Valley Replacement

Roof valleys handle more water per unit area than any other part of your roof. Where two roof planes meet, all the rainfall from both slopes concentrates into a narrow channel that must carry it swiftly and safely to the gutters below. When a valley is working properly, you don’t notice it. When it fails — or when it’s blocked and overflowing — you notice it quickly, usually as a ceiling leak or water damage in the room below.

At Roof Restoration Coffs Harbour, Nathan Locke and his team carry out valley replacements across the Mid North Coast. With over 25 years of local experience, full licensing, public liability insurance, and a 10-year workmanship warranty, we replace valleys properly — with the right materials, the right waterproofing, and attention to the details that prevent future problems.

When Do Valleys Need Replacing?

Valleys can be cleared and maintained for many years, but there comes a point where the valley material itself is the problem — and no amount of cleaning will fix that. Here are the key indicators.

Corrosion and Rust

Metal valleys — whether galvanised steel, lead-coated steel, or other materials — are exposed to persistent moisture, organic acids from decomposing debris, and the coastal environment that accelerates corrosion in unprotected metals. Over time, the valley iron corrodes through. Small rust-through holes initially don’t cause obvious leaks because the adjacent tiles often redirect water, but as corrosion progresses, the valley loses its ability to contain the water flow and leaks develop.

In Coffs Harbour’s coastal environment, this process can be faster than in inland areas. Galvanised steel valleys that might last 30+ years in a dry inland climate can show significant corrosion within 15–20 years in a saltair-exposed coastal position.

Cracking and Structural Failure

On older homes, valleys may be made from materials that are now known to crack with age — including older bitumen-coated products and certain plasticised materials that become brittle. Cracked valley material provides no waterproofing — water flows directly through the crack and into the roof structure. Cracked valleys cannot be repaired effectively in the field; replacement is the only durable solution.

Persistent Blockages

Some valleys develop repeated blockage problems that aren’t primarily caused by external debris accumulation. A valley that sits at too low a pitch (typically less than 15 degrees for an open valley), that has sections with incorrect fall, or that has corrugated or damaged surfaces that trap material will block repeatedly regardless of how often it’s cleaned. When the valley geometry is the problem, replacement with a new valley at the correct pitch and with an appropriate profile is the long-term solution.

Failing Bedding and Mortar

On tiled roofs, the tiles adjacent to the valley are often bedded in mortar at the valley edges. When this mortar fails — which is common as mortar ages and loses flexibility — the tile edges can lift or shift, opening gaps that allow water to bypass the valley entirely. While repointing of the valley bedding is sometimes adequate, severely deteriorated bedding along a compromised valley often means the valley needs to come out for the full junction to be reconstructed properly.

Undersized or Incorrectly Formed

Some valleys were never adequately sized or formed for the catchment area above them. In high-rainfall areas like Coffs Harbour, a valley that was marginal in lower-intensity rainfall will overflow in storm events. Replacement with a wider or deeper valley profile addresses the capacity problem.

Valley Types: Open and Closed

Open Valleys

An open valley exposes the valley material — typically metal — along the length of the junction. Tiles are cut to line both sides of the valley and stop short of the centre, leaving the metal visible. Open valleys are the most common type on concrete and terracotta tile roofs in this region and are the standard we install.

Open valleys have several advantages: they’re easy to inspect visually (you can see the condition of the valley material from the ground or from a close inspection), they provide good flow capacity because the channel isn’t restricted by tile edges, and they’re straightforward to clean and maintain. They do expose the valley material to UV and weathering, which means material selection is important.

Closed (Woven) Valleys

A closed valley — sometimes called a woven valley — uses tiles that cross the valley junction, with courses from each side alternating or interlocking to create a continuous tile surface with no visible valley material. These are more common on certain heritage-style and slate roofs and require careful integration of the underlying waterproof membrane.

Closed valleys are more complex to install and maintain. When a closed valley leaks, identifying the entry point can be more challenging because there’s no visible valley material to inspect. Most residential tiled roofs in Coffs Harbour use open valleys, and we work extensively with this type.

Valley Replacement Process

Inspection and Scope

We start with a thorough inspection of the valley to confirm the scope of replacement needed. We assess the full length of the valley, the condition of the tiles at the valley edges, the bedding mortar, and any visible deterioration in the roof structure below. We also check the gutters at the base of the valley — valleys concentrate significant water volumes and can contribute to gutter wear.

Tile Removal

The tiles along both sides of the valley are carefully removed and set aside for reuse where they’re in good condition. On older roofs, some tiles in this area may be fragile or already cracked and will need replacing. We account for tile replacement in our quote.

