Undecided: Double or Triple glazing?

andre_xs

Dear All,
we are a little undecided what to do:
We want to replace 1 window to the front (busy road, so noise is a problem), 1 window in the bathroom, and the patio door to the garden (not too big, I think ~155cm wide; French door planned). All windows currently have quite a bit of condensation in the morning, which to some extent is probably normal (but currently we have old aluminium frames, so they are dripping wet).

We got a quote for £2800 to do this as double glazing and for £3180 as triple glazing, so £380 more (~ 14% more). I find that a quite moderate and reasonable surplus. BTW, this is London area, just outside the M25. This is all for standard white uPVC windows

The company provides the following information on the windows:
Double glazed: 20mm separation between the two sheets. Energy Rating A+ 12
Triple glazed: 12mm separation each between the 3 sheets. Energy Rating A++ 21

And on the frames:
They use 'Liniar' profile, multipoint shoot bolt locking system.
"The latest windows have frames made up of “multi-chambers”. These are multiple cavities inside the frame which make the frames themselves as thermally efficient as possible."

The only disadvantage of triple glazing, beside the costs, is that they are heavier and may cause structural problems. I was just wondering how likely this really is? Other countries have triple glazing as standard... Our house is a mid 1950s ex council house with solid brick walls with a cavity. I would think that the frame can be properly screwed to walls without a problem?

Best wishes,

Andre

Edit: Just to clarify, we are not looking to have a return of the investment in terms of lower heating costs within a few years or alike, or to raise the value of the house (we don't want to sell). I think it's really about whether it would make a difference regarding noise (front street) and/or condensation. My gut feeling says "If you already spend so much money, go for the 'best' option and take triple glazing."

Mutton_Geoff

Double glazing for heat loss/gain, triple glazing for noise which you say you suffer from so I would think extra cost worth it.

andre_xs

Thanks, and your comment reminded me of another consideration: I've read that double glazing is better at letting heat from sunshine in, while triple glazing is worth at this (probably reflects more?). But triple glazing is better at retaining heat.

Regarding the orientation of the house, the bathroom window and patio door (roughly west facing) get a lot of sun only in the summer (in winter, the sun doesn't rise enough, virtually always shade), and then (in the summer) it actually gets very hot in these rooms. So it would actually better if it wouldn't heat up the rooms so much in the summer I guess...

But to be honest, I don't know how big these effects are, after all.

Doozergirl

The effects aren't that big.   The difference between single and double glazing is massive.  The difference between older double glazing and new is noticeable.  Even when we changed one ageing uPVC DG window for a new one, the sound difference was measurable.  You should be putting in trickle vents anyway for the health of the house, so that's always going to be where the sound gets through.  

The difference between double and triple glazing isn't massive, the cost benefit used to be negligible but I think the cost difference has narrowed a lot making a bit less of a financial consideration.   The frames on uPVC will not be as insulated as the windows themselves so for me, unless we went for full-on Passivhaus frame spec,  I didn't see the point.  The only place I opted for TG in our self-build was in the roof lights, given that heat rises, so I treated it like the roof and wanted a better u-value.

You should get early morning condensation on the outside of new double glazing anyway.  

FreeBear

Doozergirl said: You should be putting in trickle vents anyway for the health of the house, so that's always going to be where the sound gets through.

You can get baffled trickle vents that reduce the amount of noise coming through slightly.. But for windows facing on to a busy road, I'd suggest alternative methods of background ventilation - A PIV or MHRV system, whilst more expensive, would provide the same effect without bringing outside noise in to the rooms.

tacpot12

FreeBear said:

Doozergirl said: You should be putting in trickle vents anyway for the health of the house, so that's always going to be where the sound gets through.

You can get baffled trickle vents that reduce the amount of noise coming through slightly.. But for windows facing on to a busy road, I'd suggest alternative methods of background ventilation - A PIV or MHRV system, whilst more expensive, would provide the same effect without bringing outside noise in to the rooms.

Most PIVs require vents in all the rooms that are to be ventilated, so unless you fit a baffled ventilator, PIVs aren't going to be a solution. MHRV on the other hand will ventilate without the noise, as they suck the stale, moist air from the rooms that mostly have this, and replace it with fresh air that is pumped into the living rooms from the MHRV system.    

diystarter7

Triple glaze has their advantages when compared with DG if done well. Downsides the price.

IMO, as DG firms can vary a lot in quality, personally I'd got for very decent, well-made DG windows rather than possibly poorly made TG that will b more costly to install and repair should the go wrong.

If you have a chance o comparing different DG windows and frames, you will note there can be a vast difference.

The windows we have, people often say they look really nice, different to the ones they have. I don't want to insult them and say ours cost a lot more but they did and you can tell. NB: Yep, you can get rubbish DG windows that cost a lot more than next door but that applies to almost everyhting

Also check, read up on the quality of glass as there are variations