With the exception of vertical and steeply sloping work, the finished asphalt must be sand rubbed to reduce the incidence of crazing.
Where asphalt is laid onto efficient insulation in a warm roof construction a protective surface should be applied to all flat areas using a suitable solar reflective paint, stone chippings or promenade surfacing.
SOLAR REFLECTIVE PAINT
The use of an approved reflective paint provides adequate protection for asphalt however, periodic repainting will be required. Exposed asphalt skirtings and vertical areas require a reflective paint finish.
A single layer of 10 – 14mm dust free stone shippings will act as a permanent surface protection for the full life of the asphalt.
When the chippings are well bonded to the asphalt removal can be difficult and therefore it is preferable to provide a minimum bond to ensure that they remain in place. This can be achieved by using a cold applied bitumen solution.
Porous concrete tiles provide a decorative lightweight and durable surface finish to asphalt. They are particularly suited for areas where pedestrian traffic or point loads are anticipated, such as balconies and terraces. The tiles are bonded directly onto the asphalt with either bitumen or proprietary adhesive in accordance with the manufacturer’s instructions. (Fig. 1.49)
Concrete paving slabs are also suitable as a promenade surfacing and are usually bedded in sand and cement mortar. A single layer of building paper is required beneath the bedding to allow for differential movement between the surfacing and the asphalt. (Fig 1.51).
An allowance for expansion is necessary and it will usually be sufficient to set the tiles or slabs back 75mm from the vertical at the roof perimeter and around interruptions with intermediate joints at 3m centres.