Removing the Old Valley Material

The old valley iron, PVC former, or other material is removed. We clear all debris, remove any residual sealant or bedding mortar, and inspect the underlying battens and structure for moisture damage. Any damaged structure is repaired before the new valley goes in.

Installing the New Valley

New valley material is cut to length and positioned correctly in the valley channel. For metal valleys, this is typically Colorbond or Zincalume valley iron, selected for its corrosion resistance and available in profiles appropriate for the roof pitch and catchment area. The valley material is fixed to the battens and sealed at the eave end where it connects to the gutter.

Waterproofing

Waterproofing at the valley is critical — this is a high-flow area and any gaps or inadequacies in the waterproofing will be found by the first major storm. We apply appropriate underlays or flashing materials beneath the valley iron where required, and seal all edges and junctions. On valley sections that adjoin walls or parapets, step flashings are integrated correctly.

Tile Replacement and Bedding

Tiles are relaid at the valley edges, cut to the valley line, and bedded in mortar or fixed mechanically as appropriate for the tile type. The bedding at valley edges is critical to preventing water ingress at the tile-valley junction and must be completed carefully.

Testing

We test the completed valley by running water down it from the ridge, checking flow performance and confirming no water is penetrating at any point.

Valley Replacement Materials

Colorbond Steel

Colorbond is our standard recommendation for valley replacement. The zinc-aluminium alloy and baked enamel coating give excellent corrosion resistance in the coastal NSW environment, and Colorbond valley iron is available in the standard range of colours. For a tiled roof, a colour-matched valley creates a neat, professional appearance.

Zincalume Steel

Zincalume (without the painted finish) is a silver-grey alternative with excellent corrosion resistance. It’s appropriate where the valley will be largely concealed or where appearance is less critical.

Aluminium

Aluminium valley material is completely rust-proof and is an excellent choice for properties with very high coastal exposure.

Valley Guard Installation After Replacement

After a valley replacement is completed, we strongly recommend the installation of valley guards to protect the new material and reduce ongoing maintenance requirements. See our valley guard installation page for more information.

Why Choose Roof Restoration Coffs Harbour

• 25 years of experience — extensive experience with valley work on the full range of roof types found in the Coffs Harbour area.
• Licensed and insured — qualified roofing tradespeople with full insurances.
• Free inspections — no charge to assess and recommend.
• 10-year warranty — all replacement work fully warranted.
• Correct materials — we specify and install materials appropriate for the coastal NSW environment.

Book Your Free Valley Inspection

If your valleys are showing signs of wear, or if you’ve had a ceiling leak that might be valley-related, the first step is a free inspection. We’ll get up on the roof, assess the valleys, and give you an honest picture of what’s needed.

Call Nathan and the team at Roof Restoration Coffs Harbour on (02) 6638 9959. Our full range of roofing services is available at our services page. We service Coffs Harbour, Woolgoolga, Sawtell, Bellingen, and surrounding areas.

Don’t let a failed valley turn into a ceiling repair. Call (02) 6638 9959 for your free inspection today.

Valley Replacement and Roof Restoration

Valley replacement is frequently part of a broader roof restoration job. When we restore a roof — cleaning, recoating, repointing ridges — we assess the valleys at the same time. If the valleys are failing or close to end of life, addressing them as part of the restoration is far more efficient than completing the restoration and then returning to carry out valley work. We include valley assessment in all roof restoration inspections and provide a clear quote for any required valley work as part of the overall scope.

Similarly, if you call us for a valley replacement, we’ll inspect the rest of the roof and give you an honest picture of its overall condition. You may find the valleys are the only issue — or you may benefit from knowing the broader maintenance picture for planning purposes.

What to Expect After Valley Replacement

After a professional valley replacement, your new valleys should perform reliably for many years with appropriate maintenance. You can expect:

• Leak-free performance from the valley area, provided the installation has been tested and signed off
• Significantly reduced maintenance requirements compared to the failed valley being replaced
• A 10-year workmanship warranty covering the installation

To maximise the life of new valleys, we recommend installing valley guards at the same time or shortly after replacement — they protect the new material from debris accumulation and slow moss and algae establishment. See our valley guard installation page for more information, or ask us about including guards as part of your valley replacement quote.

Choosing the Right Contractor for Valley Replacement

Valley replacement is detailed work that requires understanding of roof structure, tile handling, waterproofing, and flashing integration. The consequences of a poorly executed valley replacement — a valley that continues to leak despite the work — are frustrating and expensive. When engaging a contractor, ensure they’re licensed, insured, and prepared to provide a written warranty on their work. That’s what we offer, and it’s what you should expect from any professional you engage for this kind of work.