Technical specifications

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Find the right specifications, materials and product details for your Modular Skylights solution here. You’ll also find EN classifications and IEEE certifications below.

Technical specifications

Modular Skylights system – unit function

Fixed skylight module


Motorized comfort venting skylight module
Opening up to 410 mm


Motorized smoke venting skylight module
Opening up to 700 mm in less than 60 seconds

One module fits all rooflight solutions

All modular skylight solutions are based on the same single skylight module and the same basic installation process. In other words, you are not required to specify different modules to different solutions. The modular concept is in every sense a “one module fits all”, meaning you can apply the same module specifications, regardless of whether you prefer longlight, ridgelight, northlightor other. This unique modular feature makes the design process much more straightforward, leaving more time to develop aesthetics, ventilation properties, heat and daylight control etc.

Size grid

How to measure the modules

Width and height of the modules are determined by the exterior W and H dimensions of the frame – not the measurements of the cladding, flashing or brackets.

Module – Main components

Module – Electrical components

Remote control Power supply and control unit Rain and wind sensor unit Wall switch Interface for external wall switch Interface for external control devices
KLR 200 KLC 400 KLA S105 KLI 110 KLF 050 KLF 100

Read more about electrical products in Electrical Handbook 

Sash and frame

The main structural profiles of VELUX Modular Skylights consist of pultruded composite, containing approximately 80% continuous fibreglass treads and 20% two-component polyurethane resin.

The composite guarantees high heat insulating performance and thermal stability as well as excellent profile shiftiness and strength. In combination, the characteristics of the VELUX composite gives the slim profiles self-supporting strength and an ability to support installations of considerable size. In addition the material is maintenance-free, non-corrosive and electrical non-conductive.

In combination with low-energy glazing units the VELUX ­Modular Skylights are able to achieve one of the lowest overall U-values for frame and glazing assembly within the skylight market. 

Frame and sash assembled


Frame for fixed skylight module


Frame and sash for venting skylight module


1. Thermal conductivity (W/mk)

– A low score means high insulation performance

Profiles used for VELUX modular skylights consist ofan extremely low-conductive pultruded fibreglass and polyurethane composite resulting in high insulation performance.

2. Linear expansion coefficient (10-6 m/m K)

– A low score means high thermal stability

Whereas traditional skylight materials are bound to fluctuations in form due to thermal changes, the composite of VELUX Modular Skylights will maintain its dimensional properties, ensuring tightness of joints and prolonging the expected lifetime of the application.

3. Flexural Modulus (E-Modulus) (GPa)

– A high score means little deflection

The high rigidity of the pultruded composite material results in very stiff frame and sash, ensuring reliable performance with very little deflection of the profiles and better aesthetics of the skylight.

4. Flexural Strength (N/mm2)

– A high score means high strength (resistance to breakage)

The very high strength of the pultruded composite material allows for design and production of longer and slimmer frame and sash profiles than traditional skylight materials. This enables design of large skylights with slim profiles resulting in better aesthetic performance.

1) Accredited external tests   2) According to EN ISO 10077-2   3) Value identical to fibreglass   4)   5) Internal VELUX test

Glazing unit

VELUX Modular Skylights come with a standard low-energy double-glazing unit. Alternatively the skylight modules can be supplied with improved solar protection or a triple-glazing unit for extra-low U-value. All glazing units include a toughened outer glass layer and a 3+3 or 5+5 mm safety inner glass layer with two layers of 0.38 mm interlayer PVB foil. For technical values on glazing units, please refer to the chapter about Product Data.

The triple-glazing units have a heat-strengthened middle glass layer. Heat strengthened glass is also utilized for the inner pane of triple-glazed units with a 5+5mm inner pane.The cavity between the panes of the glazing units is filled with argon gas as a default.

All glazing units consist of a warm edge spacer and they are produced with warm edge technology to minimize the risk of condensation at the pane edges to provide the glazing units with the most durable insulation capabilities.

