To be able to inspect the installation properly, sufficient inspection hatches are required. The hatches should be fitted in the right place and be of sufficient size. Preference is given to components with inspection hatches. In addition to the hatches for components requiring service which are not fitted with an inspection hatch, it is recommended that additional hatches are fitted in shafts, technical rooms and floors. The hatches must be easily accessible and clearly indicated on the drawing by the coordinating party. Preferably NEN-EN 12097 must be used as the basis for the inspection facilities.

Insulation
The insulation should be installed in accordance with the manufacturer's instructions. In the case of fibrous material in particular (internal insulation), seams and the like should be finished in such a way that the fibrous material cannot be carried away by the air current.