Är korslaminerat trä ett bra alternativ för påbyggnader? Studiens syfte är att utreda hur väl påbyggnader i CLT står sig som alternativ i konkurrens med andra metoder att ta fram nya bostäder inom tätort där ett behov av förtätning finns. Studien riktar sig till en eventuell byggherre och i första hand till uppdragsgivaren: AB Gotlandshem. Kvartert Höken 1 är uppfört i början på 1960-talet. De aktuella byggnaderna för en eventuell påbyggnad är tre hus om två våningsplan och källare. Dessa byggnader benämns: B, D och F. Bärande väggar i stommen är uppförda i varierande material. I studien har två väggar valts ut som särkilt intressanta. De undersöks närmare genom statiska beräkningar enligt EKS 9. Studien konstaterar att de har tillräcklig tryckhållfashet för att bära en påbyggnad. Studien undersöker även ekonomiska förutsättningar för en påbyggnad i CLT. Detta görs genom att särkostnader identifieras och jämförs. Givetvis är kostnaden för materialet en särkostnad när valet står mellan två material, men studien identifierar även produktionskostnader för montering av bjälklag och installationer som särkostnader. Den ekonomiska jämförelsen indikerar en möjlighet att göra en besparing vid ett val av CLT-bjälklag. Studien visar att det är möjligt att utföra en påbyggnad av hus B, D och F i kv. Höken 1. Dessutom visar det sig att CLT är ett gott alternativ ur ekonomisk synpunkt. Materialet har fördelar som medför rationell produktion. Det innebär att CLT kan vara en billigare lösning för en påbyggnad. / Is cross laminated timber a suitable building material for adding storeys to a building? The purpose of this study is to examine how good an alternative CLT makes in comparision with other methods of developing new homes in urban areas. This study aims to a property developer and primarily to the client: AB Gotlandshem. The block Höken 1 was built in the beginning of the 1960s. The buildings of current interest are three houses with two stories and basement. These buildings are designated: B, D and F. The load bearing structure is constructed in varying materials. Two walls has been selected as especially interesting. They are examined closer through static analysis accordnig to EKS 9. The study concludes that they are sturdy enough to carry an added storey. The study also examines the ecomonic premises for adding a storey made from CLT. Separate costs are identified and compared. Naturally is the materials cost a separate cost in the choice between two different materials, but the study also identifies costs for mounting subfloor construction and installations as separate costs. The economic comparision indicates a possibility to cut costs by choosing subfloor constructins of CLT. The study shows that it is possible to add a storey to house B, D and F. Furthermore is CLT a good alternative from an economic viewpoint. The material has advantages that results in rational production methods. From this follows that CLT may be a cheaper solution for adding a storey.

Denna studie beskriver och analyserar de viktigare delarna kring branddimensionering för exponerat korslaminerat trä (utan beklädnad) med avseende på anslutningar med inslitsade plåtar och dymlingar. Det är dock brist på beräkningsmetoder för sådana anslutningar. Med fyra handböcker för limträ, kontra en för KL-trä, utgivna av Svenskt Trä finns det en hel del information om det materialet och dess anslutningar. Studien analyserar de två materialen för att undersöka om det finns möjlighet att nyttja forskning gällande beräkningar i limträ, för att därefter modifiera och applicera dem på KL-trä. Syftet med denna jämförelse vid brand av förband emellan grundas i att bredda kunskaperna inom området för KL-trä och eventuell kunna se intressanta samband. Målet för studien var att genom att identifiera dessa samband och tillföra nya aspekter relevant för KL- trä driva forskningen framåt. I studien gjordes en litteraturundersökning som visade att materialen har liknande egenskaper vid brand gällande brandens inledningsskede, förkolningsprocess, delaminering och de olika brott som kan ske under brand. Skjuvningsbrott i anslutningar med inslitsade plåtar och dymlingar anses vara det brott som bör dimensioneras för vid brand på grund av uppvärmda ståldelar och förkolning av träet. Därför samanställdes en beräkningsmetod för skjuvningsbrott i KL-trä med utgångspunkt i de befintliga beräkningarna för limträ enligt handboken Fire Safety in Timber Buildnigs - Technical Guideline for Europe. De två metoderna jämfördes och resultatet gav snarlika värden, vilket kan indikera på att utgångspunkten i limträ var rimlig men vidare studier krävs i form av undersökningar och eventuella brandtester. Andra typer av dolda anslutningar, t.ex sådana med självborrande skruvar, bör analyseras på liknande vis för att fastställa dess brandmotstånd.

