Getting your measurements right before ordering a roller door is the most important step in the whole process. Order the wrong size and you're looking at delays and a returns process — neither of which you want when the garage is out of action.
This guide covers everything you need to measure: opening width, opening height, available headroom, and side room. It takes about 10 minutes with a tape measure.
What You're Actually Measuring
NZ roller doors are specified by opening size — the width and height of the hole in the wall that the door needs to cover.
The manufacturer adds the overlap automatically. For Windsor doors, the curtain extends 40mm beyond the opening on each side (80mm total) with standard guides, or 63mm each side with high-wind guides. For Garador doors, the guides sit 25mm either side of the opening in standard configuration, or 50mm with windlock guides.
You measure the opening — not the door size. DoorsNZ confirms the correct curtain size for your opening when you order.
Step 1: Measure the Opening Width
Measure the clear width of the opening — from the inside face of one structural element (timber framing, concrete block, or steel) to the inside face of the other side.
- Measure at the top and bottom of the opening — if they differ, use the smaller measurement
- Do not include any existing door frame, architrave, or lining in this measurement
- Measure to the nearest millimetre
Common NZ garage opening widths:
- Single garage: 2400mm–2700mm
- Double garage: 4800mm–5500mm
If your opening is a non-standard width — for example 2350mm or 3100mm — that's fine. Both Windsor and Garador manufacture to custom widths. See our guide to custom size roller doors for more detail.
Step 2: Measure the Opening Height
Measure the clear height of the opening — from the finished floor level to the underside of the lintel (the horizontal beam or concrete above the opening).
- Measure in the centre of the opening and at both sides — use the smallest measurement
- Measure from the floor, not from any existing threshold or door bottom seal
- If the floor is uneven, measure from the lowest point
Common NZ garage opening heights:
- Standard: 2100mm–2200mm
- High clearance: 2400mm–2500mm (suits vans, utes, high-roof vehicles)
- Extra high: 3000mm+ (boats on trailers, tractors, lifestyle shed use) — see our high-clearance garage door guide
The most popular roller door height in NZ is 2200mm — it fits the majority of standard residential garages built in the last 40 years. If you have a van, SUV with roof bars, or a trailer you want to drive straight in, measure your vehicle height first and allow clearance.
Step 3: Check Available Headroom
Headroom is the distance from the top of the opening (the underside of the lintel) to the ceiling or the nearest overhead obstruction — pipes, beams, joists, or existing ceiling lining.
Minimum headroom required:
- Manual door (no opener): 300mm
- With automatic opener: 350mm
- Reverse-roll configuration (drum on outside): reduces headroom requirement significantly — ask us if headroom is very tight
If you have less than 300mm of headroom, a standard roller door installation may not be possible without structural modification. Contact DoorsNZ before ordering — get in touch here.
Step 4: Check Available Side Room
Side room is the wall space on each side of the opening, measured from the edge of the opening to the nearest obstruction — an internal corner, pipe, meter box, light switch, or shelving unit.
Minimum side room required:
- Standard guides: 80mm each side
- Windlock (high-wind) guides: 95–100mm each side
The door guides run vertically up both sides of the opening and need clearance from the wall edge. If your side room is less than 80mm on either side, contact us — there are sometimes alternative guide configurations available.
Step 5: Note Your Wall Construction
Standard NZ timber frame construction (90mm stud with cladding) is no issue for any roller door installation. Let us know if your walls are:
- Concrete block or poured concrete
- Double brick
- Steel portal frame (common in sheds)
- Unusually thick (over 200mm)
Wall construction affects guide fixing method and whether any adaptor hardware is needed.
Standard vs High-Wind (Windlock) Guides — Which Do You Need?
Standard guides are fine for sheltered, inland locations. If your property is in any of the following situations, windlock guides are strongly recommended and may be required by your building consent:
- Within 500m of the coastline
- On an exposed hillside or ridge
- In a region with frequent high-wind events (Wellington, coastal Canterbury, Marlborough, Northland exposed areas)
- On a lifestyle block or rural property with no wind shelter
Windlock guides grip the curtain edge more firmly, preventing the door from racking or lifting under wind pressure. Garador windlock guides sit 50mm either side of the opening (vs 25mm standard) — so your side room needs to accommodate this. Windsor high-wind guides sit 63mm each side.
When in doubt, specify windlock guides. The price difference is modest and the performance difference in a storm is significant.
Measurement Checklist — Before You Order
Confirm you have all of the following before placing your order:
- Clear opening width (mm)
- Clear opening height (mm)
- Available headroom above the opening (mm)
- Available side room both sides (mm)
- Wall construction type
- Standard or windlock (high-wind) guides
- Zincalume® or Coloursteel® finish — and colour if Coloursteel
- Manual lock, centre lock, or automatic opener
- Coastal location? (within 500m of sea — Coloursteel Endura required)
Ready to Order?
Once you have your measurements, browse the DoorsNZ range to find the right door for your opening size and get an instant price — no quote process, no waiting.
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Not sure about your measurements? Contact DoorsNZ — send us your numbers and we'll confirm the right door size before you order.