Manufacturers of
Rooflights, Structural Glazing,
Canopies & Walkways


N.B. This technical specification is incorporated into NLS’s Terms & Conditions of Supply of Goods and/or Services (“the Ts & Cs”) and should be read in conjunction with the same. The Definitions found within the Ts&Cs shall apply to this document.
  1. Asbestos
    All asbestos management/removal works are to be completed prior to our works commencing on site. Certification that all work areas affected by asbestos have been cleared of the material will be required prior to our installation team attending the site to commence works. Should asbestos be found on the project the removal will have to be carried out by others without loss of revenue to NLS and programme adjustments notified in writing to NLS to allow the rescheduling of any installation work included in the Order.
  2. Fragility
    If a non-fragile requirement exists for the glazing it must be specified at the tender stage with this system, as its later introduction may have cost implications.
  3. Material Delivery / Storage
    Materials will be produced to suit the agreed programme dates. Unfortunately, we are unable to provide storage at our premises. Excessive delays to delivery will result in the materials being stored off-site with all associated costs being added to your account.
  4. Protection of NLS works.
    Protection of NLS’s works following the completion of our installation is not included within our current quotation.
  5. Protection of adjacent roof works. Before any installation work begins, protection will be required, to avoid damage, to both adjacent roof areas and roof areas needed for access. This protection will need to be provided by yourselves and not NaturaLight Systems Ltd.
  6. Protection of standing seam roof
    We strongly recommend that all adjacent metal roofs are protected by others prior to our site attendance, to ensure no damage may occur.
  7. Strip out existing
    We have not included for the removal of existing structure or glazing which should be carried out prior to our site commencement.
  8. Existing Kerb
    All new / repair work to the existing kerb(s) will be deemed to be undertaken by others. We have assumed that the Rooflight will sit on a suitably prepared builder’s kerb.
  9. Kerb / Support structures.
    NLS’s price is based on foregoing trades completing their works timely and to a suitable acceptable trade tolerance. NLS do not accept limiting or fully exonerating pre-commencement inspection clauses that are both unreasonable and contradict the above, and fully expect the main / roofing contractor to take on their responsibility for ensuring that the new kerbs/support structures are installed correctly and to industry-accepted tolerances. Should the supporting structure be inadequate, inaccurate, or unfit for our Rooflights installation, NLS reserve the right to charge for any abortive time from our sub-contract labour. For the avoidance of doubt the above will supersede any conditions within our direct sub-contract or any back-to-back conditions amended thereto, and should NLS have commenced work prior to any sub-contract documents being signed and returned, then the above and not the sub-contract conditions will prevail.
  10. Supporting Structure
    If required NLS can provide a set of structural engineers’ calculations, giving the horizontal and vertical loadings at the kerb of the Rooflight. Please allow 2 weeks for this facility if required. Your consultant/site engineer should utilize these figures when detailing the kerb design criteria. For absolute clarity, it is your responsibility to ensure the existing/new kerb is suitable to withstand all dead/live loads that the Rooflight, during its normal function, may impose.
  11. Concrete Pads
    All our quotations include standard concrete pads; to dig out to 500mm deep, make good and reinstate to ground level using concrete. We have not included any additional works for alteration due to mains underground services that may be found during excavation. Where underground mains services are found it will be the Client/Contractor’s responsibility to have the necessary underground services amended, additional works will be charged at day rate costs of £500.00 per day + materials.
  12. Paint Finish
    Where a quotation has been given for polyester powder coated paint finished and no colour specified, it has been assumed that this will be one solid colour tint of standard RAL colour, if more than one or a non-standard RAL colour is required this  will incur additional costs
  13. Concrete / Foundations (External Canopies)
    Steelwork support columns are produced along with packing shims to accommodate 20mm maximum variance between finished surface levels of foundations/footings. Please ensure that the finished top surface of all concrete bases falls within a maximum 20mm range. Failure to provide the above finish may dictate additional works and any associated costs including abortive site attendance/prep’ work and standing time may be charged to your account.
  14. Builders Work.
    We have not included for any associated building work, I.e. lead flashings, etc.
  15. Builders work/existing lead work.
    Nothing has been included in the above quotation for replacing any of the existing lead work. It is our experience that on removing existing glazing the current lead work will split, crack and rip. We would therefore strongly recommend that a qualified lead worker is employed to replace the lead work and to tamp it over our glazing on completion. NLS are not qualified lead workers and all remedials to this item of work must be carried out prior / during our site attendance by a suitably qualified lead worker.
  16. Cleaning Down (Polycarbonate)
    Polycarbonate sheet is delivered to site with a poly film protection which must be removed when the panel is installed. Thermoplastic material is prone to static after this protective layer is removed, which may attract dust. We have not included for any further cleaning down after installation works. Any subsequent dirt removal should be carried out in accordance with the relevant polycarbonate cleaning instructions.
  17. Cleaning Down (Glass)
    We have not included for cleaning down the glass once we are complete and have left the site. Once all building works are complete, we would strongly recommend that the unit is carefully washed down with clean, warm water, to remove the accumulation of building ‘Dust’.
  18. Cleaning down (self-Cleaning Glass)
    Due to self-cleaning glass having an easily damaged ‘Soft’ coating, we would strongly recommend it only be cleaned during long dry spells after the accumulation of building dust. Normally a simple hosing down with water will suffice. However, in extreme cases, a soft cloth and soapy water can be used. UNDER NO CIRCUMSTANCES SHOULD SPECIALIST CLEANING OR ABRASIVE ACTION BE USED – THIS WILL DAMAGE THE SPECIAL SELF-CLEANING COATING.
  19. Control Panels / Wiring
    The NLS quotation specifically excludes the control panel to operate the actuators. This is deemed the interface with the electrical sub-contract and part of their separate package of works. In like manner, all wiring from the actuator is also deemed part of the electrical package. The actuator is supplied with a short 1m length of flex that will require terminating at a fused spur or similar. An approved commissioning contractor should be used when a control panel is required with the order. For expedience and cost, we would suggest that this work is arranged directly with the commissioning contractor. All wiring must be in place and access to the Rooflight made available for a successful commissioning operation.
  20. Electrical actuator control/wiring
    Should there be a requirement for electrical actuators/openers to our Rooflight product. Please note that NLS has not included within our costs for any electrical wiring to the motors or for any control equipment. Please note the control of these actuators is generally part of the mechanical and electrical specification, and such is NOT part of NLS’s quotation to you. Should you require further advice or assistance on controlling these motors, please contact our technical department on (01670) 530333 for further information.
  21. Alternative Products.
    By inspection of the specification (and the project requirements), we have selected and proposed what are considered to be the most appropriate NLS systems that will deliver the required performance criteria, in general terms. Where we have offered systems as an alternative to our competitors, the system performance will be similar – unless clearly stated. The NLS structural systems we implement are comparable with those provided by our competitors and as such we expect the design characteristics to be similar. However, as our roof glazing system is under constant review we have not instigated formal test procedures for the same, with regard to the aforementioned we can only assume the constraints of the system by analysis of former projects which are currently installed UK-wide.
  22. Site survey
    We have not included for a site survey. We anticipate manufacturing from a set of approved drawings, based upon consultants’ details. Please ensure an up-to-date set of drawings are issued with any order. Should architects/engineers drawings not be available at the time of order, we will, if required, carry out a site survey before manufacture. This will be charged at £250 + VAT and must be added to the contract sum. In such instances an additional week will be required to be added to the programme to accommodate this additional work.
  23. Design Criteria.
    Our systems are designed in accordance with:

