TECHNICAL SOLUTIONS > WATERPROOFING > Waterproofing of roofs > Waterproofing of roofs with roof-tiles fixed with strong cement mortar adhesive

Waterproofing of roofs with roof-tiles fixed with strong cement mortar adhesive


The waterproofing of a tiled roof made up of tiles fixed with a strong cement mortar on an inclined concrete slab requires the application of a waterproofing layer between the slab and the tiles, which must:

  • Provide effective waterproofing.

  • Have high resistance and reliability through time, because any future intervention would be difficult due to its position.



The flexible, brushable sealing slurry AQUAMAT-FLEX forms an ideal solution for waterproofing of the roof under tiles that are fixed with mortar. It can be applied on top of the roof's concrete slab and:

  • Provides complete waterproofing, even for roofs that are slightly inclined.

  • Bonds completely to the concrete slab, because it is cement-based.

  • Has high elasticity, enabling itself to adjust to expansion and contraction of the concrete slab without cracking.

  • Has high strength and is long lasting.

  • Can be applied easily with a brush, which enables easy working on difficult parts of the roof, such as rain gutters, roof windows etc.

  • Is vapor-permeable, which prevents the condensation of water vapor.

  • Provides an appropriate substrate for the bonding of thermal insulating layers, when sprayed polyurethane is used.



Substrate preparation

  1. Any cavities, cracks, or other imperfections in the concrete slab should be filled in with DUROCRET polymer modified cement mortar or with a cement mortar reinforced with ADIPLAST polymer latex.

  2. Along the entire length of intersections formed by the concrete slab and vertical elements such as chimneys, parapets, etc., it is recommended to form a triangular groove of 5-6 cm length per side, with DUROCRET polymer modified cement mortar or a cement mortar with ADIPLAST, in order to facilitate the application of AQUAMAT-FLEX.

  3. Subsequently, the substrate is thoroughly dampened, but without creating water puddles.


Application of the AQUAMAT-FLEX sealing layer

  1. The content of the 25 kg bag (component A) of AQUAMAT-FLEX is added into the 8 kg of liquid (component B) under continuous stirring, until a uniform viscous mixture is formed, suitable for brush application. A low-revolution mixer may be used for mixing.

  2. 2-3 layers of AQUAMAT-FLEX are applied to the roof's concrete slab.  Each new coat is applied after the previous one has dried. Layers thicker than 1 mm should be avoided, because the material may crack.
    Consumption: 2-3 kg/m2 in total.


Recommendations for the application of thermal insulation and roof tiles

Insulation with sprayed polyurethane

In case of application of thermal insulation with sprayed polyurethane foam, bonding of the polyurethanes to the sealing layer is perfect, and so no further measures need to be taken.

Thermal insulation with extruded polystyrene

If insulation is applied in the form of extruded polystyrene boards, the following are recommended:

a) Proper reinforcement rods are placed on the concrete slab, so that the thermal insulation boards can be fixed mechanically, or alternatively:

b) Polystyrene boards are fixed on top of the sealing layer of AQUAMAT-FLEX with an appropriate adhesive.

In both cases, it is recommended for the thermal insulation layer to be covered with a light wire mesh, which is fastened around the perimeter of the board, in order to protect the insulation material from slipping.

Fixing of the roof tiles

  1. In order to reinforce bonding of the cement mortar to the thermal insulation layer, it is recommended that a spatterdash reinforced with ADIPLAST polymer latex is applied first. (cement : sand : ADIPLAST : water = 1 : 1 : 0,25 : 0,25 parts by volume).

  2. It is recommended that the roof tiles are fixed using a strong cement mortar with ADIPLAST polymer latex (cement : sand : ADIPLAST = 1 : 3 : 0,20 parts by volume).
    Consumption of ADIPLAST: approx. 0,8 kg/m2/cm of layer thickness.



  • Alternatively for this application, AQUAMAT-ELASTIC can be used instead of AQUAMAT-FLEX.

  • During the application the temperature must be between +5OC and +30OC.

  • Consult the instructions for safe and precautions written on the packaging.