How many square metres of double glazing your Endeavour Hills house needs
Straight answer: a 1980s brick veneer here carries 20 to 28 square metres of glazing across 12 to 16 window openings plus one sliding door, which is about 12 to 18 per cent of the floor area. Measure the opening, not the glass, add 8 to 10 per cent for the windows you will forget, and count the sliding door on its own because it is a quarter of the total. The estimator below sizes the job first and then prices it.
Size the job, then see what that size costs
Move the two sliders to the quantities you have measured. The estimator shows the glazed area and the number of openings, and then prices them for the approach you pick. This is a sizing tool: the per opening rate card is on the pricing page.
What this estimate assumes
- Ground floor access with a clear path to each opening, and one or two parking spaces out the front.
- New windows going into the existing openings at the existing sizes, with no structural change and therefore no building permit.
- Standard powdercoat colours and standard hardware, with no custom extrusion runs.
- Per opening allowances for packing, levelling, perimeter sealing and basic internal make good are included in the openings slider.
- Excludes painting, new blinds or curtains, security screens, enlarging an opening, and any asbestos removal.
- This is a 2026 budgeting guide, not a quote. A firm price needs somebody on site with a tape.
How to measure it properly with a tape and a phone
Twenty minutes with a five metre tape gets you a number good enough to budget with. Do it in this order and you will not have to do it twice.
- Label every opening first. Stick a piece of masking tape on each pane and write a code on it: L1 and L2 for the lounge, K1 for the kitchen, B1 to B4 for bedrooms, BA1 for the bathroom, and so on. Every quote, every defect notice and every conversation for the next three months will use those codes, and it saves genuine confusion later.
- Measure the opening, not the glass. From outside, run the tape across the brickwork or cladding from one side of the hole to the other, then top to bottom. That is the opening. The visible glass is 10 to 20 per cent smaller because the frame eats 90 to 140mm of it, and every quote you receive prices the opening.
- Take three widths and three heights. Top, middle and bottom for width; left, centre and right for height. On a reactive clay site in Endeavour Hills the difference between the three can be 5 to 15mm, and that variation is itself information about how much the house has moved.
- Work in millimetres and convert once. Width in mm times height in mm divided by one million gives square metres. A 2400 by 1200 lounge slider is 2,400 times 1,200 divided by 1,000,000, which is 2.88 m².
- Photograph each one straight on. Stand back about three metres from outside, get the whole opening plus a bit of the wall in the frame, with the masking tape label visible. Then take a close shot of the bottom corner of the sill, which is where rot and corrosion show first. Those two photos per opening let anyone quote you sensibly by email before a visit.
- Note the direction each one faces. Use the compass on your phone and write N, S, E or W next to each code. This is the single most useful thing on the list, because it decides the glass makeup, which is explained on the glass specification page.
Send us your photos and we will size it for you
Email or text the labelled photos and rough sizes and we will come back with an area total and a budget band before anyone visits the house.
Rules of thumb and the allowance to add
- Glazed area as a share of floor area. Older brick veneers in Endeavour Hills, Hallam and Doveton generally run 12 to 18 per cent. Homes built after about 2005 with big sliders and stackers run 20 to 30 per cent. If your own total lands well outside those bands, you have probably measured the glass instead of the opening, or missed some openings entirely.
- Add 8 to 10 per cent for the ones you forget. Every single time, the missed openings are the same list: the highlight window above the hallway, the toilet, the laundry, the obscure ensuite pane, and the side panels beside the front door. Add the allowance rather than walking the house a second time.
- Count doors separately, in units not just area. A 1.8 metre sliding door is about 3.8 m². A 3.6 metre stacker is around 6.5 m². Beyond the area they carry a track, rollers, a threshold and mandatory safety glass, so they cost $1,400 to $3,200 more than the same area of window. See the doors page.
- Leave a clearance allowance around every frame. Frames are made 8 to 12mm smaller than the opening on each dimension so they can be packed square and sealed. That gap is not sloppiness, it is what absorbs seasonal movement on clay and what the flashing and foam live in. A frame made to the exact opening cannot be levelled and cannot be sealed.
- Round up, not down, when budgeting. Fabrication is priced in size bands, so an opening 20mm over a band threshold costs the next band up. Budget on the larger of your three width measurements.
- Never order off your own numbers. Yours are for budgeting. A check measure to plus or minus 2 to 3mm happens after you sign and before anything is cut, and that is the measurement anyone is liable for.
