hi all-i am soon to have all new windows and doors fitted by a guy who does this for a living but is doing it for me out of hours so to speak!-i am applying for the fensa cert myself however i have read that the most important aspect of new windows is the quality of the installation,all the windows and doors are upvc made by kommerling and i am led to believe they are one of the top makes of windows available-i just wonder what the fitter could possibly do wrong that i should look out for-ps the importance of sound proofing is high as a busy road runs along the back of my house-any info would be greatly appreciated!