5 facts of a good rooflight dome


Various factors influence the quality of a rooflight dome – we explain the 5 facts that make a good rooflight dome.


Reading time: 10:00 min.

Rooflight domes for health, safety and productivity

Daylight: Probably the most important factor for human well-being. Optimal lighting in buildings is an essential factor for physical and mental performance. Only when we take in a certain dose of daylight during the day do many of our vital bodily functions run optimally. Lack of daylight, on the other hand, causes disturbances in metabolism and hormone regulation in humans. Skylights, such as rooflight domes, flood large office, administrative and industrial buildings with daylight, thus creating workplaces with good visual conditions. For many decades, rooflight domes have been an integral part of contemporary construction. The skylights are particularly economical because they combine three functions at once:

Be it safety, energy saving or health, the tasks of a rooflight dome are versatile. In order for the rooflight dome to be prepared for all building types, areas of application or weather conditions, it must meet a number of requirements. It is above all the 5 factors (flexibility, quality, energy efficiency, ease of use and service) that make a good rooflight dome. We explain the must-haves of a rooflight dome in detail.

Flexibility ensures customised solutions

With a skylight, flexibility stands above all for precisely fitting solutions in all building applications. Whether it's a new building, renovation, industrial hall, shopping centre or educational institution: Every building and every construction project has individual needs that must be met. A rooflight dome should adapt to these needs in order to produce the optimum result on the roof. The choice of various designs, different upstands and a wide range of accessories allow architects and roofers to put together the rooflight dome in a customized manner.

Wide range of glazing combinations

A good rooflight dome should also offer a variety of glazing combinations. A distinction is made according to the number of individual rooflight dome shells: double-shell, triple-shell and four-shell rooflight domes. With the increasing demands for modern and energy-saving construction, the triple-shell rooflight dome is now the norm. With a U-value according to DIN EN 1873 of at least 2.5 W/m²K, it can be installed in almost all situations. Four-shell rooflight domes are used for increased thermal insulation requirements. The U-values then reach as low as 1.5 W/m²K. You can find out exactly what the U-value means in our article "The U-value – a simple explanation". Roughly summarized, however, you could say: The lower the U-value of the rooflight dome, the better.

Specialists such as LAMILUX also offer rooflight domes with multi-chamber glazing, as real glass glazing or special glazing made of glass-fibre reinforced composite. The GRP rooflight domes offer special safety. This is because the skylights with composite glazing are considered normally flammable and do not drip on fire. For special fire protection, there are shells made of GRP that are resistant to flying sparks and radiant heat in accordance with EN 13501-5, or hardly flammable and non-dripping shells that serve as fire protection for special requirements.

Accessories of a rooflight dome

A wide range of accessories for rooflight domes rounds off the flexibility package. Whether roof exit, burglar protection grid, wind and rain sensor set, controllable sun protection system or insect protection grid: In order for a rooflight dome to meet the requirements of the building project, architects, planners, as well as roofers, should be able to choose from a wide range of accessories, as offered by LAMILUX as a manufacturer of skylights.

Quality and stability ensure a long service life

Another important factor for a good rooflight dome is quality, especially in the materials of the components. The skylight consists of glazing border frame and upstand. The upstands are made of either steel, aluminium, glass-fibre reinforced composite (GRP) or PVC. The rooflight domes themselves are supplied with a PVC border frame in combination with an internal steel tube. The border frame should ensure stability, protect the glazing with good thermal insulation, and additionally meet the industry standard DIN 18234 for large-area roofs.

GRP upstands in particular ensure quality and stability, thus ensuring a long service life. LAMILUX offers seamless manufactured upstands made of glass-fibre reinforced composite. The GRP upstand creates a clean interior view and requires no joints at the corners – for optimum appearance and the highest quality. It also removes the need for annoying, additional drywall work. Durability is also associated with quality "Made in Germany". Be it testing for the Driven Rain Index, which tests waterproofness under heavy rain and storms, or certification according to DIN EN 1873 – 2014 in terms of wind and snow load absorption: These are just a few of the features that make LAMILUX Rooflights stand out. The expert for skylights and sales manager at LAMILUX, David Plaetrich, describes the unique quality of the manufacturer as follows:

"You could almost call the rooflight dome the mother of all skylights. We have been planning, manufacturing and installing this skylight system for over 70 years and have been constantly improving since then – in every process step, quality and performance. Today, a rooflight dome covers much more than daylight gain. It is a real energy and safety system."

