James Henderson’s Earth Floor

James Henderson, of Henderson Clayworks, is a natural builder from Australia currently living and working in the northwest United States. Over the past 10 years he’s developed a reliable earthen floor system described in detail below.

1)  Compact a 100mm drainage layer, preferably volcanic rock to increase insulation.

Pumice stone

2)  Cover the drainage layer with a geotextile filter fabric. A less expensive option is shade cloth.

3)  Compact at least 100mm of road base or compactable fill, up to 25mm of the finished floor level.

4)  Apply 19mm of a course, sandy floor mix, at least 4 parts sand to 1 part clay. Load bearing strength is provided by the sand, and the amount of clay has to be reduced to eliminate shrinkage cracks.

 

James checking the mix

Application of first 19mm layer.

5)  Embed a fiberglass plastering cloth in the first layer.

Pressing in the fiberglass mesh

6)  Apply another 6mm of the floor mix with a little more clay to attain a finish thickness of 25mm.

Application of the finish 6mm layer.

The additional clay increases hardness and durability, and introduces more fine particles to get a smoother finish.

7)  Before repeating the process, remove the last 100mm of the 6mm top coat from the previous pass to expose the mesh.  This acts as a guide when applying the next 19mm layer. 

70-100mm overlap with the previous fiberglass sheet

8)  When embedding the next sheet of fiberglass plastering cloth, overlap the sheets 70-100mm.

9)  Complete the entire floor in one-day without cold joints.

Working in consecutive courses complete the floor in one day

Application Complete

10) The following day compress the floor with a wood float, preferably mahogany. The wood float should sound dry and grind, not slide.  Use Styrofoam knee-boards to prevent point loads. If the knee-boards make an indentation in the floor, the floor is still two wet and should be allowed to dry longer.  After compression with the smooth wood trowel is complete, compress the floor with a steel finishing trowel. Mist with water as needed.

Compressing Floor

11)  Allow the floor to dry for several weeks. When completely dry, apply four to six consecutive coats of raw linseed oil, one after the other, all in one day.  After the final application, do not allow the oil to pool on the surface of the floor and remove any excess oil. If allowed to pool on the floor it will take longer to dry.

To note, 19mm and 25mm were chosen because 19mm and 25mm are standard guide thicknesses in Australia.