Answers From The Experts: Cross Laminated Timber the New Log Home?
We are excited to start 2017 with another edition of our Answers from the Experts series.
In this episode we speak with Darren McAvoy a Forestry Program Associate at Utah State University.
He’s an advocate for Cross Laminated Timber (CLT) and has recently obtained a grant to build the first CLT building in Utah.
We speak to him about all things CLT including if it can be used to build log homes and what advantages CLT offers over traditional logs.
For people unfamiliar with Cross Laminated Timber, please can you explain what it is?
Cross Laminated Timber, or CLT has been more common in Europe over the last 20 years but is just being used in the USA. It is a means of using waste wood to make massive wood walls; by joining together small boards, traditionally using glues or metal joinery, walls up to 15 inches thick can be built that have high thermal mass, are structurally sound and relatively fire resistant.
Please can you explain what your involvement with Cross Laminated Timber is?
I am the chair of the Utah Biomass Resources Group, we try to find value for waste wood. Euclid Timber Frames is a company in Utah that I work with on CLT structures. They have invented a system called Interlocking CLT, this uses no metal or glues, only wood joinery, such as four-way dove-tails, to create the massive wood walls. Together we received a Wood Innovations Grant from the US Forest Service for $160,000 to design Utah’s first public CLT building, at the Utah Botanical Center in Kaysville, Utah.
Example of Interlocking CLT
Could you please tell me more about this first public CLT building…
The building will be a 4000 square foot, open floor plan facility that can hold up to 200 people in a single room for Extension educational events. It will also be rented out for banquets and weddings and such. It will have a demonstration kitchen so that programing will include cooking instructions for disadvantaged youth. The building will be the centerpiece of the already existing Utah Botanical Center so in one facility we can teach people how to grow, harvest, prepare, cook, and enjoy their fruits and vegetables that grow just outside the door in the edible demonstration garden and nearby orchards. This will be a holistic Extension facility that will seamlessly deliver outreach activities that include components of agriculture, horticulture, family and consumer sciences, natural resources, and more, all under one roof. It will also be a place where architects and builders can gather for programming on Cross Laminated Timber construction, while in a CLT building!
To your knowledge have any log homes already been built using CLT?
I refer to CLT construction as the modern log home, partly because it feels similar to a log home; being surrounded by wood. There have been many buildings made from CLT in Europe, and there are perhaps a half dozen built or being built in North America.
How sustainable is CLT when compared to other building materials such as traditional logs, concrete or steel?
CLT is very sustainable; the energy required to build a building is much less with CLT than with concrete or steel. Log homes are great, but not for everybody. CLT buildings are currently being constructed that are more than 20 stories tall, and there are plans to make one 100 stories tall, a wooden Empire State Building, so to speak. Another joking term for them is ply-scrapers, like plywood and skyscrapers mixed.
You previously mentioned that Cross Laminated Timber is the modern log cabin? Does it offer advantages over building with traditional logs?
We can use small diameter logs that are otherwise useless, this allows us to thin forests which can improve forest health and reduce wildfire danger. It also offers the chance to build taller structures, with fewer air gaps and more insulation value.
What are the insulation properties of Cross Laminated Timber when compared to log construction?
This is hard to say and dependent on many variables, but as I said, very few gaps and thicker wood outside.
Would you be able to give a rough cost comparison between log construction and Cross Laminated Timber?
CLT costs perhaps 25% less than stick constructions, I don’t have a number for log construction, but compared to stick, the finished walls and insulation are already included, making it more cost effective. Another advantage is that most of the work is done in the shop and assembly of the pre-manufactured wall sections is quick, which is important in cold climates by reducing costs and snow delays.
At this point I’d like to thank Darren and Utah State University for taking part in the interview. I hope it’s been helpful to all of our readers.
If you have any questions about CLT and its use in cabin construction please be sure to leave a comment below and we will do our best to get Darren’s response to these questions.