Insulation on top of the rafters

Wall build-up 3: Insulation with reed insulation panels on top of the rafters (also suitable for new buildings)

e.g. rafters (6 x 18 cm). General Requirements:
EnEV: U-value: 0.30 W/(m²K) (Exception: In the case of a refitting of an insulation between the rafters where the height of the rafters does not allow for a sufficient insulation.)
DIN 4108: R ≥ 1.20 (m²K)/W. No calculation of condensate is necessary if the conditions of DIN 4108-3: (non-ventilated roofs) are met. Insulation on top of the Rafters:
2 x 80 mm reed insulation panels on top of the rafters, coated with clay from below and covered with sarking felt.
U-value : 0.29 W/(m²K). Details on the Use and Application of Reed Insulation Panels as Insulation on top of the Rafters:
  1. Apply the first layer of reed panels extra (d = 80 cm) on the rafter. For static reasons the stalks of the first layer have to be placed crosswise to the rafters. Fix to the rafter with wood screws and insulation discs.
  2. Apply the second layer of reed panels extra (d = 80 mm) staggered to the first one. Then fix as described above.
  3. Fit the sarking felt (non-vapour retarding) as a protection against wind and weather (follow the directions of the manufacturer!)
  4. Fix the sarking felt and the reed panels with cross lathing (e.g. 30 x 50 mm) attached to the rafters with screws or nails. After that you can continue with roofing works.

Disclaimer of Liability

The information given above is based on the calculations and information of HISS REET Schilfrohrhandel GmbH and the product specifications of the manufacturer. The content is only a selection of especially important information. The author reserves the right not to be responsible for the topicality, correctness, completeness or quality of the information provided. Liability claims regarding material or ideal damage caused by the use of any information provided, including any kind of information which is incomplete or incorrect, will therefore be rejected, unless there is evidence of intentional or gross negligence on part of the author. The information provided cannot substitute individual specialist advice by a planner. Authors Dipl. Ing. Stefan Neumann
Dipl. Kfm. Philip Kullmann