Eucalyptus as constructional timber

In Ireland, Eucalyptus are mostly thought of as a firewood crop with a few enthusiasts growing specimens for their personal pleasure.
Oh and not to forget the floral foliage industry, a big earner for Ireland πŸ™‚

It is certainly true that Eucalyptus have a bad reputation when it comes to their use as constructional timber. Is it deserved πŸ€”

The main issues seem to be:

  • Eucalyptus retain moisture, and when the wood dries out the timber cracks and splits.
  • If left to dry out naturally the wood can become very fibrous and difficult to machine.

Moisture retention and cracking / splitting

My research so far suggests that this can be negated by felling during the dry months. Quite difficult here in Ireland I know, though we are seeing extremes of climate and drought periods as the effects of climate change become increasingly apparent.
Sealing of the ends of logs to prevent them drying out too quickly also seems to be beneficial.

Historical uses

When Europeans first discovered Eucalyputs in Australia and Tasmania, the timber was highly prized and for this reason the seed was exported in huge quantities to Europe and around the world.

Why πŸ€”

  • Fence posts that lasted in boggy ground for fifteen years without treatment.
  • Railway sleepers resistant to termites, other insects and fungal rot.
  • Very long lengths of salt water resistant timber for the keels of sailing ships. Also used as planking and decking.
  • Attractively grained and coloured timber for dwelling and building construction.

I had a customer right here in Ireland who had a big Globulous they cut down for beams to replace the oak ones in their old farm house. They never mentioned any issues with cracking / splitting or difficulty with machining ?

One historical report from early Irish attempts to process Eucalyptus were hampered by the machinery and techniques used to remove the bark, though these were easily overcome.
Fence posts good for fifteen years in boggy ground without treatment, this must surely be a big plus both commercially and environmentally; no chemical treatments, creosote, mighty 🀣

So growing Eucalyptus for constructional timber is viable here in Ireland. I can’t say how commercially profitable it would be, though I definitely think it is worthwhile re-evaluating. Most reports and commercial trials of Eucalyptus grown generally with a view to their suitability for constructional timber are now very dated.
Ireland isn’t currently (2020) self sufficient in constructional timber. Climatic conditions have changed significantly since the first trials and the trend towards global warming will undoubtedly continue for several decades to come. This may favour Eucalyptus forestry above other species.

Modern equipment and timber processing techniques may help alleviate the early issues found with processing Eucalyptus for use as constructional timber.

As the examples below demonstrate, Eucalyptus is currently used as constructional timber and I am a bit perplexed as to why, at the very least further trials of growing Eucalyputs aren’t underway here in Ireland.
I guess farm subsidies and grant aid deter rather than encourage 😏

Examples of constructional timber

So here’s a few photographs of examples of Eucalyputs used as constructional timber.

Tasmainian Oak, Eucalyptus Regnans used as constructional framing. Imagine using high quality oak for framing here in Ireland. Very strong, and because this is Eucalyptus it will resist rotting and insect damage without treatment, outstanding.
Eucalyptus Regnans grows very fast, very straight and very tall. So good commercial logs in a fraction of the time that English / traditional oak takes.

Photo by reawaraent

Tasmainian oak, constructional timber framing

My Irish customer said, they used their Globulus beams in the Kitchen ceiling. A bit lower than in the photo below I suspect.
Whoever constructed this ceiling didn’t seem to have any issues with cracking or machining, and it does look to be quite old, so no modern tools.

Photo by Steve Settles

The block work does look to be modern, so perhaps not so old and created for effect. Even though !

Eucalyptus internal roof structure

Eucalyptus timber is frequently used for furniture making. With it’s anti rot qualities an ideal choice for outdoors.

Photo by Janet Jenkins

Eucalyptus furniture

I suspect the wood in the photo below is Eucalyptus Robusta, common name Swamp Mahogany, easy to see why. A beautifully rich deep red / brown close grained hardwood.

A premium product that grows very quickly, though not the hardiest. I am still experimenting with Robusta, though also another variety prised for its deep red brown timber, Eucalyptus Botryoides.

Photo by Kenneth Steeves

Eucalyptus mahogany

There is a huge variation in hue and patterning in Eucalyptus timber, with Nitens being used as planking / flooring. It has a light colour and fine grain similar to oak.

Another Species to consider for constructional timber is Paulownia, though you will be growing it for light weight construction:

  • Furniture
  • Surf boards, skis
  • Musical instruments
  • Smaller boats

Though don’t be fooled, Paulownia has an exceptional strength to weight ratio, it is very light. It also has good torsional strength. Both properties making it good for furniture, surf boards etc.

Paulownia timber

Conclusion

At the very least growing Eucalyptus constructional timber for small scale private projects is currently feasible in Ireland. The examples above and that of my customer replacing ceiling beams is testament to this.

Timescales aren’t prohibitive, with returns on investment within twenty years maximum. Regnans can grow at a couple of metres a year. My Nitens have grown by at least a metre and a half per year in the last couple of years. I’m also hopeful that this growth rate will increase now they have established. So thirty metre trees in twenty years. You’ll get decent sized constructional timber from a thirty metre high tree for sure !

Fence posts are a commercial industry in Ireland, though the creosoted ones the farmers local to me use actually come from the Netherlands. Environmentally unsustainable both in terms of the carcinogenic chemicals in creosote as well as transportation fuel and other costs. Environmentally friendly and climate sustainable fence posts can be grown right here in Ireland, and quickly, mighty 🀣 Not sure that fence posts can be classified as constructional timber, though definitely a commercial proposition πŸ˜‰