X-One X-Two X-Three X-Four X-Five U Value (2.2 required for Part L) Shape Rectangular Circular   •   •   • •   •   • • All Glazing Colours • • • • • Glazing Material Polycarbonate Single   Triple Glass Single   Double   • •   • •   • •   • •   • • Ventilation • • •   • Security Security Fixings Security Frame Intruder Grid   • • •   • • •   • • •   • •   • • • Kerbs PVC Metal GRP Circular   •   •   •   •   • Flexible Base Adapter • •

Introducing the Range

This section looks in detail at individual rooflights, generally with polycarbonate glazing but also glass in metal frames. As the leading independent manufacturer, Xtralite offers the widest range of rooflights available, suitable for all applications and building types. All Xtralite rooflights are individually manufactured to order and so are effectively bespoke products, offering the widest possible flexibility. However, to help designers build up specifications to suit their specific needs, products are
organised into X-Ranges as summarised in the table below. Options and accessories for each range are illustrated with relevant product codes.

Categorisation by Thermal Efficiency

The range primarily reflects the level of thermal efficiency
(U value) and hence its appropriateness for particular applications. It is recommended that the appropriate range be selected first, followed by required size, shape and glazing, then options and accessories—so building up the specification. Cross referencing to the earlier technical sections of this guide will prove helpful in guiding the specification process.

X-One

The Future of Rooflights

This latest range from Xtralite represents the future of rooflights, with an exceptionally low U-value of 1.3 meeting and beating the requirements of Part L now—and for some time to come—and low air leakage rate to match. Unlike other rooflights, the X-One rooflight is designed and constructed in three distinct zones to clarify specification and maximize performance and flexibility: 

Upper zone—Glazing section 

Mid zone—Accessory frame 

Base zone—Roof attachment

Glazing Section 

The X-One is triple glazed as standard and formed from enhanced UV protected polycarbonate with breathing airspaces between the glazing elements. The integral cascade water management system ensures that moisture drains to the outside of the building. 

Accessory Frame 

This feature is the key element that ensures compliance with Part L and gives X-One its unique capability in terms of environmental control. The frame is constructed from a single, highly complex, PVC profile designed to efficiently ‘dock’ between the glazing module and either the kerb adaptor profile or the kerb, creating a secure, weathered and warm connection with no cold bridges. 

The accessory frame arrangement is flexible depending on the specifiers requirements. For example it can include the following features:

A unique continuous hinge is available which facilitates the opening of the accessory frame and glazing (manually or electrically actuated).  This allows for high volume air ventilation.

A PVC extruded profile rotary ventilator system can be mounted in the sidewall of the accessory frame. The cylindrical shape protects it from the outside elements using a continuous cowl feature and can be protected with integral insect mesh. The design of  the vent ensures that there is no cold bridging between the outer and inner surfaces. When the vent is closed it forms a virtual triple skin chamber with both air leakage and sound attenuation performance second to none. The ventilation system is simply operated by rotating the operating handle. Refer to the Rotary Vent drawing in the Ventilation and Roof Fixing section for more information.

Roof Attachment 

Xtralite have developed unique mounting systems to aid attachment and make the process of incorporation easy.

A versatile metal foot will allow for varying thicknesses of roof insulation, whilst allowing ‘flexible’ matching of rooflight to roof opening as well as ‘cut to falls’ variable depth insulation systems.

Fixing direct to the roof deck allows for the kerb to be attached direct to the supporting structure which could be above the insulation layer or by using a kerb adaptor direct to any pre-constructed builders kerb.

The kerb has three main insulating chambers ensuring not only compliance with current regulations but also with projected future changes, by the addition of high performance insulation to the chambers. The kerb is designed to be equally suitable for, and compatible with, both polymeric and PVC roofing membrane systems, bituminous membrane and mastic asphalt systems. 

The rooflight assembly includes a unique termination detail to ensure that the ‘top edge’ of the roofing membrane is fully protected. A special ‘key’ finish to  the PVC-U kerb increases roof membrane fixing options and the PVC-U kerb torch-on system friendly. Simplified assembly allows the roofing finish to be applied to the upstand prior to clipping the Glazing Section and Accessory Frame into position. This procedure minimises damage and the need for protection, and eliminates dressing around the vents.

X-Two

This range also meets and beats the requirements of Part L with an impressive 1.9 U value using ‘all thermoplastic construction’ for outstanding thermal efficiency, high resistance to weathering and low maintenance. The X-Two is formed from enhanced UV protected polycarbonate with vented airspaces. The integral Cascade water management system ensures that moisture drains to the outside of the building and air leakage meets Part L criteria. Key features include:

• Aluminium trim and extruded gasket sections 
• Steel security insert housed within the PVC-U section 
• Rooflights easily removed and replaced with special keys
• Available in four versions—fixed; worm-gear opening; hit and miss;  access hatch.

A 2 mm thick wall thickness ensures weld strength and a weather seal on all opening rooflights maintains weather-tightness. A special ‘key’ finish to the PVC-U kerb assist adhesion of membrane and the PVC-U kerb torch-on system friendly. X-Two can be delivered in two parts for easy handling and more efficient installation. 

X-Three

This thermally broken, metal system offers considerable flexibility whilst complying with the maximum allowable U-value (under Part L) of 2.2. Frames and kerbs are finished in white as standard but coloured kerbs are also available. X-Three rooflights can be double glazed or triple glazed in polycarbonate. The integral Cascade water management system ensures that moisture drains to the outside of the building and air leakage meets Part L criteria. The security frame is also available as an option.

X-Four

This GRP kerbed system is designed for circular rooflights whilst also complying with the maximum allowable U value (under Part L) of 2.2. Rooflights are triple glazed as standard with enhanced UV protected polycarbonate and vented airspaces, and air leakage meets Part L criteria. 

X-Five

his metal system offers considerable flexibility for unheated areas where thermal insulation is not an important criterion. Frames and kerbs are finished in white as standard but coloured kerbs are also available. X-Five rooflights can be square, rectangular or circular in shape and single glazed as standard with enhanced UV protected polycarbonate or glass. The security frame is also available as an option.