In many cases, a homeowner can reattach a lifted metal roof sheet edge using tek screws as a straightforward repair — but only if you can do so safely, the damage is minor, and no underlying structure is compromised. If you're unsure about roof access, the extent of the damage, or whether a building consent is needed, it's always worth getting a qualified roofer to assess the job first.
Understanding the Risk Before You Climb Up
Working at height is one of the leading causes of serious injury in New Zealand. Before you even think about grabbing a drill, honestly assess whether you can access the roof safely. WorkSafe NZ requires that anyone working at height takes all practicable steps to prevent a fall. For most single-storey homes with a low-pitch roof and safe ladder access, a careful homeowner can manage a small repair. For two-storey homes, steep pitches, or wet/windy conditions, stop and call a professional.
Always use:
- A stable, correctly angled ladder secured at the top
- Non-slip footwear
- A roof ladder or crawl board to spread your weight
- A buddy on the ground
- Never work alone or in wet, frosty, or windy conditions
What Causes a Roof Sheet Edge to Lift?
Lifted sheet edges on corrugated or trapezoidal metal roofing are usually caused by:
- Wind uplift pulling at the sheet edge or lap
- Failed or missing fasteners (tek screws that have backed out, corroded, or were never installed correctly)
- Thermal movement over time causing the sheet to work loose
- Incorrect original installation — wrong screw spacing or screws missed the purlin beneath
Before reattaching anything, check whether the purlin (the horizontal timber or steel beneath the sheet) is sound. If the timber is rotten or the steel is badly corroded, a screw won't hold and you'll need more than a quick fix.
What Are Tek Screws?
Tek screws (also called self-drilling screws) are the standard fastener for metal roofing in New Zealand. They have a drill-point tip that bores through the metal sheet and into the purlin below without needing a pilot hole. For roofing, you'll need:
| Feature | What to look for |
|---|---|
| Material | Class 4 corrosion-resistant (for most NZ coastal and inland areas) |
| Head type | Hex head with bonded neoprene washer |
| Length | Long enough to penetrate the purlin by at least 25–30 mm |
| Colour | Matched to your roofing colour where visible |
Class 4 screws are the minimum recommended for most NZ conditions; in coastal or high-corrosion zones, check with your roofing supplier about Class 5 or stainless options. You'll find suitable screws at Bunnings, Mitre 10, or PlaceMakers.
Step-by-Step: Reattaching a Lifted Sheet Edge
1. Inspect the damage from the ground first
Use binoculars if needed. Confirm it's just a lifted edge or lap, not a buckled, cracked, or extensively damaged sheet.
2. Locate the purlins
Purlins run horizontally across the rafters. You should be able to see the existing screw lines — new screws must hit solid timber or steel, not just air. Screwing into nothing gives zero holding power.
3. Gently press the sheet back into position
Don't force a badly kinked sheet — you may crack the paint or the metal. If it won't sit flat, the sheet may need replacing.
4. Drive the tek screw
Use a cordless drill/driver with a hex bit. Apply firm, steady pressure — let the drill point do the work. Don't overtighten: the neoprene washer should compress slightly but not be crushed flat, which would cause it to leak.
5. Check the washer seal
The washer must sit flat and seal around the screw head. A crushed or missing washer is a common source of leaks.
6. Apply neutral-cure silicone if needed
If an old screw hole is enlarged or stripped, fill it with a roofing-grade neutral-cure silicone sealant before driving a new screw nearby. Avoid acetoxy (acidic) silicones on metal roofing.
Does This Work Require a Building Consent?
Like-for-like repair work — reattaching an existing sheet with screws — is generally exempt from building consent under Schedule 1 of the Building Act 2004, as it is maintenance rather than new work. However, if you're replacing a whole sheet or making changes to the roof structure, consent rules may apply. Always confirm with your local council before doing anything beyond straightforward maintenance. You can find guidance at MBIE Building Performance.
When to Call a Professional
Call a qualified roofer if:
- The roof is two storeys or steeply pitched
- Multiple sheets are lifted or the damage is widespread
- The purlins or roof structure appear damaged or rotten
- The sheet itself is cracked, badly kinked, or corroded through
- You're not confident working at height
- The roof is under warranty (DIY work may void it)
- You're a landlord — Tenancy Services Healthy Homes standards require rental properties to be weathertight
A licensed roofer will also be able to identify whether the original installation met the requirements of NZS 3604 (timber-framed buildings) and the NZ Building Code Clause E2 (External Moisture), which governs weathertightness. You can find qualified local roofers on tradedirectory.co.nz.
Roofing Association of NZ (RANZ)
Licensed Building Practitioner (LBP)
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