Glass Options for Secondary Glazing
Clearview secondary glazing is available with a range of glass options, including toughened, laminated and a choice of obscure finishes. There are choices for thermal, security, acoustic and privacy. Our standard option is 4mm toughened glass, giving enhanced safety and security – and, of course, meeting Building Regulations.
Given the range of glass choice it is understandably a confusing area as to which is the right glass for you. It is also very common for the glass to be considered as critical to the performance, whilst it is important it may not be as significant as you may think. You may end up paying more than you need or be put off purchasing when comparing prices without a full grasp of the facts.
At Clearview, we want you to get the best advice for your specific and individual needs maximising the best performance within an affordable budget.
The number one insulation performance enhancement is simply installing Clearview Secondary Glazing, the glass is then just fine tuning to optimise the final benefit. to get the best outcome, we recommend:
- For sound proofing: maximise the glass to glass air-gap, if you can achieve 100mm or greater, 150mm to 200mm is the best. Then subject to your individual sensitivity to the noise problem and budget, choose a thicker glass. If your window design is such that a reasonable gap is not possible, then a thicker or acoustic glass can offset some of this distance limitation. If you compromise the air-gap you will compromise performance.
- For Thermal Insulation: The air-gap is less critical and we recommend 50mm to 80mm as a reasonable distance. Glass thickness is also far less important for thermal insulation and will do little to keep more heat in or cold out. Using a Low-E (low emissivity glass) gan offer a 5% to 10% enhancement over standard glass but is affected by the condition of the primary window.
- Condensation: following the above thermal principle is the same for tackling condensation, whilst secondary glazing cannot guarantee complete eradication of the problem, it does have a very good track record of significantly reducing the problem and enabling a far more effective management option.
- Security: Both toughened and laminated glass are very good security enhancements, laminates in particular , just by secondary glazing being installed, would be intruders are often put off attempting a break-in as they see a second layer of defence and a further obstacle to tackle, they usually move on to a less challenging window.
4mm Toughened This is our entry level product, a good starter for general use. it can offer around a 50% + enhancement in thermal insulation and with the right air-gap 45dB sound reduction, If your primary window is assumed to be 4mm or you have standard double glazing, we recommend trying to mix glass thickness. 4mm toughened glass 2-4 times stronger than ordinary glass (float/annealed glass) of the same thickness. This safety glass is a minimum requirement where building regulations demand health and safety considerations, including the distance from floor and doors.
6mm Toughened this is 50% more material than the 4mm option. it can offer around a 50% + enhancement in thermal insulation and provides excellent sound reduction performance, with the right air-gap 49dB + . 2-4 times stronger than ordinary glass (float/annealed glass) of the same thickness, providing enhanced, security and health & safety
Obscure Toughened Privacy textured glass, e.g. bathroom windows, available in 4mm and 6mm toughened thicknesses, offering the same performance values as detailed above, see below for design options.
Satin Toughened Frosted effect Privacy glass providing a higher degree of obscurity to textured glass. available in 4mm or 6mm toughened thicknesses. Providing the same performance values as the above 4mm & 6mm options.
Low E (emissivity) toughened Glass (widely known as Pilkington K glass) This is a thermal performance enhancing coating applied to the glass. The coating is an invisible, proven technology capable of increasing the insulation performance of the glass by 65% up to 10% more than a non-coated option, this is equivalent to a mid ranged double glazed sealed unit with a certificated U-value of 1.868 W/m2K With special thin-film metallic or oxide coating allowing short-wavelength solar energy to be transmitted into a building, but preventing long-wavelength energy of the heating systems within a building from escaping; so conserving heat. Available in 4mm, 6mm toughened glass and 6.4mm Laminated glass offering the same strength, safety, acoustic and security performance as their equivalent non-coated versions.
6.4mm Clear Laminate 2 sheets of 3mm plate glass with a sheet of 0.4mm transparent ethylene-vinyl acetate (EVA) between. Moulded together under heat and pressure. The glass will crack without shattering. Also known as shatterproof glass.This thickness is considered a Class B safety glass (2B2). Enhanced sound proofing properties, equivalent or marginally better then a 6mm version.
6.8mm Clear Laminate 2 sheets of 3mm plate glass with a sheet of 0.8mm transparent ethylene-vinyl acetate (EVA) between. Moulded together under heat and pressure. The glass will crack without shattering. Also known as shatterproof glass.This thickness is considered to be a Class A safety glass. Enhanced sound proofing properties, equivalent or marginally better then a 6mm or 6.4mm versions.
6.8mm Stadip Silence Acoustic Specially developed acoustic glass comprises of a PolyVinyl Butyral (PVB) interlayer which acts as a dampening core to prevent sound frequencies from vibrating from one pane of glass to the other. This absorbs and weakens sound energy, helping to act as a barrier to noise. This plastic interlayer also has the additional safety and security properties of laminated glass. This thickness is considered a Class A safety glass (1B1). Stadip Silence acoustic glass offers optimum sound reduction performance approx 51 dB to 53 dB is possible. However, it is a premium product and priced accordingly.
Please note it is air-gap between primary and secondary glass which is the most important factor in sound reduction. If 100mm+ is available and where possible of 150mm-200mm, significant sound proofing performance can be achieved using a 6mm or standard laminated glass without the added expense of an acoustic version, so if budget is an issue, don’t be persuaded to consider a lower cost system just to secure an acoustic glass. obviously where a larger gap is not possible the acoustic glass will assist.
Other glass options available on request:
In The Forte Range:
8.8mm Laminate / 8.8mm Low-E Laminate / 8.8mm Acoustic.