The increased popularity of timber buildings has heightened the demand for more knowledge on how tomake these buildings safer. In many cases, parts of wooden constructions are prebuilt in factories that later are delivered to the building site. Transportation by road limits the sizes of the parts. When the structural timber parts arrive on site, they are ultimately assembled into the building. Some of these smaller parts, specifically cross-laminated timber (CLT) floor boards, create joints when connected together. The EI criteria of these joints will be examined in this bachelor thesis.  The purpose is to show the requirements to satisfy the EI criteria for CLT joints and evaluate different types of joints with the help of screening tests using the fire furnace at Luleå tekniska universitet (LTU). While doing so also collect more information and become more familiar with the material and engineering methods used.  Previous evaluations of joints have shown that it is essential that they are fully airtight for them to meet the EI criterion. However, this was with different types of structural timber, combined with different core joints and thicknesses of floor boards. Results have shown various viable CLT joints, airtight and semi-airtight, that met the EI-90 criteria and other non-viable joints that explored non-airtight solutions with a twist. The method, results and other observations during testing were analysed and discussed to assess their feasibility and the impact some error sources may have had. The conclusion is that all joints met the EI-criteria. While straight joints have a lot of smoke emissions, the temperature at the top of the joint do not exceed critical temperatures for the gap sizes in this thesis.

Historicly speaking wood is our moste important building material and it’s usage streches far back in time. Todyay it’s low density makes it possible to prefabricate whole wood bodies in factories that are later shiped out to building sites where they can be asembled. To meet the requierments of todays housing market, Lindbäcks Bygg AB has started a project where a 14-stories house is the be developed. To build on the height is a necessity due to rising land prices and the land has to be used mor efficient. A build of this high put a great demand on the constructual soulution in order for the wood body to withstand high columnloads on the lower flear, while it is stable enough to withstand the wind. The purpose of this report is to show you a possible way of constructing a 42 m high 14-stories hos usinga cross laminated timber(CLT). For the calculation a preliminary floor used, that has not been entirely completed. This gives the calcultations and arbitrary soulution that can work for similar buildings with varying floor plans. For this reason utilization of the CLT is a bit lower than what is otherwise wanted for cost optimization. In order to wind stabilize the building two differet methods are beging evaluated. In the first one the stabilazation is acheived by stairwells made of concrete In the other one it’s acheived by using 120 mm thick CLT-panels. In both cases the CLT is supporting the vertikal loads that are acting on each floor. On every fifht floor concrete slabs are placed of which the task is to miminize the load effect on the weaker parts of the body. By using composit theory according to (Blass & Fellmoser, 2004), the CLT-panels are controlled if they are in risk form shear, deformation or compression. The CLT-panel can be concidered as gluam wood, GL28h if it consists of C24 timber, which  this report is based on. Since the CLT panel is concidered as a solid element it experienced a reduced compressive and lifting forces, that it would otherwise if it was mad by a column system. The calculations shows that the CLT is strong enogugh to withstand the compressive and horisontal forces that is acting on them. When the building is stabilized using a concrete stairwell, this leads to and horisontal load that the concrete needs to be strong enough to withstand. The result shows that when concidering static loads, it is possible to construct a 14-stories building wtih a CLT-body that meets the requirements of Eurocode. However, when the building is stabilized with concrete towers it generates a load on against the stairwells. It has not been investigated whether or not the concrete is strong