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X-Two - Dome

Unplasticized polyvinyl chloride (PVC-U) rooflight; triple glazed in UV protected polycarbonate, which achieves a U-value of as low as 1.6 W/m²K.

Features and benefits:

  • The interchangeable PVC-U extrusions are designed to ensure both splayed and vertical upstands/ kerbs are available to suit a precise height, enabling the kerb to be fixed directly to the roof deck no matter what the insulation depth.
  • Suitable for use with all popular roofing membranes.
  • The upstand has 2 mm thick walls with 15 mm air gap, and double gaskets between the glazing and the top of the kerb.
  • Provides 60 mm protection cover at the weather edge of the membrane.
  • Non-fragile – polycarbonate rooflights achieve a Class B rating to ACR[M]001:2014, and glass options are available with a Class 2 “deemed to satisfy” specification in accordance with CWCT TN92.
  • The polycarbonate glazing has vented airspaces between the glazing elements, and an integral water management system that ensures moisture drains to the outside of the building.
  • CE marked.

X-Two can be delivered in two parts for easy handling and more efficient installation.

General information


See 'Options' below and insert requirements.


High performance U-value, wide range of sizes, vent, and kerb fixing options,


PVC-U, Polycarbonate


Rectangular / square on plan, with dome top


Manufacturer guarantee

Uniclass 2015

Pr_30_59_72_31 Framed rooflightsPrimary


L10/45 Rooflights

L10/460 Rooflights

Specification data - Framed rooflights

Product Reference

X-Two Rooflight


X-Two V Rooflight






See 'Options' below and insert requirements.

Upstand/ kerb



PVC-U, white self-finish

Roof attachment

To suit flat board insulation – Code A

To suit cut to falls insulation – Code B

To suit a cold roof – Code C

To suit a built up kerb – Code D

To suit a new timber ground – Code E

To sleeve over an existing curb or upstand – Code F

To suit an existing timber ground – Code G

Glazing details



Double pane glass – Code IGL

Hybrid (glass and polycarbonate)

Triple pane glass – Code IGL3

Triple-skin polycarbonate – Code 03



Dome – Code DM

Polycarbonate only.

Flat insulating glazing unit – Code Glass

Flat sold panel – Code Solid

Pyramid – Code PY

Polycarbonate only.







Not required

Solid lid – Code ISL


Intruder grid – Code IG

Tamper resistant fixings – Code SS


Unventilated – Code 00

Hit and miss vent – Code 01

Rota vent – Code 02

Permanent vent – Code 08

Extract vent, 150 mm – Code 13-150

Extract vent, 225 mm – Code 13-225

Extract vent, 300 mm – Code 13-300

Trickle vent – Code 14

Other requirements

Insert requirements.


Insert requirements.

Standard product features

Fire performance (to BS 476, Part 7):

  • Polycarbonate: To BS 476, Part 7: Class 1, AA designation (national classification), or Broof (t4) European classification for spread of flame.
  • Glass: AA designation (national classification), or Broof (t4) European classification for spread of flame.

Product Options


Size range includes:

- Rectangular:

  • 600 x 900 mm.
  • 600 x 1200 mm.
  • 600 x 1500 mm.
  • 600 x 1800 mm.
  • 600 x 2400 mm.
  • 900 x 1200 mm.
  • 900 x 1350 mm.
  • 900 x 1500 mm.
  • 900 x 1800 mm.
  • 900 x 2400 mm.
  • 1000 x 1500 mm.
  • 1000 x 2000 mm.
  • 1200 x 1500 mm.
  • 1200 x 1800 mm.
  • 1200 x 2400 mm.
  • 1500 x 2400 mm.

- Square:

  • 600 x 600 mm.
  • 750 x 750 mm.
  • 900 x 900 mm.
  • 1000 x 1000 mm.
  • 1050 x 1050 mm.
  • 1200 x 1200 mm.
  • 1350 x 1350 mm.
  • 1500 x 1500 mm.
  • 1800 x 1800 mm.

Intermediate sizes may be available. Consult manufacturer for details.

Upstand/ kerb – roof attachment:

Xtralite has developed unique mounting systems to aid attachment and make the installation process easier.

  • To suit flat board insulation – Code A: Add vertical risers to suit the depth of insulation specified - as standard supplied with a 120 mm vertical attachment to ensure a good interface between board insulation and the rooflight kerb.
  • To suit cut to falls insulation – Code B: Add vertical risers to suit the maximum depth of the tapered insulation scheme.
  • To suit a cold roof – Code C: Suitable for a splayed or vertical kerb, 160 mm high.
  • To suit a built up kerb – Code D: For fixing direct to an existing or new builders kerb.
  • To suit a new timber ground – Code E: 160 mm high, for fixing to the of a newly constructed timber ground equal to or greater than the depth of the new insulation.
  • To sleeve over an existing curb or upstand – Code F: Vertical risers are added to ensure the ventilation modules and or glazing do not foul the existing protrusions.
  • To suit an existing timber ground – Code G: Variable height using PVC-U plugins for fixing to an existing builders kerb or plinth.

Glazing details:

- Material:

Double glazed insulating glass units offer a low U-value alternative to polycarbonate: selection of high specification glass can reduce solar gain and rain noise while retaining non-fragile status. Consult manufacturer for recommendations.

- Colour:

Available in four colours:

  • Bronze: Reduces light transmission and solar gain.
  • Clear: Offers high light transmission and allows full vision of views or objects.
  • Diffused: Offers high light transmission and prevents vision of views and objects.
  • Opal: Prevents vision of views and objects.


Xtralite offers a range of security options to prevent unauthorized access, depending on the level of security required.

  • Intruder grid (IG): Located between the rooflight kerb attachment and roof to reduce the risk of unwelcome intruders. In the case of access hatches, grids can be manufactured hinged and lockable.
  • Tamper resistant fixings (SS): Screws with inaccessible thread assemblies.


Xtralite rooflights can incorporate a range of ventilation and access systems.

  • Unventilated (00): Fixed rooflight, ideal for situations where ventilation is not required.
  • Hit and miss vent (01): Provides minimal background ventilation.
  • Rota vent (02): The unique rotary action vent controller offers variable ventilation, distinctive internal appearance and smooth, silent operation; prevents 'in-blown' roof debris and water ingress.

Consult manufacturer for details and recommendations.

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