1. Technology KENO Home
1.1 What is Keno Home modular home technology all about?
Keno Home modular house technology consists of the prefabrication of residential modules in cross-laminated timber (CLT) construction in one of three design standards. This technology allows us to produce, for example, single-family homes, apartment buildings, hotels, residential homes, retirement homes, holiday homes, and much more.
1.2 What is modular construction?
Modular construction is a construction method in which entire building sections are produced in a factory in the form of modules, i.e. boxes, which have a floor, walls, and a ceiling and are finished both inside and out to a standard ordered by the customer. The finished modules are transported to the construction site on trucks. At the construction site, the foundation and installation connections must be prepared beforehand. The modules are removed from the truck with a crane and placed on the foundation, then bolted together and to the foundation. On the construction site, only the installations between the modules must then be connected, connected to the intended connections and the house must be completed, depending on the expansion standard of the modules ordered by the customer.
1.3 In what finish can the modules be manufactured?
The modules can be manufactured in the factory in one of three finishes:
Our customers can choose from one of three finishing standards:
- raw state
- developer's state
- turnkey state
For detailed information on the scopes of the above finishing standards, our sales representatives are available to provide assistance.
1.4 Are Keno Home modular homes usable all year round?
Keno Home's modular homes can be used all year round and meet the standard of the Technical Conditions that apply from 2021.
1.5 Are Keno Home modular homes mobile?
Keno Home's modular homes are designed to be installed on a foundation so they are fixed to the ground. However, the modular technology, which makes it possible to transport the house in several parts from the factory to the construction site, also makes it possible to separate the modules again after some time, after having lived there, and transport them to another place. This means that our house no longer has to be built in one place and is permanently tied to that place, as with traditional construction, but can travel with us when we want to move. So when we move, we don't have to sell our house and look for a new one but can take the house we feel comfortable in with us.
2. CLT wood
2.1 What is CLT wood?
CLT (Cross Laminated Timber) is a load-bearing construction material in the form of panels from which we make our modules. It is made entirely of solid wood and usually consists of 3, 5, or 7 layers of wood lamellas that are alternately glued together crosswise. This arrangement of layers ensures high strength in both directions and high rigidity of the structure. The wood species used are mainly spruce and fir in strength class C24.
2.2 What are the advantages of CLT wood?
CLT timber has several advantages:
Precision and quality of workmanship - CLT panels are manufactured in the factory and cut to the project-specific size with CNC machines to an accuracy of up to 1 mm, eliminating dimensional errors that are common in reinforced concrete and masonry buildings. By using CLT technology, we no longer have to mill out a hole for a door that doesn't fit or remeasure after the wall is built. You can order the door sooner because the door opening is cut into the CLT panel to an accuracy of 1mm.
Durability - CLT is a very strong and durable building material that can withstand high multidirectional loads, unlike ordinary construction timber. Owes this to the technique of cross-bonding.
Speed of assembly - thanks to the fact that CLT panels are made to measure in the factory, the time needed to build a house is significantly reduced compared to reinforced concrete and masonry techniques. We even go one step further and, thanks to prefabrication, move most of the construction process to the factory floor where our modules are manufactured. In this way, the assembly of the house on site can be shortened to a few days. This means the house can even be ready for occupancy much faster than with frame construction.
Very good insulation and thermal properties - CLT panels are closer to insulation materials than concrete and masonry in terms of thermal performance. This allows the use of a thinner thermal insulation layer on walls, floors, and roofs compared to conventional technologies, which translates into savings in house construction. Our modular houses meet the goals of low-energy houses.
Diffusion openness.
Airtightness.
Phase shifting.
Very good acoustic properties.
Fire resistance.
Durability.
Lower dead weight - due to the high strength of CLT panels with a low thickness of structural elements (walls and ceilings), the weight of the entire building is much lower than in reinforced concrete and masonry structures, which affects the much lower cost of making the foundations. At the same time, CLT panels are part of solid wood construction, so we do not have to worry about our house blowing away in strong gusts of wind, as we do with frame construction.
Ecology and sustainability - Wood as a natural raw material for CLT panels has many advantages over conventional technologies: it is renewable - it constantly grows back; it is a natural carbon sink; it binds CO2 and thus actively contributes to climate protection; it is a natural energy store; it can be 100% ecologically recycled.
Wood is beautiful and cozy - by using CLT as the construction of our modules, we emphasize the beauty of wood as a natural raw material. A house made of CLT is not only cozy because it is warm, but also because staying in a house made of wood has a calming effect on our senses and improves our mood, and the smell of wood relaxes and calms us.
