Can I replace a window in a flat?

[Daisyinchains]

Has anyone had a window in their (leasehold) flat replaced? How much did it cost and was it a hassle?

I live in a small block of flats and the double glazed window in my bedroom is letting in all the noise from the road outside (the other windows are totally fine). It's been gradually getting worse over time. I may as well be sleeping on the street.

I've had the seal replaced and the window mechanism tightened so it closes tighter, but it's not really made much difference. I just can't sleep at all and I'm losing my mind. I suspect there are bigger issues and will need the whole window replaced as the building is 15 years old.

Flat owner here, and a director of the management company.
Look at your Lease, it should explain who is responsible for replacing windows . Then contact the Managing Agents. In our block you can replace but they need to be the same appearance as the existing ones. We managed to replace the single glazing with double glazing. In a friend's flat the Leaseholder had to organise replacement windows and it was really expensive.
There is another block where we looked at purchasing a flat and we were put off it as replacing the windows was a free for all and when we went past a year or so ago it was a real hotch potch.
I think we paid about £3.5K for 4 windows and 2 sets of patio doors about 5 years ago. Local specialist company.

Op I don't know but we have a similar window problem I hope someone can answer what we need for make it completely sealed from the road

Could you get the glass replaced? We had a couple of blown double glazing units and I found a brilliant guy locally who replaced the glass in the exact same style. They now look brand new and are as god as the new ones we had put in our extension.

Thanks @Daisymay2 that's really helpful.

The lease just says it's the leaseholders responsibility to maintain windows but we have to get permission from the freeholder before doing anything major involving external walls or windows. I've been reading we'd have to hire scaffolding and get some sort of works permit from the council because the scaffolding would need to go up in a pedestrian area (we live on a high street). Sounds like so much hassle...

I would approach the Managing Agent, the ones you pay the service charge. They might have a plan to replace the windows or have a company who have done work.
If you need to get one replaced, look at Which Trusted Traders or get recommendations. You might, with a bit of luck,

sorry, you might be able to find someone who can do it from the inside or use a cherry picker .

Lots of windows can be fitted internally with no need for scaffolding. Worth phoning a few places to discuss your options

You need to contact your freeholder/managing agent and get permission. I paid a £200 that probably vary. Not sure you need a scaffolding...might be wrong.

Window fitters will not proceed until you produce a letter from freeholder agreeing to this.