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Pre-purchase borer inspection

Pre-purchase borer inspection for Auckland buyers

A building report gives you the whole house in a few hours. When it mentions borer, or when the house is the kind that usually has some, a second look at the timber alone turns one vague line into something you can price, negotiate on or walk away from while your offer is still conditional.

A pre-purchase borer inspection is a timber-only check carried out while your offer is still conditional. The inspector names the beetle from its holes and dust, says whether it is still emerging, lists which framing and flooring members are affected, and flags any timber soft enough to need a builder, so you know what the line in the building report means for this house.

The borer inspection costs $285 + GST. The fee is credited against the treatment if you go ahead with the recommended work through the same operator.

What does a pre-purchase borer inspection add to a building report?

It adds detail on one item. A standard pre-purchase building report follows NZS 4306, is visual, and covers the roof, cladding, plumbing, moisture and everything else in the time available, so borer usually earns a sentence. The borer inspection spends that time on the timber only and answers the questions the sentence leaves open: which beetle, live or old, which members, how weakened.

The government's Consumer Protection site lists borer among the signs a building inspector looks for, next to rot and damp, and warns that a visual inspection cannot find what is hidden behind finished surfaces. A borer check does not change that limit, but it does go further into the roof space and subfloor, where most of the untreated framing in an older house can actually be seen.

The two reports are meant to be read together. If you have not yet seen how borer is usually worded in a building report, the guide to borer in a building report sets out what each common phrase can and cannot tell you.

When should a buyer book a borer inspection?

Book it inside your building or due-diligence condition, as soon as the building report raises borer or as soon as you know the house is a likely candidate. Findings that arrive after you go unconditional can still guide treatment, but they can no longer shape your decision. Ask for the timing you need when you book, and leave room for a builder's visit if the report flags structural timber.

  1. Offer accepted

    Note the date your building or due-diligence condition expires.

  2. Building report

    Read the borer lines. If they are vague, or the house is pre-1952 or from the late 1990s or early 2000s, book the borer check.

  3. Borer inspection

    Roof space, subfloor, cladding and any floors or joinery the report mentions.

  4. Written findings

    Species, activity, affected members, moisture and any structural flag.

  5. Decide before the date

    Proceed, negotiate, ask for more time, or withdraw, with your lawyer's advice on the contract.

Whether your condition can be extended, and how to rely on it, is a question for your lawyer. This page explains the inspection, not the contract.

What does a buyer receive from a pre-purchase borer inspection?

You receive written findings for each part of the house that was reached, in the same order every time: the beetle, whether it appears live, which timbers it is in, the moisture conditions around them, and whether any member is weak enough to need a builder's opinion. Areas that could not be reached are listed as not inspected, so you can see the gaps as clearly as the findings.

  • A species for each area. Round holes of about 1–2 mm point to the common house borer, Anobium punctatum. Oval holes of about 3–7 mm point to the native two-toothed longhorn.
  • Live or historic. Old damage with no fresh dust often needs nothing. Live borer needs treatment, timed before the next emergence.
  • Affected members by name. Rafters, piles, bearers, joists, floorboards or weatherboards, so a builder or a treatment quote can work from the same list.
  • Moisture notes. Damp subfloors and blocked vents are recorded because they keep borer going.
  • A structural flag. Timber that crumbles or dents under a probe is passed to a builder, not to a treatment quote.

Where weakened timber turns up, with your agreement the findings go to a builder who quotes the repair. The borer inspection page describes how each part of the house is checked.

Which Auckland houses need a pre-purchase borer check most?

Three groups stand out. Houses built before 1952, when boron treatment of framing timber was first introduced, are mostly untreated native timber. Houses built or extended during the untreated-framing window of about 1995–2005 may contain kiln-dried framing with no preservative. And renovated houses mix the two, so new treated framing can sit beside old untreated boards.

Build era and borer exposure (Standards New Zealand timeline)
Build era Typical framing What a buyer should know
Before 1952 Untreated native timber such as rimu and kahikatea Villas and many California bungalows. Expect some old borer; the question is whether it is live and where.
1952 to mid-1990s Boron-treated framing became standard practice Framing is treated to resist borer, but floors, joinery and later repairs may not be.
Sept 1995 to about 2005 Untreated kiln-dried framing allowed (NZS 3602:1995, cited in B2/AS1 from Feb 1998) Treated framing was required again for consents from 1 April 2004; some houses consented earlier were finished untreated up to 1 April 2005.
After 2005 Treated framing Lower risk in the structure; check any recycled timber or older furniture.

In Auckland that puts the inner-suburb villas and bungalows at the top of the list, along with late-1990s and early-2000s houses whose framing is not stamped as treated. The library guide to house borer by build year goes through each era in more detail.

What can a pre-purchase borer inspection not see?

It cannot see inside closed walls, under fixed floor coverings or behind linings, and no visual inspection can. Borer larvae spend years inside the wood before they leave, so a timber can carry a live infestation that shows few holes yet. The written findings should say which areas were hidden or unreachable, and that list is as useful to a buyer as the findings themselves.

Season matters too. The common house borer emerges mostly from November to January according to the NZ Farm Forestry Association, so a winter inspection may find fewer fresh holes than the same house would show in summer. That is a reason to read activity notes carefully, not a reason to wait. The two-toothed longhorn works through heartwood as well as sapwood and can leave a member looking sound outside while it is hollow inside, which is why probing is part of the check.

Is a pre-purchase borer inspection worth it?

For a newer house with treated framing and a clear building report, often not. For a villa, a bungalow, a house from the untreated-framing years, or any report that says borer and recommends a specialist, it usually is: the inspection costs a small fraction of what a few replaced bearers or a subfloor treatment would, and it arrives while you can still act on it.

Prices for the inspection and the treatment ranges you might be negotiating over are on the borer inspection and treatment cost page. If the findings are mixed, the guide on whether borer is a deal breaker sets out when borer should change an offer and when it should not.

Questions people ask

What are the borer red flags in a pre-purchase inspection?

Fresh, pale dust under holes in framing or floors; oval holes in piles, bearers or joists, which suggest the longhorn; timber that dents or crumbles when probed; and a damp, poorly ventilated subfloor. Any one of these turns a line in a report into something worth a closer look before you commit. Old, dark holes on their own are far more common and usually much less serious.

What should I look for at an open home?

Look at the edges of rimu floorboards in cupboards, the underside of stairs, window sills and lower weatherboards for small round holes. Check whether there is fine dust in board gaps or on sills. Ask whether you can open the roof hatch and look into the subfloor. None of this replaces an inspection, but it tells you early whether to book one.

What gets checked in a pre-purchase borer inspection?

The roof space and subfloor first, because untreated framing is exposed there, then cladding, floors, stairs and joinery. For each area the inspector records the beetle, activity, affected timbers, moisture and any weakened member. Furniture is not usually part of a pre-purchase check, because it leaves with the vendor.

How much does a pre-purchase building inspection cost in Auckland?

Published Auckland prices for a standard pre-purchase building inspection run from about $400 to $1,200 + GST, depending mainly on the size of the house; treat that as a guide and confirm it with the building inspector. A borer inspection booked through this site is a separate fee of $285 + GST, credited against treatment if you go ahead with it through the same operator.

Can I rely on the vendor's own building report?

You can read it, and it may tell you where to look, but it was commissioned for the seller and may be months old. Borer findings in particular depend on the season and on how far into the subfloor the inspector went. Many buyers get their own report; your lawyer can advise on what reliance you can place on the vendor's.

Read before you go unconditional

Sources

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