Valley Flashings in Auckland — Custom Made & Powder Coated
Valley flashings line the internal intersections where two roof planes meet, channelling rainwater down and off the roof without allowing it to penetrate the roof structure.
Get A Free QuoteWhat Are Valley Flashings?
A roof valley is the internal V-shaped junction where two pitched roof planes meet. Rainwater from both roof planes runs toward this junction, making it one of the highest water-concentration points on any roof. A valley flashing is the formed metal liner that sits in this junction, providing a watertight channel that carries the combined water flow down and off the roof without letting it infiltrate the structure.
Valley flashings are installed under the roofing material (corrugated iron, tiles, slate, or other) and must extend sufficiently up both roof planes to contain the water flow even during heavy rainfall. The profile can be a simple V or U shape, or can include upturned edges (sometimes called valley soakers or valley liners) that prevent water from being blown back under the roofing material in high winds.
At Coating Lab we manufacture valley flashings to order in your specified width and length, in your choice of material and colour finish.
Where Are Valley Flashings Used?
- At every valley (internal roof corner) on pitched roofs — where two sloping planes meet
- Between the main roof and a dormer roof on the lower slopes
- At the intersection of two wings of an L-shaped or T-shaped house roof plan
- Between a main house roof and an attached garage or lean-to roof
- Under mono-pitch roofs that drain to a centre gutter
Materials Available
We manufacture valley flashings in the following materials:
- Stainless Steel — superior corrosion resistance, excellent for coastal and high-moisture environments
- Galvanised Steel — traditional choice, durable and widely used across NZ residential roofing
- Aluminium — lightweight with excellent corrosion resistance, good for coastal locations
- Colorsteel — pre-painted to standard roofing colours for visible open-valley installations
Profile Options
We offer both standard profiles and custom-made to spec. We manufacture valley flashings to drawing or sample. The key dimensions are the total width (to suit both roof planes and provide adequate water containment), the depth of any upturned edge, and the length of the run. For complex valley angles or large-scale projects, provide drawings or site measurements.
Colour Options
For open valley installations where the flashing is visible, powder coating to match the roofing colour improves the visual result. Available colours include:
- Colorsteel colour range — Karaka, Ironsand, Ebony, Grey Friars, Sheerstone, Dune, Gull Grey, Thunder and others
- Resene colour matching
- Dulux colour matching
- Full RAL colour range
- Custom colour matching from a physical sample
Who Uses Valley Flashings?
Our valley flashing customers include:
- Builders — detailing roof valleys on new builds with L-shaped or complex roof plans
- Roofers and roofing contractors — replacing failed valley flashings during re-roofing jobs or sourcing custom widths
NZ Building Code Considerations
Flashings play a critical role in meeting the weathertightness requirements of the New Zealand Building Code. Valley flashings must be wide enough to contain the design water flow for the roof catchment area and roof pitch. They must be correctly lapped at joints and turned up at the head. Always consult your building consent documentation for specific requirements.
Related Flashings
Valley flashings are part of a complete pitched roof weatherproofing system:
- Roof Flashings — the broader family of weathertight junction profiles for pitched roofs
- Apron Flashings — for roof-to-wall junctions where a dormer meets the main roof
- Ridge Cappings — for the apex of the same pitched roof
- Drip Edges — for the eave and rake edges of the same roof
Frequently Asked Questions
In an open valley, the metal valley flashing is visible between the two roof planes, with the roofing material cut back from the centre to leave a clear channel. In a closed or woven valley, the roofing material covers the valley and the flashing beneath is fully hidden. Open valleys are common with corrugated metal roofing; closed valleys are typical with tiles.
The required width depends on the roof pitch, the valley angle, and the rainfall exposure of the site. A steeper pitch or a more acute valley angle generally requires a wider flashing to handle the volume of water and prevent overtopping. Contact us with your roof details for guidance.
Yes. We can powder coat valley flashings in any RAL, Resene, Dulux, or Colorsteel colour. For open valleys this improves the visual integration with the roof. For hidden valleys, the finish is less critical but powder coating can still improve corrosion resistance.
Galvanised steel is the traditional choice for valley flashings due to its durability and cost. Aluminium is a good option for coastal locations, and stainless steel is available for high-corrosion environments. The choice should also consider compatibility with the roofing material above — some metal combinations can cause galvanic corrosion when in contact.
Valley flashings are lapped at joints, with the uphill piece overlapping the downhill piece by a sufficient distance to prevent water entry under the joint. We manufacture flashings in the lengths you specify — contact us with your valley length and we will advise on optimal piece lengths. We can manufacture flashings up to 3 metres in length.