This is the end view of an end panel that was used as part of our rammed earth form system.
Some readers have asked how we made the fancy bevel at the end of each wall.
That was accomplished by installing "chamfer strips" in the end panels of our rammed earth form work.
For sturdiness, you don't want a 90 degree corner made of rammed earth, it's bound to chip off. Better to install a small piece of wood in the corner of the form to blunt the edges of the wall. By using a thick piece of lumber at the end, we cut off another corner and double the bevels. This extra feature didn't noticeably increase the amount of hand- tamping required in the corners.
We used a "sandwich system" where the form ply is clamped to the end panels and footing with pipe clamps and walers. (All you concrete form-workers out there, no snickering)
This is by no means the only way to build a form work for rammed earth construction , but it certainly was economical for an owner-builder project of modest size such as this one.
Here is an exploded view of one of our end panels:
DIY enthusiasts might like to know that we used 57 3" screws and 63 2" screws in one panel. Double that comes to $1.50 for two end panels. There might have been some finish nails to attach the chamfer strips, maybe fifty cents worth. (All prices are approximate and in Canadian funds, of course)
We also used:
4 – 9’ pieces of 2x4 $4.00
4 -8' pieces of 2x4 $5.00
4 – 9’pieces of 2x6 $10.00
1 or 2 sheets of ¾”4'x8' paper faced Crezone signboard $60 each
(Two 19.5” by 8’ pieces per panel plus extra for chamfer strips)
for each set of end panels.
It took about a day to make two sets. Call that anywhere from zero to $100 to $400 in labour, depending on who you know.
Let's say $400 to make a set of end panels.
We found at this price it was economical to construct two sets of end panels (four total) so we were able to let a freshly rammed wall sit in the form work until we had finished forming the subsequent one.
In addition to the cost of end panels we also needed form ply. (You can't form a wall with just end panels, silly...)
We chose to use Crezone sign board because it gives a nice smooth finish but it's not cheap at $60 a sheet. We used 20 for our modest project.
Sticklers for extremely fine finishes should budget for fresh form-ply for each wall. Those with more restricted funds can just get used to the rough and ready look that serves our colleagues in Germany and Australia so well..
We used about 16 14' 2x10s ($15.50 apiece) per wall for the walers. We also needed an assortment of shorter sized pieces to form the corners. $500 pretty much covered it.
Pipe clamps were about $20 apiece and we used two per waler, so about $360 for them.
Doing the math very loosely, one could spend under $3000 and have a *complete* rammed earth form system that would last through a house or two, maybe a few garden walls, depending on how smooth a finish was required.
When you didn't need the materials for ramming any longer you can still use the wood for regular old boring stick frame construction. You can give the pipe clamps to friends as gifts when you are finished with them. Who doesn't need a pipe clamp?