Inverted Ballasted Roof

Most popular hot melt system build up, usually installed onto a concrete deck (alternative decks can be used).

  1. Concrete deck primed with Permatec Primer
  2. 2 coats of Permatec Ecowrap incorporating Permaflash-R reinforcement
  3. Permaguard-F protection layer
  4. Rigid board insulation
  5. Water control layer
  6. Minimum 50mm layer of 20-40mm rounded washed aggregate
  7. Minimum 50mm thick paving slabs on proprietary supports
20 Year System Guarantee

Substrate preparation
The surface of the substrate (concrete, plywood, calcium silicate board, metal/insulation composite etc.) should be suitably prepared to accept the Permatec fully bonded system. Joints, cracks or interfaces between different substrate materials should be detailed in accordance with Permatec Standard Drawings and Masterspec 4414AP specification.

Using a suitable spreader or squeegee, the first coat of hot Permatec compound is applied to the prepared substrate at a nominal coat thickness of 3mm. The Permaflash-R polyester reinforcement is brushed into the Permatec compound whilst it is still hot. All laps in the Permaflash-R should be at least 75mm wide and fully sealed with the Permatec compound. The second coat is applied in the same manner ensuring complete coverage of Permaflash-R at the nominal coating thickness of 3mm. The second coat of Permatec must be protected.

Permaguard-F sand surfaced bitumen membrane is the standard protection layer. It is applied directly to the second coat of Permatec whilst it is still hot and tacky. It is used on the main horizontal area which is to be subsequently covered with a range of system components such as insulation, separation layer and loading coat (stone ballast, concrete paving etc). It is also used on unexposed detail items. The Permaguard-F protection layer should be rolled into the hot Permatec as quickly as possible. Laps in Permaguard-F to be minimum 75mm and sealed using hot Permatec compound.

Permaguard-M slate surfaced bitumen membrane is used on exposed upstand details. It is applied to the second coat of Permatec by controlled torch application. Laps in Permaguard-M to be minimum 75mm and fully sealed.

Rainwater outlets and penetrations in the roof waterproofing system should be detailed in accordance with Permatec Standard Drawings and Masterspec 4414AP specification.

System components
A standard Permatec inverted roof system will include a range of system components including: XPS insulation (thickness in accordance to “R” values requirements), water control layer and loading coat (stone ballast or concrete paving).

Inverted Ballasted Roof System

Fabric Apartments, Onehunga

Fabric Apartments, Onehunga