Single Glazed Sash and Case

[Duddy]

We have a B listed/ category 2 townhouse. Our upstairs drawing room sash and case have large gaps between upper and lower sash windows. You can almost fit a finger in the gap.

We have lots of work to do in the house, but we're wondering whether to (a) restore (b) put in an application for thin double.

The (b) option would mean it's well fitting and, double glazed. But we're not sure if it'll get through the planning team. I've read of success stories. Or should we maintain the original feature of single glazed windows, with terrific clarity. I find the room is quite noisy from road traffic, but I don't notice it as much downstairs perhaps because the single glazing downstairs is slightly better fitting.

Anyway, I guess looking for opinions on whether an upgrade to thin double sash and case is a no brainer for thermal, sound and aesthetics.

 

[fernicarry]

You can almost fit a finger in the gap.

When you say gap between top and bottom sashes you mean between the meeting rails? Normally the catch would pull them close together. If its a very wide window it might need more than one catch. A picture would be good.

Its possible the meeting rails have been planed down at some point particularly if the company whose name begins with a "V" have been let loose on them. They did that to mine. You could build one or other up to reduce the gap by gluing a thin fillet of timber on. The two meeting rails should actually have a profile so that they overlap each other when closed to prevent a miscreant from easily sliding something up between them to knock the catch open. Locking devices are also available.

You can do a lot to improve existing single glazed sashes and cases. Draftproofing brushes can be added round the perimeter of the sashes and you can add a brush or rubber seal between the meeting rails. If that hasn't already been done I'd look at that first rather than wholesale replacement. Replacement is likely to be quite a significant outgoing and if you have a lot to do you might want to keep your powder dry in case anything else comes up.

If the current windows have historic glass in them then you absolutely should keep them and if performance is still a concern look into secondary glazing. That's discussed on here quite often.