Pitchglaze In Plane Fixed Roof Window

Glass can become slippery when wet and common sense should be applied when specifying this material for walk-on applications such as walk-on rooflights. This is of particular importance when the glass is being installed where the public can access it. In a private dwelling it is less likely that the glass will be used if it is raining, but the same cannot be said for commercial and public applications. Applying an anti-slip glass surface finish to glass that is designed for walk-on applications should always be considered; the same finish can also provide some obscurity to the glass if required. A screen printed frit that includes particles within the ink to create a rough texture can be applied to the glass in a variety of patterns, which will significantly increase the slip resistance of the glass. Alternatively the surface of the glass can be sandblasted which will result in more diffused light and improved obscurity. Slip resistance is measured using mean Pendulum Test Values (PTV); the higher the figure the better the slip resistance. A PTV of 0-24 has a high slip risk, 25-35 has a moderate slip risk and 36+ has a low slip risk. The test is carried out in wet and dry conditions and the lowest figure is obtained when wet. Generally sandblasted glass achieves a PTV of 50 and fritted glass achieves a PTV of 60, providing better slip resistance than the sandblasted. However both are well above the threshold of 36 to be categorised as having a low slip potential.

We all have a predilection to well lit, inviting spaces, so increasing the use of glazing products in the built environment is almost always an efficient way of improving an internal space. But what is the difference between these glazing products: is a skylight window different to a rooflight, or a rooflight different to a roof window? There are plenty of benefits to bringing natural light into a building – from boosting occupants’ wellbeing, through to saving energy. Roof windows, rooflights and skylights are all popular options for letting the sunshine in and improving the look and feel of an internal area, but what’s the difference between these products – and how do you know which one is the right choice for your project? Is it A Roof Window, Rooflight or Skylight? It’s fair to say that the terminology used to describe glazed units in roofs can be a bit tricky to understand – so don’t worry if you’re not sure what the difference is between roof windows, rooflights and skylights. It’s also fairly common to see terminology being used inconsistently, which increases confusion. Let’s take a look at each product type to help clear things up. What are roof windows? These are probably the easiest to define because they are covered under BS EN 14351-1:2010. The standard stipulates that roof windows must be installed in the same orientation and ‘in plane’ with the surrounding roof, typically at a minimum 15° pitch. Once installed, they should be weatherproofed using a skirt or flashing. Roof windows must be UKCA marked before they can be sold and manufacturers are expected to provide a declaration of performance (DOP) to advise specifiers how each unit performs under test conditions. Typically, this will cover things such as tests to simulate prolonged and heavy rainfall, how the roof window withstands increased air pressure, glass deflection and monitoring any air leakage to ensure the product does not create drafts or allow in damp. Roof windows are usually only available in standardised shapes and sizes and are typically smaller than rooflights. However, new products have recently become available using improved glass specifications that allow much larger sizes to be manufactured. Rooflights.com stocks the sleek Glazing Vision Pitchglaze Roof Window which is a fixed roof window that can be installed in roof pitches between 15° and 60°, it offers completely frameless internal views. What Are Rooflights? ‘Rooflight’ is a generic term that can sometimes mean different things. Typically, the term refers to a glazed unit installed on a flat roof, or where installed on a pitched roof it is likely to be fitted ‘out of plane’ with the level of the tiling. Rooflights are commonly installed using an upstand or kerb system to support the actual product and act as a surface for any weathering to be fixed to; on flat roof systems the upstand will provide enough height to ensure that the rooflight remains watertight. The rooflight quite often has to be installed at a certain height to maintain any guarantees supplied by suppliers of waterproofing systems. Rooflights come in a huge range of designs and styles, and as well as providing natural light, they’re also often used for ventilation or access. Options include frameless fixed rooflights, which offer a minimal appearance and sky-only views, such as the Glazing Vision Fixed Flushglaze Rooflight. Other rooflight options include hinged rooflights, sliding rooflights, fire rated and AOV rooflights, and box rooflights, which are often used to provide access to roof terraces. What Are Skylights? Skylight is another generic term, and it’s often used by manufacturers for a variety of different products, ranging from small-scale domestic units installed on traditional pitched roofs to larger bespoke glazed units designed