Insulation Below the Rafters

Roof build-up 1: Insulation of an old building with reed insulation panels below the rafters

Rafters (8 x16 cm), lathing, roofing with bent tiles, no insulation. 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. Requirements:
No calculation of condensate is necessary if the conditions of DIN 4108-3: (non-ventilated roofs) are met. Insulation below the rafters:
20 mm bituminised roof boards (e.g. Pavatex), 30 mm reed insulation, 80 mm reed insulation, loam rendering.
U-value : 0.38 W/(m²K). Details on the Use and Application of Reed Panels as Insulation Below the Rafters:
  1. Attach a bituminised roof board on the rafters by screwing or with a staple gun. Before, you should even out the surface.
  2. Fix the reed insulation panel (d = 30 mm) with screws and insulation discs. If possible the screws should be attached to the rafters.
  3. Fix the reed insulation panel (d = 80 mm) with screws and insulation discs. If possible the screws should be attached to the rafters.
  4. Apply a loam rendering of 2-3 layers.
    All over the clay a jute cloth should be applied.
  5. Wall heating: If an additional wall heating is fitted the heating pipes or coils can be attached directly to the wire of the reed panels by means of tie wraps. A horizontal chase, containing inlet and outlet pipe, can be installed at the base point of the roof.

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