Repairing a section of lath and plaster in an older New Zealand home is a different job from patching modern gib. The wall can be brittle, the keying system is often fragile, and if you rush it, the repair can crack again or sit proud of the surrounding surface.
If you’re dealing with a hole, loose plaster, or a section that has broken away, the aim is to make the damaged area stable first, then rebuild the patch in layers so it blends properly with the rest of the wall.
1. Work out how bad the damage is
Start by checking whether the damage is just to the plaster face or whether the lath behind it has also failed. Light tapping can help you find hollow or loose areas around the break. If plaster is crumbling, lifting away from the timber laths, or you can see movement, the repair will need more than a skim over the top.
Before you begin, clear away any loose material, dust, wallpaper, old paint flakes, and anything hanging off the edge of the hole. Use a scraper carefully so you don’t enlarge the damaged area more than necessary.
- Remove all loose plaster back to solid edges
- Brush away dust so the patch can bond properly
- Check for cracked or broken laths behind the surface
- Make sure the area is dry before you repair it
2. Stabilise the lath and build a sound base
If the laths are still in place, the new plaster needs something to grip to. In older homes, the original plaster keyed through the gaps between the timber strips, so your patch should imitate that as closely as practical. Where lath is missing or loose, you may need to secure backing material behind the opening before patching.
For smaller repairs, a backing strip or repair board can be fixed behind the hole to support the new plaster. For larger sections, a more substantial base may be needed so the repair doesn’t sag or crack later. The important thing is to create a firm edge and a stable surface for the patch to bond to.
- Fix any loose laths before patching
- Use backing support where the opening is too large for plaster alone
- Avoid forcing modern fasteners through fragile old plaster unless needed
- Keep the repair flush with the surrounding wall thickness
3. Apply the patch in thin layers and finish carefully
A good repair also depends on the paint prep. Seal the patched area before painting so the finish coat does not flash or absorb unevenly. If the wall has been previously painted with older products, it is sensible to test for compatibility before coating the whole section.
When to call Steve
If the damage is wider than a small patch, the plaster is moving, or you’re not sure how to make the repair blend into an older wall, it’s worth getting advice early. Steve, a Kiwi and a trade-qualified painter, can assess the condition of the lath and plaster, recommend the right prep method, and carry out a repair that is ready for a quality paint finish.
That’s especially useful in older Auckland homes where one section of wall may have been altered, patched before, or painted many times over. A proper assessment can save time, reduce the chance of cracking, and help the finished wall look consistent with the rest of the room.
Frequently Asked Questions
Can I repair lath and plaster myself?
Small, stable patches can often be repaired by a careful DIYer, but older lath and plaster walls can be brittle and unpredictable. If the wall is loose, cracked widely, or already has multiple repairs, it’s safer to get a professional opinion.
What should I use to patch lath and plaster?
Use a plaster repair product suitable for interior wall repairs, and build it up in thin layers. The exact system depends on the size of the hole, the condition of the laths, and whether the wall needs backing support.
Why does my patch keep cracking?
Cracking usually means the base was not stable, the repair was too thick in one go, or the edges were not properly prepared. Movement in the old wall can also cause new cracks if the underlying issue has not been addressed.
Need a hand with your project?
Happy to tackle some of it yourself? Great — but for anything you’d rather leave to a professional, Steve Lunjevich is a Kiwi and a trade-qualified painter with 20+ years’ experience. Call or email for honest advice or a free, no-obligation quote.