to be installed on flat roofs or terraces. Skylight is a generic term that can sometimes confuse consumers, since the products it refers to may differ quite drastically in terms of size, scale, function and application. In some cases, the use of the term skylight is actually completely inaccurate as far as the Building Regulations are concerned, where more appropriate terms should be used that are recognised in British Standards. Specification Considerations: Advantages and Disadvantages In most cases, choosing between a roof window or rooflight (or skylight) is easy: if it’s going on a pitched roof, you’ll want a roof window; and it will be rooflights for flat roofs. However, there are other issues to think about. Off-the-shelf design vs customised Roof windows are very popular and widely used having been adopted by many major national house builders. They are robust, reliable and offer value for money. The advantage of standardised sizes and specifications means that they are usually available to buy ‘off the shelf’. The disadvantage of this is their flexibility – particularly when it comes to scale. If you’re looking for larger sections of glazing on your roof then roof windows presently only offer a limited amount of scope. Rooflights (or skylights) tend to be offered in a much wider range of shapes, sizes, specification and function. However, they tend to be more expensive than roof windows due to their bespoke nature, and since they are usually built to order, there will be a lead time of several weeks. External appearance Rooflights and roof windows are both available in frameless designs, which means you only see glass when looking up at the unit from indoors. However, these products look quite different from the outside. Since roof windows are designed to sit flush with the plane of the roof, they offer aesthetically pleasing clean lines, which rooflights sometimes struggle to match. That said, rooflight manufacturers are beginning to respond to client demands for the flexibility and scale of a rooflight, but with a low external profile that can be installed flush with roof tiling lines in the same way that a roof window can.

Glass, when installed overhead in rooflights and skylights must be ‘safety glass’, which is often referred to as Toughened or Tempered Glass. Toughened glass is 4-5 times stronger than standard annealed glass of the same thickness; it’s a key safety feature in the specification of domestic rooflights and skylights as it is designed to crumble into granular type fragments when broken, rather than shatter into jagged shards like annealed glass. This significantly helps to reduce the risk of injury. How is Toughened Glass Made? Toughened glass is produced by passing annealed glass through a furnace, heating it to above 600°C before being rapidly cooled. A balance of high compressive stresses at the surface and tensile stresses in the centre of the glass increase its strength. When the glass breaks it is the release of these stresses that causes it to break into small pieces – usually accompanied by a large bang as the energy is released. Toughened (tempered) glass is a preferred option for rooflights but there can be disadvantages. Firstly, glass needs to be cut to the required size and shape before it’s treated. Secondly, toughened glass has been known to spontaneously fracture for no apparent reason with the most likely culprit being Nickel Sulphide (NiS) inclusions within the glass. NiS is a chemical contaminant that can manifest itself during the toughening process; as it gradually changes state over time it can cause the glass to fracture. This can happen at any time, from a few weeks to many years or not at all. One of the most effective ways of combating this is to subject the glass to 'Heat Soak Testing'. What is Heat Soak Testing? Heat soak testing is carried out during the manufacture of the glass and will filter out around 95% of problem units. This involves heating tempered glass up to 290 degrees Celsius and holding it at that temperature over a controlled period of time. This process accelerates any NiS inclusions reverting back to their Beta state, which could result in glass failure. Whilst more expensive, this method of testing identifies any issues with toughened glass before it’s used in manufacture. This is of particular importance when specifying larger structural rooflights or those used for walk on applications, where heat soak testing is a requirement of Building Regulation. What is Laminated Glass? Annealed laminated glass can also be specified for some rooflight applications, to conform to BS5516 Part 2 – pane sizes above 3m2 and between 5mts and 13mts from floor level should be laminated. Laminated glass is produced by combining two or more sheets of float glass with one or more interlayers. Glass integrity is maintained from a ‘laminated’ interlayer, commonly PolyVinylButyl (PVB), which is processed with heat and pressure under factory conditions. Should any damage occur, the interlayer holds any fragments together preventing them from falling, reducing injury risk even further. Combinations Toughened Laminated or HST Toughened Laminated are also common glass specifications, particularly when the glass has to perform a structural function, as in a glass floor or structural glass fins.

