The most commonly used form of roof insulation in sloping roofs is insulation between rafters. Here, the thermal insulation is precisely installed between the rafters. Ideally, an additional insulation layer of ISOLAIR or PAVATHERM-PLUS is to be laid above the rafters as a sarking to reduce thermal bridging in the rafter area.
Cut PAVATHERM with the insulation blade for jigsaws, a hand-held circular saw or a table saw. Similarly, PAVAFLEX insulation boards are cut with an insulation knife, reciprocating saw or bandsaw.
Vertically and horizontally oversized PAVAFLEX is installed between the rafters. The PAVAFLEX insulation board is squeezed in vertically between the rafters and pushed into the cavity with light pressure.
The top PAVAFLEX insulation board is similarly cut oversize and squeezed in. With multiple insulation layers, attention must be paid to offset joints. Thanks to flexibility and the resulting clamping effect, PAVAFLEX fits spaces up to 900 mm in the structure, quickly, easily and without gaps.
Push the cut insulation boards tightly between the rafters, secure against falling out, if necessary. Multiple insulation layers are installed with offset joints.
With clear rafter spacing over 60 cm, the cut-offs can be progressively installed in the subsequent rows of boards.
Before installation of the internal cladding, the insulated roof area is covered with an airtight, vapour-control membrane (e.g. PAVATEX DB 3.5 or DB 28), which is stapled to the rafters. All membrane overlaps, connections and penetrations must be made airtight by taping with PAVATEX sealing products (e.g. PAVAFIX 60).
If PAVAFLEX is used as supplementary insulation over existing roof insulation in a renovation, the requirements for maximum clamping widths are not applicable. Depending upon structure, cavity characteristics and when placing without cutting, the values can be deviated from slightly and should be adapted to on-site conditions.
| Plattendicken | max. Klemmweite | Übermass |
| 40 - 50 mm | 400 mm | 4 mm |
| 60 mm | 500 mm | 6 mm |
| 80 mm | 700 mm | 10 mm |
| 100 mm | 800 mm | 10 mm |
| 120 - 240 mm | 900 mm | 10 mm |
