secondary glazing of a sliding door?

I have a north facing sliding door on a room in my house.

It is double glazed aluminium frame (fairly old now tho).

The room is cold. I get a lot of condensation on the frame.

I was thinking of replacing it with a window but that would require planning permission.

Now thinking about secondary glazing.

Can I do it that size about (7' by 7')?

Is it a good idea?

Expensive?

Pros and cons please?

Would love some opinions on this please.

North facing double glazed windows by themselves can only do so much particularly in houses with no insulation in the walls [I'm guessing] and with a frame that isn't thermally broken [I'm pretty certain of this from your description].
If you can buy or get a loan of one of the infra red or remote thermometers from Boots or some other chemist [the battery powered ones that you can stick in a child's ear as opposed to a thermometer], you can go around the house checking the temperature of external surfaces.
From my own experiements an uninsulated wall at 0-4 degrees outside will give around 14 degrees inside with the heat on for a while.
Under the same conditions a double-glazed UPVC window with a roller blind will give 18-20 degrees.
These aren't u-values, just comparisons of how cold a wall "looks" to a thermometer.
The point being that a good double glazed window system with a 1mm canvas blind can perform better than in unsulated 10" [250mm] cavity wall.

Adding secondary glazing could certainly improve the insulation, but could well cause other problems, apart from the obvious one of access.

I don't know who told you replacing a door with a window would require planning permission.
Section 4(i)(h)of the Planning and Development Act 2000 allows a lot of leeway for interpretation and a chat to your local planning officer costs the price of a phone call.
I'd be surprised if replacing the door with a full height window - or even one with a low sill - actually required planning permission.
regardles of that you could in general replace the old door with a uPVC model, assuming the house isn't a protected structure.

But really, it sounds to me like you need to do a lot more than just replace the door to improve the u-value of the property and you could investigate what grants might be available.
One thing is certain, energy isn't going to get any cheaper in the long run, so reducing dependency on it is the best way to deal with future increases in demand.
Can I say that its heartening that so many people are now focussed on this issue as its important on many levels to reduce energy consumption.



FWIW

ONQ.

[broken link removed]

THanks for your long and detailed reply.

Some assumptions in there, so, just to address some of the points raised:

the walls are pumped, the attic blown to 300mm, all windows new DG with argon and e-glass. Have a condensing boiler etc as well.

However, I realise that this door is the weakest link, and being the coldest spot is a magnet for condensation of any moisture in the house.

I would prefer not to replace it as I would have to do same for matching front porch door. Hmm, thinking about it, maybe I could get a similar looking one with a better spec frame and glazing...........

It is indeed thermally bridging very badly, aluminium not being a good insulator.

Access is not really an issue, I don't open this door as I prefer not to have all the heat sucked out of the room in under 10 seconds ;-)

Will check out the PP side of things again but not optimistic as its on the front elevation.

Hence looking for alternative, and thought 2ndary glazing might be an option.

Thanks again.

tbh, I'd have thought the visual appearance of window, instead of a patio door, would be a good thing - can't see any co co having an issue with that.

galwaytt said:

tbh, I'd have thought the visual appearance of window, instead of a patio door, would be a good thing - can't see any co co having an issue with that.

Click to expand...

Fair point, assuming logic counts for anything.

I think I might have to make an application under a Section 5 - that's what the planner told me last time.

Not sure how much it would cost, I know the initial fee is 80 euro, would that be all the fees, and would I have to get drawings etc done up on top of that?

Must talk to the planner again.

Just been told by the local planner that this would require full planning application complete with drawings by architect or engineer.

Awaiting confirmation of that.