditions. This causes ineffectiveness, uneven quality and expensive on-site preparations. With prefabrication, work can be done in a controlled environment.
Good quality ratings, and technical elements such as airtightness, have meant that more customers want projects to use modular massive timber.
The main reason for prefabrication is to shift work from the construction site to manageable conditions in the factory. The highest product in this evolution is volumetric modular elements, where up to 95% of the product can be prefabricated. This means that up to 80% of the entire project can be done in controlled-climate conditions, providing great savings of time, better logistics and better quality. Additionally, working in standard conditions is safer.
When dealing with modular systems, the whole building process must be thought out differently. As a result, surface quality, connections and installations are better. Moving from on-site production to something more like the assembly line of the car industry causes a leap in productivity, which means better quality with lower costs.
Tall Wood Building Enclosures
Speaker: Graham Finch, RDH, Canada
The construction of taller mid- to high-rise mass timber buildings is quickly becoming more common across Canada and the United States. These buildings utilize engineered mass timber components such as cross-laminated timber, nail-laminated timber, and glulam to meet the structural and fire requirements at these greater heights. The increased time and exposure to weather and new timber construction methods pose unique challenges for design and construction teams. The design of the building enclosure and associated details requires careful attention to maintain acceptable durability, fire protection, and energy efficiency. In response, the prefabrication of whole floor, wall, or modular components using new and innovative wood systems is also common in these buildings to speed up construction and protect assemblies from moisture. The presentation shares guidance on building enclosure design and detailing for tall wood buildings from recent mass timber industry guidelines and case studies from several of the new tall wood buildings in North America. Lessons learned from the design and performance of the building enclosures for these buildings will be covered.
Resistance of wood construction envelopes to driving rain
Speaker: Julien Lamoulie, FCBA, France
To guarantee the durability of tall timber buildings, from structural parts to insulation materials, their outer skin has to be completely uninterrupted and watertight, regardless of external climatic conditions and the precast factory manufacturing level of the timber façade units. These two factors lead to distinctive designs for high-rise timber buildings: The proposed technical solutions must be able to withstand driving rain pressures to which multi-storey buildings are subjected, not only for ordinary parts, but also for all the special or singular points of the building enclosure. These include vertical and horizontal junctions between prefabricated façade elements, the periphery of windows openings, end-to-end enclosure crossings, etc.
With a view to economic optimization, specific work has been carried out in recent years in order to match driving-rain-resistance performance of timber buildings façades, actual climatic requirements, and the expected lifetime of the facing.
Jieying Wang is a senior scientist in FPInnovations’ Building Systems group. Since joining FPInnovations over 13 years ago, she has focused her research on wood durability, moisture management, and thermal performance of wood-based building envelopes by conducting laboratory testing and field monitoring. Through collaboration with other professionals, she has been extensively involved in developing design guides and codes/standards on durability and building envelopes.
Toni Kekki is a 43-year-old master of engineering, father of two and grandfather of two who has worked in the field of structural engineering for the past 20 years. His career has included the design of concrete and steel structures, product development, development of prefabrication methods and project management. Since 2010 he has been working with massive timber almost full-time. The projects have been mostly multi-storey (>4 storey) residental housing projects, primarily in Finland, with some export projects. His largest projects have been Puukuokka in Jyväskylä and DAS Kelo in Rovaniemi, while the tallest projects were Tuuliniitty in Espoo (13-storey, responsible designer) and the Joensuu Lighthouse (14-storey, structural analysis consultant). Mr. Kekki stongly believes that timber is a useful and traditional material, and we haven’t seen its full potential yet. His mission is to create sustainable solutions for the reasonable use of natural resources and he is working for a better future for generations to come.
Graham Finch is a Principal and Senior Building Science Specialist with RDH. He has a passion for technology and improving energy efficiency in new and existing buildings. He is actively involved in numerous projects, ranging from building research studies to forensic investigations, building monitoring, hygrothermal modelling, and new construction across Canada and the US. Mr. Finch is regularly invited to present to industry groups on the latest building science topics and has co-authored several publications and practical industry guidelines on high-performance building enclosures. Related to mass timber, these have included the Guide for Designing Energy-Efficient Building Enclosures, the Building Enclosure Design Guide for Wood Frame Buildings, Building Enclosure Chapters within the CLT and NLT Handbooks, and the Guide for Tall Wood Buildings.
Engineer Julien Lamoulie has been in charge of liaison with professionals in the field for the Technological Institute FCBA (Institut Technologique Forêt Cellulose Bois-construction Ameublement) since 2009. His work involves consultancy, innovation support, technical support for companies, contractors and clients. He works on standards with several Standards Commissions and has piloted national and transnational research projects. He has edited a number of technical documents (Professional Rules, Technical Guides, etc.), published international scientific papers and participated in several national and international technical and scientific colloquia. From 2005 to 2008, Mr. Lamoulie was a chargé de mission for Néopolis/CCI Drôme and specialist in “construction and environment” and “sustainable development and construction”. He has also coordinated long-term internships (60 interns/year) and was a resource person for the architecture school in Lyon. A specialist in tropical woods (École Nationale du Génie Rural des Eaux et Forêts), he worked previously in Mayotte, Costa Rica, Cameroon and French Guyana.