The sizing mistake that costs the most here
It is measuring the visible glass rather than the opening. It sounds trivial and it is not. On a standard aluminium slider the frame and the interlock take 90 to 140mm out of the opening, so a hole in the wall that is 2400 by 1200 shows perhaps 2200 by 1080 of glass. Measure the glass on fourteen openings and your total comes out around 15 to 20 per cent light. On a 24 square metre house that is roughly four square metres you did not budget for, which at 2026 rates is $2,500 to $4,000. People then assume the quote is padded, when in fact their starting number was wrong.
The second most expensive mistake is leaving the sliding door out of the count until the end. It is the largest single piece of glass in most houses here, it needs safety glass by law, and the track has to be dead level, which is half a day of work on its own. Put it in the count first, not last.
The third is assuming windows repeat. In the estates built through Endeavour Hills in the early 1980s, three bedrooms that look identical from the street are frequently 1800, 1500 and 1500 wide, and the two ends of the same living room slider can differ by 10mm because the house has moved. Measure every opening. It takes twenty minutes, and the alternative is a remake, a boarded up hole and a fortnight of waiting.
A worked example: a 1982 Endeavour Hills brick veneer
Single storey, 165 square metres of floor area, four bedrooms, original single glazed aluminium sliders, one sliding door to the back deck. Here is the whole count, opening by opening, in the order you would walk it.
| Code and room | Opening size | Area | Facing |
|---|---|---|---|
| L1 lounge slider | 2400 x 1200 | 2.88 m² | West |
| L2 dining | 1800 x 1200 | 2.16 m² | West |
| F1 family | 2400 x 1200 | 2.88 m² | North |
| M1 meals | 1500 x 1200 | 1.80 m² | North |
| K1 kitchen over sink | 1200 x 900 | 1.08 m² | East |
| B1 main bedroom | 1800 x 1200 | 2.16 m² | South |
| B2 bedroom two | 1500 x 1200 | 1.80 m² | South |
| B3 bedroom three | 1500 x 1200 | 1.80 m² | East |
| B4 study | 1200 x 1200 | 1.44 m² | East |
| BA1 bathroom | 900 x 900 | 0.81 m² | South |
| EN1 ensuite | 600 x 900 | 0.54 m² | South |
| T1 toilet | 600 x 600 | 0.36 m² | South |
| LA1 laundry | 900 x 900 | 0.81 m² | East |
| H1 hallway highlight | 1200 x 600 | 0.72 m² | North |
| 14 window openings, subtotal | 21.24 m² | ||
| Plus 8 per cent allowance for missed openings | 1.70 m² | ||
| D1 sliding door to deck | 1800 x 2100 | 3.78 m² | North |
| Total glazed area | 26.7 m² |
Twenty six point seven square metres on 165 square metres of floor is 16 per cent, which sits neatly in the expected band, so the count is probably right. Put 23 square metres of window area, 14 openings, full replacement in standard aluminium with clear Low-E argon units, one sliding door, disposal and safety glass into the estimator above and it returns roughly $16,400 to $30,300. On a house exactly like this we would expect the fixed quote to land in the low to mid twenties, and the same house done as a retrofit into sound frames sits closer to $11,000 to $20,000. Which of those makes sense for you is what the budget guide works through.
Note what the orientation column tells you before anyone quotes. Two west facing openings carrying five square metres of glass are why that lounge is unbearable in February, and they are the two that should get toned solar control glass. Four south facing bedroom and bathroom openings are where the winter condensation is, and they want a warm edge spacer more than they want a fancy coating. That is a $700 decision made properly with a phone compass and a tape.
When the honest answer is "you need less than you think"
Sizing the whole house does not mean glazing the whole house. Three cases where we say so out loud.
- Under about 8 square metres of glazing in total. The measure, the travel and the setup cost the same whether it is two windows or twenty, so a small flat or unit gets a much worse rate per square metre. Secondary glazing on the two worst rooms at $580 to $1,400 each is usually the whole sensible job.
- Half the house is south facing and rarely used. The toilet, the laundry and a spare bedroom are 1.98 square metres of the example above and contribute almost nothing to your comfort. Leaving them single glazed saves $1,200 to $2,000 and you will not notice.
- The frames are failing rather than the glass. If sills are soft and sashes are racked, the area calculation is not the question you have yet. Work through the signs your windows need replacing checklist first, and read the retrofit page to see whether your frames are candidates at all.
We also do not quote off a homeowner’s measurements alone, no matter how carefully they were taken, and we will not take a deposit before a check measure. If you want to see how the install week runs once the sizes are locked in, that is on the installation day page, and how we work in your suburb is on the Endeavour Hills page.
Send your measurements and get a real number back
Give us your area total or just the room count and we will confirm the sizing, then measure on site and quote within 7 days.