01 · Challenge
Extra storey on a gallery-access flat in Almere-Stad
The owner of a 1984 gallery-access flat in Almere-Stad wanted to expand the top floor by adding an extra storey. The municipality of Almere actively encourages adding a storey as a densification strategy and has established policy rules for this. The challenge lay in the original concrete structure: the columns and load-bearing floors had not been calculated to carry an extra storey. The new storey had to be lighter than the existing floors and either hung from or placed on the existing facades.
02 · Our approach
Prefabricated steel frame, compliant with policy
We designed a prefabricated steel addition that transfers its load through the exterior facades to the foundation piles. The extra storey has a flat roof with a sedum roof for water retention. We made use of the Almere adding-a-storey scheme, which simplified the aesthetic review procedure. The structural calculation showed that the existing exterior walls could carry the extra storey. All documents for the building permit were submitted in one package to the municipality of Almere.
03 · Result
48 m² additional apartment, permit obtained in 9 weeks
Thanks to the simplified aesthetic review procedure and the complete permit file, the building permit was granted within 9 weeks. The prefabricated steel structure was installed in three days, after which the exterior finishing followed. The result is a completely new roof-storey apartment of 48 m² with large window sections and views over Almere-Stad. The residents of the floors below experienced minimal disruption due to the short installation period.