Rooflights are versatile construction products, available in pitched rooflight and flat rooflight variations to provide daylighting solutions in a whole host of roof constructions. They can flood homes and apartments with natural light while contributing to the energy efficiency requirements of Part L, providing ventilation and combatting overheating, and having stunning aesthetics – possibly through visual effects. To do some or all these things means specifying glass in the rooflights accordingly. Maybe a pitched rooflight requires solar control, or a flat rooflight needs to be safe to walk on. To meet the different performance requirements demanded by modern construction projects requires more than just standard glass, and this blog post gives an overview of some of the available variations. What Heat-treated Glass Types are used in Rooflights? Annealed glass is free of internal stresses caused by other heat treatments, but it breaks easily into large shards and is considered unsafe for certain uses in buildings. Annealed glass can be used as safety glass when it is incorporated into a laminated pane but the risk of thermal heat stress should be considered. This can be caused by partial shading from external objects or close-fitting blinds on the inside of the glazing. Thermal stress in glass can lead to thermal cracking of the glass. Toughened glass is a product that breaks into smaller pieces or granules, and is therefore considered a safety glass. It is produced by rapidly cooling annealed glass to make the surface of the glass more resistant to tensile failure. This tempering makes toughened glass some five to six times stronger than annealed glass, and more resistant to blunt impact. Heat-strengthened glass is tempered in a similar way but cooled more slowly. It is only around three times as strong as annealed glass (or half as strong as toughened glass). If it breaks, it exhibits similar behaviour to annealed glass. It cannot be used as safety glass on its own but does lend itself to use in a laminated pane. Bonding two panes of glass with an interlayer produces laminated glass, a catch-all term to cover the various combinations of glass and interlayer. Because the interlayer holds the glass even when broken, laminated glass is typically used where security is a priority, as well as in safety applications like overhead and walk-on glazing. Another advantage of laminated glass is that it offers an acoustic performance benefit. Read more about the differences between toughened and laminated glass. Considering the issue of safety further, most rooflights are designed to be non-fragile, and to provide a level of non-fragility equivalent to the surrounding roof. They should not be taken as being safe to walk on, instead being designed typically to prevent people or objects falling through in the event of an accident on the roof – unless specifically designed for floor loadings. For overhead glazing the first choice for the inner pane should always be a laminated glass to ensure it is considered non-fragile and to protect building occupants below from falling glass shards if a pane should ever fail. What Other Specification Options are Available for Rooflight Glazing? As part of contributing to the thermal efficiency of the building fabric, the glass in rooflights can be treated to provide solar control and reflectivity. It can also receive a low emissivity (low-e) coating to allow short-wave radiation from the sun into the building while restricting the loss of long-wave radiation back out of the building. However, these options are not different types of glass, they are treatments and coatings applied to the chosen glass. A development that does fall into the category of a different ‘glass type’ is heated glass. For applications where the moisture load/humidity is particularly high (such as swimming pools), heated glass raises the surface temperature of the rooflight, reducing the potential volume of condensation occurring on it. Other uses for heated glass include evaporating rainwater or dew and melting ice and snow. When wet, however, walk-on rooflights are slippery, and anti-slip finishes provide an antidote to the inherent risks. Sandblasting the surface of rooflight glass is one way to increase slip resistance, while also adding obscurity and creating light diffusion. More commonly, ceramic frit is used. Modern techniques screen-print the frit onto annealed glass before tempering it to achieve the desired performance. Fired permanently into the surface of the glass, the frit provides the slip resistance. Textured glasses offering slip resistance are also available. Ceramic frit and screen-printing techniques can be used for decorative effect as well, especially in conjunction with enamelled glass. Ceramic paint is applied to the glass before toughening, and the toughening process fires the paint into the surface of the glass. Using enamelled glass in conjunction with LED lights can create striking patterns of colour and light in the glass. These decorative uses of glass, and other situations where clarity is particularly desirable, lend themselves to the use of low-iron glass. The silica used in the initial glass production is selected for its low iron content removing the natural green-blue colouring that occurs otherwise. Other visual effects can be achieved using switchable or electrochromic glass. Switchable glass turns from opaque to clear when a current is passed through it, while electrochromic glass darkens to provide solar control when a current is passed through it. Are There Low Maintenance Glazing Options for Rooflights? As part of the specification process for rooflights, operational treatments can be requested that reduce the maintenance burden for homeowners. Suited to glazing installed at a 30-degree pitch or greater, self-cleaning glass features a coating that organically breaks down dirt, leaving it ready to be washed away during the next rain shower. As self-cleaning glass is not compatible with silicone, an alternative is the proprietary glass treatment, Enduroshield, which acts like a ‘non-stick’ frying pan coating. Whichever option is chosen, periodic cleaning by building users is still required and recommended.

