Measuring & Installation Guide
Measuring & Installation Guide
Please note size you purchase from the drop down menu on the website is based on the external upstand dimensions. If you purchase a 1000mm by 2000mm from our website then your external upstand dimension would be 1000mm by 2000mm. We have +20mm tolerance all around built into our sizes so if your external dimensions were 1020mm by 2020mm this would still fit. The width of your upstand should be minimum 85mm wide and 150mm high.
Brett Martin Roof Lantern rooflights are intended for installation onto a fully weathered and insulated builders upstand on flat and low pitch roofs. The surface of flat roofs normally require some degree of pitch to ensure adequate water runoff. For aesthetic reasons we recommend that the upstand is built with 0° pitch i.e. not parallel with the pitched roof surface. The rooflight can accommodate being installed on an upstand with a pitch of up to 5° but please note that this will likely result in a ‘lopsided’ appearance.
Sizes and Configurations
Brett Martin Roof Lanterns can be supplied in 4 pane or 6 pane configurations:
Available with clear self-clean or blue solar-control self-clean glass as standard. Other glazing options are available on request. If non-standard glass is used, glazing performance may differ from the table shown.
Thermal transmittance of rooflights is assessed in the horizontal plane for compliance with Part L of building regulations. There is currently no method set out for assessing the thermal performance of lantern rooflights, so the method shown in NARM NTD2 has been adopted as the most appropriate. All variants of Brett Martin Roof Lantern have a better thermal transmittance than the limiting value in Part L of 2.2 W/m2K. The thermal transmittance values (assessed horizontally) are shown below. For Ud values calculated in the vertical plane please contact Brett Martin Daylight Systems.
Brett Martin Roof Lantern units achieve a direct airborne sound insulation value of 35db (Rw).
Wind and Snow Loads
Brett Martin Roof Lantern has been tested to show that, when correctly fitted in accordance with our instructions, will resist wind loads calculated in accordance with BS EN 1991-1-4: 2005, and imposed loads in accordance with BS EN 1873: 2005.
Brett Martin Roof Lantern rooflights are manufactured using double glazing which includes an inner pane of annealed, laminated safety glass, which is essential for ensuring the safety of those below the rooflight through the prevention falling glass from accidental breakage. In some circumstances, annealed, laminated safety glass can be subject to thermal stress fracture in the event of uneven heat build-up directly under the glass. Installation of blinds, or any other alterations made to the lightwell below the rooflight, must be done so with consideration to the risk of thermal stress fracture. In the case of blinds, the risk of thermal stress fracture can never be fully removed, but it can be reduced by choosing light coloured blinds and positioning them as far away from the glass as possible. More detailed guidance can be obtained upon request – please contact the technical department.
Product Dimensions & Weights
A 10-year manufacturer warranty is included as standard with the Brett Martin Roof Lantern.
Delivery & Lead Time
Production and delivery time for the Brett Martin Roof Lantern is 3-5 working days for the 4 pane glass option with clear of blue glass. Lead time for other specification will be 15-17 working days. Both the glass and the frame will arrive on the same day.
Please ensure that on delivery there is a suitable person present who is able to unload the lantern glass roof lights from the lorry.