New Construction - Double Glazing 70sqm variation cost 28k??

Hi All,

I need your advice to validate the price quoted by the builder for double glazing all my windows and sliding doors (approx 70sqm of glass) as part ot achieving the 6 star energy rating.

I have been quoted 28k which seems ridiculously high. I have rung a couple of double glazing companies to check the price. They reckon it should only cost about 100 - 120 per sqm to go from single to doube glazing as variation. This equates to about $7000 to $8400 for the enire house (quote is for aluminium framed double glazed windows).

Since the labour and the price of single glazing is already included in the base construction price , I should only be charged for the difference in price for double glazed window.

I wish to seek your opinion on the price, so I can talk to the builder and gets things sorted. Thanks.

Regards,
Kris.

Are the aluminium frames thermally broken? Is the double-glazed glass argon filled? Low-e glass? Viridian Lightbridge? You need to be sure that you are comparing apples with apples when you rang the independent companies that provided you the alternate square metre costs.

Issue 143 of Renew magazine published by the Alternative Technology Association

http://www.ata.org.au/

has an article by Anna Cumming about replacing her windows for double glazing in Melbourne. Maybe this will give you a yardstick.

Her brief was as follows:

1. 1420 x 1770 part casement part fixed
2. 1200 x 1210 part casement, part fixed
3. 400 x 1810 fixed window
4. 1100 x 1750 part sliding part fixed
5. 2040 x 820 fixed window with attached frame for double doors

Check my maths but to me this works out as 8.28 square metres

Apparently she got quotes between $4100 and $8300 though in each case the specs were slightly different ie. thickness of glass, gap between panes.

She ended up with PEFC certified Victorian Ash double glazed units from Pickering Joinery in Geelong. The cost came to $7400 including $1000 for pre-finishing with varnish. She admits this was not the cheapest quote. This did not include installation and in your case your builder would be adding his cut on top.

Hope this helps.

If the original windows in your build were identical type i.e. awning, then IMO the quote is what I call ridiculous. But if you are moving from sliding to awning then that adds some cost.

Depending on brand, then original single glazed say $18,000 (awning), double glazed with clear glass say $28,000 TOTAL COST. - leaving out bifold doors and upgraded glass.

But don't rely on these figures unless you understand the differences.

The original plan and the base price did include a mix of awning and sliding windows, so there is no extras with the type/style of the windows. The only upgrade we are doing is to go from single to double glazed for 70sqm of windows. And the frames are aluminium and the glass is standard double glaze, nothing fancy.

So looking at the figures I am guessing I shouldn't be paying more than 10k maximum? which comes to about $140/sqm. Is this is a reasonable expectationn?

I believe the above quotes are to retrofit or to replace existing single glazed windows which would have included additional labour (to remove existing glass and install new double glazed glass) and the cost of double glass. In my case, the labour and the cost of single glazing (including the frame) should already be factored in as they are already in the base price and plan and should only be quoted for the difference in double glazing. I am just curious on the variation price not the new double glaze install.

No the frames are standard aluminium,not thermally broken. The double glazing will be standard builders upgrade (U value = 4.5 and SGHC = 0.61). So therefore the price quoted from few companies are for the same standard about $120/sqm to upgrade.

The cost didn't include removal of the old windows or installation of the new. It was purely for the double glazed units alone. But you're right that in your case you are talking about an upgrade so the cost of the single glazing should be deducted.

Would you know the cost per sqm for single glazing ? Just so that I am aware what would be the difference in price. Thanks.

Yes, that is reasonable. But many suppliers, like us too, do not supply a double glazed sliding window. So an upgrade to double glazed is an upgrade to awning as well...

Hello Ed, Have an option for 6.5 ComfortHush clear for south and north and 6mm Smartglass float on east and west.

Pls advise if this is better cost effecting option than double glass.

Thank you.

I believe there is a huge difference between different types and quality for the profiles, quality of glass, quality of the window hardware, etc.

