Picking the right timber for an outdoor project is one of those decisions that seems straightforward until you're standing in the yard with a coffee, staring at three very different options. Treated pine, macrocarpa, and cedar each have genuine strengths — and real trade-offs. Whether you're building a deck, a fence, a raised garden bed, or a pergola, this guide will help you make a confident, informed choice for New Zealand conditions.
A Quick Overview of Each Timber
Treated Pine
Treated pine (typically radiata pine pressure-treated with preservative) is the workhorse of the NZ outdoor timber market. It's widely available at Bunnings, Mitre 10, and PlaceMakers, and it comes in a huge range of sizes and profiles. The preservative treatment — usually a copper-based compound — protects against rot and borer, and timber is graded by Hazard Class (H) to match its end use. H3.2 is the minimum for above-ground exterior use; H4 is required for ground contact and H5 for in-ground or in-water applications. Always check the hazard class stamp before buying.
Because it's a plantation-grown softwood, treated pine is the most affordable option and the easiest to source. It does have a tendency to warp, twist, and check (surface crack) as it dries, and its green-tinged appearance isn't to everyone's taste. Left uncoated, it weathers to a grey-brown. It can be painted or stained, but needs regular maintenance to stay looking good.
Macrocarpa
Macrocarpa (Cupressus macrocarpa) is a naturally durable NZ-grown timber with a warm, golden-brown colour and a distinctive, pleasant aroma. It's a favourite for rustic outdoor furniture, raised garden beds, pergolas, and fencing — particularly in rural and lifestyle settings. Macrocarpa contains natural oils that give it good resistance to rot without chemical treatment, making it a popular choice for vege gardens where people prefer to avoid preservatives near food.
It's not as widely stocked as treated pine, so you'll often source it from specialist sawmills or timber merchants. Quality and dimensions can vary more than with commercially graded timber. It's a moderately hard softwood — easier to work than hardwoods but slightly more prone to checking than cedar.
Cedar
Cedar — most commonly Western Red Cedar (Thuja plicata) imported from North America — is the premium choice for outdoor cladding, decking, screening, and feature structures. It's lightweight, dimensionally stable (meaning it moves very little as humidity changes), and naturally resistant to rot and insects. Cedar has a beautiful reddish-brown colour that weathers gracefully to a silver-grey if left unfinished, or can be maintained with oil or stain.
The main drawback is cost: cedar is significantly more expensive than treated pine, and somewhat pricier than macrocarpa. It's also a softer timber, so it can dent and mark more easily in high-traffic areas like decking.
Head-to-Head Comparison
| Criteria | Treated Pine | Macrocarpa | Cedar |
|---|---|---|---|
| Durability (untreated) | Poor — needs treatment | Good — natural oils | Very good — natural oils |
| Durability (treated/finished) | Very good (H3.2–H5) | Good | Very good |
| Appearance | Functional, green tinge | Warm golden-brown, rustic | Rich reddish-brown, premium |
| Dimensional stability | Moderate — can warp/twist | Moderate | Excellent — very stable |
| Weight | Moderate | Moderate–heavy | Light |
| Maintenance required | High (paint/stain regularly) | Moderate (oil or leave to grey) | Low–moderate (oil or leave) |
| Suitability for ground contact | Yes (H4/H5 grade) | Not recommended | Not recommended |
| Safe for vege gardens | Debated — check grade | Yes | Yes |
| Availability in NZ | Excellent | Moderate (specialist mills) | Good (most timber merchants) |
| Ease of DIY | Easy — cuts and nails well | Easy–moderate | Easy — lightweight |
| Rough cost guide | $ (most affordable) | $$ (mid-range) | $$–$$$ (premium) |
Cost guide is approximate and varies by region, supplier, and timber dimensions. Get quotes from your local merchant.
NZ-Specific Considerations
New Zealand's climate varies enormously — from the humid, wet West Coast and Northland to the dry, UV-intense Central Otago summers and the salt-laden coastal environments of places like the Coromandel or Wellington's south coast. BRANZ research consistently highlights that moisture and UV exposure are the two biggest enemies of outdoor timber in NZ.
- In high-humidity or coastal areas, natural durability matters more. Cedar and macrocarpa hold up better without constant recoating.
- In ground-contact applications (fence posts, retaining walls, pergola footings), only H4 or H5 treated pine is appropriate — neither macrocarpa nor cedar should be used in direct ground contact.
- For decking, the NZ Building Code and NZS 3604 set out requirements for structural timber. Treated pine H3.2 is the standard structural choice; if you want macrocarpa or cedar decking boards, they're typically used as the top surface over a treated pine subframe.
- Raised garden beds for food growing: many gardeners prefer macrocarpa or cedar here, as there's ongoing debate about copper-based preservatives leaching into soil. If you use treated pine, look for current-generation treatments and avoid older CCA-treated timber.
Finishing and Maintenance
All three timbers benefit from a quality finish. Resene and Dulux both offer exterior timber stains and oils suited to NZ conditions. As a general rule:
- Treated pine needs a penetrating stain or paint system and regular recoating (often every 2–3 years depending on exposure).
- Macrocarpa can be left to weather naturally or treated with a UV-stabilising oil to preserve its colour.
- Cedar is similar — a quality exterior oil or clear finish every couple of years keeps it looking great, or simply let it silver off naturally.
Always allow new timber to dry and acclimatise before finishing, and follow the manufacturer's preparation instructions.
Cost Considerations
Treated pine is consistently the most budget-friendly option and is ideal when you're covering large areas or working to a tight budget. Macrocarpa sits in the mid-range — you may pay a premium for well-dried, clear-grade boards. Cedar is the most expensive, but its longevity and low maintenance can offset the upfront cost over time. Get quotes from at least two or three suppliers, as prices vary significantly by region and timber grade.
Our Recommendation
Here's practical guidance for the most common NZ scenarios:
- Deck structure (joists, bearers, posts): Use H4 treated pine — it's the right tool for the job, code-compliant, and cost-effective.
- Deck boards (surface): Cedar is the premium pick for looks and stability; macrocarpa for a rustic, local feel; treated pine if budget is the priority.
- Fencing: Treated pine (H3.2 rails, H4 posts) for economy; macrocarpa for a natural, character look.
- Pergolas and garden structures: All three work well above ground. Cedar's light weight and stability make it a joy to work with.
- Raised garden beds: Macrocarpa or cedar are the go-to choices for food gardens.
- Retaining walls: H4 or H5 treated pine only.
If you're unsure about the structural requirements for your project, or if it involves anything that needs a building consent, it's worth talking to a qualified carpenter. You can find licensed local tradespeople at tradedirectory.co.nz who can advise on the best material for your specific situation and build it to last.