enough to withstand this load. / Historiskt sett är trä vårt viktigaste byggmaterial där användandet sträcker sig långt bak i tiden. Idag gör dess låga vikt det möjligt att prefabricera hela trästommar i fabrik för att sedan fraktas ut till arbetsplats där de kan monteras på plats. För att möta behoven och på bostadsmarknaden har Lindbäcks Bygg AB startat ett projekt där ett 14-våningshus ska projekteras. Att kunna bygga högt ligger i linje med ökade markpriser, eftersom marken måste utnyttjas på ett effektivare sätt. En sådan hög byggnad ställer stora krav på konstruktionslösningar för att kunna klara av stora pelarlaster i botten på byggnaden och samtidigt vara stabil mot vind. Syftet med denna rapport är att visa hur det är möjligt att konstruera ett 42 meter högt 14-våningshus med KL-trästomme. Vid beräkningar används en preliminär planlösning, som inte är helt färdigställd. Detta är för att ge möjlighet att visa en godtycklig lösning som kan fungera för byggnader med olika planlösning. Av samma anledning är nyttjandegraden för KL-träskivorna lägre än vad som önskas för att en byggnad skall anses kostnadsoptimerad. Det resultat som redovisas är med avseende på statiska laster. Dynamiska laster och svängningar har inte beaktats. För att vindstabilisera byggnaden undersöks två olika metoder. I ena metoden utgörs stabiliseringen av trapphusen av betong. I det andra fallet stabiliseras byggnaden genom skivverkan med 120 mm tjocka KL-träskivor, vilket även används till att bära upp de vertikala lasterna i bägge fallen. På var 5:e våning i byggnaden används betongbjälklag, som bidrar med att minska lastens fördelning på de svagare delarna i konstruktionen. Med kompositteori kontrolleras KL-träskivorna med avseende på skjuvning, deformation och tryck. Skivan kan betraktas som limträ av klass GL28h om C24-virke används, vilket är antaget i denna rapport. KL-träskivorna ses som ett homogent element när de tar upp horisontala krafter. Detta medför att skjuvkrafterna kan spridas genom hela skivan, vilket medför lägre tryck och lyftkrafter i ändarna av de stabiliserande skivorna, jämfört med en traditionell gipsvägg. KL-träskivorna som används visas vara tillräckligt styva för att klara av vindlasterna och trycklasterna. Då en byggnad stabiliseras med betongtrapphus antas det att betongstommen utformas så att den kan ta upp de horisontala lasterna som leds in till betongtrapphusen. Resultatet visar på att det är möjligt att med avseende på statiska laster konstruera ett 14-våningshus med en KL-trästomme, som uppfyller kraven enligt EKS9. Då byggnaden vindstabiliseras med betongtorn så uppkommer det en last mot trapphusen. Det har inte undersökts om betongens kapacitet är tillräcklig för denna belastning.

The construction industry in Sweden face increasing demands for sustainability and reduced greenhouse gas emissions and with the introduction of climate declarations for new projects marking a significant development. There is a rising interest in sustainable materials like cross laminated timber (CLT). Analyzing CLT-joists and their complementary materials impact on projects economically, environmentally, and structural performance can enhance decision-making in the early stages of a project. This study conducted a structural-, climate impact-, and cost analysis along with a multicriteria assessment. The structural analysis, based on Eurocodes and using the software FEM-design showed that all joist types met structural requirements, with type 3 being more versatile due to its cooperation with concrete. It also showed that type 11 with its lighter weight made it easier for installations and a possible reduced transport emission. The climate impact analysis, done through an LCA in OneClick LCA, revealed that type 3 had the highest impact mainly due to its concrete layer, while type 9 had the lowest impact. In term of costs, a cost analysis was done with the use of BidCon. The results of the cost analysis showed that type 3 is the most expensive due to its longer installation time and material costs, while type 11 was the cheapest. CLT and concrete were identified as the costliest materials. The multicriteria assessment concluded that type 11 is preferred for its affordability, sustainability, and performance efficiency. However, if solely pursuing sustainability, type 9 could be considered despite its slightly higher costs.