E.g.

My house has around 60 sq m of glazing including one huge double lift and slide door (5.6x2.4 m), one 3x2.4m stacker door and one 2.4x2.4 m stacker door.

One quote, which I have received from high quality Chinese UPVC (https://www.chinaropo.com/) window supplier, was around US$20K featuring German Veka tropical profiles, German Roto hardware, insect screens, Low E glass where needed, etc. Plus shipping, plus VAT, plus import duty and logistics, which roughly puts me into ~AUD$32K-33K territory total when delivered to my site.

Keep in mind those doors and windows U values range 1.6-2.2 which is quite good for double glazing.

Another quote I have received for those windows from Kinzel UPVC (https://www.kinzelindustries.com.au/) windows was AUD$56K. U values in 1.8-2.2 range.

The third quote I have got online from those guys here:

https://www.laros.com.au/windows-doors/ ... -estimate/

for top quality Timber/Aluminium tripple glazed German windows with average U value well below 0.8.

Depending on the profiles and type of timber being used, I have received 3 quotes for $66K, $78K and $95K respectively.

Obviously, having windows and doors which insulate almost as good as your walls and perform acoustically as good as average brick veneer wall, is something everyone has to make his own choice.

I personally believe that good quality windows pay off in the long run when it gets to the heating and acoustic comfort and also can drive 5% premium on your house selling price quite easily.

On the other side, $50K of upfront difference is definitely a huge difference for the house which costs $500K, however, it is really not so significant for the $2.5-3M house.

The bottom line here is: know your options, stay smart and try to get the best price/value combo satisfying your budget and expectations.

What is the whole purpose of this exercise to begin with? Just to get a better energy rating to pass your BASIX for the council or to noticeably improve your thermal and acoustical comfort?

Retrofitting double glazed glass to the standard aluminium frame won't change things much when it gets to thermal efficiency.

Just move from 4 mm standard glass to 10.76 mm glass and you will get your U=4.5.

There is really not much sense to go double glazing for anything above 3.0. Even some 11 mm single glass windows can give you U values as low as 3.

Glass thickness makes hardly any difference to Uw.

Well Known Residential Awning Window Results in WERS

Glazing	Uw	SHGC
3Clr	6.6	0.66
5Clr	6.6	0.64
6.38VLam	6.5	0.61
10.38ClrLam	6.4	0.47

Hi Ed,

You are right here, it is rather has to be thicker glass + better profile combination.


However, moving from clear glass to Low E glass should definitely reduce Uw, having this Low E on a thicker glass will also help to improve acoustical properties.

I just got a detailed quote today from the builder but the breakdown is not for cost rather the window/sliding door specs..overall cost is $27400 for 30 Windows (70sqm of glass and upgraded frames)

I have been provided with 4mm/10mm/4mm double glazing using 18mm dgu. I was told that it's a good spec for residential purpose. I have been quoted a mix of clear float and clear toughened glass.

I was wondering why not all be toughened instead of float as toughened is more stronger and heat resistant. Does anyone know the cost/sqm to upgrade from float to toughened? $8-10/sqm?

I was also thinking if I should upgrade to a thicker glass say 5mm or 6mm. Again not sure how much per sqm for the upgrade from 4 to 6mm. $25-30 per sqm?

Appreciate your responses. Thanks.

Regards,
Kurshid

• [ul]
  [li]Overall cost is $27400 for 30 Windows (70sqm of glass and upgraded frames)

This is on the high side for the windows as a total cost, and I am not talking upgrade. Upgrade of $15k would be in the ballpark.

• 4mm/10mm/4mm double glazing using 18mm dgu.

Sounds like A&L. The rebate of 18mm is fixed, if you increase the glass thickness, you get less gap and therefore lower energy performance.

• Why not all be toughened instead of float as toughened is more stronger and heat resistant

Simply put you don't need it. Toughened is used as per AS1288, wherever there is a chance of human impact breakage. It has no effect on energy performance.





