Inverted ballasted single ply roofing systems offer an excellent solution for situations where access or recreation is a priority. Ballasted systems also provide maximum resistance against roof membrane damage and UV degradation, protection against thermal shock, fire or noise and maintain the lowest surface temperature of all system types.
A ballasted system relies on the weight of a ballast material, such as pebbles or paving slabs to secure the single ply membrane and system in place.
- Concrete Paving Slabs.
- River washed pebbles.
- Water reducing/Filter layer.
- Thermazone IVR Insulation.
- Icopal Universal®.
- Protection/Separation Layer.
- Structural deck
Icopal Universal® membranes are suitable for use in ballasted roof situations. Icopal Universal WS membrane incorporates a root retardant additive that makes it ideal for use beneath green roof systems ensuring the membranes performance is not compromised.
The membrane is rolled out loose laid with adjacent sheets of membrane positioned to allow an overlap which is then hot-air welded together with a hot-air welder to provide a continuous waterproof covering.
For inverted roofs the single ply roof membrane is applied directly to the deck and so the suitability of this method will be dependent upon the condition of the substrate. A protection layer should be placed beneath the waterproofing membrane.
In an inverted ballasted roof, the insulation boards are then placed over the waterproofing.
A filtration layer is then installed over the insulation to prevent fines from entering the drainage zones and the whole system is then ballasted using paving slabs on support pads, or 20-40 mm diameter river washed pebbles. The ballast should be sufficient to provide resistance to wind uplift and prevent floatation of the insulation boards.
Positioning the insulation above the waterproofing requires additional performance criteria to the type of insulation used. As it is placed in the wet zone, the board should have a low water absorption and a higher compressive strength to accommodate the weight of the ballast above.
Icopal offers a range of thermal insulation boards.
Typical insulation board used: Thermazone Hydroshield IVR board