The use of fabric as the primary construction material of a two storey house is almost unheard of. To get the effect of fabric, a different, more stable material has to be used- Fabric formed concrete may be the answer.

Reinforced concrete has been used since 1853 in the construction of buildings. The low tensile strength and ductility of normal concrete are counteracted by using metal bars within the length of it.

Few people have strayed from the naturally uniform form of the material, favouring instead straight, geometric lines. Recently, however, this has been set to change.

I first heard of research on fabric formed concrete taking place in the University of Manitoba, yet it seems that this has caught on. It involves casting reinforced concrete in flexible formwork, using fabric as the main material of the frame. As fabric can only work in tension, the wet concrete is held in place, while the fabric bulges out, creating forms which mirror the natural curvature. The concrete also retains the imprint of the material used, adding to the effect.

In simple terms, it is like a much larger version of plaster of paris cast using textiles.

But would this work on a full scale two storey building?

It seems it already has.

Kenzo Unno, designer and building contractor is one of the forerunners of this technique. As a response to the problem of quick rebuilding in Japan after the Kobe earthquake of 1995, Unno turned to perfecting the art of fabric formed concrete for domestic use. By using insulation as the part of the frame (the part the concrete is cast against) an insulated structural wall is created with minimal construction waste.

Two different types of form have been developed and used in his houses:

The frame method, where netting is stretched on the inside of a brace stud wall and vibrated by poking it from the outside with a stick.

wall process kenzo unno

And the quilt point method, where the frame is supported by a pattern using standard form ties on the fabric, with washers placed on the outside. The vibration method is the same.

quilt point wall process detail wall

Another method being developed is that of thin shell panels, created by spraying concrete at fabric hung like curtains. This creates a much more natural folded effect with deep indents. However, as of yet, this has not been used to create structural walls.

fullsized panel detail of wall panel Curtain full sized wall panel process model hanging formwork

In Chile, bulge wall technology was used to create features within The Open City, Ritoque. This uses the standard rigid formwork technique, lined with fabric. shapes are cut into the plywood making up the rigid formwork, which leaves space for the lining to bulge outwards with the weight of the wet concrete. This technique can also be used to make columns.

bulge wall cast plaster model of bulge wall diagrams bulge wall cast full size The open city bulge wall

Columns themselves are a feature which works even better with fabric formwork than when creating walls. Forms can be stitched, almost like sleeves, and then hung using simple scaffolding, for the fabric to be poured through. The result- surreal treelike structures, not unlike the forms of Gaudi’s architecture.

fabric cast concrete columns concrete columns a cast wall with two columns

Surely this means that it could be incorporated into creating a reinforced concrete slab ceiling for the building?

How can I use this in my building?

The form of my building is very much based on fabric. This is the perfect material and technique to use for it to work. However, the forms currently used to create structural walls are too structured for what I want.

There needs to be some way I can combine the thin shell panel method with one of the other formwork methods. It should just be a matter of using plaster versions of the thin shell panels (this which they used to develop this method) as casts which can then be broken off.

This could be used for the external facade as an extension of the Unno method of fabric formwork- therefore integrating the insulation within the wall itself.

Another method I could use is the bulge wall technique, which I like, but would mean that the design of the outside wall would have to be made a lot simpler and less natural. However, for things like the windows, and the outside stairway, this could be a very interesting option.

Concrete could also be made into a fabric-like form, in a way reversing the idea of fabric formed concrete, curtains could be made out of quilt-shaped squares with integrated rods that could then be chained together. This could solve the problem of coordinating the exterior and interior.