Skylight: What must be considered in the soffit?

When skylights are installed, a natural window reveal is created around the window. How to proceed with this reveal best, and what you have to consider when disguising the soffit, you will learn in detail in this post.

Insulation of the soffit

The soffit of the roof window must be insulated. Required is an insulation thickness, which should correspond to the thickness of the insulation of the roof in any case. This has to be considered in advance in the planning.

In any case, the installation of the skylight should be done by a qualified specialist company, which is also familiar with the selected window type and its installation. When planning, make sure that the insulation thickness is chosen as high as possible.

Skylight: What must be considered in the soffit?: considered


Too little insulation of the skylight reveal has led to numerous problems in the past. Due to the temperature difference between the lower-insulated soffit edge and the more insulated surrounding wall, a cold bridge is created.

This cold bridge can cause moisture condenses in colder outdoor temperatures and the soffit is moistened over time. Then threaten mold and other structural damage, which are extremely expensive to fix.

Connection of the soffit to the surrounding wall

The connection of the soffit and the cladding are best done with plasterboard. There are also installation aids from the larger window manufacturers, which, however, often have to be individually adapted to the respective window in individual cases.

When connecting is to pay attention to some things:

  • Wooden battens for secure fixing of the plasterboard
  • exact cutting of the GK panels (dimensions can change after the insulation has taken place - measure!)
  • Edge protection (the soffit edge is very shock-sensitive and susceptible to impact, as it is unfavorable, edge profiles for protection are therefore recommended)

Airtight finish

The entire building envelope must be airtight sealed according to the EnEV, in order to limit heat losses and to avoid thermal bridging. This also applies to the window reveal and the skylight. When installing the vapor barrier, therefore, ensure a secure, durable and completely air-tight fastening.

Tips & Tricks

When designing the roof reveal pay attention to the best possible incidence of light. The soffit should be designed so that as much light as possible can be used by the skylight in the room (dart board perpendicular to the window surface, angled connection above and below the skylight).