‘Standard’ interior doors do not, as a rule, meet any requirements regarding hermetic sealing, sound insulation, fire resistance or smoke protection.
It is not uncommon for light to pass through the rebate area of such doors. In the case of standard interior doors, this is not a defect, as there are no requirements regarding hermetic sealing – neither in standards nor in legislation.
The rubber profiles often designated by consumers as “gaskets” are, in technical terms, “damping profiles” (see DIN 68706-2, Nos. 3.8 and 3.9). The damping ensures that – as was previously standard – the door leaf does not strike the casing directly when closing. The aim: the sound of the door closing is dampened by the profile. Damping sections do not provide any hermetic sealing for the door system.
Consequently, the door may have leakage – whether for air or light is irrelevant.
It is not uncommon for light-coloured or transparent damping profiles (or weather strips) to be used. The colour scheme or lack of colour can cause the plastic profile to ‘glow’. This effect cannot be regarded as a defect either – unless this has been contractually excluded (advice: in which case, use profiles that are as dark as possible).