Y2013-E1 The collapse of a half-span roof over an entrance to a grocery store in Meri-Rastila, Helsinki, on 23 March 2013

A roof over an entrance to a grocery store collapsed in Meri-Rastila, Helsinki, on 23 March 2013. No personal injuries were caused by this accident.

The wooden roof had been mounted onto the concrete wall by means of wedge anchors. These broke and caused the roof to collapse. The mounting method differed from the one indicated in the structural plan, which dated back to the early 1990s. The built structure was weaker than indicated in the plans. The wedge anchors failed to bear the weight of snow which had accumulated at the junction of the roof and the concrete wall.

When building surveys are conducted, structures are inspected or repair work is carried out, account should be taken of the possibility of an accident of the kind that occurred in Meri-Rastila. Collapses of half-span roofs of this kind are always accompanied by a risk of serious personal injury.

When new half-span roofs are planned, due attention should be paid to snow loads and their consequences for structures. In turn, the building process must adhere to the plans. Should the need arise to deviate from the plans for any reason, the issue must be agreed with the designer, with new plans being drawn up for the affected structure.

In the case of Meri-Rastila, the mounting method used was based on wedge anchors with an inferior strength classification; this deviated from the plans. When procuring fasteners, due attention should be paid to their strength classification, with the procuring organisation ensuring that the strength classification, size and number of fasteners are sufficient for the intended purpose. For example, anchors and bolts with an inferior strength classification abound on the market. Some products available today have no strength class markings at all, or the marked class has not been tested against the applicable requirements.

Report only in Finnish.

Y2013-E1 Report (pdf, 0.78 Mt)