Cladding choices
First impressions count. The cladding we choose for our homes will be the first thing anyone sees. We know that judgements will be made as soon as a visitor catches sight of the dwellings. Psst – the picture at the top of this post bears no resemblance to our homes just in case you’ve already started judging the look.
We want our cladding to be effective and low maintenance. However, we have to be careful not to end up with homes I would call functionally beautiful. Those are the ones where the residents continually explain the benefits of the house’s appearance. “Of course, it does look really unusual, but you need to know about the [insert environmental benefit here].”
Using the reverse brick veneer construction method means our cladding is just there to protect the insulation from the weather. Insulation is what stops heat reaching the thermal mass of the internal walls or heat leaching out of the internal walls. Cladding is a thin layer, intentionally. On hot days, a thin layer will heat up quickly but, equally, it will cool faster at night. This arrangement reduces the overall heat load on the underlying insulation. In winter, the insulation will do its job of preventing heat from inside the home leaking out. The cladding is not designed to be a last line of defence for heat loss.
We have chosen a palette of four materials – panels, steel, wood and Timbercrete (also known as Lignastone).
Our choices were influenced by information taken from the Your Home website. It’s a Government initiative that is designed to provide useful information about environmentally sustainable homes.
Panel cladding provides a neat, clean look.
Panels cover large sections, but the rectangular shapes offer a more interesting appearance than a blank wall. The eastern elevation of Unit 3 shows the panels running along the eastern wall and around to the northern wall.
Now, sir and madam, what type of panel would you like to use? We’re likely to use either plywood or fibre cement panels.
Plywood panels are a renewable resource when sourced from plantation forests. Another advantage is the panels can be re-used if the cladding is ever removed. They do require sealing and painting initially. Maintenance requirements can be further reduced by specifying a higher grade of plywood. But, like most things in life, there is a trade-off. Higher grades are more weather resistant due to the glues/preservatives added to the wood. What is a good balance between exposing our builders to these chemicals and maximising the life of the material?
Fibre cement such as Scyon is another common cladding material. The name gives a clue to the mixture of advantages and disadvantages. Using wood fibres from sustainable plantations is a positive, but the cement component brings a high embodied energy content. Manufacturing can add another dose of embodied energy, depending on the process used. Maintenance requirements for fibre cement are quite low as, like the plywood panels, repainting is needed to ensure the surface stays waterproof.
Steel cladding chosen for western walls.
Summer sun takes its toll on western wall claddings. We chose Klip Lok steel (or an equivalent) because of steel’s ability to take this punishment. It appears to be the low maintenance choice for western walls. When installed with care to avoid scratches, it will last and last. Coated steel can age gracefully and doesn’t require regular painting.
Traditionally people think of corrugated iron as steel cladding. But, using a product like Klip Lok on walls instead of a roof offers a more elegant surface. The ribs will create a range of shadow patterns as the sun passes overhead.
Once again, sustainability positives and negatives come into play. Steel has a high embodied energy and is made from a non-renewable resource. On the upside, committing those resources makes a product that lasts. Other materials might be less-energy intensive in their production, but will they represent good value when compared to something that can last 100+ years? Another positive is future uses for steel cladding. If someone decides to replace the cladding, it is easy to find another home for it or send it off for recycling.
Recycled wood is a feature cladding.
To create some areas of feature cladding, we are using timber reclaimed from the house currently on the site. Everyone is quite excited about the prospect of de-constructing the 60’s era house to see what can be re-used. If the floorboards we uncovered in the front room are anything to go by, there is some good timber here.
The aim is to use a section of timber cladding to draw the visitor’s eye to a front entrance. The natural colours of timber are warm and soothing – just the thing to welcome visitors.
An idea we are exploring is to have the timber cladding flow into the air-lock section of the house. This avoids a sharp contrast between outside and inside, making a connection between the two spaces.
Re-using milled timber is the big sustainability benefit for this cladding. That timber is already on-site and waiting to be put to use. The life of this wood could go well beyond 100 years once it’s included in the new dwellings.
Some walls have no cladding.
Another feature cladding is to have no cladding. Let the Lignastone (Timbercrete) blocks stand out proudly to show what the rest of the walls are built from. Obviously the sustainability benefit in this case is avoiding the use of any additional resources for these walls.
One example of a cladding-free zone is the external wall on the air-lock leading into Unit 3. The drawing above shows the southern elevation of this unit. Having an exposed Timbercrete wall on the right hand side, complemented by a timber wall on the left, marks the location of the front entrance. You can’t see a door because it is tucked behind the Timbercrete wall.
Garage walls are another case where cladding isn’t required and the wall becomes a feature.
What’s behind the cladding?
What highly insulating yet sustainable material is going behind the cladding? I’ll let you know in the next post.
