Double glazing in a grade II listed house

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Has anyone had any success with this and might be willing to share tips for getting it approved?

A few more specifics:

• we fall under Stroud District Council
• the house is a derelict, 18th century farmhouse
• the windows are rolled steel/Crittall type, although the date they were installed is under dispute. Council think 19th century, so still not original windows, but they want them restored and retained regardless. We think they are newer and therefore could be deemed inappropriate anyway

If anyone has had success with this and might be able to share contacts for a heritage specialist or anyone else who might help (possibly someone sympathetic to our cause?!), give any tips for how to get it through the planners or can provide any other info we’d be very grateful!

Op, I guess we need to agree to disagree, we live in different areas of the Uk, but in my experience, six years into living in a listed building that we have now spent close to six figures renovating, there is no give and take when it comes to the fabric of the building. Unless you’re talking about an extension of sorts.

I don’t think it looks naff if done correctly and many beautiful homes have been done.

clearviewsg.co.uk/heritage-listed/

@ivfdreaming I agree! What we’ve asked for are timber casement heritage/slimline double glazing

Every part of a listed building is protected, that includes windows and, as someone has pointed out, the Crittal windows are part of the history of the house. I would move forward with assumption that either the existing windows are to be kept and repaired or you can replace them like for like as in an exact copy in material and detail. You will probably not get permission to change them to timber casement unless you have evidence of what the building looked like before the Crittal windows were installed that show timber casement windows. Unfortunately just wanting double glazing isn't enough of a reason to alter a listed building and any proposals you make will be assessed by a team of heritage professionals working with robust policy designed to protect the building for future generations, not just for the convenience of the current owner.

If they are multi pane i.e. have a number of smaller panes within each window then double glazing isn't going to get you the effect you want due to the large surface area of the frames. English Heritage have done many studies and secondary glazing is more efficient at heat retention and noise reduction than double glazing multiplane windows. You can get frameless secondary glazing that sits directly on the existing frames and is almost invisible.

We could not get permission for double glazed windows, unfortunately although for us noise isn't a problem as we're not on a road. But security was a concern, with inferior single paned glass so we went for toughened glass instead. If we had been on a road I think we would have been really pushing for DG though.

NB the windows have to be as at the time of the listing, even if they aren't the same period as the house. Our house is 17th century farmhouse and we wanted to put in oak window frames. We were told we had to have softwood painted ones (they even specified the colour, cream). It does look lovely but I did want the oak!

If you're wanting them for insulation purposes, just to say that when we replaced all of our windows and doors, it was at the same time as we put a new roof on the house. The roof was well insulated (they specified sheep's wool which was expensive but effective) and the insulation from that and the better-fitting windows and doors is so good now that we wouldn't have needed double glazing anyway.

@bilbodog do you know which brand of secondary glazing this was? Yes, it might be worth us contacting Crittall, they should definitely be able to confirm if they’re theirs, thank you for that suggestion.

@MariaDingbat our argument though is that they are not repairable. Multiple restorers have said they are likely to get them back to their workshop where the timber will turn to sawdust and there will be so many rusted sections that more will be replaced than save anyway. So if we have to replace them, then why not use slim, heritage double glazing? Especially given that other mid 20th century Crittall windows in the same Council have been deemed inappropriate and granted permission. I guess it may all hang on whether they are 20th or 19th century. They are not multi-pane, they are large panes of around 30x40cm, which is one of the reason we don’t think they are 19th century.

@AlwaysLatte that is a very good point, thank you for bringing it up! There have been multiple break ins along the same road recently (my fiancé’s parents, who live opposite, had their house broken into about 18 months ago on the same night as another neighbour, plus several others over the years). The village in general appears to be a target and once it’s done our house is likely to be one of the most expensive. We also have a baby on the way, so we want to make it as secure as possible for our family.

Thank you again everyone

I think you’re probably talking about something like Pilkington Spacia, which is soooo expensive, and argon filled with only something like a 5 year guarantee. We are not listed, conservation only, but we are stuck with the original wooden windows, which are beautiful but cold, and even secondary isn’t that easy to do because they are mostly bay windows

Sorry i dont know who did the secondary glazing. One was a 14th century house in east sussex and it was done before friends Bought the house. Another was years later in an old cottage - i dont think they had permission but unless someone tells listed building control they dont check themselves as far as i am aware And the owner told me how much warmer their house was with secondary as opposed to replacement double glazing which someone nearby had.

