Here we’ve tried to answer some of the most common questions that arise when choosing which fixed rooflight to buy. If there’s anything you’re still unsure of, please give us a call or send us an email and we’ll get straight back to you.

frequently asked questions

  • Why is your glass rooflight better than your competitors?

    The Blade rooflight’s unusual contemporary good looks combine with a robustly engineered box section structural main frame which is fully thermally broken, unique curved outer aluminium profile and floating infinity glass to distinguish the frameless rooflight from other roof window suppliers. We are confident that it’s the best looking, strongest and one of the most thermally efficient flat roof windows available in the industry.

    Commercial grade ‘silicone sealed’ and warm edge spacer bars (no metal) are used in the Blade rooflight glazed units which are designed for longevity and have been proven time and time again in extreme environments such as skyscrapers and large commercial buildings.

    Our lifetime guarantee reflects our confidence in the contemporary glass skylight’s long term performance and reliability. We are the only rooflight supplier to offer this level to protection to the purchaser.

  • Why does the Blade rooflight have an overhanging 'infinity' glass edge detail?

    Firstly, because it makes the roof window look good. Simple as that to be honest. We are rooflight design junkies! The infinity glazing gives the rooflight its beautiful unique, modernist ‘floating’ effect.

    Secondly, the structural silicone is not exposed to the elements and is hidden discreetly below the rooflights top up to 10mm glass pane. Most other suppliers’ rooflights have an exposed silicone detail and if poorly applied this can make flat roof windows look unattractive. Additionally, as the structural Dow Corning sealant is protected from the elements, this will improve the aluminium rooflight’s long term reliability and performance.

  • How strong is the Blade rooflight?

    The Blade rooflight is incredibly strong. Our infinity top glass pane is a substantial up to 10mm thick as opposed to other roof window manufacturers who supply cheaper and weaker 4mm or 6mm glass. All exposed glass edges are polished for rooflight aesthetics and this also makes them less prone to cracking.

    Our rooflight’s aluminium frame is without question the strongest on the market. We ‘double cleat’ all rooflight corners and use not only Dow Corning 121 fast cure commercial grade silicone sealant to bond the rooflight glass into the rooflights frame but we also use 3M VHB structural bonding tapes which are used to hold jet airplane metal panels in place.

  • Is the Ofset Blade a ‘frameless’ rooflight?

    Yes and no ! It’s actually both.

    From an aesthetic viewpoint, a ‘frameless’ look when viewed from the inside is far more attractive, allowing more valuable light to flood into the building providing an ‘all glass’ vista. Yet structurally it is far better to have a solid, box section aluminium rooflight frame which improves the rigidity and longevity of your contemporary roof window.

    The Blade rooflight’s unique profile gives you the best of both worlds. Ofset’s exclusively designed aluminium rooflight frame, if plasterboarded over, will give your rooflight the appearance of being frameless. When the rooflight is seen from outside you are aware of the beautiful curved outer rooflight profile and the distinctive floating, infinity glazing.

    No ugly exposed silicone lines or bulky squared edged roof window frames in sight.

  • What if I prefer a ‘framed’ rooflight look from inside?

    No problem! If you prefer this look either for aesthetic reasons or to match other glazing products, you can simply finish your plaster line 10mm below the top inside edge of the rooflight frame to create a coloured internal line. Don’t forget to ask your plasterer to use a ‘stop bead’ detail at the finishing edge of the plaster against the rooflight as it looks neater if seen from above or below. 

  • Are your roof windows British made?

    Our rooflights are designed by our UK based team, we manufacture the windows in the UK and source all materials from the UK. We are not a ‘reseller’ of bought-in rooflights. Unlike many of our competitors, we do not buy Chinese aluminium, albeit it is cheaper, and we do our utmost to support British manufacturing and the British economy. 

  • Are Ofset rooflights eco-friendly?

    We hope so. We source all materials from England so limit emissions due to long haul deliveries from abroad. Our rooflight frames are made from aluminium, thus 100% recyclable. In addition, both Double-A and Triple-K Blade roof windows are two of the most energy efficient glazed rooflight units available.

  • How thermally-efficient is my Blade skylight?

    Extremely. Both our standard Double-A and Triple-K rooflight glazing options have very impressive overall thermal efficiency ratings (Ud values – see U-values Simplified section of the website for explanation) which go way beyond what is required for minimum heat loss requirements by Building Regulations. Our rooflights achieve a Ud value from just 0.8 w/m2k for Triple-K and from 1.1 w/m2k for the Double-A rooflights. Building Regulations maximum permitted Ud level for rooflights in domestic installations is 1.6 w/m2k and 1.8 w/m2k for commercial rooflight installations. You can view The Blade u-values here.

  • What are u-values and why are they important when choosing a rooflight?