Rooflights featuring toughened or laminated glass, or both, have different applications in construction projects. Broadly, toughened glass provides superior strength, while laminated glass offers better security as it is designed to remain intact when broken. For rooflights designed to take foot traffic, our view is that the outer pane should be toughened, heat soak tested and laminated. When ‘basic’ float glass is annealed, it produces glass that is free of internal stresses caused by other heat treatments. However, annealed glass breaks easily into large shards. That is considered unsafe for certain uses in buildings, and toughened glass and laminated glass are both ways in which float glass can be treated to improve safety. What is Toughened Glass? For a product that breaks into much smaller pieces or granules, and is therefore suitable for safety applications (including overhead rooflights on pitched or flat roofs), toughened glass must be used. Annealed glass is heated, then rapidly cooled to make the surface of the glass more resistant to tensile failure. Glass cracks due to failure at the surface. The tempering balances compression at the surface with tension in the centre of the pane, making toughened glass some four or five times stronger than annealed glass, and more resistant to blunt impact. Toughened glass cannot be cut or worked, so all processing has to be carried out prior to toughening. As it is resistant to large and variable changes in temperature, toughened glass is suited to spandrel panels where there is a risk of thermal cracking. It also offers good resistance to wind pressure on tall buildings and, in particular, corners. Something to consider is that the heating and cooling cycle required to produce toughened glass causes optical distortion in the surface. When annealed glass is heated again, it sags slightly between the rollers carrying the glass through the furnace; the subsequent cooling results in ripples, or ‘roller wave distortion’. Roller wave mainly shows up in the reflections of the glass, and eliminating such distortion entirely is impossible. It can only be reduced, mainly by design and control of the manufacturing process and the way in which the glass is heated and cooled, and moved through that sequence. Thicker panes of glass generally remain flatter, while larger panes typically show up more distortion. Why Does Toughened Glass Benefit From Heat Soak Testing? Spontaneous fracture is known to occur in toughened glass, due to the stabilising of nickel sulphide (NiS) present in the material. The risk of breakage is relatively low, but unpredictable – it could occur within weeks or years of manufacture, if at all. Heat soaking filters out about 95% of potential problem units. Toughened glass is heated to 290°C and held at that temperature, accelerating the process of any nickel sulphide inclusions reverting to their ‘beta state’ and causing failure. Inevitably, heat soaking adds cost but improves product quality and consistency, reducing the use of potentially faulty glass in the manufacture of rooflight products. The use of heat soak testing is not regulated, but reputable manufacturers are more likely to undertake it than not – especially for large structural rooflights or in walk-on applications.  Heat soak testing is not a guarantee that glass will remain failure-free, so manufacturers will not accept any claims for spontaneous failure, but it does reduce the instances of potentially faulty glass entering the supply chain. What is Laminated Glass? Bonding two panes of glass with an interlayer produces laminated glass, a catch-all term to cover the various combinations of glass and interlayer. Because the interlayer holds the glass even when broken, laminated glass is typically used where security is a priority, as well as in safety applications like overhead and walk-on glazing. By far the most common interlayer is polyvinyl butyral (PVB). Ethylene-vinyl acetate (EVA) is also popular; other interlayer materials include cast-in resins, polyurethanes and ionoplast materials. Where transparent plastic materials, like PVB and EVA, are used as the interlayer, the bond is achieved through the application of heat and pressure in a controlled environment; however, plastic interlayers make cutting difficult. Resin is a more versatile adhesive and allows for the production of curved laminates. Demanding performance specifications are driving the development of interlayer solutions, some of which fail to offer adequate levels of adhesion. Manufacturers of proprietary interlayers, such as ionomer-based ionoplast, claim improved performance for especially demanding applications. PVB, however, remains the popular option. 

