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How to build a walipini

Check with your local council about building regulations on your property before starting any build.

1 SITE/ORIENTATION

All-day sun is preferable, but if this is not possible, a site that gets the first sun of the day through to mid-afternoon could work. The orientation of the walipini depends on the angle of the sun, especially over cooler weather. There are online resources that can help you with the latitude and solar angles. But in the southern hemisphere, you would roughly be looking at having the larger taller heat sink wall on the south of the building and the shorter wall on the north side of the building. So a north-facing hillside would be ideal. If time is on your hands, you could start sketching sun angles at certain times of the year like the solstices and equinoxes – this will help when it comes to the roofing.

2 INSULATION/DEPTH

Check your water table level – your regional council or a local drilling company might have the information. Due to the variables of soil types and water tables, find out the correct distance between your build and water table before starting. A depth of 1.5-1.8m is adequate for the dig. Then build up the soil on the south wall – up to approximately 3m tall so there is enough thermal mass to warm up during the day. Reinforcing the walls is important due to the amount of pressure and weight the soil packed in and pushed up against them will deliver. So posts concreted in the right depth for your build is important (another reason having the help of a builder/engineer can save a lot of stress and danger down the track). In a very cold part of the country, you might even look at insulation for the walls.

3 GLAZING/ROOFING

Polycarbonate roofing comes in many forms but the twin wall or triple wall variety is better to keep heat in. In warmer climates that don’t have frosts, you could get away with a thinner variety or even thick plastic sheeting if you can’t stretch to polycarbonate. The pitch of the roofing will vary from site to site, so it’s best to get help from a local builder or engineer who can help with dimensions and work out the correct angles of the build to ensure the sun is hitting your back heat sink wall for a good portion of the day. There are also a lot of great resources online that can assist.

4 VENTILATION/WINDOWS AND DOORS

Windows and a door that you can open and close to form a good seal are going to keep that heat in overnight and allow airflow during the day. Look at cross-draft ventilation where air can go straight through the structure. Vents and exhaust fans can also be used.

CANTERBURY

en-nz

2023-06-01T07:00:00.0000000Z

2023-06-01T07:00:00.0000000Z

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