Draughty doors and windows are one of the most common complaints from New Zealand homeowners — and one of the most fixable. Whether you're battling the damp southerlies in Wellington or the cold Central Otago winters, sealing up gaps around your joinery can make a real difference to your comfort, your heating bills, and even your compliance with the Healthy Homes Standards.
Why Weatherproofing Matters in New Zealand
New Zealand's climate varies enormously, but most regions experience wind-driven rain, humidity, and cold snaps that can push moisture and cold air through even small gaps. Beyond comfort, uncontrolled moisture ingress can lead to mould, timber rot, and damage to wall linings — issues that can become costly if left unchecked. BRANZ research consistently shows that draughts and poor sealing are among the leading causes of heat loss in NZ homes.
For rental properties, landlords must also meet the Healthy Homes Standards, which include requirements around draught stopping — so this isn't just a comfort issue, it can be a legal one.
Finding the Draughts First
Before you buy anything, locate where the air is getting in:
- Hand test: On a windy day, slowly move your hand around door and window frames, hinges, and sills. You'll feel cold air on your skin.
- Candle or incense stick: Hold it near suspected gaps — the smoke or flame will flicker where air is moving.
- Visual inspection: Look for daylight showing around closed doors, cracked or missing sealant, and gaps between the frame and the wall.
Common culprits include the gap under external doors, the meeting rails of double-hung sash windows, around sliding door tracks, and where frames meet the wall cladding.
Products and Materials to Use
New Zealand hardware stores stock a good range of weatherproofing products. Here's a quick guide:
| Gap Type | Recommended Product | Where to Buy |
|---|---|---|
| Under external doors | Door bottom seal / door sweep | Bunnings, Mitre 10 |
| Door frame sides & top | Foam, rubber, or brush draught strip | Bunnings, Mitre 10 |
| Window sashes (timber) | V-strip (tension seal) or foam tape | Bunnings, Mitre 10 |
| Frame-to-wall gaps | Paintable acrylic sealant / gap filler | PlaceMakers, Bunnings |
| Larger structural gaps | Expanding polyurethane foam | PlaceMakers, Bunnings |
| Exterior frame/cladding joins | Flexible exterior sealant (e.g. Sika) | Bunnings, Mitre 10 |
Tip: For exterior applications, always choose a sealant rated for outdoor use and UV exposure. Sika offers a range of flexible sealants suitable for NZ conditions.
Step-by-Step: Sealing an External Door
1. Door Bottom Seal
This is often the biggest source of heat loss. Measure the door width, then choose either a door sweep (screws to the inside face of the door) or an automatic door bottom (rises when the door opens, drops when it closes). Cut to length with a hacksaw and fix with the screws provided. Check the seal compresses evenly across the full width when the door is closed.
2. Door Frame Draught Strip
Clean the door stop (the rebate the door closes against) with a damp cloth and let it dry. Peel-and-stick foam or rubber compression strip is the easiest option — press it firmly into the door stop so the door compresses it when shut. For a longer-lasting result, choose a kerf-in rubber or brush seal that slots into a groove routed into the timber.
3. Threshold Seal
If there's a gap between the door bottom and the threshold, a door threshold seal or weather bar can be screwed to the floor. Make sure it doesn't create a trip hazard.
Step-by-Step: Sealing Windows
Timber Sash Windows
These are common in older NZ villas and bungalows. V-strip (tension seal) works well — cut strips to length and press them into the channel where the sash slides. They're nearly invisible and last for years.
Aluminium Joinery
Check that the existing pile weatherstripping (the fuzzy brush-like strip) inside the frame isn't worn or compressed flat. Replacement pile strip is available at most hardware stores and simply pushes into the existing channel.
Frame-to-Wall Gaps
For gaps between the window or door frame and the surrounding wall or cladding, use a flexible acrylic sealant on interior surfaces (paintable, so it can be finished neatly) and a flexible exterior sealant on outside surfaces. Apply with a caulking gun, smooth with a wet finger, and allow to cure fully before painting.
Exterior Cladding Joints and Flashings
If you notice gaps where the frame meets the exterior cladding, or where flashings have lifted, these need attention before water gets into the wall cavity. Small gaps can be sealed with a quality exterior sealant, but if you suspect water has already been getting in — look for staining, soft timber, or bubbling paint — it's worth getting a professional assessment. Moisture in wall cavities is covered under NZ Building Code clause E2 (External Moisture), and repairs may need to meet those requirements.
Painting Over Sealant
If you're sealing interior gaps and want a tidy finish, use a paintable acrylic gap filler rather than silicone — silicone cannot be painted over. Resene and other paint suppliers stock suitable gap fillers and can advise on compatible topcoats.
When to Call a Professional
Most draught-proofing is straightforward DIY work, but call a qualified tradesperson if:
- You find rotted or damaged timber in frames, sills, or surrounding structure — this may need a Licensed Building Practitioner (LBP). Check lbp.govt.nz.
- There are signs of significant water ingress into wall cavities.
- You need to replace joinery entirely — this is more complex and may require building consent depending on scope.
- Electrical wiring is near gaps you're working around — never disturb wiring yourself. All electrical work must be done by a registered electrician (EWRB).
For a reliable local handyman or builder to help with weatherproofing, you can search tradedirectory.co.nz to find qualified tradespeople in your area.