The secondary glazing was black framed aluminium i think which looked good on these houses that had Oak framed windows with leaded light panes.

@Flamingolingo thanks for the info, just looked them up and they could be a good alternative. Says they have a 10yr guarantee online too and that they can fit into steel, which ours are. They don’t really have pricing info online though, when you say ‘sssoooooo expensive’ are we taking twice the price of secondary glazing? Twice the price of replacement heritage glazing? More?! You’re lucky yours at least look good, if the planners have their way we’ll have to spend a fortune attempting to do up windows that look like they belong in a factory warehouse! And I’m not sure they’re capable of being restored anyway!

I don’t think I have a price for it, but I know it is one of the most expensive options out there. We looked at replacing all of our glass with double glazed panels at one point but it was something like £60k for the whole house. We decided not to but I think if we were going to change the glass we would go for laminated toughened glass because it won’t ever fail like a double glazed unit could

@Flamingolingo that does sound pretty pricey! Ours is c.270sqm/2900sqft property and I think 17 windows. Is that for a similar sized property?

We’d not considered laminated or toughened glass. How does that compare to double glazing for thermal efficiency? That is really our main priority, with security an additional consideration.

Thanks again for your help

Very similar square footage but we have 9 bay windows and an assortment of others. The windows are all made of a larger lower pane and a smaller fanlight above (house is 1915), so it works out as about £1000 for each section. The glass itself, heritage double glazing but not spacia, was about £8k if I remember, the rest was for both carpentry and painting

Op, if the council have told you that you won't get permission, the buck stops with them. No matter how much you want it. There are strict legal tests for listed buildings that they will be applying.

To be honest if you say things like "I was about to say they have to move into the 21st century at some point, but sometimes I think they’ve yet to make it to the 20th!" then maybe taking on a listed building isn't for you? I mean it kindly but you have to work with the building not against it. Double glazing actually isn't the be all and end all for energy efficiency either.

We have secondary glazing and it's amazing. So sound proof and v good for what it is - it's removable too. We wouldn't have been able to get double glazing but I have to say the secondary glazing does the job and does look great I think.

I agree re: secondary glazing. We had it in our old house and I loved it. Unfortunately it’s not that simple in our new house, because we have so many large bay windows. Of course, it’s possible to secondary glaze a bay, but in my experience it’s not as practical, and the units become quite large

Thanks again @Flamingolingo

We’ve not yet been given a firm no/refusal @OliviaBenson, this is just their informal, verbal guidance following a pre-app site visit. So we have many more stages to go before a definitive answer, which is why I’m trying to find out if and how others achieved it. Perhaps this is my fault and I haven’t explained thoroughly, but I think the point a lot of you are missing is that there isn’t much building left to ‘work with’! We do not live in it because it isn’t habitable, to the point that it was unmortgageable when we bought it and it’s now been removed from the valuation office listing because they agree (they didn’t even want a site visit to judge that, photos were apparently enough!). This applies to the windows too; we’ve been reliably told we could spend a fortune (£20k+) trying to repair them, when in all likelihood rot and rust will mean they fall apart trying. We don’t have £20k to waste on a council vanity project, so what is our alternative?!

@TheNightManager which brand is this? Several people have said it ‘looks good’ and ‘works well’ (although you did at least caveat that with ‘for what it is’, presumably acknowledging that it does have limitations compared to other glazing?), but nobody has given me an example. I promise you, I have looked online at it and so far my view hasn’t changed; I have seen no brand that is ‘invisible’ or even almost invisible and it’s a pain to open the windows (then becoming even more noticeable once opened) and they’re impractical and hard to clean.

I seem to remember that cylinder glass is still made in Bulgaria and it's its imperfections that give the sealed units their normal rather than blank look. 1 pane float glass 1 pane cylinder glass.

Ages ago we looked into re-installing sash windows in a Victorian terrace that looked Georgian.

In that case you need to work together with the conservation officer at your local council. Most are really nice people who are just interested in doing the best thing for the building. We have managed to do some things that are completely ‘new’ over the years (in two different houses - but both conservation not listed). Essentially the buck stops with them - they can’t let you do anything illegal in terms of the listed building, but sometimes they can help you find pragmatic solutions

@newtb not heard of cylinder glass, will take a look, thanks