A Backbone Emerges

Witnessing the forging of the rammed earth walls over the past week has triggered an immense sense of wonder and inspiration amongst those on site. Not one person could resist running their hand over the raw elemental mass and giving it a good rap with their knuckles - these actions usually followed by a raising of eyebrows in an expression of awe and impression. Being the oldest building material in the world, earthen walls and structures seem to activate a vestigial memory and respect in our human psyche. After the final formwork was taken down for the 'keystone' piece (a technique that to our knowledge has not been put into practice in rammed earth structures) there was a certain astonishment and dream like surreality about the scene. Although the spanning section had its skeptics, the engineering seems to have transferred from paper to palpable existence. So without any further ado here are some pictures of the glory that is rammed earth:

This photo is of the 'keystone' piece nestled between its two supporting wall sections with angular and lip/notch connections. To give you a bit of a step by step here are two prior shots of the walls before the keystone and with the form work in place.

One of the most unique aspects of rammed earth, is the ability to place nooks and embed objects into the wall anywhere you like as it is being tamped. For this home's walls we kept it simple and did a few knock outs with Volume Displacement Boxes (V.D.B.'s). In the picture below are the 2 wall sections that will be what the headboard of the bed will be against in the master bedroom.

Above you can see the 3 day old wall segment on the left with its V.D.B.'s removed standing in contrast to the recently stripped section on the right with the V.D.B.'s still in place. We decided that we had to utilize the potential of the V.D.B.'s and created little spaces for 'nightstand' alcove areas on either side of the bed. Because the walls are 4 meters (13 ft.) we also decided to break up the face of the wall by adding a few more recessed spaces for candles/books/art or the insertion of a thick shelve. Below is a picture taken from the top of the form work looking inside the form's cavity (as it fills with earth). Although the photo below is a bit disorienting and confusing, you might faintly make out the top of a V.D.B. covered by a thin layer of sifted earth (one of the short ones in the bedroom wall). When trying to solve this view, keep in mind that you are looking down into the form and that the leg and foot on the left side is standing on the current tamped level of the rammed earth. The V.D.B. is screwed in the desired area to the inner-side of the panel, and buried carefully.

Along with the V.D.B. you can also see the white conduit for the electrical outlets (also implanted in the wall) on the left, and some black rebar on the right which connects the footing to the top of the eventual concrete bond beam.

For your video viewing pleasure, we have posted two new clips on our youtube channel (both embedded below) associated with the rammed earth process.
First off, is a short segment capturing a part of the mixing and preparation of the 'brew' to be put into the forms.

The 'brew' consists of earth sourced from the Cardrona Valley (30 km/19 mile away, near Snowpark) which itself is roughly 80% gravel& sand and 20% clay. This is then mixed with a 10% add mix of cement and water. The mix is kept surprisingly (at least to the novice eye) dry and then transported to the wall and shoveled in approximately 100 mm (4 in.) loose layers and tamped down to slowly build the wall. Below is a quick glimpse at some of the tamping action.

The video above was taken from a scaffold and the end pan of the site is an attempt to show the scale of the home (final drawings/plans coming soon!!), but we will leave of with a couple more shots of the two rammed earth monoliths, as well as the staple before and after shot.

And the biggest visible change yet!

If you have any additional questions or requests shoot us an e-mail at: altshiftnz@gmail.com, or post them in the comment box below. If any of you are looking for a greater amount of detail and info on the rammed earth procedure, look on the weekly detailed blog this coming Sunday. Also, Blogger has changed its photo formatting recently and the photos in this post are unfortunately as large as I can get them, but we should be able to figure something else out soon, so if you are looking for larger pictures check back in a few days or e-mail us and we will be happy to send them to you as an attachment.

Lastly, many thanks to Jimmy Cotter, Joe, and Shane of Down to Earth - it was great working with all of you! To have been a part of the experimentation (evolution?) of rammed earth construction with the implementation of the keystone piece, 4m. high walls, and XPS foam V.D.B.'s was remarkable and rewarding.

As always, thanks for reading and talk to you soon.


  1. Fantastic work.

    I've not seen a "keystone" piece like the one above your door.

    Best of luck on your project.



  2. Great stuff! YOu did a fine job with the rammed earth wall, it is indeed quite impressive. I was just wondering why have you decided to go for the keystone, what are are the advantages of using this in the case of a rammed earth wall?

    Look forward to seeing more updates! :)

  3. Hello cmcm! The keystone was a bit of an experimental technique for creating a door/opening in the rammed earth. The other option would be having the door as one giant V.D.B. or buck inside the form work and ramming around that, we decided to see what the keystone would look like. It adds a bit of dynamism to the wall. We could have also done the spanning above the door with another material, but there will be north facing clerestory windows beaming in low winter sun, so we wanted the thermal mass of the rammed earth as a receptor for the solar gain at that height. Thanks for your question, and let us know if you have any more. PEACE.

  4. Mesmerizing! Truly! Look forward to watching the continued evolution of your home.