Energy miracle - rooflight dome

The quality of a rooflight dome also depends significantly on its energy efficiency. Thanks to a multi-layered seal system and up to quadruple composite glazing, the rooflight dome has also become a true energy miracle. The multi-layered seal systems ensure compact system tightness and excellent thermal insulation. The high thermal insulation and energy efficiency of the rooflight domes is also due to the torsion-free border frame, thermally insulated upstands made of glass-fibre reinforced composite and optimized isothermal profiles. But what exactly is the isothermal curve?

The isothermal curve graphically shows the temperature distribution within a component or in the transition between different components. Isotherms are lines that connect all points of equal temperature within components, and thus represent the calculated temperature distribution within components with each other. The isothermal curve of the 10° curve is particularly important for the evaluation. Because if the 10° isotherm is in the building component at a window connection, no condensation is to be expected. For rooflight domes without a border frame, the course of the 10° isotherm is very unfavourable and the risk of condensation is very high.

Optimized isothermal profiles are one of the focal points of LAMILUX Rooflights. The compact system tightness of the skylights not only saves heating costs, but also minimizes the risk of condensation. In addition, the LAMILUX Rooflight F100 stands out among conventional rooflight domes, as it has even been assessed for use in sustainable buildings according to the LEED, BREEAM and DGNB green building certification systems. It also features a good life cycle assessment and comprehensive environmental product declaration according to DIN EN ISO 14025 and DIN EN 15804.

Ease of use facilitates assembly

In addition to flexibility, quality and energy efficiency, the ease of use of the rooflight dome should not be forgotten. Rooflight domes are components that penetrate the roof surface. Therefore, various design and processing requirements must be observed. The safety and long-term durability of a roof waterproofing system depends on the care taken in the detailed planning and execution. This task is in the hands of the processors. To facilitate their work on the roof, a good rooflight dome should be user-friendly.

The upstand of a rooflight dome plays a major role here. This is because it is an essential component of the entire rooflight dome system and, due to its stability and thermal insulating properties, it forms the base for the rooflight dome construction. It provides a thermally optimum connection to the building structure. It is particularly helpful if roof connections can be realized individually. The manufacturer of skylights offers many options for this:

1. Heat-insulated base flange: The thermally insulated foot flange made of glass-fibre reinforced composite can be individually adjusted to the height of the roof insulation. The possibility of connecting bitumen roofing membranes directly to the foot flange in a system-compatible manner eliminates the need for a time-consuming raising of the roofing membrane at the upstand.  Optionally, this connection capability is also available for PVC roofing membranes, thanks to the integration of a PVC connection rail directly in the foot flange.

2. Hard PVC connecting rail: Hard PVC connecting rail is circumferentially laminated onto the base flange at the factory and seal-welded in the corners. The advantage here: PVC roofing membranes can be welded directly to the PVC connecting rail at the foot flange. In this way, a material-locking, all-round tight connection with the upstand is ensured.

3. Bevelled base flange: For a structural attachment on profiled roofs, the LAMILUX range features the GRP upstand with a foot flange folded on two sides. For further requirements, e.g. on-site upstand, it is also available in a four-sided bevelled design.

An additional great relief for the roofer is when the complete rooflight dome is delivered pre-assembled to the construction site. This saves processors a lot of time during installation, prevents mistakes during installation, and ensures that the roof opening closes quickly. LAMILUX Rooflights F100, for example, offer this advantage. The products are delivered completely pre-assembled in safe and environmentally friendly wooden crates and guarantee user-friendly installation on the roof.

Service – fast, reliable and uncomplicated

In addition to good product characteristics of a rooflight dome, one important point must not be forgotten: Service for you. Comprehensive consultation from the manufacturer, fast and reliable delivery and competent service for repairs speak for themselves. It is best to get comprehensive advice on all factors. There are professionals who have specialized in the construction of rooflight domes for decades. Here, the focus should be on a personal consultation and fast delivery times, which ensure that your dream project for your building project is quickly turned into reality.

LAMILUX offers you the highest level of comfort and service. As a manufacturer of skylights as well as SHEV systems and their control technology, the professionals have all the expertise to advise you on the most diverse variants of skylights as well as integrated systems for natural smoke and heat extraction and their pneumatic or electrical control technology. Highest service quality means fast and competent advice at your site. A competent service around the use of rooflight domes in your building project facilitates your work and guarantees durability, quality and satisfaction.

Key facts at a glance