Roofs around the world can be broadly divided into domestic glazed tile roofs, concrete flat roofs and mental roofs. For the installation of rooftop solar power plants, "waterproofing" has to be considered a very important factor!

The general principle of roof waterproofing is that it is better to guide than to block, i.e. in case of heavy rainfall, ensure that the nodes can be treated smoothly so that the water cascades off and the roof does not leak.

Waterproofing of PV Mounting for Concrete Flat Roofs

For new buildings with concrete flat roofs or villa concrete sloping roofs (covered with tiles), the bolts should usually be pre-built at the time of design and the roof waterproofed in accordance with conventional practice. For both types of existing buildings mentioned above, the roof structure should be identified first. When connecting the PV module base to the structural layer, the perimeter of the metal embed parts at the top of the base is the weak point for waterproofing. If not handled properly, rainwater can easily seep down into the structural layer from around the bolts of the buried parts, causing corrosion to the structural layer's reinforcing steel and creating a safety hazard.

Waterproofing of PV Mounting Installation for Mental Roofs

For mental roofs, the steel structure of the PV mounting system needs to penetrate the original waterproofing layer and the pressed steel sheets and be fixed to the main steel structure of the building. Then refer to the mental roof waterproofing practice for vapour barrier, insulation and waterproofing treatment. The focus of construction is on removing rust and corrosion, sealing, and applying a waterproofing coating to the substrate and periphery. For local leaks in mental roofs, a high quality neutral weather resistant sealant should be used to apply and seal them. For colour plates with severe localized corrosion, they need to be replaced before installing the PV modules.

1)For cases of colour steel plates with trapezoidal rib sections: The PV Mounting is usually connected to the colour steel plate from the side face or top side by means of self-tapping bolts. Self-tapping bolts must be supplied with matching weather-sealed waterproof gaskets. And after fixing the self-tapping bolts, the screws shall be coated with a high quality neutral weatherproof sealant.

2)For cases with cable sleeves through roof panels: Practices are available on existing national standard drawing sets. They can be used in design and construction to suit the actual project.

3)For cases with cables through roof panels: Waterproofing can be carried out using Dektite Cover. It is a roof waterproofing structure, often used in the presence of coloured pressed steel roofs, with good physical properties and chemical resistance to overcome problems such as leakage of rigid waterproofing materials.

Waterproofing of the Roof Perforations Made by the Mounting Manufacturer

For existing buildings with concrete flat roofs or villa concrete sloping roofs (covered with tiles),  the thickness of the protective layer or the applied surface layer should be confirmed first if chemical anchor bolts are used to fix the PV mounting. For prefabricated floor roofs with large unit area load bearing, the base fixing method of prefabricated cement piers can be used on the roof. And the brackets can be fixed using chemical anchor bolts after curing. For sloping roofs with overlapping tiles, the depth of the perforation should be confirmed. After fixing the chemical anchor bolts, the position of the bolts through the tiles should be well treated with a waterproof sealant.