I denna studie studerades det hur ett 14 våningar högt bostadshus med en kärna av korslaminerat trä (KL-trä) och färdiga lägenhetsmoduler med regelstomme kan byggas på ett industrialiserat och enkelt sätt. Våningsantalet och produktionstypen fastslogs tidigt, i samråd med RISE, för att effektivt kunna granska ett sannolikt sätt att bygga hus i en nära framtid. Dynamiska modalanalyser utfördes för byggnadens olika modeller i FEM-programmet Robot Structural Analysis (kommer fortsättningsvis även beskrivas som Robot) för att ta fram egenfrekvenser. Sedan följdes en beräkningsgång från Eurokod och EKS för att ta fram den toppacceleration som vind orsakar på byggnadens högsta plan. Detta värde jämfördes sedan med det rekommenderade komfortkravet från ISO 10137. Byggnaden som studerades är ett punkthus med en central kärna och 14 moduler, av storlek 4 x 8 meter, per våning. Dessa placeras runt den 8 x 8 meter stora kärnan, vilket gav ett totalt fotavtryck på 24 x 24 meter. Över 20 olika datormodeller studerades där bland annat variationer av placering och mängd av KL-trä i fasad, placering och andel betong i huset och påverkan från gipsskivor i inner- och ytterväggar. Även infästning mellan moduler tillhör några av de ändringar som studerades. Resultatet visar att det är möjligt att bygga den modell som benämns 1400KL i vindlastzon 24 och terrängtyp tre, förutsatt att den mekaniska dämpningen är satt till 2 procent.  Det framgår även att modulernas egna lägenhetsavskiljande väggar har signifikant betydelse för stommens totala stabilitet och att en ökning av styvheten i dessa är ett effektivt sätt att förbättra de dynamiska egenskaperna. Betydelsen av mycket massa högt upp i byggnaden är också tydlig utifrån detta arbete. Det framkommer även att stabila betongvåningar nederst i stommen bidrar mycket till att förhindra att översta våningen i huset rör sig obehagligt mycket vid stor vindbelastning på byggnaden. Detta är en beprövad teknik i basen av flertalet hus som byggs idag. Rotation har visat sig vilja förekomma i de tidigare modeller som använts i denna rapport. Detta är något som måste testas specifikt för alla varianter av basmodellen då rotation är ofördelaktigt ur dynamisk aspekt, då det saknas beräkningssätt för dynamiskrotation i teorin från Eurokod. Generellt kan tillägas att ett 14 våningar högt trähus i vindlastzon 26 och terrängtyp 0 har väldigt svårt att klara av de dynamiska förutsättningar som krävs utan att husets stabiliserande element till största del består av betong. Däremot finns flera trä-modeller i denna rapport som klarar vindlastzon 25 och terrängtyp tre, en mycket mer vanlig situation. Enklare statisk analys antyder att limträpelares dimensioner möjliggör montage mellan moduler utan större produktionsanpassning. Även korslaminerat trä inkluderas fördelaktigt i kärna och fasad, innanför och utanför modulerna, utan att det påverkar de traditionella konstruktionsmetoderna för vare sig moduler eller KL-stomme väsentligt. / In this study, it was examined how a 14-story tall residential building with a core of cross laminated timber (CLT) and prefabricated apartment modules can be built in an industrialized manner. The number of floors and production type were determined early, in consultation with RISE, in order to effectively examine a likely way of building houses in the near future. Dynamic modal analyses were performed for the building's various models in the FEM program Robot Structural Analysis to generate eigen frequencies. Then the method provided in Eurocode and EKS were followed to calculate the top acceleration that the wind causes at the buildings highest floor. This value was then compared with the recommended comfort requirement from ISO 10137. The studied building is a high-rise tower block house with a central core and 14 modules of size 4 x 8 meters per floor. These were placed around the 8 x 8-meter-wide core, giving a total footprint of 24 x 24 meters. Over 20 different computer models were studied with variations in placement and amount of CLT in facade, placement and number of concrete floors and walls. The impact of gypsum inner and outer walls is also being tested. Connections between modules also belongs to some of the changes that were being made between models. The result shows that it is possible to build the model named 1400KL in wind zone 24 and terrain type III, with the mechanical dampening set at two percent. It is also apparent that the walls of modules separating apartments have considerable significance for the overall stability of the frame and that increasing their stiffness is an effective way of improving dynamic properties. It can be concluded from this study that placing a substantial mass at the top of the building is of high importance. It also appears that rigid concrete stories at the bottom of the core contribute greatly to prevent the top floor of the house from exceeding the comfort criteria under high wind loads. This is a widely used technique in the base of houses being built today. Rotation has been shown to appear in the models used in this work. This is something that must be tested specifically for all variants of the base model since rotation is disadvantageous from a dynamic aspect. This