Single vs double glazed windows

[leyasg]

Hi all,

I'm about to embark on the ups and downs that come with owning a Grade II listed building. We've exchanged on a beautiful late 17th century house and looking forward to moving in shortly. It's got brick elevations and is timber framed. I have a 1Y old, and need to make sure the house is fit for purpose (warm enough to house us). It has an oil central heating system and a wood fire in one room as well as an AGA in the kitchen. The pipes for the heating are all on display in the ground floor just below the ceilings. The windows (and doors) are all single glazed, wooden but not sash.

My first question, of many no doubt, to get advice of people who have been through this all before is whether changing the windows to double glazed should be my first priority, and will it make the house considerably warmer? There are places where we can see daylight from the window frames around the corners (which can be repaired - but is it better to replace now and take one hit?). In a conventional house (my mum's for example) we had the windows changed to double glazed uPVC and it increased the temperature of the house by about 4 degrees. But this house would be different with little wall/floor/loft (where one exists) insulation and walls with lime render. Your opinion, and experience, would be greatly appreciated.

I have put aside a budget to do it, along with a million other things which need to be sorted out. And it would take planning permission which I am hoping I should get, as the house has been modified (roof replaced from thatch to tile, flooring changed, and windows definitely changed). At some point, I want to get solar panels on the garage and look at underfloor heating with some sort of a ground source heat pump. Current EPC for the building is a nice and solid F. We saw the house during summer, and went to look at it last week when the weather was cooler. It was very noticable!

Your thoughts are appreciated!

 

[Cubist]

Hello and Welcome to this motley band Period Property Masochists,

Sounds like you're in the very early stages of your becoming a steward/custodian of a Listed Building and believe me there is more to owning a piece of paper that allows others to send you demands for money, some would say extorting, to keep and maintain the home of your choice. Forgive me, some might accuse me of being too cynical but I prefer the 'Realist' description - my/our rose tinted spectacles were consigned to a drawer years ago and only ever see daylight on brilliant sunny days but there are many up-sides to the experience as well. Only you can decide whether that experience was worth the trials, tribulations, sweat, tears and the spilt blood was worth it 'after the event'. We did and do.

That aside and regarding your immediate query.The chance of your local Conservation Officer approving double glazing are most likely in the order of 10% or less - considerably less. Much will depend on the personality and background of the CO and the Building Control team behind them but I would not get my hopes up. Right now I would recommend that you begin investing in lots of wooly clothing - jumpers, thick socks, long dressing gowns/house coats and the like - to protect you during the long months and years you might spend just navigating the planning and approvals process.

Frankly all the plans you're considering right now for your new home? Make a list but do nothing for a year or so. Get used to the house and let it become your home/ Like your new son/daughter it will soon start telling you what it needs from you but unlike that off-spring it will still be making 'feed me' demands in 20, 30, 40 years time.

Good luck, you're in for the ride of a lifetime.

 

[Kearn]

Couldn’t agree more.
Live with it through 4 seasons, you don’t know what’s needed, broken, annoying yet. Nor do you know where best to spend your budget. And I’ll bet my granny’s pension that your budget will unlikely be adequate for what you need to repair. Therefore there will be trade-offs, prioritisation and a lot of time passed wondering why the hell did we do this…!

Windows do let a lot of heat out, however they are not the only problem with an old house.

The simple, and much cheaper solutions - thick heavy lined curtains. Secondary magnetic glazing. No LBC required.

These are also BETTER than double glazing.

A CO may allow slimline heritage double glazing. It looks awful (flat glass), costs multiples more than standard thickness, provides less heat retention. And still fails. Plus warranties are far shorter. Avoid.

Timber framed means thin infills, if they’re brick they will be less good than original daub panels. However, if they are dry, then they will insulate. But I bet, they have cement pointing/render and/or plastic paint on the outside. Probably gypsum skim and plastic paint internally. Therefore the fabric within this sandwich is not dry. It’s wet. And therefore it’s now a great conductor of heat.

Single skin brick at 9” isn’t that bad thermally, when fully breathable and dry.

Fixing this is far more important than windows due to the much greater surface area. But it’s costly, messy and intrusive.

