The choices in cladding systems appear to be endless. When we start our designs, we have an image in mind of how we would like the building to appear. In Habitat’s case, we were aiming for a striking silhouette of the angular form. Therefore, the cladding had to be:
- Monolithic or with very subtle detail.
- Capable of withstanding a dark colour.
- Be easily cut into desired shapes, so not to detract from our overall angular vision.
Early on, we decided that we wanted to use charred larch as a feature cladding. In order to make the larch a ‘feature’ of the building, it needed to be complimented with another, simpler cladding. It is vital that the building’s environment is factored in to cladding selection. Dark claddings in particular, need to be chosen very carefully to ensure they withstand heat from the sun – especially in areas like the Wairarapa where summer temperatures can reach the mid 30s. Some examples of claddings that are suitable for dark colours include:
- Rendered plaster.
- Fibre cement.
- Selected timbers with the right treatment (thermal modification and charring for instance).
After much consideration, we settled on James Hardie EasyLap Panel, which are large format, uniform sheets of fibre cement, that can be cut on site. These panels arrive pre-primed and can be finished in any colour standard paint or with a roller applied acrylic texture paint (including darks). The effect from afar is that it is a monolithic cladding, but up close there are subtle joins. The difference between EasyLap and other fibre cement panels, is that they have shiplap joint (see above image), rather than an expressive vertical set and control joint. This means installation is much faster and the joins between panels far more refined. They have the additional benefit of fire, moisture and rot resistance, giving peace of mind to the future owners.
The James Hardie EasyLap Panels are installed over cavity battens, which creates an air gap between the cladding and the pre-cladding (in this case, we have used James Hardie RAB). This is vital to allow a ventilated draining cavity between the two materials, and will eliminate the issue of trapped moisture. The EasyLap system uses CLD structural cavity battens (see above image), which are also made of fibre cement, making them stronger and longer lasting than traditional timber cavity battens. They are also wider than your typical timber cavity batten at 70mm, and are structural, so form a structural fixing substrate for the cladding panel as opposed to a normal cavity batten which is purely a cavity spacer. They offer the same benefits as the Easy Lap panel with fire, moisture and rot resistance.
To perform their function as structural cavity battens, the CLD battens are fixed through the RAB (rigid air barrier) to the timber framing with nails, along the entire length of the batten. The number of battens and fixings required depends on the wind zone. The higher the wind zone, the more fixings and battens needed. The EasyLap panels are then glued to the outside face of the CLD batten with adhesive sealant and then fixed with either stainless brads or screws, through the panel to the CLD batten. We’re using the stainless brad fixing method for a cleaner method (see above image). Once all panels are installed they can have textured coatings and paint applied. This allows for the system to have a 15 year product warranty.
The team are partway through installing the EasyLap panels and are finding the process extremely smooth and straightforward – keep an eye out for videos of how they cut and install the panels. Once the panels are all installed, we will experiment with a few options for the textured coating. From there the plan is to paint the panels before the windows are installed, not only to avoid the time consuming task of masking up the aluminium frames, but also to ensure the paint coats the entire panel thoroughly.