New Zealand · Generic / secret-fix

Secret-fix tray calculator

CoP secret-fix is 3° cladding pitch and a drainage check after 60 m. Type the pan cover before you trust the sheet count.

Job name

Profile Generic / secret-fix Tray / secret-fix (~30 mm)

NZS 3604 wind zone Override cover (mm) Sheet length cap (m) Waste override (%)

Placeholder tray width. Override cover width on the takeoff if you have the actual pan.

Tray cover widths vary widely (often 265–500 mm). Enter a custom cover if you know the product.

Section name

Form Plan length (m along ridge) Plan width of plane (m) Pitch (degrees) Eave overhang (m) Barge / verge overhang (m) Valley count

Supplier pricebook (optional)

Sheet $/lm Ridge $/lm Barge $/lm Valley $/lm Underlay $/m²

Your rates, GST exclusive. Totals add 15% GST. Hip flashing uses the ridge rate.

Takeoff

Check before order

Sloped area: 77.55 m²
Sheets: 41 @ 6.45 m
Cover: 300 mm · 3°
Waste: 5% → 81.42 m²
Ridge / hip: 0.00 / 0.00 lm
Barge / valley: 12.82 / 0.00 lm
Flashing cover: Cat A · ridge 130 mm · barge 75 mm

Generic / secret-fix Tray / secret-fix (~30 mm) sheetsCover 300 mm · length 6.45 m (rounded up 50 mm from 6.409 m) 41 sheets
Sheet lineal metres 262.77 lm
Underlay (10% lap allowance) 85.40 m²
Barge flashing (75 mm profiled cover)1 upstand may suffice on trapezoidal Cat A — confirm detail 12.85 lm
Apron / head flashing (skillion high side) 12.10 lm

Pitch is at or near the minimum

Low-pitch roofs need more flashing cover, more care at side laps, and a drainage check. Confirm as-laid pitch after deflection.

Cladding pitch is not design pitch

NZMRM CoP 7.1.1A: tabulated minimums are roof cladding pitch, not the building-design roof pitch. Wide purlin or portal spacing can leave the as-laid pitch below the table even when the drawings say otherwise.

This is a takeoff, not a quote

Numbers assume rectangular planes, constant pitch, sheets laid ridge-to-eave, and published nominal cover widths. Hips, valleys, penetrations, stop-ends, and end laps change the order. Confirm on the current product sheet and the latest CoP at metalroofing.org.nz.

Spec this page uses

Cover: Type the pan width. 300 mm is only so this CoP row can run, and it is not a product cover.
Overall sheet width: Type it from the same sheet. 325 mm is the placeholder blank, not a product width.
Rib height: 30 mm
Min cladding pitch: 3°
Check run: 60 m
Manufacturer extra: Tray cover widths vary widely (often 265–500 mm). Enter a custom cover if you know the product.
Source: NZMRM CoP 7.1.1A secret-fix 30 mm → 3° / 60 m

FAQ

What does the CoP row say for secret-fix?

Generic secret-fix around 30 mm rib is 3° cladding pitch and a drainage check after 60 m. A named pan can be stricter than that row.

Which cover width should the sheet count use?

The cover printed on the pan’s current sheet. Real NZ pans are often 265–500 mm. Leave the override empty only while the product is still unnamed, and treat that sheet count as provisional.

Secret-fix tray calculator

Spec this page uses

FAQ

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