Does anyone have experience with acoustic double glazing/ vacuum glazing installed in old timber window frames?

[PinkCamelias]

We bought a house, which we are now renovating, on a fairly busy street with trams and we need soundproofing. The current windows, over 100 years old, are single glazed. The facade is listed and if we replace the windows, they would have to be identical and also made of wood. I have not asked for quotes yet, but I know it will be very expensive. My builder has also pointed out that all the woodwork around the windows would be affected while replacing, so I have to take additional work and cost into account.

The windows are simple, with no special decorative elements as far as shape is concerned, but they have pretty, slender frames and brass “cremone” closing mechanism, so from the aesthetic point of view I’d very much like to keep them and replace the glass only. The frames need to be repaired if we fit new glazing in. They are overall in an ok condition and the builder confirmed that there is no rot. The windows are quite big, so the glass area is significant. This is a French casement window type, opening to the inside, with one wing slotting into the other while closing (no vertical bar in the middle). There is a limit to how much insulated they can be (it’s not possible to add weatherstripping for instance, there is no space for it).

I have a quote for Fineo acoustic glass and although the price is high, it is acceptable because we’re in Belgium where it’s produced so the price is lower than in the UK, and we can later get some subsidies for renovation. It seems like an ideal solution, because the acoustic laminated double glazing will only be ca. 11 mm thick, so will fit into the old frames, while standard double glazing wouldn’t. The expected reduction of noice is 39 dB.

My problem is that I cannot assess how much soundproofing we will get while keeping the old frames. The glass has amazing values, like triple glazing, but will it matter is noise leaks though the frames, as it probably will? Most information I find focuses on the thermal insulation aspects, which is important too, but here the noise is my main issue, especially as one of the front rooms is a bedroom.

Can anyone perhaps offer advice, hopefully from experience?

We had double glazed panels put into old Victorian wooden windows (non acoustic ) and had a ventrolla system installed to get rid of drafts and the sound from the road was reduced quite a lot just by that. I would assume the accoustic glass would be even better. Thick, lined curtains might also help.

Thank you for your reply! I've not heard about Ventrolla and googled it now; however it seems to be uk only. Great to hear that in your experience there is an improvement!

Secondary glazing is much better for noise reduction. I don't know the performance of a sealed 11mm unit but I fear it will not be very good.

It works better if the glass is thick, and the inner and outer panes are different thicknesses (so they have different resonant frequencies).

If you are having sashes made or refurbished, close fitting and rubber seals will prevent air and noise getting in through gaps.

If you are keeping the old window frames they are hopefully well sealed into the wall. New frames are sometimes fitted with clumsy gaps, which need to be sealed with acoustic caulk, and filled with expanding foam, which also prevents draughts and rain penetration.

@PigletJohn Of course you are right about double glazing, the thicker the better. That's why it would be difficult to fit it into my frames without some modifications (adding the slates around the glass to conceal the glass being wider than the cavity). However Fineo is think because it's a vacuum glazing. I found a leaflet in English here: www.energlaze.co.uk/wp-content/uploads/2020/02/A4-Fineo-Spec-Sheet-2020.pdf You can see that it can be as thin as 8 mm, but my quote is for an acoustic version with laminate glass, which makes it a bit thicker.

So I'm not worried about the glass, but the overall effect in old frames. Not sashes; they seem to be well attached to the wall (and all the gaps will be filled in as well as possible) but they are very thin, so surely they must let vibrations pass through? It is not possible to add rubber seals to this kind of frames. They work on a basis of wood fitting tightly against each other.

There are three elements to consider: (1) lobbying council to reduce the road speed limit from 30 to 20 mph is by far the best noise reduction strategy, (2) soundproofing from window replacements plays on: a large gap between the two panes and having the second pane with soundproofing quality, (3) dressing the room for noise reduction involves thick curtains, carpeting and soft elements on walls. Triple glazed windows can never be a good soundproofing solution because the space between the panes is never big enough to block sound waves. Again, by far the most effective solution is to reduce road noise in the first place which involves road resurfacing and speed reduction, both nearly impossible to get since they are never a priority in the UK (unlike in the NL, Germany, France, Denmark, etc...), because Britons rarely vote for the people whose priority is maintaining great roads.

Would it be possible to have secondary glazing ?