Subfloor system

Consultation on development of subfloor systems

Boverket’s strict requirements on load capacity, stability and durability demand effective material assessment. Plastic material in subfloor systems developed by Granab AB was approved on the basis of material assessment by Swerea.

Since 2014, building products have been subject to stricter type-approval requirements. According to Boverket’s (National Board of Houseing, Building and Planning) building regulations and recommendations for application of European building standards, building materials must meet greater type-approval requirements for load capacity. 

New requirements called for product development

Granab AB, which makes subfloor systems for homes, offices, schools and public buildings, is subject to these regulations. The steel subfloor joists have sound-dampening
elements, while the supports and fixtures are made of reinforced plastic material. The plastic material needed further development to meet the new requirements. Swerea conducted material assessment of the plastic.

“By gathering data on the intended material, doing stress computations on the existing design and performing complementary mechanical testing, the effects of various loads were assessed,” says Daniel Wendels.

Product ready for approval after Swerea assessment

Both short and long-term effects were assessed, as were changes in the material due to mechanical stress and ageing. After some material adjustments, Swerea deemed the product ready for approval.

Granab subfloor systems are type-approved with respect to the new requirements for dynamic loads and strength. “Previously, Swerea has helped us to assess, among other things, the short and long-term effects of mechanical loads on our floor joists. Therefore, it was only natural that we should consult them again. The outcome was a successful further development of our system,” says Fredrik Blom, managing director, Granab AB.