Loose weatherboards are a common issue on older New Zealand homes, especially those clad in native timber or radiata pine that has dried and shrunk over the years. The good news is that re-nailing them is well within the reach of a careful DIYer — as long as you use the right nails, the correct technique, and take your time to avoid splitting the board.
Why Weatherboards Come Loose
Weatherboards work loose for a few common reasons:
- Nail corrosion — older galvanised or plain steel nails rust and lose their grip, particularly in coastal or high-rainfall areas
- Timber shrinkage — as timber dries over time it shrinks across the grain, which can cause boards to cup or pull away from the framing
- Inadequate original nailing — some older homes were nailed with too few fixings or nails that were too short
- Framing movement — seasonal movement in the wall framing can gradually work nails loose
Before you start re-nailing, check whether the boards are simply loose or whether there is underlying rot, moisture damage, or structural movement. If boards are soft, discoloured, or crumbling, replacement may be needed rather than re-nailing. BRANZ has good guidance on assessing weatherboard condition.
Tools and Materials You'll Need
- Hammer (a 450–500 g claw hammer is ideal)
- Nail punch (to set nails below the surface)
- Pry bar or flat bar (for gently easing boards back into position)
- Drill with a fine bit (for pre-drilling — more on this below)
- Stainless steel or hot-dipped galvanised lost-head nails — 75 mm is a common size for standard weatherboards into framing
- Exterior filler or putty (to fill nail holes before painting)
- Exterior primer and topcoat — Resene and Dulux both offer quality NZ exterior paint systems
Choosing the Right Nails
This is critical. Always use stainless steel or hot-dipped galvanised nails for exterior weatherboard work — never bright (uncoated) steel, which will rust and stain the boards. For most standard 150 mm bevel-back weatherboards, a 75 mm lost-head nail driven into the stud framing gives a solid fix. Check the nail length is sufficient to penetrate at least 40–50 mm into the framing behind the cladding and building wrap.
Step-by-Step: Re-Nailing Without Cracking
1. Locate the Framing
Nails must go into the wall studs, not just the cavity or building wrap. Use a stud finder or look for the existing nail pattern — studs are typically spaced at 400 mm or 600 mm centres in NZ framing to NZS 3604 standard construction.
2. Pre-Drill to Prevent Splitting
This is the single most important step for avoiding cracks. Always pre-drill a pilot hole through the weatherboard before driving a nail, especially near the ends or edges of boards, or in older, drier timber. Use a drill bit that is slightly smaller in diameter than your nail shank — roughly 2.5–3 mm for a standard lost-head nail. Drilling removes the risk of the nail wedging the timber grain apart.
3. Ease the Board Back Into Position
If a board has bowed or lifted, gently lever it back toward the wall using a flat bar with a piece of timber behind it to protect the board face. Don't force it — if there is significant cupping, work slowly and consider dampening the back of the board slightly and allowing it to relax before nailing.
4. Drive the Nail at a Slight Downward Angle
Angle the nail very slightly downward (about 10–15 degrees) toward the framing. This helps pull the board tight and improves holding power. Drive the nail until the head is just proud of the surface, then use a nail punch to set it 2–3 mm below the surface. Never hammer the nail flush with a hammer head alone — you risk bruising or denting the board.
5. Fill, Prime, and Paint
Fill the nail holes with a good-quality exterior filler once the nail is set. Allow to dry, sand smooth, spot-prime, and apply a topcoat to match the existing paint. Skipping this step allows moisture to track into the nail hole and accelerate future problems. Wattyl and Resene both stock suitable exterior primers and fillers.
Tips for Older or Brittle Timber
- Work on a mild, overcast day — timber is less brittle when it isn't bone dry from summer heat
- If boards are very dry and prone to splitting, a small amount of beeswax or soap rubbed on the nail shank reduces friction
- Avoid nailing within 25 mm of the end of a board without pre-drilling
- If a board cracks despite your best efforts, exterior-grade filler can repair minor cracks; significant splits may mean the board needs replacing
Building Consent Considerations
Re-nailing existing weatherboards in the same position is generally maintenance work and does not require a building consent. However, if you are replacing a significant area of cladding or altering the cladding system, you may need consent — always check with your local council. The MBIE Building Performance website has clear guidance on what work falls under Schedule 1 exemptions.
When to Call a Professional
Call a qualified builder if:
- You find rot, moisture damage, or mould behind the boards — this may indicate a weathertightness issue requiring proper remediation
- Boards are cracked, warped, or damaged beyond simple re-nailing
- You suspect structural framing damage behind the cladding
- The job involves significant areas of cladding that may trigger consent requirements
A Licensed Building Practitioner (LBP) is the right person for cladding work — you can find qualified local builders on tradedirectory.co.nz. Check that any builder carrying out restricted building work holds a current LBP licence at lbp.govt.nz.
Sources & Further Reading
- BRANZ – Weatherboard maintenance and repair
- MBIE Building Performance – Building consent and Schedule 1 exemptions
- Licensed Building Practitioners – Find or verify an LBP
- Standards NZ – NZS 3604 Timber-framed buildings
- Resene – Exterior paint and primer systems
- Dulux – Exterior coatings for NZ conditions