is due to the fact that the codes do not consider dynamic rotation. In general, a 14-storey high-rise wooden house in wind zone 26 and terrain type 0 does not fulfil the comfort requirements without most of the stabilizing elements of the house being concrete. On the other hand, there were several wooden models in this study that can endure wind zone 25 and terrain type III, a much more common situation. A simplified static analysis suggests that glulam columns can have dimensions that allow them be placed between modules without major adaptation in production. Also, cross-laminated timber is advantageously included in the core and facade, inside and outside the modules, without significantly affecting the traditional design methods for modules or the cross-laminated frame.

House construction today is largely project-based, where the buildings are tailored tounique conditions and locations that are rarely the same as another build on anotherbuilding site. In addition to the building itself and the building site, involved actorsusually also change from project to project. As a result of today's project-basedconstruction, there is a lack of a standardized and systematic work process forconstruction work. A systematic work process could contribute to all the players' pursuitof profit. To explore the possibilities of creating an improved work process, this study focusedon balconies of wooden houses. The purpose and objectives of the work were therefore designed to evaluate today'sconstruction work for the design of balconies in wooden houses, where possible areasof improvement were evaluated to create a systematic work process for constructorsin designing and dimensioning balconies in wooden houses.In order to achieve the purpose and objectives of the work, four questions have beendeveloped that focus on the production of systematic work processes, the current workprocess of the construction work, design methods and balconies in wooden houses.Existing research and published material were found through a literature and contextstudy to further develop the study’s work. Theory regarding systematisation and process development, balconies,dimensioning of supporting structures, etc. was the basis for how the work would becarried out. The systematized work process for balcony design was, however, createdusing information from the qualitative interview study with a total of eight (8)respondents in different roles I house building. The work process was then partiallytested in a quantitative verification. The work resulted in a systematic work process in the form of a checklist that includesgeneral tips as well as a chronological workflow that describes how, when, with whomand what should and can be done at the balcony design to get the best possible results.A description of the existing balcony types has also been developed to simplify workand to clarify important points and tasks in the design of a particular type of balcony. The workflow is divided into the activities of the design and dimensioning, such asstart-up, design and dimensioning of the balcony's main components, detail designand dimensioning of fastening components, drawing up drawings and assemblydescriptions, and follow-up and development of the work process. Based on the results of the study, the questions were answered with a description ofthe four (4) types of balcony, which were based on theory and were strengthened bymeans of empirical data from the respondents. Two (2) of the balcony types are viiiconsidered more common, balconies with pillars to land and rods above the balconyplate, where the latter is considered the most common in wooden houses at present.Today's construction work for designing and dimensioning balconies in woodenhouses is similar in large part, but due to the use of prefabrication and standardizationdegree the work differs from each other. The verification of a part of the work process resulted in a balcony solution with crosslaminated timber as a balcony slab and in a comparison between results from aproposed software and hand calculations. The comparison showed that the softwarecan be used for dimensioning balconies with cross laminated timber, with the exceptionthat the dimensioning for fire must be done by hand because of deficiencies in thesoftware's settings. The study has shown that systematisation is often based on LEAN Production, whichwas created by the Japanese automotive industry, which focuses on creating efficientwork processes by circularly examining, testing, evaluating and developing workprocesses. The conclusion of the work is that it is possible to systematise construction work, butunlike the manufacturing industry, the work process must have adjustment possibilitiesduring the work to meet the commonly occurring changes in house construction.However, in order for the systematisation work to be carried out, increasedunderstanding and involvement from and by other actors than constructors arerequired. A systematic work process together with type solutions and standardized calculationmethods can shorten the design time, improve and secure the solutions, and allowmore time for creative thinking to further improve the balcony solutions and the workprocess.

