How to Strip Paint Off an Old Kauri Timber Floor

Stripping paint from an old kauri timber floor is a rewarding project that can reveal stunning grain and character beneath decades of paint. Kauri is a prized native timber, so it pays to take your time and use the right methods to avoid gouging, scorching, or over-sanding this irreplaceable wood. Here's a practical guide to getting it done well.

Assess the Floor First

Before you reach for a sander, take stock of what you're dealing with:

• How many paint layers? Multiple thick layers may need chemical stripping before sanding.
• Lead paint risk? Homes built or painted before 1980 may have lead-based paint. This is a serious health hazard. Use a lead test kit (available at Bunnings or Mitre 10) before you start. If lead is present, read WorkSafe NZ's guidance on lead paint and consider hiring a professional.
• Floor condition? Check for loose boards, protruding nails, or rot. Hammer down any nail heads below the surface before sanding — a proud nail will tear a sanding belt instantly.
• Floor thickness? Kauri floors can only be sanded a limited number of times before the boards become too thin. If the floor has been sanded before, check the remaining thickness carefully.

Gather Your Tools and Materials

You'll typically need:

• Drum sander (hire from a tool hire shop) for the main floor area
• Edge sander or orbital sander for perimeter areas
• Detail sander or hand scraper for corners and tight spots
• Chemical paint stripper (gel type is easier to control on horizontal surfaces)
• Heat gun (optional, for stubborn areas)
• Dust masks (P2 rated), safety glasses, and gloves
• Plastic sheeting to seal off doorways and protect the rest of the house from dust
• Vacuum and tack cloths for cleanup between stages

Method 1: Mechanical Sanding

For most kauri floors with a few layers of paint, drum sanding is the most efficient approach.

1. Start coarse, finish fine. Begin with a coarse grit (around 40–60 grit) to cut through paint quickly, then work progressively through medium (80 grit) and fine (100–120 grit) passes to smooth the surface.
2. Keep the sander moving. Never let a drum sander sit still on the floor — it will gouge the timber in seconds. Work with the grain, not across it.
3. Overlap each pass by about one-third to avoid sanding lines.
4. Edge sander for borders. Use an edge sander along skirting boards, then a detail sander or hand scraper for corners.
5. Vacuum thoroughly between grit changes to avoid coarser particles scratching the surface during finer passes.

Dust warning: Sanding generates enormous amounts of fine dust. Seal off the room, wear a P2 dust mask, and ensure good ventilation. If lead paint is present, do not sand — use chemical stripping instead and follow WorkSafe NZ guidelines.

Method 2: Chemical Stripping

Chemical stripping is slower but gentler on the timber, and is the preferred method when lead paint is present or when the floor is too thin for aggressive sanding.

1. Apply a gel-based paint stripper generously with an old brush. Gel formulas cling to horizontal surfaces better than liquid types.
2. Cover with plastic sheeting and leave for the time specified on the product label — often 30 minutes to several hours depending on the number of paint layers.
3. Scrape off the softened paint with a wide plastic scraper. Avoid metal scrapers on kauri as they can leave marks.
4. Neutralise and clean the surface as directed by the stripper manufacturer before sanding.
5. Follow up with a light sand (80–120 grit) to smooth the surface and open the grain for finishing.

Always work in a well-ventilated space and wear chemical-resistant gloves and eye protection when using paint strippers.

Method 3: Heat Gun

A heat gun can soften paint for scraping and works well on smaller areas or moulded edges. Keep the gun moving constantly and hold it at an angle — kauri can scorch easily. This method is best used as a supplement to sanding or chemical stripping, not as the sole technique for a whole floor.

Dealing with Lead Paint

If your test confirms lead paint, this changes everything. Sanding lead paint creates hazardous dust that is dangerous to breathe and difficult to clean up. WorkSafe NZ recommends using wet methods or chemical stripping to minimise airborne dust, wearing appropriate PPE, and disposing of waste correctly. For large areas, seriously consider engaging a professional with lead-safe work practices.

Finishing Your Kauri Floor

Once stripped and sanded to a smooth, clean surface, kauri responds beautifully to a range of finishes:

• Penetrating oils enhance the natural warmth of the grain
• Polyurethane or water-based floor coatings provide durable protection
• Hard wax oils offer a natural look with reasonable durability

Check the technical data sheets from suppliers like Resene or Wattyl for floor-specific products and application instructions. Always apply a test patch first to check the colour and sheen level before committing to the whole floor.

When to Call a Professional

Consider hiring a qualified floor sanding and finishing professional if:

• Lead paint is confirmed and the area is large
• The floor is very thin and at risk of being sanded through
• You're not confident operating a drum sander (they can cause serious damage quickly)
• The floor has significant damage or uneven boards that need specialist attention

A skilled painter or floor finisher will have the right equipment and experience to protect your kauri floor. You can find qualified local tradespeople on tradedirectory.co.nz.

Sources & Further Reading

• WorkSafe NZ — Lead Paint Safety
• BRANZ — Timber Floors
• Resene — Floor Coatings and Finishes
• Wattyl — Floor Paint and Stain Products
• Bunnings — Tool Hire and Supplies
• MBIE Building Performance — Healthy and Safe Homes