What should be taken into account when determining the dimensions of a roof hatch?
Choosing a roof hatch often comes down to browsing a catalog and picking a model that "looks right."...
What should be taken into account when determining the dimensions of a roof hatch?
Choosing a roof hatch often comes down to browsing a catalog and picking a model that "looks right." However, in industrial and public utility construction, hatch dimensions are not a matter of chance – they must result from legal regulations, the building's purpose, and user convenience.
Here are the key factors to analyze before purchasing:
1. Minimum legal requirements According to technical and construction regulations, a roof hatch serving as a technical exit to the roof should have clear opening dimensions of at least 0.8 x 0.8 m. This is the space that allows an adult to pass through freely and safely.
2. Purpose and frequency of use If the hatch is only to serve a chimney sweep once a year, the standard 80x80 cm dimension will be sufficient. However, if:
- Tools or spare parts for rooftop equipment (e.g., air conditioners) will be carried through the hatch,
- Regular maintenance work takes place on the roof,
- The hatch is to serve as an evacuation route, ...it is worth considering larger models, e.g., 90x90 cm or 100x100 cm, offered by Wirmet. A larger opening means less risk of catching on the edge and greater freedom of movement.
3. Roof structure and purlin spacing The hatch dimension must be correlated with the load-bearing structure of the roof. In the case of steel halls, it is most convenient when the hatch width fits within the spacing of the roof purlins.
- If the hatch is wider than the spacing of the structural elements, it will be necessary to perform an additional structural exchange (reinforcement).
- Choosing a dimension adapted to the roof module significantly reduces installation costs and prevents interference with the building's statics.
4. Height of the hatch base Dimensioning is not just about width and length, but also height. The hatch base must project above the final roof covering (taking thermal insulation into account).
- Standard base heights are usually 15, 30, or 50 cm.
- In areas with high snowfall intensity or on roofs with a thick layer of insulation, higher bases are recommended to prevent the cover from being blocked by lingering snow and to ensure the tightness of the connection with the waterproofing.
5. Opening method and access When determining dimensions, it is worth thinking about how we will reach the hatch.
- Will there be a vertical ladder under the hatch?
- Will there be attic stairs? The exit width must be synchronized with the width of the ladder to ensure that climbing is natural and safe.
Important: Remember that the commercial dimension (e.g., 100x100) is usually the dimension of the opening in the roof. The "clear passage" after installing drives or hinges may be slightly smaller. Always verify the technical parameters in the product data sheet.
Summary
A well-chosen hatch dimension is an investment in peace of mind for years. An opening that is too small will be burdensome to use, and one that is too large may generate unnecessary structural costs.
Need help fitting a hatch to your project? Wirmet experts will help you calculate the necessary parameters and propose a solution that is optimal in both technical and financial terms.