How Glass is Made

A to Z Glazing faq
  • How do I decide what type of glass to use? When buying glass you should tell your supplier the exact position of installation, the use and any known history, for example has it been vandalised regularly? A good professional organisation will be able to advise you.
  • A replacement is needed for my broken double glazed unit, do I need to contact a FENSA Member? No. FENSA deal with frame & glass replacement, not the glass alone.
  • Can I use self-cleaning glass for my shower screen? There would be no advantage to this because that product is designed for exterior use and needs water plus sunlight to activate the cleaning process.
  • I have a broken down double glazed unit, do I need to replace it with another with up to date U values? No, Document L only applies when the whole window, including the frame is replaced. However, Regulations linked to safety will apply.
  • I would like to put a mirror on the wall which houses a plug socket, will I need to have the socked moved first? No. We are able to measure and make cut outs in the mirror to enable sockets to still be used. However, the wiring will need to be long enough to allow for the extra spacing.
  • What is 'U-value'? The U-Value is an indication of how good your windows are at keeping heat in. The lower the U-Value the better the thermal performance, expressed as W/M2 (watts per Metre Square Kelvin)
  • Can we open an account for future use? We are happy to open Accounts for new Commercial Customers, subject to the normal checks. Unfortunately, we do not open accounts for the domestic market, with the exception of 'Landlord's'.
  • Will installing Double Glazing instead of the single glazing I have at present cure condensation problems inside my windows? Condensation is a ventilation issue and will not be cured purely by installing double glazing. However, it will be reduced. Heating & ventilation play a large part.
  • Can I obtain samples of products? Yes. We can supply samples of all products, Mirrors - Painted Panels - Units etc. However Non-Account customers are charged a small Fee of £8.25+ VAT per sample to cover our costs, which are refundable against any order placed. Make your request to or use our contact page.
  • Where can I find a glass supplier near me? We cover a wide area of Kent and London. Contact us to find out if we supply and fit glass in your area. Make your request to or use our contact page.
  • Why does my double glazing have moisture inside and look fogged up? Double glazing can sometimes fail and become misty, cloudy or blown. Double glazing is held together by a seal around the edge that prevents moisture getting in. Double glazed windows normally contain special gases such as Argon, which escapes when there is a broken or faulty seal. The broken seal allows regular air and moisture into the panes of glass, causing condensation to form. The condensation can appear as water droplets or streaks within the glazing. The condensation forms when there is a difference in temperature either side of the pane, causing the moisture to condense on the double glazing and form the water droplets in the glazing. It is important to fix faulty double glazing as this can cause damage to your property by rotting your window frame or a build-up of black mould. Condensation in double glazing becomes unsightly and causes a fogged and misty view. In winter, the broken double glazing may let heat out of your property costing you money.
  • How do I know if my double glazing is blown? Common signs that your double glazing has blown is water droplets appearing within the window panes. You may also feel a draught or see visible damage to the panes such as cracks or chips. A blown double glazing window may cause water to leak through the frame causing rot and mould to appear.
  • Why are my double pane windows cloudy? Double pane windows become cloudy if the seal that protects them is broken. The seal that runs around the edge of the glass is used to keep a special gas locked inside. The gas, typically Argon, will leak out and be replaced with normal air which contains moisture. The difference in air temperature from outside to inside the building will cause condensation to form, which results in a cloudy mist on the inside of the window pane.

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