Timber could help deliver Ireland’s housing needs

Analysis: Why aren’t we using Irish wood to build Irish homes quickly, cheaply and sustainably at a time when we are in desperate need?

By Michael Morris, TCD

Like many nations in the developed world, Ireland has a desperate need for new homes. But we face the dual challenge of building them quickly and well – whilst also meeting environmental commitments to cut our carbon emissions by 51% by 2030.

Unfortunately, our traditional methods of construction, like bricks, mortar, concrete and steel, come high in embodied carbon. It’s clear we need an alternative. One environmentally favourable option is to increase the use of timber in construction. It has a vastly lower carbon footprint than concrete and steel and is a sustainable product when gown and used properly. It can also accelerate building speed: by some estimates, it’s around 30% faster to build with.

Yet, here in Ireland, less than a quarter of the homes we build are timber frame constructions. That’s half the rate in the rest of the developed world. And most of those homes built in Ireland using timber are single or two-story constructions. Meanwhile, elsewhere in Europe and throughout America, Asia and the antipodes, you can find towers 20 stories high built using timber frames.

From Futureville, How stronger timber could help deliver Ireland’s housing needs

So why aren’t we using Irish wood to build Irish homes quickly, cheaply and sustainably at a time when we are in such desperate need?

A significant problem is that we grow our major wood source (Sitka Spruce) in Ireland very quickly – approaching two or three times faster than an equivalent tree in Scandinavia. That’s because we have ideal growth conditions and longer growing seasons. However, faster growth means lower density. And that means wood that’s weaker – more than adequate for internal use, but not for external or weight-bearing applications.

We do have a healthy timber export market. However having strong exports means moving to different wood sources that take longer to grow is financially challenging for growers. But, at the Research Ireland funded Amber Research Centre at Trinity College my team and I have devised a way to make Irish timber more suitable for construction.

There is a natural polymer within the wood structure, called lignin, that provides the wood its durability and strength. However, the internal structure of Irish wood compromises its strength. It has a highly open pore structure and is of relatively low density. We have developed a way to remove the lignin from Irish timber, such as ash, and this allows strengthening processes to be used.

After the lignin is removed, the wood can be densified by compression to yield a high density material that can exceed the strength of the strongest natural woods. We are currently looking at methods to remove the lignin and replace it with a modified lignin that bonds to the fibrous cellulose structure of the wood and increases the strength.

These methods use sustainable materials (i.e. lignin) and can produce wood approaching the strength of steel. These materials could transform house construction in Ireland, by creating a cheaper, abundant and highly sustainable building material right here on our doorsteps.

Source: RTE