Valley (Gutters) Building Codes & Rules

4th rib if corrugated

Notching^{Tools™ Best Practice}

• ≤ 3mm gap
• Tight to rib

≥ 15^{NCC 2022 HP, 7.4.4 (4) (c)}

W

≥ 150^{NCC 2022 HP, 7.4.4 (4) (b)}

Sarking

• 25mm turn down & seal over gutter^{HB 39:2015, 5.3.2 (o)}
• Protect from UV^{Tools™ Best Practice}

Upturn Freeboard

D

Overhang

Blanket Insulation

Sarking

Purlins

Purlins

Roof Structure

≥ 12.5°^{NCC 2022 HP, 7.4.4 (4) (a)}

≥ 25^{HB 39:2015, 5.3.2 (o)}

Overhang

Eaves Gutter

Pitch

Roof Structure

End of Valley turn down

Valley Board

Fall

Blanket Insulation^{HB 39:2015, 3.10}

• Cut back insulation at fascia / sheet end
• Profiled foam filler strip or end cap to roof sheet

Fastening^{HB 39:2015, 5.4 (d)}

• Galvanised nail, or
• fixing cleats bent down at ≥ 500mm CTS

≥ 150^{HB 39:2015, 5.4 (f)}

≥ 12.5°^{NCC 2022 HP, 7.4.4 (4) (b)}

≥ 300^{HB 39:2015, 8.2 (b)}

Discharge Width

Roof Sheet

Lap Joint

Ridge Capping^{HB 39:2015, B4.1.3}

• ≥ 150mm cover > 5° roof pitch
• ≥ 200mm cover < 5° roof pitch

Catchment Area

≥ 15^{Tools™ Best Practice}

≥ 25^{HB 39:2015, 5.4 (e)}

≥ 20m^{2HB 39:2015, 5.4 (k)}

≥ 19^{HB 39:2015, 5.4 (h)}

≥ 150^{NCC 2022 HP, 7.4.4 (4) (b)}

Metal Roof Sheet^{Tools™ Best Practice}

• Spans & fixings to manufacturer's profile specification
• Profile to suit pitch & rainfall intensities
• Install hail guard angle above all box guttering

Valley Gutter

• Width (W) & Depth (D) designed according to intensity of rainfall^[1]
• < 12.5° Pitch must be designed as a Box Gutter^[2]

Valley Gutter Dimensions

NCC 2022 V5

NCC 2022 Vol 1, F1D3

NCC 2022 Vol 2, H2D2

NCC 2022 HP, 3.3

NCC 2022 HP, 7.4.4 (4) (b)

HB 39:2015, 5.4 (i)