Rainproofing: More than just watertight
If a roof is considered rainproof, it does not mean that not a single drop of water will penetrate. Rather, rainproofing according to recognized technical standards means that the roof construction reliably drains rainwater outwards – even with wind pressure and driving rain. This concept is particularly relevant for roof penetrations in PV systems.
DIN 4108: What it regulates
DIN 4108 deals with thermal insulation and energy saving in buildings. Part 3 of this standard addresses climate-related moisture protection and defines requirements for the building envelope, including the roof. Additionally relevant are:
- ZVDH technical rules: The Central Association of German Roofers defines what constitutes a rainproof underlayment
- DIN EN 14963: Continuous rooflights and roof penetrations
- Manufacturer specifications: Additional information from tile manufacturers on minimum overlap
Requirements for PV roof penetrations
A roof penetration for PV cables must meet the following criteria to avoid impairing rainproofing:
- Sufficient overlap: The tile above must completely cover the penetration
- Water drainage: Rainwater must be directed over the penetration without entering the construction
- Watertightness of cable entries: The openings for the cables must be designed so that no water penetrates
- Durable resistance: The material must not become brittle due to UV radiation and weathering
How the NEXCAPE penetration keeps the roofing intact
NEXCAPE roof penetrations are designed to integrate into the existing tile roofing. Important design features:
Material choice: TPU
TPU (Thermoplastic Polyurethane) is UV-resistant and flexible. In contrast to rigid materials, TPU conforms to the tile contour and lies friction-free against the solar cable without lifting the tiles. This leaves the roofing undisturbed, which ensures rainproofing.
Three lengths for correct overlap
The correct length ensures that the tile above completely covers the penetration – thus maintaining the effectiveness of the roofing:
| Length | Recommendation |
| 105 mm | Small-format tiles with narrow covering width |
| 125 mm | Standard tiles, most common choice |
| 150 mm | Large-format tiles, maximum overlap |
Tool-free installation without tile processing
A significant advantage: NEXCAPE penetrations require no drilling or cutting of tiles. Any processing of the tile is a potential weak point for rainproofing. Since the penetration is placed between the tiles without tools, the roof covering remains intact.
Practical tip: Don't forget documentation
Professional solar installers document the correct installation of the roof penetration photographically. This serves as proof to the client and protects against later complaints.
PV roof penetrations (TPU abrasion protection) for your projects: find suitable PV roof penetrations
