Frequently Asked Questions

How long does it take for a tree to mature?

New Zealand radiata pine is grown throughout New Zealand, and comprises around 90% of the nation's plantation resource.

Rotation age varies from forest owner to forest owner, but generally trees are felled between the ages of 27 to 35 years.

Wood density increases from pith to bark in the pattern most closely related to number of rings from the pith. A broad distinction is made between the lower-density corewood (10 to 15 rings from the pith) and the higher-density outerwood beyond the fifteenth ring. This density variation is little affected by growth rate.

The moderate density (375-475 kg/m3) gives the lumber excellent fastening and gluing characteristics which combine with typical softwood strength properties to allow its use in a wide variety of both small and large lumber structures. Staining and surface-finishing operations are readily carried out, it is relatively easy to dry, or season, and it is very permeable to wood preservatives making it suitable for a full range of end uses.

Douglas Fir accounts for 5% of the plantation resource in New Zealand, with a rotation age of approximately 45 years.

It has a high proportion of heart-wood, which is pinkish brown, and has marked alterations of high and low density in the annual rings. Douglas fir is used mostly for structural aopplications because it is moderately strong and can be used in untreated or treated building options.

How serious are checks and why do they appear?

A. Surface checking in splits occur as timber is allowed to absorb moisture then dries out. Surface fibres are more severely exposed to these variations than the inner core and as a result of this movement in the fibres as they dry and shrink surface splits may occur. Changes in atmospheric conditions will affect the appearance and disappearance of these checks. They are only superficial and do not usually have any affect on structural performance.

Do splits along glue lines mean delamination has occurred?

Actual delamination is a failure in the laminating process. While an opening along a glue line may be indicative of delamination, there are more common causes. Typical checking that occurs in large section timber in response to moisture variation will most naturally occur in glulam along a glue line where the natural continuation of the timber fibres is interrupted. This is often mistaken for delamination.

Will CCA treated Stratalam cause corrosion on galvanized fixings?

A. Stratalam does not act in the same way as solid unseasoned timber. This is because all glulam is manufactured from material that has been kiln-dried after treatment and the treatment salts are thoroughly fixed into the timber. This means they will not subsequently leach out or affect galvanized fixings. For additional protection bolts may be greased before inserting into treated glulam that is exposed to weathering.

Can finished Stratalam beams to pre-cut and drilled?

Any cutting, drilling or slotting that exposes unsealed timber must be protected

with an application of an appropriate weather or treatment sealer. Avoid cut-outs, rebating or drilling in the top and bottom edges. This could cause serious weakness and tension in compression areas. Consult the manufacturer or designer first.

Do I need special connections for my beams?

Stratalam can be treated as natural solid timber when it comes to fixings. The use of standard nailing systems and bolts is normal. In exposed situations dark stains can appear from the use of unprotected steel brackets and bolts. Use galvanized metal where there is any possibility of moisture.

How long should I keep the wrapping on?

Wrapping is not designed to be a water-proof protection. Wrapping should be slit to provide drainage and can be left on glulam beams for as long as possible (even during construction to protect against accidental marking). Also be aware that partial removal of wrapping to access connections may cause patches of discolouration by exposure to weather.

How can I avoid damaging my beams?

Avoid the use of chains or hard ropes that might damage the edges of beams. When lifting ensure the beams are evenly supported and use fabric slings properly secured to prevent any slipping. Be careful not to handle and lift long beams on their weak axis – flat – as they are designed to act as a beam and not as a plank.

Why should I use Stratalam instead of solid timber?

Stratalam is manufactured from selected grade, kiln-dried material and it is stronger and more stable than a solid timber beam of the same section. The tendency of large section solid timber to twist, split and shrink is greatly minimized in glulam. A glulam beam can reduce the overall section of members by up to 40% compared to unseasoned timber

Why should I use Stratalam instead of steel?

Here are just a few of the reasons. Stratalam is easier and lighter to handle and fix; more environmentally friendly; stores carbon rather than creating it; it’s the only truly renewable construction material; plantation timber uses 14 times less energy to produce than the equivalent steel beam; has superior fire resistance compared to steel; lower maintenance because Stratalam does not rust or corrode; it’s cost effective requiring no boxing in or covering of steel beams; will not buckle or distort in response to temperature changes; direct fixing of plates, joists and other connections is much easier and finally Stratalam has the natural warmth and beauty of timber that cannot be reproduced in steel.

What finish should I ask for on my beams?

If your beam is going to be used in a situation where appearance is important such as house interiors, halls etc - apperance Grade A should be specified. This calls for a flush, filled and sanded surface. Appearance Grade B is intended for applications where surface appearance is not so critical and a machine planed finish that may have occasional skips and other minor voids is acceptable.

Is there a difference in quality from where I source Strata?

All Stratalam product is made to precisely the same specifications anywhere in New Zealand and all have the same quality assurance of the Bureau Veritas Certification.

What is the life of a Strata glulam beam?

Glulam beams have a service life of at least 50 years as stipulated in the NZ and Australian Building Code. In fact we don’t have the upper limits for the life of a glulam beam. They are still in service around the world since inception in 1896.

What is the difference between Stratalam and LVL?

Glulaminated product is produced from a minimum of 3 single pieces of dressed sawn timber of a maximum thickness of 45mm, faced glued to end user specified dimensions.

Laminated veneer lumber (LVL) is from laminated parallel grained 3mm wood veneers, again manufactured to end user specified dimensions. LVL is processed as a 1.250 metre width continous billet in various standard thicknesses.

Are we using more trees than we plant?

No, in fact we plant more trees than we harvest and this encourages more planting which in turn stores more CO2.

How can these checks be minimized?

Stratalam beams should be coated to control the ingress of moisture into the timber which is done before the beams leave the factory. If the beams are exposed to weather for a period greater than 8 – 10 weeks a further coating should be applied.

For coatings to protect beams that are permanently exposed to the elements consult a coating specialist.

Which building material is least harmful to the environment throughout its life cycle?

Wood is significantly more environmentally friendly than for example steel or aluminium.

It's wrong to cut down trees isn't it?

No. New Zealand’s trees are harvested from managed plantations and replaced as they are harvested. In fact the total tree plantation area is increasing constantly. New forests are being planted on marginal land and this saves the naturally growing native forests and makes use of otherwise unproductive land.