Commence installation of the Sisalation® by laying the product longitudinally over the rafters working from the eaves to the ridge of the roof. The roll should be unwound so that the printed surface faces upwards, exposing the 150mm overlap line. Each horizontal layer must be evenly tensioned across the rafters. In severely exposed and high wind regions a counter batten method of fixing the Sisalation® should be considered to reduce flexion. Roof tiles should be placed as soon as possible to minimise exposure to the elements.
Sisalation® must be fixed between the rafters and battens and must overlap horizontally and vertically by at least 150mm at all joins. If waterproofing is required for boxed eaves, the first run of material must be brought over the tilting batten and turned down into the gutter. In the case of open eaves, the first run of material must commence 50mm beyond the outer wall face.
The minimum recommended width of horizontal laps is 150mm. Laps should preferably be made under a batten, however where a lap occurs between battens, an additional batten should be used to secure the undertile membrane. In the case of vertical joins, the minimum lap should be 150mm and must be secured on a rafter using galvanized clout nails.
Whilst Sisalation® has been designed with adequate strength properties to meet the application requirements, it is not designed to carry the direct weight of installers or tile loads. Battens should therefore be installed as work progresses from the eaves to the ridge, which will assist with stepping for feet, thereby avoiding damage to the Sisalation®. Particular care should be taken where product overlaps between battens. As an added precaution, and to assist installers, two additional battens can be loose laid on the upper side of the fixed batten to create a larger stepping area. The loose laid batten should be moved up the roof as work progresses.
At the eaves, Sisalation® should be used in conjunction with an underlay support tray to enable run-off water to be directed into the gutter.
Courses of the underlay membrane over a hip should be overlapped by a minimum of 150mm. Each course should overlay the underlay on the adjacent elevation of the roof.
At ridges and hips a 600mm wide DPC layer should be positioned over the apex on top of the Sisalation® membrane. Care must be taken to ensure that the Sisalation does not come into contact with wet cement.
In valley’s a strip of DPC underlay at least 600mm wide must be laid under the Sisalation® and held down by the valley battens. The Sisalation must be dressed over the valley battens and continue under the valley gutter.
Standard methods of workmanship should apply at penetrations and abutments. Ensure that the Sisalation® is turned up not less than 50mm at all abutments to be overlapped by the flashing, and that it overlaps the lining tray by not less than 100mm at the back of any abutment.
Penetrations by soil and vent pipes and the like, must be dealt with as follows:
Sisalation® must be star-cut carefully to prevent tears, closely fitted over the pipe ensuring that all the tabs project upwards along the pipe, and then the tabs taped around the circumference. A proprietary collar must be fitted over the pipe to protect the tape.
Should any repairs be required to the Sisalation® this can be carried out be overlapping the damaged areas with a layer of additional material ensuring a 150mm overlap all round, but ensuring that the up-slope side is overlapped by the next higher horizontal run of Sisalation® and secured under a batten. A good quality self adhesive foil tape, 50mm wide is recommended for sealing minor puncture holes and for taping of overlaps where quired.
Use 1,6mmØ Galvanised wire at 367mm centres securely fixed to the top and bottom purlins could be used to support the SUPER SISALATION® between purlins.