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Macrocarpa

Macrocarpa has a range of uses including ceiling sarking, exposed beams, flooring, wall panelling, framing, furniture, solid wood bench tops, architraves and skirtings.

It can be used outside for weatherboard, surfeit, facia, pergolas, decking and outdoor furniture. It is not recommended in-ground for construction purposes (including in-ground posts for fencing, decking and pergolas).

Sustainability of Supply

macrocarpa_90Macrocarpa supplied in New Zealand is grown within New Zealand as an exotic tree.

The timber comes from either a forested plantation source, or farm shelterbelts.

Supplies of good-quality timber are increasing, either milled to specific requirements, or available from specialist suppliers as finished products (for example, mouldings and flooring profiles).

In the early 1950s, it was estimated that there were about 360 ha of pure macrocarpa plantations in State forests, 255 in mixtures and another 405 ha in private plantations.

Well-managed plantations of cypress have since been established. The National Exotic Forest Description (NEFD) (Ministry of Agriculture and Forestry, 2006) estimated that, in 2006, there were about 7,000 ha of standing cypress plantations.

Cypress timbers currently make up the third most commonly used exotic timber species in New Zealand, with approximately 20,000 m3 cut per year.

Therefore, for small landowners, the species represents a viable economic alternative to radiata pine for woodlots.

The increase in market demand for cypresses offers farmers both a low-cost way to reduce negative impacts of farming on the environment, and a lower-impact land-use option than radiata pine.

In New Zealand, the timber is graded into Clears, Dressing and Utility grades. Supply of timber milled to larger sizes is limited in certain parts of the country, and sizes larger than 150 x 50 mm can be difficult to source.

Summary fact sheet for Macrocarpa (pdf)

Macrocarpa1

Tsunami Apartments, Mt Maunganui

Botanical name: Cupressus macrocarpa

Other common names: Macrocarpa, Monterey Cypress

Strength: Macrocarpa is a low-to medium-density softwood that looks and works like kauri.

Durability: Both the heartwood and sapwood of macrocarpa are naturally borer resistant (Anobium) for interior housing purposes. The heartwood is moderately durable for above-ground purposes, but the sapwood is non-durable. The timber cannot be pressure treated with copper, chromium and arsenic (CCA), but sapwood can be boron diffusion treated to resist insects (but not decay).

Finishes: Macrocarpa, when dry, will accept a variety of paints, oils, two pot resins and varnishes.

Working properties: Macrocarpa has a fine grain and machines and sands well to give a high-quality finish.

Appearance: The heartwood is golden brown and has a speckled lustre, which is rare in timber.

Description

Macrocarpa is a low- to medium-density softwood that looks and works like kauri.

The heartwood is golden brown and has a speckled lustre, which is rare in timber.

The sapwood is very light brown and typically occupies about five growth rings.

Freshly cut timber has a fragrant spicy odour, which is typical of cypresses. It is a very stable wood, is easily sawn and has relatively low surface hardness, with good working and finishing characteristics and relatively uniform wood properties.

This allows even small diameter logs of 15–20 cm, and young ‘teenage’ trees, to be sawn to produce quality timber.

Performance

Durability

Macrocarpa heartwood is naturally durable for above-ground purposes, but sapwood requires treatment.

The timber cannot be pressure treated with copper, chromium and arsenic (CCA), but sapwood can be boron diffusion treated to resist insects (but not decay).

For this reason, if macrocarpa is to be used for outdoor purposes, heartwood should be specified and supplied.

Above ground, the heartwood timber should be sound for 20 to 30 years, and if exposed to the weather, but protected from direct sun and rain, will last 40 to 60 years.

A 50 x 50 mm stake will last 10 to 15 years in the ground.

Both the heartwood and sapwood of macrocarpa are naturally borer resistant (Anobium) when used for interior housing purposes.

Mechanical Properties

Macrocarpa can be used both structurally and decoratively.

Please note these comparative measures of strength are “laboratory” values using standardised short lengths of clear timber. These will not be the same strength properties as structural lengths of timber. For the properties of structural length timber please see the tables under the structural design section.

For 12 percent moisture content defect-free timber, of average density, from trees felled at 30 years of age, the average properties measured on small specimens (20 x 20 mm cross section) are:

Modulus of elasticity5.79 GPa
Bending strength87.8 MPa
Compression strength parallel to the grain44.6 MPa
Shear strength parallel to the grain12.7 MPa
Side hardness (refers to indentation)3.44 kN
End hardness4.50 kN
Density543kg/m3
Tangential shrinkage - green to 12% moisture content3.3%
Radial shrinkage - green to 12% moisture content1.6%

Machining

Macrocarpa has a fine grain and machines and sands well to give a high-quality finish.