Floors and roofs are also significant areas of heat loss when not the correct materials/insulation approach.

Dare I ask the condition of the timber frame? This is where the bulk of the spend will go…

 

[LadyArowana]

On the topic of windows and GII properties there has, and I believe will continue to be, a shift in thinking towards the approval of certain changes to improve thermal efficiency. I remember when a council was the first to announce that there would no longer be an automatic presumption against some of these upgrades. I couldn’t find that exact report, but this from Mid-Suffolk Council may be relevant. From memory I think it was the same Local Authority. https://www.midsuffolk.gov.uk/w/tho...could-benefit-from-innovative-planning-change

Even Bath and NE Somerset has approved some non original but original style sashes on GII buildings in visible locations to be replaced with Slimline DG.

I totally agree with the idea of living in a place for a while before making any big changes, and aside from any glaringly obvious dangers which should be mitigated kids are quite resilient and a few layers of insulation applied to them is much easier then fixing an entire 17th C building, although they tend to grow out of things which doesn’t happen with properties.

 

[Mulder]

Hi and welcome,

The above advice to live in the property and spend the time researching what needs to be done and the best way to go about it will save you time and money down the road and hopefully avoid some expensive pitfalls, like reducing breathability via new plastering and painting or even blocking up all ventilation.

On the topic of windows, you can absolutely swap for double glazing, but it will depend on how significant the windows are..if they are original lead single glazed you can forget about it. If they're something less original and more modern and are rotten to the point of needing replacement, you could easily justify replacement with something like slim-lime metal windows or even timber.
Don't expect to get the modern thick double glazing though. And if you have to go metal, expect huge expense.

Blocking up visible air gaps is a no-brainer and draft proofing strips and heavy curtains around doors can go a long way too.

 

[mardinor]

Just to echo the advice above. Full length, thermal lined curtains were standard 20 years ago and are as effective as double glazing. And put them on external doors too - add a portiere rod.
This is the first generation that hasn’t grown up with single-room heating and ice on the insides of bedroom window. You will survive.

 

[Kearn]

Wiltshire are also fairly ‘forward thinking’ with allowing slimline DG… doesn’t make it the right option, but there are LAs who are considering pragmatic ways to look after our buildings.

 

[Stevers]

Windows are the eyes of a period building, and nothing spoils the look quite like sucked in DG units with or without heavy placcy frames.

We have fourteen original sash windows (from 1879), all serviced by me and my late father when we moved here in 1997 and all still working well. They are draughtproofed with Stormguard 'V' self-adhesive strip - which is also well worth it for noise reduction and stopping rattles in windy weather.

 

[Cubist]

It tickled and annoyed me at the same time when, after suggesting DG installation during one of our accompanied pre-purchase visits the CO poo-pooed the notion saying that light refraction through the DG units produced a significant negative visual impact. The reason for my amusement and annoyance? The house sits circa 15 feet above the lane and is completely hidden by trees and hedges.

 

[Kearn]

It tickled and annoyed me at the same time when, after suggesting DG installation during one of our accompanied pre-purchase visits the CO poo-pooed the notion saying that light refraction through the DG units produced a significant negative visual impact. The reason for my amusement and annoyance? The house sits circa 15 feet above the lane and is completely hidden by trees and hedges.

I guess trees and hedges aren’t per an eg though…

It’s one of those things that stands out way more than it should, bright shiny flat reflections from perfect glass

 

[Mrs McG]

I’m not negative about replacing windows, it’s always ‘horses for courses’ and I replaced my own about 18 months after moving in. Although there were two panes of old glass and a few bits of window furniture nothing pre-dated 1970s and they were in bad repair. When I say bad repair I mean that a biro could be poked 0.5cm or more into some window frames and when I made the mistake of letting a local window cleaner wash them the water came through the single glazing, hit the secondary glazing, came through THAT and then ran down the wall inside.

My local CO was fine about replacing them but sticky over the gap (4mm only) but even so I’ve noticed how fast the cottage heats up now and how much better it retains heat. Yes it’s expensive and my front windows costs just over £10,000 but it’s specialised glazing, solid hardwood frames and handmade to fit so it’s all relative!