Some advice please would be appreciated. I am in the process of getting double glazing quotes for my victorian house. 13 windows to be replaced and 3 of those will be vertical sliding sash. I have had a very competitive quote from a well known regional firm that have been going for 40 years and advertise on television etc i.e., a respectable outfit. They are a member of Network VEKA. The quote is £6400 and I am happy with that but I have 2 reservations. The first is that the majority of firms who have quoted state that their units are Argon gas sealed. But the company I am thinking of going with has no gas within the unit. They state that the benefit of gas sealing is additional thermal qualities but because we are in the south west of the country, which is very mild, it is not required. If that is the only benefit I am not too worried. My second reservation is the one I am more worried about. I found a website that gave a lot of informative information about double glazing and it stated that the minimum profile you should consider is 60mm and preferably 65 or 70mm. Most of the companies stated they did 65 or 70mm, but the company I am favouring is only 58mm. Should I be concerned?? As I state they are well respected in the south west and belong to VEKA. thanks.