“Boverket” the Design Regulations in Sweden, also called BKR has for a long time been the mandatory standard that has guided and regulated construction design. But at the end of 2010 BKR was replaced with Eurocode. This report deals with the comparison of these two standards when it comes to wood construction. During winter 2009/2010 there were many roof collapses due to excessive loads on the roofs across Sweden. The majority of these roofs were made during 1980 when BKR was the existing norm, therefore, this report will investigate whether there is a big difference between designing of such roofs according to Eurocode instead of BKR. These two norms were compared by looking at the design of roof structures that consist of beams and columns. The roof beam was checked for buckling which is designed to support the tennis center in Nyköping, and also a centrally loaded pillar holding up the roof beam and superimposed loads. The result of this investigation showed that to design according to Eurocode would be more substantively economically because the design load bearing capacity becomes slightly larger. It was also observed that, there isn’t a big difference between designing according to BKR or Eurocode, therefore these roof collapses couldn’t occur due to designing according to BKR. Designing according to BKR is even safer, but not substantively economically as Eurocode. A comparison between the results indicate that the slight difference is mostly caused by the the differences between the parameters/coefficients used for design. The roof collapse in Nyköping was caused by carelessness or ignorance, this tennis center is undersized.

Denna rapport som behandlat ämnet snölast och takras skrivs som ett gemensamt examensarbete till samhällsbyggnadsprogrammet och författas av Edwin Häggkvist och Jacob Lahti som är studenter vid Luleå tekniska universitet. Snölast och takras som årligen är ett återkommande ämne och problem och ändå verkar inga större förändringar ske. Vi har genom en litteraturstudie studerat olika takkonstruktioner, taklutningar, vad försäkringsbolagen säger, om snön är den största faktorn eller om det kan vara något under byggprocessen som gör att tak rasar in. Det vi kunnat konstatera är att projekteringen är den största boven, de underliggande problemen i denna del är att det varken finns någon beräkningsstandard eller något standardprogram för hur man ska beräkna snölast i kombination med vind och i och med detta så blir de flesta taken feldimensionerade då det inte tas tillräcklig hänsyn till snedbelastning. Takkonstruktioner moderniseras och förändras över tiden, precis som snömängder varierar och förändras över tid, vi har jämfört nyare och äldre takkonstruktioner.   Ett särskilt fall som vi kunde studera på plats är en carportlänga som rasade nu i vår där vi kunde ta några bilder och diskutera och se över eventuella fel på konstruktionen. / This study has processed the subject of snow loads and collapsing roofs and is written as a cooperative examination paper for the built environment programme by Edwin Häggkvist and Jacob Lahti who are students at Luleå Tekniska Universitet. Snow loads and collapsing roof are a yearly recurring subject and problem, yet no significant changes seem to occur to apprehend this. We have through a literature study studied different roofing constructions, different roof inclines, what the insurance companies are saying, if snow is the biggest factor or if something else in the building process is behind the collapsing roofs. We have established that the projecting stage is responsible for a lot of the problems, the underlying problems to this is that no real calculation standard or standardized program for calculations for how to calculate the snow loads in combination with wind, and with this a majority of the roofs wrongly dimensioned when not enough consideration is given to the uneven loads. Roofing constructions are modernized and changed over time, just as the amount of snow varies and changes over time, we have compared certain newer and older roofing construction methods. We have been able to study one certain case in person, which is a quite long carport construction that collapsed this winter locally here in Luleå. There we were able to take pictures, discuss the construction and its eventual faults.