Was the old unit DG and did you have the same problem? Depending on that, either go back to your installer and complain or you were expecting a better result than the DG can give in which case as said secondary glazing is the answer.
I may look in attic too as DG window sits just under the wide soffit. I dont think there is anything above the soffit except the attic! We been in house (Bungalow) 4 weeks and this noise really annoys me. I guess i will have to peel off the plastic strips around the windows too to check if expanding foam etc has been used. I think the fact that the window sits directly under the soffit may be an issue in itself. If it is, what can i do?
What about the issue with possible noise coming from the void above the window? Best way to insulate against noise? it is in the attic. Just above sofits.
Perhaps your new glass unit is thinner than the previous one? As unpleasant as it is undoing new work, I'd run a Stanley blade through the silicone holding the trims and prise them off gently so you can put them back, fill any void with expanding foam, put trims back on and reseal around window. There should be a lintel above the window, wouldn't have thought the soffits location would contribute to that much noise, do you have rockwool insulation in the loft space?
I have thought of doing that. Prob will. Yes, attic has insulation. Not looked closely yet where window is to see what lies above it.
Well, i cut and took off fascia today and guttering etc above the bedroom window. There is about 14" of Sofit between fascia and where window start. Whole length of window like this. Just an empty 'void'. I can see how this would easily accentuate any noise. I used expanding frame foam today to fill the gaps and make a nice cushion against the fascia board. There is a gap above where the attic is which remains 'open' for ventilation. Will see if this makes a difference!
Might be able to fit a piece of ply were gap is in attic, still keeping some ventilation, but foaming below for complete sound reduction.
I replaced my windows recently and looked into the noise issues carefully. You are stuck with the windows you have, the only issues I can think of with them is if (a) the windows don't shut/seal properly (b) you have a "trickle vent". if you have (b) that's a big no no, a hole right through the frame letting in loads of noise. Get your foam gun out if so, and fill it in! I know from experience of living next to the A3, that some noise will go through the best windows and there's little that can be done. What you're doing by filling in the voids is about all you can do. Windows are undersized to the hole by about 10mm or so, so there will be a gap albeit pretty small on all 4 sides. Exposing these gaps and filling with low expansion foam may well help.
No trickle vent fitted. Seemed a 'little' better last night. Next job is take plastic strips off of inside of window as i took one slightly off the outside yesterday but the window overlaps the 'outer' wall. Is it easy to adjust the window openers to see if they are as tight as can be?
What it might be worth trying, which is what I did, is make a secondary "shield" window using twinwall 6mm polycarbonate sheeting or similar. You cut it to fit snug in the reveal against the window and temporarily fix it in place each night somehow. Thus it provides another sheet of plastic for the noise to get through and there's air in between it and the window, and in the twinwall sheet as well. Can only help and wouldn't be very expensive. Triple glazing on the cheap!!