    The lower the u-value, the better the rooflight is at keeping the heat in. There are three quoted u-values – the centre glass pane u-value (Ug), overall product u-value (Uw) which comes from glass and frame combined and the overall ‘developed area’ u-value (Ud) which measures the glass, frame and kerb/upstand together. The Ug is always lower than the others. But the Uw and the Ud values are actually more important measurements for rooflight thermal efficiency. The Ud value is the most relevant as this is what is looked at by Building Regulation inspectors.

    Unfortunately, it is confusing that some companies only list their skylights’ Ug value in their marketing. Ofset shows you all three values so you are completely clear on what you are buying. Check our ‘U-values Simplified’ section here.

    Both our Double-A rooflights and Triple-K rooflights meet and exceed all the latest UK building regulations.

  • What is the difference between the Blade rooflight's ‘easy-clean’ glass and our competitors’ ‘self-cleaning’ glass?

    Many companies supply ‘self-cleaning’ glass on their flat roof windows. However, glass manufacturers Pilkingtons and Saint Gobain state categorically that ‘self cleaning’ glass only works with a minimum pitch of 10 degrees, with 30 degrees being more ideal. Most flat rooflights are set at an average of just 5 degrees. So in essence ‘self-cleaning’ glass just isn’t the correct product for flat rooflights.

    The Blade’s glass is coated as standard with an ‘easy-clean’ coating. This acts as a ‘non-stick’ layer that repels water and dirt causing it to roll off the skylight even at a very low pitch.

    Don’t take our word for it – google ‘minimum pitch for self cleaning glass’ and judge for yourselves!

  • I am worried about noise entering through the rooflight

    As part of the Blade rooflight’s glazing, we have a 10mm infinity, floating top glass pane which is the thickest in the industry. This is a superb noise inhibitor so in most cases you should not have any problems with noise coming either from the outside into your home, or from inside out to your neighbours. The Blade rooflight has as standard two thicknesses of glass (up to 10mm & 6mm). These different glass thicknesses  ‘baffle’ sound waves whereas two panes of glass of the same thickness work less well from a noise inhibition standpoint.

    However, if you are really concerned about excess noise entering through your rooflight then we offer an upgrade to acoustic laminated rooflight glass which you will see in the ‘Bladebuilder’ or in our ‘Glass Specification’ document on the Download section of our website.

    Please note we use only ‘toughened laminated’ glass as opposed to ‘annealed laminated’ glass in our Acoustic and Security glass options. Toughened laminated is much stronger and less prone to heat stress fractures than annealed laminated glass and this is one of the reasons our laminated rooflight products can be guaranteed for life.

  • Does your glazing block out harmful UV rays?

    If your rooflight is situated in a particularly sunny position, you may want to upgrade to either solar controlled glass and/or laminated glass. Both these products block about 99% of UV rays. So no furniture or picture fade. See the ‘Bladebuilder’ for details or check our ‘Glass Specification’ document on the Download section of our website.

  • How does Ofset Blade compare pricewise with other flat rooflights?

    We hold our hands up – we’re not the cheapest rooflight supplier on the market. Our design-led philosophy and emphasis on performance means we put the aesthetics and quality of the product first. We want to supply the best contemporary glass rooflight in the business not the lowest priced.

    However we also believe strongly in value for money so have tried hard to provide an extremely high-end roof window that still compares favourably when looked at next to other premium rooflight suppliers, particularly if you compare external ‘actual product’ rooflight sizes.  

    You can control the price of your rooflights to some extent with your choice of features and options and these are all explained very clearly and transparently on the ‘Bladebuilder’.

    It is important to consider also that our external measurements are larger than our competitors’ due to our signature floating glass panel and curved outer frame. If you compare like-for-like external measurements, then we believe our rooflights are very competitively priced. Additionally if you allow for the FREE insulated upstand we genuinely feel our Blade rooflight gives the client the best ‘complete package’ offer available in the industry.

  • What is Ofset's rooflight product guarantee?

    The Ofset Blade rooflight’s guarantee is clear and concise and the best on the market.

    Ofset back the Blade rooflight for life. If it fails, we replace it. Simple.

    We are the only rooflight supplier offering this lifetime guarantee on fixed flat rooflights.

    The Blade’s structural aluminium frame, silicone sealed commercial grade glazed units and insulated kerbs are all guaranteed for life.

    As long as they are installed and maintained correctly accordingly to our guidelines, we promise your rooflight frames will never warp or twist, your kerbs will never warp, twist or rot and our glazing units will never leak or ‘mist’. 

    If there is ever a problem, we do not even expect you to return your rooflight unit to us for checking. To avoid any inconvenience to you, Ofset will send a staff member to check the product and installation on site if reasonably possible.

    If your Blade rooflight is faulty, we will simply supply you a complete new roof window delivered free to your home. No argument.

    Our ultra-thick durable paint finish has a guarantee of 20 years. Our rooflight units are powder coated with a minimum of coastal quality 60 microns thick paint, the best on the market.  

