The purpose of this document is to inform and guide customers who are considering renovating hardwood windows for better insulated and more efficient double glazed windows. Part of the quest is to know the UK building rules and L document information, as well as information on what to ask companies and suppliers, so that you get the best deal.
There is a difference of opinion regarding "interior glazing" versus "exterior glazing" as to which is the safest and most energy efficient. Some say that interior glazing is less secure and that exterior glazing is less efficient. But according to experts, while there is evidence of the truth of the two arguments, there is virtually no difference between the two. We propose you to make your choice according to the professionalism of the company and your confidence in their reliability.
However, in many cases finding the right company to replace your hardwood windows with double-glazed windows can be difficult and confusing. Although we can not tell you which company to use, we can give you some tips to choose the one that suits you best.
One thing you need to consider if you have sash windows, you have to remove the entire frame, or put your new windows in the outgoing frame. At the end of the day, it will seem like it will work better if you replace the entire frame, but it will cost more. Installing new windows in the existing frame will cost less, but it will not usually be as effective. So, one way or the other will give the desired result, but one is more efficient and the other costs less.
Another consideration is whether or not to use laminated glass or tempered glass. Both are called "safety" glass because they both have built-in functions to prevent them from breaking. Tempered glass is hard to break, but even if it was broken, it breaks into small sections that do not pose the danger of an ordinary glass. Laminated glass is thicker, and therefore more difficult to break, and will crack instead of breaking. Laminated glass is more expensive than tempered glass, but certainly a good alternative if you prefer.
The British Standard "BS 6262: Part 4: 1994 Code of Practice for Building Glazing" requires that new structures in critical areas must use "safety glass". However, by definition, "new structures" include new buildings and replacement windows. The safety glass must be used if it is a new construction or replacement. But again, both tempered glass and laminated glass are considered "safety glasses". So the choice is always yours.
Finally, the issue of using PVCu versus aluminum for replacement windows is still a concern. But, PVCu offers good insulation and low maintenance. And it is usually the cheapest way to go there. PVCu is available in the wood grain finish so it looks good. Its only drawbacks are its weak structural integrity and its direct sensitivity to the sun. But these are overcome by new technologies and strengthening measures.
Aluminum, on the other hand, offers advantages such as no maintenance, with strong structural sections. But the main disadvantage of aluminum is its poor insulation. It also costs more than PVCu.