Roof Decks

Suitable deck’s for use beneath Sika-Trocal roofing systems include profiled metal sheet, plywood, oriented strand board (OSB), timber, woodwool cement slab, insitu, pre-cast and lightweight aerated concrete.


Pre-stressed concrete, in-situ or pre-cast, without a structural topping is not suitable for mechanically fastened applications but can be used with ballasted or adhered systems.

 

Where pre-cast reinforced concrete units and composite constructions incorporating hollow tiles, pre-cast beams and planks etc are installed, a levelling screed will be essential due to the tolerances and curvature of these items.


Timber based particleboards (chipboard) and boards of compressed straw are not suitable decks for any purpose. If these types of deck are found in a roof refurbishment situation, the only recommendation is total removal.


When constructing warm roofs it is important to avoid incorporating any timber-based products into the build-up above the insulation, in order to prevent them from being adversely affected by condensation. Plywood topped insulation boards and timber based reinforcement to walkways should not be used, for example.

Rough Surfaces

Where in-situ concrete and cementitious screeds are concerned, the finish should generally be the equivalent of a power or wood float. Particular attention also needs to be paid to achieving a level surface at the correct falls; any deficiencies here will only be mirrored in the final surface of the roof. Additionally where pre-cast reinforced concrete units and composite constructions incorporating hollow tiles, pre-cast beams and planks etc are installed, a levelling screed will be essential due to the tolerances and curvature of these items.


Sika-Trocal membranes should not come into direct contact with rough or abrasive surfaces, either above or below the membranes. To prevent contact, a protective layer of Sika-Trocal Type P 300 g/m2 polyester fleece or Sika-Trocal Type A 300g/m2 polypropylene fleece, can usually be installed or in some circumstances the more robust type SBv PVC faced polyester fleece layer can be used.


Typically the surfaces that would require the use of the Type T polyester fleece are: - in-situ concrete: cementitious screeds: aerated concrete panels: brickwork: masonry: plywood and oriented strand boards: timber boarding: wood wool slabs: metal sheets: existing mineralised bitumen felts and asphalt.


Ballasted roofs of all types must always have a protective layer installed on top of the SGmA membrane prior to laying the ballast.