  • How can I get a quote for a Blade rooflight?

    Simply jump onto our online rooflight design tool, the ‘Bladebuilder’.

    While you are designing and specifying your new Ofset rooflight on the ‘Bladebuilder’, you will see the price constantly changing to reflect your choices. When you get to the end of the process, you will have your final price on-screen. You can either purchase immediately online or if you prefer, we will send you a quote via email. All online registered rooflight prices are valid for one month after your quotation date.

  • Do you welcome trade enquiries for the supply of the Blade rooflight?

    Ofset love to build relationships with architects, developers, designers and construction companies. Please contact us to discuss possibilities of using our beautiful rooflight system in your latest projects.

  • What are your payment terms ?

    We ask for a 50% payment on placing the order, then the final 50% normally 3 working days prior to delivery once the rooflights are manufactured, checked, packed, wrapped and good to go.

  • Can I cancel my Blade rooflight order?

    We offer a 24 hour cooling off period. After that time, it is impossible to cancel your order. You have ordered a bespoke roof window product which is being made to your personal specifications and once the manufacturing process has begun and your frames are cut, we cannot make changes or offer refunds for cancellations.

    So when ordering your Blade, please take your time, choose wisely, and make sure you are happy with your purchase. Then sit back, relax and soon your Blade(s) rooflights will arrive.

  • When will my Blade rooflight be delivered?

    It takes 20-30 working days to manufacture, package and deliver your new Ofset Blade(s) due to the 100% bespoke nature of the rooflight system.

  • Why the wait?

    Apologies. We are the victims of own own desire to please, offering the widest choice of rooflight designs and options in the industry. In addition, all our rooflights are bespoke and made to order.

    Once your rooflight order is placed, your Blade(s) will be manufactured to your precise exact specifications before being hand finished, quality checked, carefully packed and delivered to your door.

    We feel an Ofset Blade is worth the wait.

  • How is my Blade roof window delivered?

    Ofset offer two delivery services – an industry-standard ‘kerbside’ delivery or, to make your install process easier, we can also offer a ‘crane-in’ delivery procedure through a partner company.

    A kerbside delivery means your rooflight will be delivered on a curtain-sided lorry to your chosen address. It is then the client’s responsibility to offload the rooflight product(s) from the lorry and carry the items to the ‘fit area’. Clients and/or their building contractors must consider the size of the rooflight and the weight and make sure enough people or suitable lifting equipment are available to carry this out at the time of delivery. We offer detailed information on Blade sizes/weights in our ‘Blade Size/Weight/Design Tolerances’ document available to download in the ‘blade docs’ section of our website. We are also more than happy to advise you in person. Just get in touch.

    If you would prefer Ofset to make sure your Blade gets safely to the fit area from the lorry, we can help facilitate a ‘crane-in’ delivery option. We can help organise a mini ’spider crane’ and operators to get your Blade rooflight in place. We can also help you with craning ‘over the house’ or road closure procedures. If interested, please let us know and a project manager will contact you to discuss the options.

    For more info, see our ‘Delivery & Lifting’ doc available to download in the ‘blade docs’  section of our website.

  • How do I install my Blade rooflight?

    The Blade contemporary glass skylight is very easy to install and should only take around 30 minutes including lifting into position. We supply detailed fitting instructions for all our rooflight products. Please download the ‘Blade Installation’ doc in the ‘blade docs’ section of our website.

  • What is a rooflight kerb/upstand and why should I choose the Ofset product?

    An upstand or kerb is the structure that your flat rooflight sits on. The kerb is affixed to the roof and then the rooflight is affixed to the kerb with silicone and screws. Your kerb is an important part of your Blade rooflight in several ways. Firstly, it ensures your rooflight complies with building regulations by making sure the glass line is at least 150mm above your finished roof. Secondly it determines the angle at which your rooflight will slope. Thirdly, it is an integral part of the installation and insulation of your rooflight system.

    You can build your own or we can supply our own Ofset pre-built highly insulated upstands/kerbs that ensure your rooflight will comply with building regulations on height and thermal efficiency. Currently, we have a special offer of a free kerb with each Blade purchase (worth up to £325+VAT).

  • At what angle should my new flat roof skylight be installed?

    The minimum for glass rooflights is 3 degrees and up to 20 degrees. Our Ofset rooflight kerbs/upstands are set at 5 degrees. Ideally you want the roof window to have a reasonable ‘fall’ which will allow the ‘easy clean’ coating to perform correctly and prevent water from ponding on the rooflight glass which will leave unsightly drying marks.

still need help? get in touch

    How we handle your data

    Details which you provide here will not be shared with anyone outside of Ofset and will be kept in a safe and secure location. You may request your personal data to be removed at any time.

    We may obtain data from carefully selected third parties, including our clients. For more information read our privacy policy.