Cost of windows vs brick + gyprock + batts etc

Morning Buildnoob

This is a very interesting question.

My first reaction was "yeah off course glass is more expensive" but then i started thinking about the square meter rates we pay for each component here in Sydney, and there is probably not a huge difference.

So here goes as quick reference:

GLASS

1. Standard residential glass & frames - $350/sqm

2. Commercial grade glass and frames - $650/sqm


WALLS:

1. Brick Veneer - $220-250/sqm

2. Framing, gyprock, paint insulation etc could easily be $100-150/sqm

So maybe it is close to a 1:1 scenario if you are choosing residential grade windows rather than commercial or double glazing.

Cheers

Simeon

Should probably remember that windows let in and out a lot more heat. You might end up with an uncomfortable house in summer and winter.

Thanks folks, appreciate your thoughts.

ren_ho , in the BASIX / energy efficiency assessments do insulated walls rate more highly than single unglazed windows? Especially north facing ones?

alexp79, some of the custom builders I've spoken to all go for commercial. I'm sure it looks nicer to have a wider glass pane but it seems to me to be overcapitalising? May be justifiable if you've got picture perfect Bondi or bush landscape to salivate over, but not in the suburbs where the view is next door laundry or a busy street. Not great bang for buck. Just my 2c.

@ashington Homes, thanks for the numbers, interesting. Guess the difference might be those energy ratings (i.e. without having to upgrade everything to double glazed).

Cheers.

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The difference between commercial and residential windows is the word. There is no definition of what comprises commercial or what comprises residential, nor what the differences may be.

Windows like everything else have to be suitable for purpose, and this is defined under the standards AS2047 & AS1288. Glass thickness is defined in AS1288 and it's unrelated to residential or commercial. AS2047 is about physical testing, the products are type tested to achieve certain resistance to wind and water.

We have windows in 10 storey high-rise which don't resemble the boxy so called commercial profiles because they were designed and tested to comply, and they not only perform in wind and water, they outperform in energy performance - and that is all without the sub-sill, sub-head and sub-jamb (you don't need these if the design and manufacture are to a high enough standard).

Regarding energy efficiency, walls are significantly better than a window and it's a large factor in the NatHERS modelling (that give you the star rating).

For example, a minimum standard timber frame wall would have around R2 in thermal resistance if built properly (fairly cheap to go up to R2.5), while a single glazed aluminium frame would be around R0.16. Even triple glazed is still only R1 to R1.25. So you can see even high performance windows are massive weak points relative to a fairly low performing wall.

The modelling takes this into account. Depending on your climate, it can be pretty hard to meet the 6 or 7 star requirements if you have a huge amount of glazing, especially if it's pointing in the wrong directions.