Rooflights and Skylights – What’s the Difference?

The term rooflight or skylight is generally understood to mean a window in the roof that allows daylight to penetrate, affording extra light to the space beneath.  Roof windows (as they’re known) and skylights actually differ quite a bit.  A roof window (often mistakenly termed a skylight) is an outward opening window that is incorporated into the design of a roof and tends to be larger than a skylight, allowing a much wider view of the sky overhead.  A skylight, on the other hand, is a light transmitting window that forms all or a portion of a roof to allow more light into the building.   A roof window is also commonly known as a dormer whereas a dormer is correctly used to describe the loft space in a pitched roof.  The erroneous use has probably come about as people converted their lofts into living space, adding “dormer” windows to allow the light and air in.  These roof windows can usually be opened to allow air in too, whereas many skylights are installed for light distribution only and cannot usually be opened.

Skylights are most commonly installed on flat roofs here in the UK and there’s been an increase in the use of flat roofs over the past fifty years or so, especially in commercial and industrial buildings.  This is primarily because a flat roof is cheaper to construct and install and the long-life modern roof covering materials available nowadays are making them an attractive choice for building owners.  A flat roof also holds the advantage of providing extra space outdoors for the installation of the plant and machinery necessary for air conditioning and piping.

However, any flat roof membrane will tend to break down over time, becoming fragile and dangerous to walk on for those who need to access machinery on a regular basis in order to perform maintenance.  Any skylights installed in a flat roof are also likely to become brittle and are not suitable to walk on, in any case.  Skylights often become covered with debris and grime, making them difficult to distinguish from the surrounding roofing membrane, presenting maintenance personnel with an extra hazard in an area that is already risky to work on.

Skylights or rooflights can also provide a safe and secure means of accessing a roof and increasing usable space by converting flat areas into terraces or roof gardens (which are becoming increasingly popular).  They are often installed in order to provide less frequent access to a roof area for maintenance.  A good design will help with compliance with Building Regulations. 

Part K of the Building Regulations deals with protection from falling, collision and impact and contains a requirement to ensure protection from falling which applies to any “stairs, ramps floors and balconies and any roof to which people have access”.  This requirement can be met by using suitable guarding for the appropriate circumstance to reduce the risk to the safety of people in and around the building. 

Here at D-marc we have some flexible solution when it comes to guarding, our roof safety demarcation barriers have been designed specifically for flat roofs where they can provide edge protection and protect skylights, offering an enhanced level of safety.