Hi I wonder if you can help, I wish to replace my box sash windows and I have been in contact with four of your registered members with a view to instructing one of them to do the work. The have visited and measured up including giving me marginally similar quotes. I understand box sash windows are installed differently from other windows. I should be grateful if you would advise as to what I should be asking before the windows. Finally when the windows are installed, how do I know that the job has been done properly (ie all the work and materials behind the window). Thanks Obi 07890 521 373