Rooflights are a great way to bring natural light into your home and creating a more open feel. At Rooflight.com, we pride ourselves on stocking high quality rooflights that look great and last. If you want to keep them performing at their best then you need to regularly maintain them. Here are some simple tips to help you maintain your rooflight in excellent condition. 1) Clean your rooflight regularly Dust, dirt, and debris can build up on rooflights, which can reduce the amount of light they let in. This build up can make your rooflight appear dull and block a large amount of natural daylight, which will effect both energy efficiency and brightness. Over time, accumulated dirt can cause small abrasions on the glass, such as small scratches form fine debris like sand or grit, which may lead to more frequent cleaning requirements. If you want to avoid these abrasions, you need to make sure to use soft cleaning tools and rinse off loose dirt with water before wiping the glass surface. If you want your rooflight to keep looking and functioning at their best the you should clean it every 3-6 months.Safe cleaning methods: You should avoid harsh chemicals such as ammonia based cleaners or bleach, as they will damage the glass coating and seals. Instead, you should use mild soap, water, and a soft cloth to protect the glass and frame.Safety first: If your rooflight is accessible from the inside, you should clean it safely form within. For external cleaning, you should use a sturdy ladder, wear non-slip shoes and always avoid learning too far. You should always make sure that someone is nearby for assistance if needed. 2) Inspect for damage You should be regularly inspecting your rooflight for signs of damage, such as cracks, corrosions or sealant issues. By doing this it can prevent minor problems form becoming major repairs.Glass check: You need to look for three common types of cracks:1) Stress cracks: These are thin, hairline cracks that usually run across the glass in a straight line. They are often caused by rapid temperature changes, particularly when the weather quickly shifts from hot to cold, and they appear without any external impact.2) Impact cracks: These typically look like a starburst like crack that radiate from a central point of impact. They result from a direct force such as something hitting the glass, and show multiple lines spreading outwards from where the impact occurred.3) Edge cracks: These are cracks that appear along the edges of the glass, which is often the result of improper installation, frame pressure, or shifting of the rooflight. They usually start at the border and can extend inward, creating a jagged or uneven appearance.You should inspect particularly near edges or corners, as these areas are most susceptible to damage. If you notice any issues, you need to address them as quick as possible to try and avoid leaks.Frame and Sealant: You need to inspect the frame carefully for signs of corrosion, warping, or rust. Look closely at the joints and corners, as these areas are prone to moisture buildup. Check the sealant for any cracks, gas, or peeling, which could compromise the watertight seal. You should be looking for discoloration, bubbling or any parts where the sealant has pulled away from the frame. If you find any issues, you need to take action to either reseal or repair immediately to prevent leaks and additional damage. 3) Ensure proper drainage Proper draining is the key to preventing water damage, especially for rooflights on flat roofs is by having effective drainage. To ensue efficient drainage, you should:Clear gutters and drains: You should be keeping your gutters and drainage areas free from leaves and debris. To carry out the maintenance safely, ensure you are using a sturdy ladder and gloves for protection, you should also use tools like a gutter scoop that can help you to remove leaves and dirt. After the cleaning is done, you should use a garden hose to flush out any remaining buildup to ensure proper water flow.Prevent water pooling: Water pooling refers to standing water that accumulates on the roof when it is unable to drain properly. This can lead to structural damage and leaks. Rooflights.com products integrate seamlessly with your roofs drainage system, but regular maintenance is important to ensure gutters and drainage paths stay clear. You need to check for blockages or improper slopes that might prevent water from draining efficiently, particularly after heavy rainfall. 4) Monitor Condensation Excessive condensation can be a indicator of poor ventilation or a broken seal. To address this issue, consider the following steps:Ventilation Solutions: Good ventilation can help reduce condensation. To be able to improve your ventilation you can use trickle vents, this is where a small amount of air circulates even when the rooflight is closed, or you can just consider rooflights with integrated ventilation systems. Rooflights.com offers options to improve airflow, such as models with built-in vents or electronic opening mechanisms, this can help maintain the moisture levels in your space.Glazing Issues: If you notice condensation between the glass panes as a cloudy or foggy appearance that doesn't wipe away from either side of the glass then this indicates a broken seal and a loss of insulating gas. If you see this, it may indicate that it time to replace the glazing to maintain energy efficiency. Why choose Rooflights.com? At Rooflights.com, we offer Glazing Vision rooflights that are designed to be easily maintained and built to withstand the elements. By carrying out regular cleaning and inspections it will ensure your rooflight will continue to fill your space with natural light whilst staying energy efficient and leak free.