2.3 How are CLT panels manufactured?
The first step in the production of CLT panels is the procurement of the raw wood boards, which are dried, planed, and trimmed and then joined together with finger joints (micro-notches) to form long lamellas. Each CLT ply must be made of wood of the same strength class. For the longitudinal layers, the wood of higher grades (C24 and higher) is usually used. For the transverse layers, on the other hand, the wood of grade C16 and higher are used. Spruce is the most commonly used wood species. The boards from which CLT elements are made are generally 10 to 50 mm thick.
The second production step consists of properly arranging the previously prepared wood lamellas in layers aligned perpendicular to each other and gluing them together to form the finished CLT product. The panels consist of an odd number of layers - 3, 5, or 7. Melamine (MUF) and polyurethane (PUR) adhesives are usually used to glue the individual layers. These adhesives must meet strict standards regarding formaldehyde emissions and are harmless to health during manufacture, use, and even in the event of fire. The battens do not have to be glued on the side surfaces and may be laid with a spacing of up to 6 mm. Cross-glued timber is glued in hydraulic or vacuum presses. In both cases, depending on the gluing technique, sufficient pressure is required on the elements to be joined to ensure a permanent bond.
2.4 What are the technical parameters of CLT panels?
Dimensions of CLT panels: Thickness 60-400 mm, width up to 3.5 m, length up to 20 m.
Types of wood: spruce - the most commonly used, fir, pine, and larch.
Moisture content: 11% +-2
Density by volume: 450-500 kg/m3
Thermal conductivity coefficient λ: 0.12 W/mK
Specific heat: c = 1600 J/kgK
Fire behavior class: D-s2, d0
Airtightness: airtight for boards with >=3 layers
2.5 How can the surfaces of CLT panels be treated?
For the production of the modules, we use two types of surface treatment of CLT panels:
non-visible surface - used on the outside of the modules and also inside the modules where we know it will be covered by floor layers or plasterboard on the walls or ceiling. This surface meets all the static requirements, but does not have to meet the increased visual requirements - there may be more knots on it, gaps between the slats, discoloration, and different types of wood are allowed.
Visible surface - is used inside the modules on walls and ceilings that should ultimately remain visible. It consists of micro-bonded lamellas of a single type of wood that have a uniform appearance in terms of texture and grain. Knots and small gaps between the slats are acceptable but present in minimal numbers. The visible surface requires no further treatment; it is comparable to a plastered and painted wall in traditional construction.
3. Building physics
3.1 What are the thermal properties of CLT wood?
CLT wood has high insulating and thermal properties.
The U-value of CLT is significantly lower than that of concrete and masonry (for the same wall thickness).
If you compare a wall with a thickness of 20 cm:
for CLT U=0.59 W/m2K
for concrete U=3,2-3,70 W/m2K
for brick U=1.8-2.5 W/m2K
The U-value is a measure of how quickly heat escapes through a partition (e.g. wall, window, roof). The lower the U-value, the less heat escapes through the partition, which means that such a material is a better thermal insulator.
The heat capacity of CLT is higher than that of concrete and masonry.
for CLT c=1600 J/kgK
for concrete c=1000-1300 J/kgK
for brick c=800-1000 J/kgK
Heat capacity is the ability of a material to store heat. It also indicates how long a material gives off the heat once it has reached temperature equilibrium. The higher the specific heat, the better the material can store heat and the slower it releases heat to the environment.
The thermal conductivity coefficient λ of CLT is lower than for concrete and masonry.
for CLT λ=0.12 W/mK
for concrete λ=1.5-2.0 W/mK
for aerated concrete masonry λ=0.2-0.38 W/mK
for brick masonry λ=0,64-0,9 W/mK
for mineral wool λ=0.035-0.045 W/mK
The thermal conductivity coefficient determines how well a material conducts heat. The lower the lambda value, the better a material is a thermal insulator.
4. Façade
4.1 Which material can I use for the façade?
To obtain the best thermal and acoustic properties and the breathability of the façade, a ventilated façade should be constructed. We recommend natural materials: rock wool insulation, a wooden substructure, and natural wood cladding as the last layer of the façade. Depending on preference, the last layer can also be made of other materials.
4.2 Which materials (examples of specific products) are recommended for the final layer of the façade?
As the final layer of the façade, we recommend a horizontally laid natural wood façade panel with tongue and groove. The type and color of the wood are determined by the builder, e.g. Okuma.
