01 · Challenge
Outdated roof with leaks and poor insulation value
The owners of a 1960s terraced house in the Holtenbroekwijk in Zwolle had suffered for years from leaks at the ridge gutter and cold bridges at the eave. The existing roof structure was built with untreated pine that had been affected by moisture in several places. At the same time, the thermal insulation with an Rc value of only 0.8 no longer met current requirements by a wide margin. A complete new roof package was the only sustainable solution.
02 · Our approach
New roof from rafter to ridge tile, including Rc 4.0
We drew the complete replacement of the roof structure: new rafters, purlins and battens in accordance with current building standards. The insulation package was specified as 180 mm PIR insulation with an Rc value of 4.0. The new roof structure was fitted with a vapour control layer and a waterproof underlay. Because the roof shape does not change, a permit notification to the municipality of Zwolle was sufficient. We handled all required documents including structural details and insulation calculation.
03 · Result
Drier and warmer home, building permit in 5 weeks
The permit was granted within 5 weeks. The roofer could start immediately with the construction-ready drawings and the specification for the insulation package. After completion, the residents immediately noticed the difference: no more leaks at the ridge gutter, significantly lower heating costs and a noticeably more comfortable attic. The new roof fully meets current energy performance requirements and has an expected lifespan of 40 years.