Around the world, the perlite fills are used in the structures of slanted roofs.  

1.Perlite fill of roofs

First of all lay on top of rafters diffusely penetrating lower covering plates (for example, gypsum plasterboards). Perlite is poured in the space between the “boarding” and “laths” and then compacted by 10%.

After the lower roof layer composed of centre-beaded boards is assembled it should covered by the water-proof asphalt boards or film lining. The junctures with the gutter and passages through the roof should be insulated by thick adhesive tape.
 
The other material to heat-insulate the roof is the bitumen-perlite or perlite-concrete.

Perlite concrete heat insulation as compared to other insulating materials possesses high wind and fire-resistance. Besides, in combination with heat-insulating perlite- magnesia plates and plates covered by perlite-concrete it acquires higher thermal resistance. 

Method of application
For perlite-concrete roof insulation the following materials can be used: Circulite, Portland cement, water, air-conducting additives etc. If along with ensuring fire-resistance properties of your roof you want to strengthen it can be buttressed by reinforcing fabric.

If the weather is rather dry and the perlite-concrete insulation can sustain load of workers without damaging the surface the layers of perlite-concrete insulation can be laid each 48-72 hours.
The minimum recommended slant angle of the roof for standard water drainage is 1/8. In terms of economic efficiency, the slant of the perlite-concrete insulation is better performed by ladder-shaped layering of heat insulation plates (see picture below).

3. Bitumine-perlite heat-insulation of the roof

Bitumine-perlite is the dry granular material which consists of perlite particles covered with bitumen. This ready for use material (filled from sacks) does not require neither additional mixing nor any other additives.

Bitumine-perlite mixture can be prepared by mechanical mixing of Circulite and hot bitumen.

 Properties of bitumen-perlite

Area of application
New construction. Bitumine-perlite can be used directly on hard surfaces (such as concrete) to which cold bitumen adheres easily. If the bitumen-perlite is used on the top of the wooden base it is necessary to first apply ruberoid attached to the wood.
 

Roof repair. Bitumine-perlite is the best material you can use to repair existing roof since it can be applied to hard surfaces cleaned of dirt and delaminations and then covered with the layer of cold bitumen. On the other hand, by adjusting slants to funnels/ watering cans of inner drainage or around the circumference of the roof you can ensure not only additional insulation of existing base but also avoid accumulation of stagnant water on your roof.

Method of application
Before laying bitumen-perlite base the roof should be previously prepared. After preparation, the dry granulated bitumen-perlite should be emptied from the sacks, distributed and levelled 40% higher than the desired thickness with the specified slant. For compacting purposes the veneer sheets can be laid on the materials and packed with 180 kg roller. The final compacting is achieved by levelling bitumen-perlite with the roller directly on the material, without veneer sheets in between.

By using bitumen-perlite you can build monolithic bases for different roof types. Since the drying and hardening of bitumen-perlite takes some time you will need to cover it with rolled-strip roofing and hot bitumen immediately after it was laid and compacted.