The construction of wooden multi-storey buildings creates issues with the acoustic environment. To meet Boverkets soundproofing requirements the solutions of today results in thick partition building components taking up potential floor space. Crosslaminatedtimber is a solid timber slab that can be manufactured in varying sizes and thicknesses. These boards can then be used as supporting elements in walls, ceilings and floors. This study investigates whether cross-laminated timber can be used to streamline the construction of multi-storey wooden buildings. In this comparative survey a reference building constructed by A-hus was used and current loads, sound insulation, use of floorspace and economy were analyzed. Four different alternative walls and one floor constructed with cross-laminated timber have been studied according to the above named criteria, and then compared with the reference building. The result indicates that a wall with 80 mm cross-laminated timber board has the load capacity required, improves sound insulation and saving 16 m2 of floorspace in the reference building valued to approximately 695,000 SEK in increased sales revenue. Using cross-laminated timber in the floor does not sufficient improve A-hus current construction system and should therefore not be interesting.

Multi-story wood frame construction is a highly relevant topic today because of the need to continue to develop the relatively new building technique to create a sustainable way to keep constructing new buildings. Because the use of wood as a frame material in multi-story buildings is still new, there are still issues that come with the choice to use it. One of these issues is in the detailed technical solutions that are constructed, they often have faults that may lead to problems with moisture. The purpose of this degree project is to investigate these problems and more importantly the process behind constructing them. This work is also examining what can be done to counteract or minimize the issues in the planning phases of the construction as well as look at why it is important to continue developing wood construction. There are two parts of the method used in this degree project. The first part is a literature study which brings up the attributes of wood, factors for using and not using wood, the techniques used to build multi-story buildings in wood, as well as a look into the detailed technical solutions that are used and the planning process behind them. The second part is the interview study where experts in the field are interviewed to get answers about the issues that this work brings up. The interviews provided a lot of information that is relevant for this work and the result consists of the most important answers from them. The biggest factor for continuing to develop the use of wood as a frame material, from the interviews, was about the eco-friendliness of the material. The attitude to use wood in multi-story buildings varies quite a bit depending on which part of the construction sector is asked. The developers are curious but still a bit worried, because of this they have not yet taken the next step in using it more. The entrepreneurs are still sceptical about the use in multi-story constructions and there is not enough knowledge about it for them to earn the same amounts of money as if they were to use concrete or steel. Because of that they are also worried about taking the next step towards using wood more. The consultants, like the architects and construction engineers, are more positive to the use of wood and are inclined to use it more and more. The issues that come up the most are different types of attachments of balconies and exterior corridors, parts that are installed too close to the ground and solutions where the end grain of the wood is in water. There were three main problems that came up repeatedly. The biggest one was the lack of knowledge in the planning and the production phases. The second one was about how there is often no one who looks at the bigger picture in the projects which entails mistakes that could be caught. The last issue was in the installation where the construction workers might not do it according to the construction drawings or a lack of drawings which leads to improvisation at the construction site. Recommended improvements could be a standardisation of the solutions that are proven to work for everyone to use. There is also a need for better communication which provides feedback to the designers of the solutions, that way they will know what to do better in the future. More relevant education within the topic and better coordination will also prove vital in the continued development of multistory wooden constructions.