Window glass change - permission required?

[trojan_build]

I'm aiming to change the windows on our house. All windows are timber, made in the 80s, good quality wood. Some splicing needed in a few places, but nothing major. We are changing the glass in the openers and fixed panels, not changing the main window frames, so there should be no structural issues.

All windows are currently multiple single panes of glass puttied in - Georgian style. Maintaining these is something of a nightmare.

What we want to do is illustrated in the photo above. Reasons for doing this include:

1) Better thermal efficiency.
2) Reduced internal condensation.
3) Easier maintenance.
4) Easier cleaning.
5) Improved views.

The new windows will have sealed units (probably 4-6-4), set in with glazing tape and beading and then painted. The existing wooden dividers and single panes will go, and each panel will be re-rebated to accommodate the sealed units. There is enough timber depth to facilitate this.

Two questions:
a) Do we need planning consent?
b) Do we need building regs approval?

Our house is not in a conservation area, and isn't listed. There are no immediate neighbours, so there is no common style/theme with any other houses locally. The house doesn't form a significant part of the street scene and is in a rural location on a very minor single track road.

Any advice gratefully received and appreciated ...

 

[ronniecabers]

As you aren't in a Conservation area or Listed then no you don't need any permissions to do what you wish to do . I would like to highlight that a 4-6-4 unit will give some thermal propertie but not maybe as much as you would like , and again the reduction in the amount of condensation on the window may be minimal . Double glazing is at its most optimal at 4-12-4 and above, a 4-12-4 unit giving a Uvalue of 1.3 ( 4-16-4 and 4-20-4 will be 1.2 , but the differnece is actually quite negligible of 0.1 ) , whereas 4-6-4 will only give a u value of 2.1 ( all based on 4mm Clear Glass Front Pane , 4mm Softcoat Inner pane and 90% argon fill ...not that you get a lot of argon gas in a 4-6-4 unit ). U values are better the lower they are.

Don't get me wrong , they will perform better than single glazing but possibly not as much as you are hoping for . Also worth noting is that Condensation on windows can be reduced by altering habitats in the house that create excess water vapour

 

[trojan_build]

Hi,
Thanks for the excellent reply - appreciated.

Yes, understood about the minor thermal gain. It will be there, but narrow sealed units are not as good as the wider ones. We'll definitely see gains in terms of maintenance, cleaning and improved views.

Condensation - we manage this pretty well and extract when cooking and also when showering, plus we usually open a window or two to vent water vapour, through summer and winter. The condensation tends to affect used bedrooms, and there's probably little that we can do to reduce that.

Not mentioned above is the fact that all windows have old but very serviceable Everest secondary glazing. This again helps, especially in reducing draughts which are present in timber windows.

Anyway, thanks again for the hugely helpful posting.

 

[DiyNutJob]

I have a vague impression that anything that changes the thermal characteristics would require a re-evaluation for council tax.

 

[ronniecabers]

Nope , thermal charatestics have no bearing on council tax at all, otherwise every new installation of windows/insulation would require a re evaluation

 

[DiyNutJob]

Nope , thermal charatestics have no bearing on council tax at all, otherwise every new installation of windows/insulation would require a re evaluation

Maybe people are not aware. These things are checked when selling a property.

 

[fourtytwo]

Maybe people are not aware. These things are checked when selling a property.

Nonsense, I have recently moved property and there is absolutely no connection between thermal performance and council tax.
If you insist otherwise please provide documentary evidence.

 

[ronniecabers]

Yes if replacing the entire frame and sash it falls under Fensa/Certass and if not registered should be picked up when the house is sold but as op is only altering the sashes it doesn't fall under any building control.
Council Tax is purely on the size of the property at present... well in England anyway, I can't speak for Scotland or Wales

 

[DiyNutJob]

Nonsense, I have recently moved property and there is absolutely no connection between thermal performance and council tax.
If you insist otherwise please provide documentary evidence.

See post below yours. I vaguely remember reading thermal. But, I don't care it isn't my problem. There are lots of checks for modifications.

 

[Diver Fred]

The only paperwork changing the glazing in the lights will do is affect the EPC (SAT) rating. If you have one or could be up to 10 years before a new EPC assessment is required.
Are you having new light frames made? Will you have proper anti-draft gasket installed at the same time?
As for the old secondary glazing is that in metal frames? That does provide a cold bridge. Is the sealing brush/gasket ok. If it is then you will be almost at triple glazed effective.

 

[trojan_build]

Thanks for this.

We intend to retain all existing timber and simply re-rebate and re-glaze fixed and opening panels with sealed units. The glazing bars and current single glazing would be removed. There will be no changes to the main timber frames, and they won't be removed during the process.

In places, there is good draught strip embedded in the existing frames. This will be checked and replaced if necessary - these strips are still available.

The secondary glazing is in painted aluminium frames. No way around that, but each front edge is mostly clad in timber beading, so some reasonable thermal resistance there. Sealing brushes/gaskets are pretty good.

Were we to sell the house, we would most likely be asked whether there have been any changes to the main windows, to ensure conformity with Fensa/Certass regs etc. This is really aimed at trapping numpties who replace an entire timber frame with uPVC and don't realise that it's holding up the brickwork above. It's likely that a change to the glazing won't be flagged, and even if it is, it's a positive gain. Had we replaced sealed units with single glazing, that would ring a few alarm bells.

Thanks for the continued discussion - it's helping us to understand the broader issues here.

 

[ronniecabers]

Just replacing the single glazing with sealed units should not flag any issues when selling the property, and is not covered by Fensa etc.
A little naive to believe that Fensa etc are just to check against numpties who replace wooden frames and it's holding the entire brickwork up lol. Normally windows have a lintel holding the brickwork up, it's unusual ( but does happen ) that there is no lintel but this is rare. Fensa/Certass are all about conforming to up to date building regulations, such as fire escape, ventilation and safety glass and that's the easy bits of the regs...

 

[trojan_build]

Yes, understood - I was being a tad flippant on the numpties front.

I've seen a few Victorian bay windows sagging where the old timber frames had been removed and replaced by plastic. There were no lintels - the weight of the first floor bay above was supported by the ground floor timber window.

From what everyone has contributed, it sounds like we could proceed with this, but perhaps with a little caution.

 

[Diver Fred]

As you have stormproof light frames you do need to careful how much you cut away when increasing the glazing rebate size

Anyway, below is link to a chap who has done what you are proposing

 

[mrrusty]

I think I would keep the frames, but remake the sashes to suit a decent width DGU. Lots of standard sash profiles around, and a dowel and glue joint will be OK if you haven't got the tools for a more sophisticated joint, or you could have a local joiner make up the new sashes for you. At the same time you can make allowance for draught seal strips.

This also gets around all the remains of the glazing bar locations