Buying single glazed house - diy double glazing

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I'm hopefully moving to a house (about 90 yrs old) with the original single glazed windows.

They are in good condition and the wood is sound, apart from one one.

I'd like to replace the glass panes myself with double glazed units designed for retrofitting. According to the manufacturers website / YouTube channel they'll fit. They have a u value of 1.9.

I'd prefer this over upvc for various style reasons, although mainly budget! I've enough skill to do this as an ongoing diy job. And, there's a lot of them to do.

Anyhow:
I'm unclear if this is something I'd need building control to get involved with? I think so to get it signed off/fensa type certificate?

Has anyone experience doing this? Pitfalls to be aware of?

The windows aren't sash, rather opening casement style.

Thank
 
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As you are not replacing both the outer frame AND window sash, only the glass , then building control/fensa/certass is not a requirement , however just check that it is not in a conservation area or Listed. If Connservation area you should seek permission from the local council to change to double glazed units, if Listed , then the Listings people ( and expect them to decline your request too!)

Pitfalls ... checking you have enough rebate to take the sealed unit in depth , AND width , ideally you should not see the DGU sealant or the spacer bar sideview. Putty or beading? Puttied sealed units tend to fail within 5-10 years due to putty going hard and cracking , I do not know a supplier who will warranty sealed units that have been glazed putty. Beading , you have to allow enough in the rebate to get you bead in , remember to treat all sides of the bead before fitting
 
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Thank you, this is really good news. I need to re measure the windows now I have a unit supplier in mind/specifications to work with although pretty sure they'll fit.

I'll need to increase the rebate. The manufacturers installation instructions are silicone sealant against the inner beading and butyl putty on the outside with clips nailed in supporting the units before the putty is applied.

Fingers crossed. Cost wise they re not cheap, although, worth it if I DIY compared to other options.

Thank you for your advice, it is appreciated
 
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You can probable equal that U value by adding internal secondary double glazing units, depending on the window design. Removable units will halve the current U value and fixed units will get it below your current plan. But then opening the window is not so easy.

Insulation needs to be done holistically. Any idea on the walls? are they 9" - again there are many options. Personally I'd leave the current glass and fit a removable unit. brings the U value from 5.6 to about 2.7

First priority is alway air exchange. No point in fitting double glazing if you have open chimney's or lots of draughty windows and floors. An open chimney will exchange the air within 40 mins.
 
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Wifey has vetoed secondary glazing after a traumatic experience of poorly installed secondary glazing in the Victorian house she grew up in! I don't mind but she's the boss ...

Regarding the walls - I need to check. Due to lock down I've not been there for months although hope be next week. The EPC certificate says the house needs cavity wall insulation, although, but my gut and age of the house makes me suspect it's solid wall. It's rendered on the outside with no exposed brickwork so need to measure thickness and maybe get in the loft to try and see the brick pattern.

What are your thoughts on insulating the wooden frame?

Another slight concern is ventilation. Upvc replacements would allow trickle vents, these have none. And there is evidence of condensation issues around the bay window. Yet another concern!

[Edit]
Chimneys. Yes. Most rooms (including bedrooms and kitchen!) have fireplaces. Plan is to block them (professionally as blocking them can have damp potential apparently) apart from the front room. We'll use that fireplace (As we do in our current house) almost every day when it's cold. Wifey and I grew up with open fires and love them.
 
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