24mm vs 28mm Sealed Units

wedge69 · 25 Jan 2007

Duting our hunt for double glazing most companies are offering 28mm sealed units in their windows.

However, the company we had last night did 24mm units as standard, claiming these were better at retaining heat, though not as good at blocking out sound. They were also the cheapest quote so far.

Does any one have any comments on the relative merrits of the two thicknesses? (I assume the glass is always 4mm each, so the only change si with the size of the air gap)

philipdayton · 25 Jan 2007

The standard nowadays is 28mm
They are right in some respects in that the optimum cavity for argon gas filled units is 16mm (4/16/4) however the difference is negligable.
If you are having standard air filled units with an aluminium spacer bar there reallty is no difference to speak of.
The 28mm units are acoustically better but probably only by the same small fraction.
I suspect the 24mm unit quote was cheaper because the profiles/window system they have quoted you for is older.

Forest Grump · 27 Jan 2007

You wouldn't notice any difference between the 2.

biffvernon · 28 Jan 2007

philipdayton said:
The standard nowadays is 28mm

Really? I use 24mm. Convection is more likely to develop in a 20mm gap than a 16 mm gap. Sound insulation will be better in the thicker unit but if this is an issue you will get a bigger difference by having laminated glass as one of the layers. And use insulated spacers not the old-fashioned aluminium ones.

philipdayton · 29 Jan 2007

Yes really, most of the latest systems from leading profile company's Veka, Rehau, profile 22 Eurocell etc are 28mm systems.
Yes, 24mm systems are still available but they tend to be the older systems.
However, with the introduction of WER's optimised performance needs to be achieved in the sealed units with the use of Argon/Krypton gas.
these gases have optimum cavity widths of around 14/12mm so maybe
all will change again soon!

biffvernon · 29 Jan 2007

Well, what do these 'leading profile companies' know? They make plastic windows so they obviously don't care about the Planet.

philipdayton · 29 Jan 2007

No comment! I'm employed by one of them!

biffvernon · 29 Jan 2007

More seriously, Philip, do you know why there was a move from 16mm gap to 20mm gap in igus? Did they think that more seemed better or was it that the slightly better sound insulation was worth the slightly worse thermal insulation?

philipdayton · 29 Jan 2007

To be honest, I think it was. It wasn't as if Mr & Mrs Smith (no offence intended to anyone of that name) would realise that the units thermal performance dropped of slightly.
They were sold on the acoustics and that these 'new windows' were 28mm units so therefor must be better than the AN Other window supplier down the road..

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

24mm vs 28mm Sealed Units

Similar threads