If you are in the process of deciding whether to have new windows or double glazing, the following questions may help in your choice of product and company.
Quality and Performance
First, look for ISO 9000 accreditation (formerly BS 5750). This shows the company's quality procedures have been independently assessed. Then check that the actual window units conform to the British Standard for the material that the frame is made from. This will indicate they have passed tests for weather tightness and mechanical performance. e.g. BS 7412 or 7413 (PVC); BS 644 (Timber); BS 4873 (Aluminum or BS 6510 (Steel).
Multi chamber construction, full metal reinforcement, impact modified PVC and full ventilation. Ask to see the specification against which the windows are manufactured.
Again, look for the company's commitment to producing a quality product
through their compliance with British Standards. You may also feel more
confident through recommendations from people you know.
Security
Internal beading is generally more difficult to remove from the outside. The use of glazing clips or double sided security tape (or even both!) will also make it harder to remove the glass.
It can be quite easy, but laminated glass will stop most burglars.
If you have any doubts about the contract or the product purchased contact
the Trading Standards Department of your local council.