Help Please: New Windows Installed on Old Sealant – Seeking Industry Advice

Hi there! Tell us more about the sealant? Can you upload a photo of it?

Generally it's recommended that all sealant be removed, but sometimes it's here-nor-there in terms of how effective the windows are.

How old were the original windows and what specification were the new ones? Did you look into the thermal performance of the new versus old. This would be a U-value telling you the difference between the old and new in terms of the heatloss at a given cold temperature.

'Acoustic' is meaningless and largely just describes that the glass is thicker or the gap between that glass is wider, but the difference in thermal performance between an 'acoustic' and a standard double-glased window is minimal and only a triple-glased window would offer better performance overall.

Triple glazing is generally recommended for it's better acoustic performance due to the three layers of glass within, rather then the two in standard glazing. It's also thermally more performant, so that would have been the way forward for both requirements, but perhaps triple-glazing was ruled out by the budget?

In regards to the sealant, it's hard to know what's going on there, but in my opinion it may have been cut-back as much as possible and left as it was due to the fact that any further removal off the cill was likely to damage the paint-work, so it might be somewhat acceptable in the way it was sealed, and a fresh coat of paint would clean-up the edge… but as I mentioned - the general guidance is that all of the residue be removed, but that's subject to the finished surface, etc.

A u-value of 1.1 w/m2k is actually very low for double-glazing, it typically gets down to around 1.2 u for double (with Argon and a low-E glass) and around 0.7 for triple, so that indicates that the glass is probably 24 to 28mm wide. You can check the quality of the units by looking at the manufacturer's stamp in one of the corners, take a photo of that?

https://www.bromyardglass.co.uk/u---values

That's Diamond glass (Irish made) and the 'toughened' refers to the EN12150-1 standard for residential glazing. It's good quality but standard glass commonly used in both double and triple glazed units. I have the same glass here in mine and they weren't sold as 'acoustic' units at the time. So I don't think that this new window is any different to any other unit except for the fact that they are advertising it to be 'acoustic'.

Part of an acoustic installation would require that the frames are installed with a full packing of foam between the frame and lintel/reveal/cill. That's a significant path for noise to travel and refits of windows tend to get that detail wrong as the frames are fitted into the existing opening and never have the gaps around them packed fully.

Frankly, I think you're stuck between a rock and a hard place as it's probably fair for the installers to say that they installed a better window than the originals both thermally and acoustically, but without having the noise attenuation detail and the W/m2k U value to compare, you don't have much to use as leverage. They might be able to improve the finish cosmetically, but that's not going to improve the acoustic experience, I think that can only be improved by packing the gaps fully (not possible without tearing out the reveals) and fitting triple-glazing…

That's an unusual finish alright, it looks like the window lintel isn't complete and the external course of blocks are only half sitting on the lintel/beam. All of that should have been rendered over by whoever did the vertical wall rendering… It's a problem in terms of the fact that there is a gap for sure, but as to whether it's a structural issue or not isn't easy to say. If that's a steel beam then it would indictate that it's a cold bridge, so having the internal area around the window insulated with insulated plasterboard would improve matters and remove some of the source of cold from above the window.

My main concerns are (i) the company recommended acoustic given we are on a main road but there has been no sound improvement

Perhaps the cause of the outdoor road noise coming through to the inside has little to do with the windows but rather other general structural air tightness issues which you are not aware of?