Terrace roofs are walkable flat roofs on the top of a building which can be used for various functions. They are usually covered with a screed, depending on the nature of their use.
These areas are usually suitable for recreational purposes, designed with paving slabs and possibly with vegetation and shading structures.
The thermal insulation of inverted flat roofs and terrace roofs provides mechanical protection for the waterproofing membrane not only during the construction work, but also in the course of intensive use.
The extrusion production process used during the manufacture of extruded polystyrene (XPS) results in a homogeneous, closed-cell material structure with a smooth surface (called extrusion skin) which provides a number of favourable material characteristics:
- consistently high thermal insulation level
- water and frost resistance
- high strength
- high flexible rigidity
- high resistance to vapour diffusion
These characteristics make the XPS thermal insulation material highly suitable for terrace roofs.
In the construction of a roof terrace, the inverted roof and the strength of XENERGY™ and FLOORMATE™ used as thermal insulation offers designers special flexibility and freedom. Walkable and green surfaces, heavy flower boxes, legs of shading structures, bases of railings or street furniture can be easily installed anywhere without breaking the waterproofing membrane and creating thermal bridges. Later on, if the building needs renovating, the roof terrace can be rearranged so that work does not endanger the operational safety of the building and the waterproofing layer will not be damaged in the process.
ROOF TERRACE PAVING SLABS
Terrace roofs can be used with frost-resistant tiles placed on to the entire surface.
To avoid damage arising from thermal expansion and frost, for example concrete paving slabs with surface treatment, it is expedient to use self-supporting paving slabs with a bedding layer laid on premanufactured supporting pads.
Walking surface of terraces are generally made with:
- concrete paving slabs laid on special plastic supporting pads
- concrete paving slabs laid on screed on a vapour-permeable, non-absorbent, rotproof separation layer (polypropylene geotextile) like XENERGY™ MK placed onto the XENERGY™ XPS thermal insulation.
In the case of paving slabs laid on supporting pads, the even positioning of the thermal insulation boards should be ensured, so a levelling layer may be needed between the overlaps of the waterproofing layer if multilayer bituminous insulation is used.
Separation layers have been used in the structural build-up as a result of several decades of experience gained in refurbishing roof terraces. This considerably reduces damage caused by thermal expansion movements. The paving slabs, screed, thermal insulation and the supporting structure will be able to move independently. Great care must be taken to ensure frost-resistance of the paving slabs, as well as to that of the sloping concrete or screed on top of the waterproofing layer.
WATER DRAINAGE OF ROOF TERRACES
The efficient and quick removal of water must also be resolved on roof terraces. Water needs to be drained from the surface of both the cladding and the waterproofing membrane, and safety overflow must also be considered. Please consult professional guidelines for the slope and drainage of the waterproofing membrane. The slope of the paving slabs may be different – the easiest way to manage this slope compensation is by adjusting the screed levels.