Why is hempcrete so special?
The growing popularity of hempcrete is based on the fact that it holds a unique position as a building material, combining the qualities of thermal mass and insulation. It has thermal mass (think concrete, bricks or hot water bottle) to maintain stable temperature, bank up internal heat and shield from harsh summer sun. Interestingly, it’s also insulative due to its porous, airy, fibrous composition, reducing heat transfer and loss. These two properties work in tandem to outperform most current day wall systems whilst remaining low-tech, ecological and easy to install. Reducing electricity usage and dependence on air conditioning by tremendous margins. Its promise and interest are continually demonstrated in an ever growing raft of studies.
Hempcrete also has specific breathability properties, actively absorbing and diffusing vapour throughout its large mass. This is vitally important because there is a common misconception that temperature is the gold standard for warmth or comfort, whilst ignoring the dramatic effect of moisture content in your home. You become colder faster when moisture is present. Ever notice how quickly you freeze after leaving the pool?
Or when you’re sweating and enter an air-conditioned room, think about how quickly you become cold. Ever notice how cold you are after a shower before drying off. The more moisture, the quicker heat conducts from you. In fact, the reason your body sweats (creates moisture) is to remove excess heat from the body.
One of the gifts of Hempcrete to the industry is its strong moisture regulation and moisture buffering abilities. It protects from the moisture spikes which modern houses are known for. Creating healthy, comfortable and stable temperatured homes.
Hempcrete balances internal enclosures to a relative humidity of between 40% to 60%, the range within which humans have evolved to find comfort. We interpret spaces with stable humidity as ‘comfortable’, whereas rooms with too much moisture as ‘stuffy’ or ‘damp’
Hempcrete strength is its simplicity, or because of what it is not. A standard Australian wall can include a brick veneer, insulation, sisilation, a damp proof membrane plus external cladding; all aspects which can fail, are co-dependent and have varied lifespans. The simplicity of Hempcrete is that it can perform the duties of all these materials as a single monolithic system. Plus Hempcrete being airtight, solid and devoid of wall draughts. This is hugely important because complete thermal envelope of the house is created. Its continuity diminishes thermal bridging, probably the largest contributing factor to heat entry and exit. What is thermal bridging?
Hempcrete is a robust building material. For older houses and renovations, it is cast around existing timber studwork, therefore contributing strongly to the diagonal bracing or racking strength requirements of the frame. Hempcrete can be placed behind common exterior weatherboards, the lime binder inhibits timber rot and stabilises the timber frame, effectively preserving it.
Hempcrete also works well with standard brick veneer houses. The internal plaster and existing insulation is removed, the hempcrete is placed to fill the cavity; from the internal brickwork all the way back to the internal wall line. This creates tremendous future energy savings. Hempcrete teamed with exterior masonry works very well and is in fact the major application of hempcrete in Europe. On jobs I’ve worked on in the UK, Hempcrete was often adhesed internally to old stone walls for barn conversions.
Hempcrete also be retrofitted externally onto existing walls if existing eave size and design permits. In this case a lime render is applied to the external face of the Hempcrete.
All are fantastic options for creating a complete thermal envelope of the house, substantially increasing energy efficiency.
For houses with issues with damp, hempcrete can help to disperse and diffuse moisture. As opposed to dry walling where a false wall is ‘packed out’ to hide the damp issue
You could negate all your gains from a lifetime recycling and bike riding to work just by building a new house. A new build carries a carbon footprint of between 50 to 80 tonnes. Retrofitting or renovating your home not only looks great but also carries a huge carbon saving.
Contact William for all inquiries re Hempcrete building.