DIY Doctor UK DIY Forums

We have a number of windows with one fixed and one opening vent. One of each glass unit is always concave (either fixed or opening unit) with the consequence that at night (no curtains in place) we walk past and see a mirror reflection from the flat units and a multiple reflection (rather like the mirrors in fun fairs) which is just ugly from the concave units. This problem is due to the unit having been sealed together under the wrong conditions in the factory so that it is concave. Has anyone any experience of this poor workmanship and how to get the supplier (English based, Fensa reg) to replace them?

it may be that the glass units are toughened,during the manufacturing process this can happen.Its not uncommon,have them replaced

I'll ask the suppliers but they say they have never seen this problem even though the units are measurably concave so will not accept we need new units. I understand they sometimes put the two pieces of glass together too quickly and it sags but this is usually only larger units. Also if temperature in the factory is not controlled it can also result in concave units. 20yrs ago they used to blow in extra air but now they are argon filled I don't know how they do it. Whilst toughened glass can be more mottley it is the concavity of the units which seems to be the problem here but the supplier, builder and architect all say they have never seen this issue so I am banging my head against a brick wall (or concave unit!). Has anyone succeeded in getting units replaced?

When you drive around London, it is quite common to see concave windows.
This is where the air pressure outside, pushes the glass inwards, to the point where they touch in the middle.
It is fairly normal with older windows.
Modern windows made properly are filled with an inert gas that helps to keep them apart.
The chances are that the company you bought the windows from, bought them in turn from someone else......that is why they are not interested.
You are entitled to buy goods fit for purpose.
If they will not correct or replace them make a claim in the small claims court.

Thanks for your support- it seems the building industry is rather like the medical industry and all cover for each other. I have found the manufacturer who, when I enquired about buying some replacement units, happily told me they just make new argon units now if they come out concave as they are not "equalised units", so no problem in replacement or so it seems. I shall go back to the supplier and demand replacements.