    • BS 6399: part 1- design loadings for buildings Code of practice for dead and imposed loads.
    • BS 6399: Part 2 – design loadings for building code of practice for wind loads.
    • BS6399: Part 3 – Design loadings for buildings code of practice for imposed loads (Snow Loads)
    • BS8118: Part 1- The structural use of aluminium.
    • Thermal Performance.

    Our system is not thermally broken in the traditionally accepted form. Structural fixings penetrate from the outer member of the inner at frequencies determined by the loadings. These fixings normally at nominal 300mm spacing, produce an extremely limited thermal track with low resistance. We believe that the performance (Thermal) of the NLS system surpasses that of a traditionally thermally broken system with a continuous high resistance track.

  24. Vent area calculation – A.O.V’s
    NLS smoke venting Rooflights are always quoted at their nominal size, to avoid complications when the roof aperture is being created. It should be noted that the smoke venting actuating mechanism is mounted inboard of the minimal quoted size, on each of the two adjacent sides and this reduces the overall throat dimension by 200mm. the free vent area should thus be calculated by subtracting 200mm from one of the quoted smoke vent dimensions. Thus a 900mmx900mm unit becomes (for calculation purposes) 900mmx700mm.
  25. Condensation / Climate Conditions.
    The formation of condensation on any controlled fitting in a roof assembly is dependent on various environmental conditions such as relative humidity, internal and external temperatures, and/or natural/mechanical air movement. Condensation will generally form when warm humid air meets a surface with a lower temperature. Condensation will often be worse in the winter months when the external temperatures drop and the internal air humidity and relative temperature substantially increase because of reduced ventilation.  If humidity levels cannot be reduced or controlled by either removing the source of moisture or, by ventilation there is a very real risk of condensation forming. The situation is decidedly or pronounced when the following standard products or product combinations are used: –

    • Single or double glazed units.
    • Single skin metal upstand/kerbs.
    • Insulated metal upstand.
    • GRP upstand.

    Because the environmental conditions both internally & externally are outside of the control of NLS, there can be no absolute guarantees on the prevention of the formation of condensation.

  26. Security clearance checks/passes
    As no information to the contrary has been provided with regards and requirements for security clearance checks of our nominated labour we have made no allowances for any such security checks, applications or vetting. We reserve the right to recover any associated costs should any of the above be required.
  27. Lead-times
    The lead-time for the Order will be approximately 6-8 weeks from approval of drawings. Please note that the lead-time for the Order will depend upon material availability in the marketplace at the time of order placement. Currently ‘Clear toughened / Clear laminated’ can be delivered in 6-8 weeks with special high-performance coatings such as Suncool being delivered in 12-14 weeks.
  28. Electrical Components
    The Supplier does not provide for any onsite electrical work unless otherwise agreed in writing. It is the responsibility of the Customer to ensure that all wiring and electrical components are checked and tested by a qualified electrician before installation. All electrical components supplied by the Supplier are factory tested before dispatch and are in good working order. Any damage to these components resulting from incorrect or faulty wiring or misuse of handling will be the sole responsibility of the Customer as will be the cost of any replacement.
  29. Glass Units
    All glass units are guaranteed under the Terms and Conditions of the glass manufacturer and will be covered for a maximum of 3 years from the date of the invoice against failure. Any breakages upon delivery must be reported within 24 hours. After this period the Supplier accepts no responsibility for replacement.
  30. Packing Cases
    Unless otherwise agreed in writing with the Supplier, the Price does not include the costs of cases and other packing materials which shall remain the property of the Supplier and shall be returned in good condition to the Supplier’s premises at the  Customer’s expense and within 2 months of delivery. Should the Customer fail to return the packing materials, the Supplier reserves the right to render an additional invoice to the Customer for the cost of replacement.



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