The Hidden Cost of Kwila: Why New Zealand Should Support Local Timber Instead

Kwila, also sold as Merbau, became popular in New Zealand for a reason. It is dense, strong, naturally durable and familiar to builders. We are not pretending it is a bad material. The issue is what often gets left out of the conversation: source, traceability, forest risk, tannin bleed, and whether a local timber could do the job with a clearer story behind it.

When we talk to customers about outdoor timber, the useful question is rarely “is this timber good?” It is: good for what site, under what exposure, with what maintenance expectations, and from what supply chain?

For indoor surfaces, that same local-timber thinking carries through to our custom timber benchtops, made in Christchurch from NZ-grown timber options.

What is Kwila?

Kwila is the New Zealand trade name commonly used for Merbau, usually from the Intsia genus. It grows across parts of Southeast Asia and the Pacific, including Indonesia, Papua New Guinea and the Solomon Islands.

Its appeal is straightforward: it is heavy, hard, richly coloured and naturally durable. Those are real strengths. But a board can be durable and still raise questions about where it came from and how confidently that source can be verified.

The traceability problem

By the time Kwila reaches a New Zealand building site or retail rack, it may have passed through several hands: millers, exporters, importers, wholesalers and retailers. For a homeowner or designer, that can make the original forest source difficult to understand.

That matters because illegal logging and weak forest governance have been repeatedly documented in some Kwila-producing regions. A Chatham House report on illegal logging in Papua New Guinea estimated serious legality risks in the sector, including a widely cited estimate that around 70% of logging in PNG was illegal at the time of the report.

That does not prove every piece of Kwila sold here is illegal. It does mean vague labels like “sustainable hardwood” or “responsibly sourced” should be treated as the start of a conversation, not the end of one. If Kwila is being specified, ask for chain-of-custody paperwork, species information and supplier evidence.

Certification helps, but it does not answer everything

Good documentation is better than no documentation. Certification and supplier records can improve confidence, especially on larger architectural or public projects where procurement has to be defensible.

But certification does not change the basic trade-off. Kwila is still an imported tropical hardwood. It has travelled a long way, comes from regions where land-use and legality issues have been significant, and often competes against local materials that can be specified with a more direct New Zealand provenance.

The practical issue customers notice: tannin bleed

There is also a practical drawback that has nothing to do with ethics: fresh Kwila can bleed. When it gets wet, it may release dark reddish-brown extractives. Those can stain pale concrete, tiles, paving, walls and nearby surfaces.

This does not make Kwila unusable. It means the material needs to be detailed honestly. Pre-weathering, drainage, fixing details, surface protection and maintenance expectations all matter. Outdoor timber always needs care.

A local alternative: West Coast Red Heart Beech

At Innate, the material we keep coming back to in this conversation is West Coast Red Heart Beech. It has warmth, colour variation and a local supply story that is easier to understand than a long tropical hardwood chain.

New Zealand native timber is not a free-for-all. Legal indigenous timber harvesting and milling is controlled under the Forests Act framework, including MPI Sustainable Forest Management permits and plans for approved native timber production.

Local does not automatically mean better. A timber still has to suit the exposure, detailing, finish and maintenance plan. But when the project suits it, a New Zealand material with clearer provenance is a much stronger starting point than an imported timber chosen only because it is familiar.

How we would choose between them

If someone brought this decision into the workshop, we would not start with a slogan. We would ask where the piece is going, how exposed it will be, whether staining nearby surfaces matters, what maintenance the customer will realistically do, and whether the provenance of the timber is part of the brief.

For some jobs, a verified imported hardwood may still be chosen. For many New Zealand homes, outdoor tables, decking details and custom furniture pieces, the better answer is to compare Kwila with a well-specified local option before committing.

FAQ: Kwila decking and local timber alternatives