[/li]
[/ul]

I guess the toughened glass are less prone to breakage as it is stronger and heat resistant than float. There are only a few windows (7 or 8 ) that have been quoted with float glass. I wish to upgrade to toughened glass everywhere to keep it consistent. I know I am a little paranoid.

I would appreciate on the upgrade cost per sqm. for toughened glass. The overall area for the float glass windows come to 20sqm.

Regards,
Kurshid.

Hi
The upgrade to toughened may be around $20/m2. Custom toughened glass can be expensive.

All of our windows and doors have toughened glass now.

I felt that the cost is high as well, but I am interested in the cost that needs to be factored in for the single glazing that would have been allowed in the base price.

I checked with the builder and he reckons its between 10 and 12k they estimated for the single glazing, builders range aluminium windows and sliding doors for 36 sq DB house. I was atleast hoping for 14k difference, so we can meet halfway.

My upgraded window and door schedule is below;

Window sizes are as follows;

All are aluminium awning windows and have frame thickness of 55mm and double glazed (4/104 using 18mm DGU argon filled gap) except for the fixed glasses with different glazing and frame thickness

1. 1800 x 850w – 7 nos (4/10/4)
2. 1200 x 1810s – 3 (4/10/4)
3. 1200 x 1450w – 1 (4/8/6.38 translucent Lam I)
4. 1200 x 1450w – 1 (4/10/4)
5. 1457 x 1810w – 1 (4/10/4)
6. 1800 x 2650w – 1 (4/10/4)
7. 600 x 3600w – 1 (fixed, not openable, 100mm frame, 5/14/5 using 24mm DGU)
8. 600 x 1810w – 1 (fixed, not openable, 100mm frame, 4/16/4 using 24mm DGU)
9. 400 x 1400w – 1 (4/8/6.38 translucent Lam I)
10. 3000 x 1450w – 1 (fixed, not openable, 100mm frame, 6/12/6 using 24mm sheet bracing)
11. 514 x 1810w – 1 (fixed, not openable, 55mm frame)
12. 400 x 1810w – 1 (fixed , not openable, 4/8/6.38 translucent Lam I)
13. 1200 x 850w – 1 (4/8/6.38 translucent Lam I)
14. 514 x 2650w – 1 (fixed, not openable ,55mm frame)
15. 1200 x 2050w – 1 (4/10/4)
16. 1200 x 610w – 1 (4/8/6.38 translucent Lam I)
17. 1200 x 3300w – 1 (4/10/4)
18. 1200 x 2050w – 1 (4/10/4)

Sliding Doors sizes as follows;

All sliding doors double glazed (4/10/4 , using 18mm DGU argon filled gap)

1. 2100 x 3300w – 1 (3 door aluminium stacker boutique sliding door with d handle, frame thickness 111 mm, 4/10/4)
2. 2100 x 2400w – 1 (3 door aluminium stacker boutique sliding door with D handle, frame thickness of 111 mm, 4/10/4)
3. 2100 x 1450w – 1 (2 door aluminium sliding door, frame thickness of 101 mm, 4/10/4)
4. 2100 x 2733w – 1 (2 doors fixed, 1 door sliding, frame thickness of 101 mm, 4/10/4)

So the overall cost of the above windows and sliding door (approx 70 sqm of glass) comes to $27400 inc GST, of which the builder is absorbing roughly $10 to 12k leaving me with a difference of approx $15400 to $17400.

Is $17.5k a reasonable upgrade price to to go from single glazed builders range aluminium window (frame thickness: 38mm), sliding door (frame thickness: 80mm) to double glazed and upgraded frame size (min. 55mm for windows and min. 101mm for door) as above?

if not how much would be a reasonable upgrade to pay?

Appreciate your response, as it would help me with a win - win outcome which is usually rare when you are not owner building. lol.

Regards,
Kurshid.