NZ Grown Redwood for Windows & Doors

Timber joinery has been a significant feature in our rammed earth homes. Of the approximately 80 earth homes that I’ve built, only 2 of these dwellings have used materials other than timber for their doors and windows.

Typically 3 different timbers are used in our exterior joinery – macrocarpa for the frames, NZ grown Australian hardwood for the sills and NZ grown redwood for the doors and window sashes.
I’ve been using redwood (NZ grown only) for exterior joinery in our homes for the past 20 years with significant success. I have found that this timber, when sourced properly, produces stable, durable, high quality doors and windows that need only a relatively simple maintenance schedule to last for generations in a well built home.

The initial reasoning behind using NZ redwood was that I didn’t want to use aluminium, tanalised timber, imported timber or native timber.

Moving away from these four choices deserves a brief explanation;

  • Aluminium – requires a large amount of energy to extract and refine.
  • Tanalised timber – simply put, this process uses particularly poisonous/harmful substances that have been toxifying land used for treatment areas in our country for years.
  • Imported timber – unsustainable diesel miles and questionable/unregulated forestry activity in other countries.
  • Native timber - insufficient sustainable forestry and the encouragement of black market use (where illegally milled timber gets released into the market under the guise of sustainably milled native wood).
(Sustainability in the construction systems in the homes that I design and build has been a driving ethic for the last 25 years – since I drew a line in the sand about what I would and would not build to hopefully create a legacy of durable, attractive, healthy homes that have minimum impact on the finite resources available.)

It is important when selecting the redwood to be used for exterior joinery, that it is clear of knots and from the heart (as opposed to the sapwood which is not durable). Generally speaking in New Zealand the better redwood is grown in colder areas like the Central Plateau of the North Island. The last lot of redwood we used (see Puhoi Home) was sourced from the Gisborne area (thanks Simon and Geoff) and is among the best redwood I have encountered grown in New Zealand. On the other hand redwood sourced from the Waikato basin has been of rather poor quality with an abundance of dead knots that aren’t always visible prior to milling the log.

It’s important to maintain a regular oiling schedule on the exterior doors and windows. Joinery with high UV (sun) exposure may need to be oiled as much as once a year whereas joinery sheltered from the sun (like under a verandah or on the south side of the home may only need oiling once every 4 to 6 years.

We have been using Biopaint products exclusively now for the past 6 years now with very pleasing results. Painting the joinery is also a good option where exposure to the elements is particularly high although this does come with a higher maintenance cost than oiling.

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