As an alternative you can use
Rockpanel façade panels - these are panels whose main component is basalt; they offer a wide range of colors and give the façade a modern effect;
Equitone / Cembrit façade panels - these are fiber cement panels in a variety of textures and colors, giving you the freedom to design your façade;
Joint sheets - for a minimalist, modern façade.
4.3 Can the CLT be exposed to the outside of the building (how does it behave over time, if and how does it need to be maintained, will it turn blue, acquire a patina, lose its visual appearance?
Under Polish climate conditions, the construction of our CLT panel modules in all-season houses requires thermal insulation on the outside of the walls. Therefore, CLT panels will not be exposed to external weather conditions for long periods. They are also not usually used as the final layer of the façade, as timber façade panels are better suited for this. However, if CLT wood is exposed to the weather for a longer period, it behaves like any other wood.
Under the influence of precipitation and high humidity, the wood alternately swells and shrinks, which is called volume change. These changes are exacerbated by temperature fluctuations and can lead to the formation of micro-cracks. This does not mean that CLT wood loses its strength parameters, but it can lose its visual properties due to the gaps that develop between the lamellae. Furthermore, under the influence of UV radiation, the surface layers of the wood are oxidized, which manifests itself in a loss of color or blueing.
For this reason, we advise against using CLT as a layer that is exposed to prolonged weathering. However, if the customer wants to make elements of a garden arbor out of CLT, for example, CLT should be protected with conventional wood preservatives.
5. Project
5.1 Is a building permit required for the construction of Keno Home modular houses?
Most of the houses in our offer have a built-up area of <70 m² and therefore do not require a building permit according to current law, only a notification of the start of construction. For houses with a built-up area of more than 70 m², a building permit is required. These are the houses Syndin, Ulvik, and Trolltind.
5.2 Can the layout of the rooms be changed?
The functional floor plans of the Keno Home modular houses have been designed in such a way that the space in the house can be used as efficiently as possible for the planned number of occupants. Therefore, the room layout can only be changed slightly by installing interior partition walls in lightweight construction. However, it is not possible to cut additional window and door openings in the load-bearing walls or to move the load-bearing walls.
5.3 CLT technology has been around for about 20 years and is even used for high-rise buildings:
INTRO, Cleveland, USA - multifamily building
https://www.binderholz.com/en-us/mass-timber-solutions/intro-cleveland-usa/
Quartier Prinz-Eugen-Park, Munich, Germany - apartment building
https://www.binderholz.com/en-us/mass-timber-solutions/quartier-prinz-eugen-park-munich-germany/
Hotel MalisGarten, Zell am Ziller, Österreich - Hotel
https://www.binderholz.com/en-us/mass-timber-solutions/hotel-malisgarten-zellamziller-austria/
Kaffeeproduktionsanlage Johannson, Vestby, Norway - industrial building
https://www.binderholz.com/en-us/mass-timber-solutions/coffee-production-plant-johannson-vestby-norway/
Einfamilienhaus, Uderns, Österreich - single-family building
https://www.binderholz.com/en-us/mass-timber-solutions/single-family-house-uderns-austria/
Ausbildungszentrum 'Centre de Compétences', Bettembourg, Luxembourg - office building
https://www.binderholz.com/en-us/mass-timber-solutions/centre-de-competences-training-centre-bettembourg-luxembourg/
Wohnanlage 'Integrationen Linköping', Sweden - multifamily building
https://www.hasslacher.com/residential-complex-linkoeping
HBLA Pitzelstätten Klagenfurt-Wölfnitz, Österreich - student residences
https://www.hasslacher.com/en-hbla-pitzelstaetten
HOHO VIENNA, Vienna, Österreich - office building
https://www.mm-holz.com/en/references/hoho-vienna
WOODIE, Hamburg, Germany - apartment building
https://www.mm-holz.com/en/references/woodie
ECHO YOUTH CENTRE, Graz, Österreich - office building
https://www.mm-holz.com/en/references/echo-youth-centre
HUMMEL BARRACKS, Graz, Österreich - multifamily building
https://www.mm-holz.com/en/references/hummel-barracks
PAULASGASSE, Vienna, Österreich - apartment building
https://www.mm-holz.com/en/references/paulasgasse
5.4 Are there houses larger than 100 m² (in the 150-200 m² range)?
At the moment we do not have any houses with 150-200 m² on offer, but our range of modular houses is constantly expanding. You are welcome to keep an eye on our website and contact a seller.