What to do if your neighbour's building work cracks your house

You're working from home, the excavator next door is hammering rock, and later you notice a crack above the hallway door that you're fairly sure wasn't there last month. It's a common situation, and a stressful one. The good news is that a few calm, early steps make it much easier to work out what happened and get it fixed if the works were responsible.

This guide is general information for homeowners in NSW, not legal advice. If a claim becomes serious, speak to a solicitor.

1. Make sure everyone is safe

Most cracks near building works are cosmetic. A few signs mean something more serious may be happening:

• Cracks that are widening noticeably over hours or days
• Doors or windows that suddenly jam or won't latch
• A retaining wall, fence or boundary wall that has started to lean
• Ground cracking or sinking near the excavation, or water appearing where it hasn't before
• Falling plaster, or cracking around a chimney

If you see these, keep people away from the affected area and contact your local council straight away. The NSW Government's guidance says concerns about dangerous excavation should go to council for immediate attention.

2. Record the crack properly

Do this the same day, before anyone patches or paints anything:

• Photograph it close up and from further back, so the location in the room is obvious. Include a ruler or tape measure in the close-up.
• Measure it. Note the length and the widest point. A plastic crack-width card from a hardware store is useful, but a ruler is better than nothing.
• Mark the ends lightly in pencil with the date. If it grows, you'll see exactly how far.
• Write down the date and what the works were doing, such as rock breaking, excavation, compaction or piling. Builders' activities change week to week, and your notes help link damage to a stage of the job.
• Check the rest of the house, especially the side facing the works: walls, ceilings, cornices, floor tiles, external brickwork, paving, fences and any pool.

Take new photos from the same positions every few days. A crack that stays the same is a different story from one that keeps opening.

3. Find out whether a dilapidation report was done

Many development consents and complying development certificates require the builder to have a dilapidation report done on neighbouring properties before work starts. If an engineer inspected your home before the job, ask the builder for a copy. You're entitled to know what was recorded about your own house.

With a report in hand, check whether your crack appears in it. If it doesn't, or if it's now longer or wider than recorded, that's the clearest evidence you'll get. If it was already there at the same size, it probably isn't from the works, and that's worth knowing too.

4. Tell the builder in writing

Raise it early and keep it factual. An email to the builder, and the owner of the site if you know them, should include the date you noticed the damage, where it is, your photos and measurements, and a request that their engineer inspect. Keep a copy of everything.

Most builders deal with this regularly. A prompt written notice gives them the chance to check their methods, such as switching from rock hammering to rock sawing, and to involve their insurer if needed. The NSW Government's advice is to try to negotiate a resolution with the property owner or builder in the first instance.

5. Know who handles what

If talking to the builder doesn't resolve it, the NSW Government's guidance on neighbouring development describes the main roles:

• The principal certifier inspects the work at set stages and can issue directions where work doesn't comply with the consent. Certifiers don't supervise or manage the work day to day.
• Your local council can investigate breaches of consent conditions and take enforcement action, including stop work orders.
• NSW Fair Trading handles disputes about builders and tradespeople, and Building Commission NSW deals with complaints about licensed builders and certifiers.
• For damage to your property, the guidance points to Community Justice Centres for mediation, a solicitor, and the NSW Civil and Administrative Tribunal (NCAT) where a dispute can't be settled.

Rules and processes change, so check the current guidance on the NSW Government website before you lodge anything.

6. Get an independent engineer's inspection

An independent engineer can inspect your home, record every defect with photos and measurements, and compare it with the earlier dilapidation report if there is one. That comparison is exactly what a post-construction report does. Each item is shown as unchanged, changed or new.

If there's no earlier report, the engineer can still give a professional view on the likely cause from the crack's pattern, direction and location relative to the works. Fresh cracks often look different from old ones that have collected paint, dust or previous filler. That view is less certain than a before-and-after comparison, but it's far stronger than an owner's recollection alone.

Not every crack comes from next door

It's worth keeping an open mind. Houses move with the seasons, especially on reactive clay. Plasterboard joints open up, render shrinks, and timber frames dry out. Many homes already have cracks that nobody noticed until works next door made them look closely. A measured record works both ways. It protects you if the works did cause damage, and it saves everyone a long argument if they didn't.

If works haven't started yet

If you've just heard that excavation, demolition or a pool is planned next door, ask the builder whether a dilapidation report on your home is part of their plans, and agree to the inspection. If they aren't arranging one, you can commission your own. A record made before the first machine arrives is the simplest protection there is.

We inspect homes across Wollongong, the Illawarra, the Shoalhaven and Greater Sydney. Request a quote or call 0450 787 971.