First of all, it is necessary to inform everyone that the general principle for roof waterproofing is: preferring drainage over blocking. That is, ensure that the joint treatment allows water to drain smoothly during heavy rain and ponding, so as to prevent roof leakage.
Therefore, during the design phase, the mounting bases should first be arranged in a way that they are not perpendicular to the drainage direction and do not hinder the drainage of rainwater from the roof.
In addition, when installing a PV system on an existing roof by directly placing the mounting bases during construction, the bases have no connection with the structural layer of the original roof. To ensure structural safety, it is essential to place the bases stably and neatly, and take measures to fix them to prevent overturning, sliding, or similar incidents.
Since the bases are not connected to the structural layer, it is difficult to install additional waterproof layers. Thus, every effort should be made to preserve the waterproof layer of the original roof to avoid leakage.
For cases where it is necessary to drill holes and damage the original roof, targeted measures should be taken based on specific circumstances.
For new buildings with flat concrete roofs or sloped concrete roofs (covered with tiles) of villas, embedded bolts should usually be installed during the design phase, and roof waterproofing should be done in accordance with conventional practices.
For existing buildings with flat concrete roofs or sloped concrete roofs (covered with tiles) of villas, the roof structure should first be verified.When connecting the PV module bases to the structural layer, the area around the metal embedded parts on the top of the bases is a weak point in waterproofing. Improper handling here may cause rainwater to seep down from around the bolts of the embedded parts to the structural layer, corroding the load-bearing steel bars of the structural layer and creating potential safety hazards.Therefore, when installing the PV module bases, the waterproof layer should be extended to cover the upper parts of the bases and metal embedded parts. Additionally, the area around the anchor bolts should be sealed, and the parts where the bolts pass through the waterproof layer should be filled with waterproof sealant to block the seepage path of rainwater. Moreover, an additional waterproof layer should be added under the bases—even if leakage occurs at the top of the bases, rainwater will not reach the structural layer.
For color steel tile roofs, it is necessary to penetrate the original waterproof layer and profiled steel sheets with the steel structure of the PV system, and fix the structure to the main steel structure of the building. Then, vapor barrier, thermal insulation, and waterproofing treatments should be carried out in reference to the waterproofing method for color steel tile roofs. The key points of construction include rust removal, sealing, and applying waterproof coating on the base layer and surrounding areas.
For local water leakage points on the color steel tile roof, high-quality neutral weather-resistant sealant should be used for smearing and plugging. For color steel sheets with severe local rust, replacement is required before installing PV modules.
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For color steel sheets with trapezoidal rib cross-sections: The solar mounting brackets are usually connected to the color steel sheets from the side or top using self-tapping bolts. The self-tapping bolts must be equipped with matching weather-resistant waterproof gaskets, and after the self-tapping bolts are fixed, the screw positions must be coated with high-quality neutral weather-resistant sealant.
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For cases where cable sleeves pass through the roof panels: There are standard construction methods specified in current national standard drawings. During design and construction, appropriate methods can be selected based on the specific conditions of the actual project.
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For cases where cables pass through the roof panels: Detai covers (a type of roof waterproof structure) can be used for waterproofing. Detai covers are often applied to roofs with color profiled steel sheets, featuring excellent physical properties and chemical corrosion resistance, which can prevent water leakage issues associated with rigid waterproof materials.
For existing buildings with flat concrete roofs or sloped concrete roofs (covered with tiles) of villas, if chemical anchor bolts are used to fix the PV mounting brackets, the thickness of the protective layer or the surface layer in use should first be verified.For precast slab roofs with high load-bearing capacity per unit area, precast concrete block bases can be used on the roof for fixation, and after solidification, chemical anchor bolts can be used to fix the mounting brackets.
For sloped roofs covered with tiles, the drilling depth should be confirmed. After fixing the chemical anchor bolts, the positions where the bolts pass through the tiles should be properly treated with waterproof sealant.Chemical anchor bolts have high load-bearing capacity, excellent fatigue resistance, and aging resistance; some models can withstand dynamic loads and impact loads. They exert no shrinkage force on the base and do not generate extrusion stress, thus will not cause adverse effects on roof waterproofing.
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