The timber is relatively soft, but has fairly uniform density from pith to outer rings. It is difficult to dry and prone to collapse and checking.

Timber for interior use should be air dried to 30 percent moisture content before kiln drying to final moisture content, timber for exterior use should be air dried to the final moisture content.

SawingNo problems
Planing and mouldingGood finish, even in areas of ‘cross grain’ surrounding large knots, provided knives are sharp.
TurningTurns well at higher speeds, similar tear out on end grain to radiata pine. Keep knives sharp and free of extractive build up.
BoringGenerally good, tendency for sides of hole to be torn if a twist drill is used.
ChisellingSome difficulty with lower-density wood. The soft wood tends to compress rather than cut. Sharp chisels are essential.
SandingGenerally sands well, with little clogging. Care required with sanding lower-density wood.
FasteningRecommended to pre-drill to avoid tendency to split.
BendingPoor steam bending properties.

Technical Documents

Formaldehyde (.pdf)

Considerations

Gluing and coating considerations

Macrocarpa, when dry, has no particular concerns re coating and will accept a variety of paints, oils, two pot resins, and varnishes.

A wide variety range of glues can be used with macrocarpa.

Other considerations

The Department of Building and Housing has issued six determinations about the use of Macrocarpa or cypress timbers in buildings.

In all six cases, the question was whether these timbers, as installed, complied with Building Code Clause B2 Durability. Other factors that were common to all the determinations were that:

  • It was accepted that compliance with Clause B1 Structure had been achieved.
  • The buildings less than five years old.
  • The relevant timbers were exposed to the weather.

In brief, the determinations were:

No 2004/10. Untreated 125 x 125 mm veranda posts were deemed not to comply with the Building Code even though they were supported on brackets so that they were not in ground contact.

No 2004/71. Heart Macrocarpa veranda posts that were not in ground contact and had their ends painted with copper napthenate preservative were deemed to comply as because they had durability equivalent to Hazard Class H3.

No 2007/97. Macrocarpa posts and beams, from a 200 x 150 to 300 x 200 mm cross section were finished with a clear preservative and had their exposed ends protected by metal cappings that were deemed to comply with Clause B2 of the Building Code.

No 2007/99. A similar determination to the previous two.

No 2007/129. The use of Lawson cypress posts and beams supporting roofs or verandas was acceptable, provided it had a preservative had been applied to end grain and exposed surfaces, and that there was sufficient drainage at junctions between posts and beams.

No 2007/129. This determination also deals with Macrocarpa columns, posts and decking. The decking was deemed to be code-compliant, but the posts and columns had to be treated with preservative and painted.

In summary, cypress timbers are the equivalent to structural grade radiata pine treated to Hazard Class H3.2 and therefore comply with Clause B2 of the Building Code if:

They are heart timbers

They are not in ground contact

They are easy to replace

Their surfaces are treated with an appropriate preservative

Their cut ends are suitably capped

They have a durability of at least 50 years according to Clause B2.3.1 (a)(i).

Applications

Macrocarpa can be used for interior uses:

  • ceiling sarking;
  • exposed beams;
  • flooring;
  • wall panelling;
  • framing;
  • furniture;
  • solid wood bench tops;
  • architraves;
  • skirtings.

It can be used outside for:

  • weatherboard
  • surfeit
  • facia
  • pergolas
  • decking and outdoor furniture.

It is not recommended in-ground for construction purposes (including in-ground posts for fencing, decking and pergolas).

Case Study

Tsunami Apartments

TsunamiapartmentsTsunami Apartments in Mt Maunganui are an example of innovative and attractive exterior wood use in a multi-residential environment.

The apartments are three storeys in height, with a macrocarpa timber weather screen façade.

Peddle Thorp Architects used the natural weathering and durability of the heart macrocarpa to suggest New Zealand coastal imagery and the ideal of the iconic New Zealand bach.

The Tsunami apartments received a Regional Award from the New Zealand Institute of Architects in 2006.

Architect: Peddle Thorpe

Availability

For suppliers of Macrocarpa timber and products refer to the Suppliers database or go to the NZ Farm Forestry Association Marketplace for availability of Macrocarpa.