4.4 House with Pumice-panel Walls

4.4.1 Sectional steel load-bearing system

Technical description:

This structure essentially consists of steel channel sections with pumice panels in between.

The house rests on a reinforced-concrete strip foundation with cutouts for the steel channel sections (or profiles made of galvanized sheeting). The cutouts are filled with concrete after" the walls are properly squared.

Four wall panels of the kind described in Chapter 3.2.4 are stacked on edge between each two uprights, producing a rigid wall element measuring 2 m in height and 1 m in width (cf. relevant isometric drawing).

The wall structure gets its stability from the strip foundation at the bottom and a continuous tie beam in the form of a steel channel track at the top (cf. details in the relevant technical drawings).

The steel tracks are joined at the corners by riveting or welding (cf. 1:10 details in the relevant technical drawings).

Openings for windows and doors can be placed as desired simply by leaving out the appropriate pumice-concrete panels. The window and door cases are made of simple square timbers of the same thickness as the panels set in the channel sections.

The floor comprises a layer of coarse gravel, a layer of sand, and a layer of smooth concrete screed.

The roof consists of zinc sheeting nailed onto a wooden substructure, although any other suitable material could also be used.

GATE has also published instructions for building this house (under the name "concrete panel house"); the instructions are available from GATE on request.

Bill of quantities:

Figure 73: Plan

Figures 74 and 75

Figure 76: Section

Figure 77: Isometric view

Figure 78: Details

4.4.2 Wooden post and beam system

Technical description:

This house is built according to the same basic system as the preceding house, except that the frequently very expensive steel channel sections are replaced by relatively inexpensive wooden posts and beams. While the model house has corner posts measuring 10 × 10 cm and intermediate/interior posts and tie beams measuring 7 × 10 cm, the wooden-post cross sections ultimately depend on the thickness of the pumice-concrete panels. The posts should consist of sawn wood that has been treated against pests with chemical agents, tar, used oil, lime, saltwater, etc.

Cutouts of adequate size are left for the wooden posts in the natural-stone or concrete strip foundations. The posts are inserted into the cutouts and wedged in place. Later, the cutouts are filled with concrete. Thin laths nailed onto the wooden posts hold the panels in place. One lath can be left out at first to allow easier stacking of the panels. Only when all of the panels are in place and properly aligned should the last lath be nailed on. The horizontal joints between the panels can be closed with mortar (= grout).

Figure 79: Plan

This structural system is particularly well-suited for use in areas with easy access to cheap wood. The wood in question does not have to be straight lumber. If the wood is a little crooked, the pumice-concrete panels can be made to conform, and any residual openings can be sealed off with pumice mortar.

It is important that the wooden posts be rigidly anchored at top and bottom.

Since pumice-concrete panels are very easy to make, and since the wood and pumice-concrete are both easy to work with and mutually adaptable, the house can be built as a family-scale self-help project.

Figure 80: Detail of plan

Figures 81 and 82

Figure 83: Section

Figure 84: Isometric view