Glazing unit with sun protection coating and low emissivity coating

Glazing with low emissivity coating (LowE)

T-value = 77%
g-value = 58%
Ra = 94.47

Glazing with light sun protection coating (Sun1)

T-value = 49%
g-value = 27%
Ra = 90.39

Glazing with advanced sun protection coating (Sun2)

T-value = 19%
g-value = 16%
Ra = 86.30

EN Classifications

Resistance to Wind Load

Classification: EN 12210:2001

Classification of resistance to wind load
Wind load class A B C
1 A1 B1 C1
2 A2 B2 C2
3 A3 B3 C3
4 A4 B4 C4
5 A5 B5 C5
Exxxx Aexxxx Bexxxx Cexxxx

Note: In resistance to wind load classification the number refers to the wind load class, see table 1 and the letter to the relative frontal deflection, see table 2

VELUX Modular Skylights: Class C5

  • Frontal deflection measured at P1: 2000 Pa is less than L/300.
  • 50 cycle pressure test P2: 1000 Pa
  • After that repeated Air permeability test passed

Safety test done at P3: 3000 Pa passed with no released part

Reaction to fire

A1, A2, B: Non-combustable and not very combustable product. Over 20 minutes to flashover.
C: Moderate combustable products. Between 10 and 20 minutes to flashover.
D: Moderate combustable products. Between 2 and 10 minutes to flashover.
E: Moderate combustable products.
F: Highly combustable products (or products whose reaction to fire has not been assessed).
s1: Low smoke production.
s2: Medium smoke production.
s3: High smoke production.
Flaming droblets sub-classification
d0: No flaming droplets.
d1: Flaming droplets that persist for less than 10 s.
d2: Flaming droplets.

VELUX Modular Skylights:

Clas B, s1-d0 or d2

B: Very low combustibility
(A: Incumbustable eg steel and concrete)

s1: Lowest smoke volume
d0: No droplets in T pane variants
d2: Droplets in standard pane variant

Resistance to fire

Classification: EN 13501-2:2007+A1:2009

Presentation of classification
Load bearing capacity Integrity Insulation

Fixed module (HFS): REI30
Venting module (HVS): EI30

External Fire Performance

Test 1 – with burning brands

Test 4 – two stages incorporating burning brands, wind and supplementary radiant heat

Classification: EN 13501-5 + A1:2009

Test 1

Class Classification criteria
BROOF (t1) All of the following conditions shall be satisfied for any one test:
  • external and internal fire spread upwards < 0,700 m
  • external and internal fire spread downwards < 0.600 m
  • maximum burned length external and internal < 0,800 m
  • no burning material (droplets or debris) falling from exposed side
  • no burning/glowing particles penetrate the roof construction
  • no single through opening > 25 mm2
  • sum of all spreed opening < 4500 mm2
  • lateral fire spread does not reach the edges of the measuring zone
  • no internal glowing combustion maximum radius of fire spread on “horizontal” roofs, external and internal < 0,200 m
FROOF (t1) No performance determined.

Test 4

Class Classification criteria
BROOF (t4)
  • No penetration of roof system within 1 h.
  • In preliminary test, after withdrawal of the test flame, specimens burn for < 5 min.
  • In preliminary test, flame spread < 0,38 m across region of burning.
CROOF (t4)
  • No penetration of roof system within 30 min.
  • In preliminary test, after withdrawal of the test flame, specimens burn for < 5 min.
  • In preliminary test, flame spread < 0,38 m across region of burning.
DROOF (t4)
  • Roof system is penetrated within 30 min but is not penetrated in the preliminary test.
  • In preliminary test, after withdrawal of the test flame, specimens burn for < 5 min.
  • In preliminary test, flame spread < 0,38 m across region of burning.
EROOF (t4)
  • Roof system is penetrated within 30 min but is not penetrated in the preliminary test.
  • Flame spread is not controlled.
FROOF (t1)

No performance determined.

VELUX Modular Skylights

BROOF (t1)
BROOF (t4)


Classification: EN 12208:2000

Classification Pressure (Pa) Wind (Km/h)
1 A 0 0
2 A 50 32
3 A 100 45
4 A 150 55*
5 A 200 63
6 A 250 71
7 A 300 78
8 A 450 95
9 A 600 110
E 750 750 123**
E 900 900 134

* Equal to depression
** Equal to tropical storm

VELUX Modular Skylights: E900

No water penetration up to 900 Pa.
900 Pa equals 134 Km/h.

Air Permeability