"IT'S a no-brainer" building a house out of hemp.
That's what Hemp Homes Australia (HHA) director and builder Gary Rogers, Margaret River, said several times when I interviewed him to discuss what building a hemp house entails and the benefits.
Perhaps it was his enthusiasm for using hemp as a building material or the sustainability properties he enlightened me about, which were fact checked, but it really does seem like a no-brainer.
It's a shame this insight has come as the build of my own house is just about to be completed, which funnily enough, was the same scenario that happened for Mr Rogers.
A few years ago he was part way through building his own home when he discovered how hemp could be used in construction, known as 'hempcrete'.
"I should have built my own house out of hemp but it was too late," Mr Rogers said.
Isn't hindsight a wonderful thing.
Mr Rogers, with wife Georgina Wilkinson, was already very involved in the hemp industry as they had a clothing and body care shop and brand, Margaret River Hemp Company, so utilising hemp in his trade, now a builder of 25 years, seemed like a natural progression.
Already a common building material in Europe which has been used for decades, HHA built Western Australia's first hemp house in 2017 in Margaret River.
Since then, hemp homes have become more common in Australia but one of the main constraints on the domestic hemp industry has been limited processing facilities, including up until recently, none in WA.
But Mr Rogers was determined to change that and opened his own hemp processing facility at Margaret River on Tuesday.
He expected they'll be able to process 30 tonnes of hemp a day.
All the hemp Mr Rogers uses in his homes is grown in WA and now it can be processed in WA.
There's a sense of provenance similar to that of the agricultural industry in using locally grown and processed products for food, fibre and now houses.
Plus, as the hemp clocks up few kilometres from the paddock to processing to the construction site, it becomes an even more sustainable product.
Previously, people wanting to use hemp would have to get it processed interstate or even import it, thus overwriting much of the environmental benefit.
To be used as a building material, the crop is harvested similarly to the way canola is swathed.
The fibres are dried, baled and then ready for processing where the bast and hurd fibres are separated.
Bast fibres are mostly used in textile production, while hurd is used in construction to create hempcrete.
The hurds are removed of impurities, graded and de-dusted.
Then lime is mixed with the hurds to act as a binder.
The mixture is then used to create hempcrete walls, which petrify (set like stone) by an open-air curing process.
Hempcrete naturally acts as effective thermal and sound insulation, providing a good microclimate and protection against mould, rot and pests, as well as being fire resistant.
It also offers quality acoustics which have been reported to be comparable to conventional insulation, as being a long, natural fibre, hemp can vibrate at the same frequency with soundwaves.
The building industry also has stated that handling hempcrete is easier and safer than conventional materials as it does not require the use of protective gloves or respirators to protect against skin or airway damage.
As hempcrete is up to seven times lighter than concrete, but just as strong when set, it is very easy to work with.
During the curing process, the material absorbs carbon dioxide from the air and stores it, simultaneously while water is evaporated.
As hempcrete is a natural product, home builders need to expect a longer drying time of about six to eight weeks, depending on the weather.
Hempcrete is usually built with a timber supporting structure, which is what HHA uses.
Researchers have said while conventional building materials are effective and long lasting, their environmental impact is direct and indirect from the beginning of when they are processed to after they're disposed of.
Materials such as concrete and brick produce CO2 when they are manufactured, whereas hemp and lime absorb CO2, however with lime only in the absorption process.
This means that hemp houses are carbon negative.
Hempcrete is the only building material that can remove carbon from the air.
Hemp is also a tall, yet fast growing crop, so the yield is very high per paddock.
Being able to build sustainable homes which are non-toxic for the owners but also for Mr Rogers and his team, has revitalised his job, which was starting to become quite mundane when he was building with conventional materials.
"To be honest, as a builder I hated doing things the conventional way and using toxic materials," he said.
"We have also reduced our landfill from three skip bins down to one."
Any left over material can be used in the next build.
"We can also be very creative with hempcrete by doing things like rounded or curved walls and that's very hard to do usually," Mr Rogers said.
"And things like that add another challenge which I enjoy, otherwise building can be quite stale doing the same thing.
"It's very rewarding knowing that we are building sustainable houses and the building process is much more satisfying.
"Most trades haven't built with hempcrete before and those I have worked with have really enjoyed it.
"It is really good for carpenters and builders to have this in their tool box."
Mr Rogers believes hempcrete builds are becoming more mainstream and it's only a matter of time until larger constructions such as apartments and offices are made using hempcrete.
"I think Australia has been pretty quick to accept using hemp," he said.
"There used to be jokes about it, like 'can we smoke the clothes', or when we built the first house, 'let's set it on fire and smoke the house', but I don't get many of those jokes anymore.
"So I think people are becoming more educated now.
"The world has changed in the past few years - people are looking to be healthier and live a more green life."
The crop can produce about 15 tonnes per hectare and for a standard three-bedroom, one-bathroom house, he said he would use about one hectare worth of hemp.
Hemp is a dominant and competitive plant which drops shade leaves, making it very difficult for weeds to grow.
This means there is no need for chemical spraying.
During the season the male plant dies after the female plant is pollinated and it will decompose into the ground and act as mulch for the female plant.
Seeing as hemp houses are carbon negative and carbon credits are starting to gain traction, Mr Rogers believes hemp homeowners should be entitled to a carbon rebate.
Based on his previous clients, he said one of the main reasons that someone would want to build a hemp house was for their health.
He said the most toxic time to be in a home is after painting, which prompted him to use an alternative.
"Now I don't use paint in the homes, I use clay and mix it with hemp and it looks stunning and provides a beautiful natural smell," he said.
"I think the second or third house that we built, we did the handover and sat in that house and it smelt so natural.
"So that showed me the breathability of the home."
A commonly asked question for Mr Rogers is if he sells hemp insulation, as conventional insulation is chemical-based.
While he does sell it, with a hemp house, no insulation is needed because the hemp walls or blocks act as insulation already.
Straw bale houses have also become more common in recent years, but according to Mr Rogers the only comparison is that the key materials both come from a paddock.
"Straw bale buildings are a lot of work," he said.
"You need 50 millimetres of render each side because it is so flammable and that amount of render is very expensive.
"And rodents love it, if they get into the walls, you will not get them out.
"I haven't seen a perfect straw bale house yet without problems, but maybe I have looked at the wrong straw bale houses."
So what are the negatives about building with hempcrete?
It can't be too good to be true, right?
Apart from the point that hempcrete can't be used below ground or under water, the negatives mostly relate to the industry being new - the fact that hemp can be difficult to source, harvest, process and therefore can be expensive, some say can be eight to 12 per cent more expensive upfront.
However, given its effectiveness at insulating homes, the additional upfront cost would likely be saved over time on heating and cooling costs.
But theoretically, as the industry develops and matures, these challenges should improve.
Hopefully by the time I am ready to upgrade my house and if I decide to build again, the industry would have developed more and a hemp house could be on the cards, after all it seems like a no-brainer.
