Soundproofing existing double glazed windows

Home Retrofit
1

So we have a new build which is 3 years old and has new double glazed windows with trickel vents.

We get a bit of noise from the main road which is about 20m away, but there is about to be 1500 houses built on the other side of it and we think we need to increase the soundproofing on that side of the house. Considered secondary glazing, but I just wondered if anyone had any other ideas? I’d really not rather rip out a practuclaly new double glazed window and replace it, unless anyone knows of any good solutions?
Thanks…

2

As usual, I need to answer with some questions.

Is there adequate ventilation without the trickle vents at the front of the house,

How deep are the window reveals from inside wall to glass?

Perhaps more surprisingly, what type of floor and flooring do you have?

3

Here is something for you to ponder regarding sound waves. You will see that the sound will travel between buildings and defract around corners, so you may need to soundproof more than just the front of your house.

https://www.docbrown.info/ephysics/wavesound-2.htm

5

That is a good initial strategy but whether is is advisable or practicable depends on the answers to

100mm from inner pane to secondary glazing gives optimal sound deadening, particularly if the resultant void is lined with an acoustic material.

If the trickle vents are of the permanently open type condensation could form in the void. They would need to be sealed first.

Have you considered that the fitting could be cr@p, otherwise known as “normal workmanship”? When I removed the trim from my windows not one was properly sealed. I don’t mean to Passivhaus airtightness standard, I mean that I could see through gaps.