A rattling roof in high winds is more than just annoying — it can signal loose fixings that, left unattended, may lead to lifted sheets, water ingress, or even structural damage. In many cases, yes, you can add extra screws to tighten things up, but it pays to understand what's causing the rattle first and to use the right fixings in the right places.
Why Is Your Roof Rattling?
Before reaching for the drill, it's worth diagnosing the cause. Common culprits include:
- Loose or missing screws — the most common cause on corrugated iron or tray-profile metal roofing
- Worn or missing neoprene washers on existing screws, allowing the sheet to move
- Thermal expansion — metal roofing expands and contracts with temperature changes, and over-tightened or incorrectly placed screws can cause popping and creaking
- Loose flashings or ridge caps — these are often the source of rattling rather than the main sheets
- Purlin spacing issues — if purlins are too far apart for the profile and wind zone, sheets can flex and drum
Take a careful look (from the ground or a safe vantage point) to identify where the movement is happening before you start adding fixings.
Is This DIY-Friendly Work?
Adding screws to an existing metal roof is generally considered owner-builder maintenance and does not require a building consent or a Licensed Building Practitioner (LBP) for straightforward re-fixing of existing sheets. However, if you are making structural changes — such as replacing purlins, altering the roof framing, or re-roofing — that work may require consent and/or a licensed tradesperson. Always check with your local council if you're unsure. You can find guidance on what requires consent at MBIE Building Performance.
Safety first: Working at height is one of the leading causes of serious injury in New Zealand. Use a properly secured ladder, wear non-slip footwear, and never work on a wet or frosty roof. For anything above single-storey, strongly consider engaging a professional. Check WorkSafe NZ for working-at-height guidelines before you start.
Choosing the Right Screws
Using the wrong screws is a very common DIY mistake that can cause leaks and accelerate corrosion. Here's what to look for:
- Self-drilling roofing screws with a neoprene bonded washer — these compress to form a weathertight seal
- Material compatibility — for Zincalume or Colorsteel roofing (common NZ brands), use screws rated for that substrate. Stainless steel or hot-dipped galvanised screws are generally recommended; avoid plain steel which will rust quickly in NZ's coastal and high-rainfall environments
- Length — screws must be long enough to penetrate the purlin by at least 25–30 mm. Measure your purlin depth before buying
- Diameter — typically 10-gauge (4.8 mm) for standard residential roofing
You'll find suitable roofing screws at Bunnings, Mitre 10, and PlaceMakers. Always check the manufacturer's datasheet or ask in-store for the correct screw for your specific roofing profile and substrate.
Where to Place Additional Screws
Placement matters. Follow these guidelines:
- Screw into the crest (high point) of the corrugation or rib, not the valley — screwing in the valley is a common mistake that creates a leak point
- Fix into purlins only — screws must land on solid timber or steel purlins, not just through the sheet into air
- Lap ends and edges — pay extra attention to the overlapping ends of sheets and side laps, as these are the most vulnerable areas in high winds
- Ridge caps and flashings — check that all ridge cap screws are tight and washers are intact; these are a very common rattle source
- Don't over-tighten — compress the washer just enough to seal without distorting it, which can cause cracking and leaks over time
| Location | Screw into crest or valley? | Fix into purlin? |
|---|---|---|
| Main sheet field | Crest | Yes |
| Sheet end laps | Crest | Yes |
| Side laps | Crest | Yes |
| Ridge cap | Crest | Yes (into top purlin) |
| Flashings | As per flashing type | Yes |
NZ Wind Zones and Fixing Requirements
New Zealand has defined wind zones under NZS 3604 (Timber-framed buildings), ranging from Low through to Extra High and Beyond. The number and spacing of fixings required increases with wind zone. If your home is in a High, Very High, or Extra High wind zone — common in Wellington, exposed coastal areas, and parts of Canterbury — standard fixing patterns may not be sufficient, and you should consult a roofing professional or check your original building consent documentation for the specified fixing schedule.
BRANZ publishes useful guidance on roof fixing and wind performance that is worth reviewing.
When to Call a Professional
Call a qualified roofer if:
- The rattling is widespread or sheets appear lifted or buckled
- You find cracked, corroded, or missing sheets that need replacing
- Your home is in a high wind zone and you're unsure of the correct fixing schedule
- The roof is steep, high, or otherwise unsafe to access yourself
- Flashings or ridge caps need significant re-working
- You suspect the underlying structure (purlins, rafters) may be damaged
A qualified roofer can assess the whole roof, identify all loose fixings, and re-fix to the correct specification for your wind zone. You can find experienced local roofers on tradedirectory.co.nz.