1. Modular, which consists of making solid blocks of mud, often reinforced with straw or other fibre, dried by sun and air, and laid as ordinary brickwork with a mud mortar. This is adobe.
2. Monolithic or pise-de-terre, which consists ot ramming slightly dampened earth of a sandy, loamy nature between forms with steady pulsations which conpacts the. material into solid unbroken walls.

It is basically important to regard a mud wall as a mud wall and as nothing else. This is no slur on the material. Good architecture gives it an individual beauty and history confirms its capacity to survive.

To this day more than half of the world’s dwellings are built of mud. Only Western society has turned away from mud, because of new methods and machinery. But the house-hungry post-war world saw a renewed interest in the medium.

Mud mixed and ready for shovelling into the moulds. Soil should contain from 30 to 70 per cent, of clay, along with sand. The secret of good mud brick making, Mr Knox says, is to intermix the clay and sand thoroughly and then to percolate it with water so that 18 to 20 per cent, of the mixture is liquid. If the clay con- tent is high, add straw, which makes the mud bricks dry evenly and prevents their cracking.

Australia is a particularly suitable country for mud building—climate, soil and space contributing equally.

Here are some of the main points about it:—
Cost of a mud house is comparable with timber, no dearer than brick veneer, and less expensive than machine-made brick.

If the site is large enough for use of modern earth-handling equipment, if the soil is naturally stable, excellent labor obtainable, and the house planned to comprehend these potentialities, the cost of the building would be perhaps less than the equivalent house in timber. But costs rise as these factors become un- balanced. A complicated site, tricky soil or an unsuitable plan will cause prices to move up considerably.

The objective of the designer of a mud building is to co-relate his plan to the possibilities of site, soil, etc., as economically as he can while giving due regard to the aesthetics of his problem.

Earth is required for the walls. If the site slopes, the plan should exploit the levels so that what is removed for levelling purposes will suffice to build the walls. It is cheaper to cut into the ground to a reasonable distance than to build up.

Tamping the mud into the moulds. Tamp lightly - it is done to make sure the mud fills the corners of the moulds. Mr Knox’s first bricks were 12in. x 9in. x 6in. and 18in. x 12in. x 4in. But, as the fruit of experience, he has standardised on 15in. x l0in. x 5in. for external walls and 15in. x 8in. x 5in. for internal walls. These dry faster than 6in. bricks and don’t break as easily as 4in. bricks. They look well in walls, and allow 10in. walls to be built to a height of 10ft.

Because of this, it is better to use concrete slab floors over which timber, tiles, or any other flooring may be laid. The cost of the excavation and concrete is more than compensated for by the saving in wall heights, the flexibility of the building, its relationship to its environment, temperature control, durability and beauty. Preconceived notions of what the house should be must be held in reserve until one determines what the site will allow. A plan that defers prejudice to topography is half way to success.

Details of typical footing and wall sections are shown in accompanying sketches. Height considerably affects the cost of a mud house for two reasons:

1. The higher the wall the thicker it must be;
2. The greater the labor in raising large quantities of heavy material to that height.

If reinforced concrete is used in the lintels there is practically no limit to the size of window openings or to the flexibility of the plan.

Smoothing off the top of the bricks with a shovel. The bricks are reasonably light to handle, the maximum Weight usually being about 40lb.

The slope, or lack of it, of the land, its relationship to the sunny north or shaded south, and the view, all converge naturally into the plan considerations. They must be resolved hand in hand.

If the site is a plain as far as the eye can see the house would naturally take on a long, low look. Nothing could be more out of place than a tall building with a small ground plan in such an environment.

Mud building is undoubtedly more suited to open or rural sites than close, small suburban blocks. Space for working, drying bricks and using equipment is most important.

A very bad site in this respect alone could well add more than 10 per cent, to the overall cost.

Immediately after they have been tamped and smoothed off, the bricks are slipped from the moulds. The higher the sand content the easier it is to slip the bricks from the moulds

Mud building sites are best where the bricks can be made at 100 yards distance and hauled by truck to their exact building position. This minimises handling and makes for clean, uncluttered building that streamlines costs to a remarkable extent.

The feasibility of building in mud is in inverse ratio to the general prosperitv of the country. When wages are high and labor scarce, mud building becomes disproportionately expensive to other building forms because so much manual labor is performed on the building site. In bad times, however, when materials are relatively dearer than labor, the reverse position applies.

With all types of mud building no absolutely straight lines are found, as would be the case in timber and machine-made brick work. This necessitates either a simpler detailing or a large amount of finishing labor.

Half-dried bricks being turned on their edges to cure. On average, bricks are turned when two days old, but leave them longer in wet weather.

Tradesmen do not relish completing work that has not a straight beginning. They generally regard mud somewhat balefully, for it does not show off the quality of their craft as well as many other surfaces. For this reason it is an ideal medium for the enthusiastic amateur to complete. Some of the best post-war mud houses have been erected by professional labor and finished by the owners.

Equipment is the great modern contribution to mud building. Ploughs of all kinds, scoops and other farm machinery will always save hard labor, and therefore money. For big excavations nothing can touch a bulldozer, but for general building work on a farm or else- where by far the best answer for mud-brick building is a well-equipped Ferguson tractor. By forming grids of timber (see diagram, page 9) and using a scoop to collect the mixed mud, two men and a tractor should make up to 700 bricks a day. When it is realised that 2500 bricks each 15 in. x 10 in. x 5 in. and 1500 bricks each 15 in. x 8 in. x 5 in. would be sufficient for a normal house, it will be seen how efficient the result is.

Bricks are laid in the same way as traditional bricks, except that mud is used as mortar. The mud mortar should be made of topsoil. Choose a sandy loam, free of stones and vegetable matter, and mix to a squashy consistency. The bricks are firmly worked into a full half-inch bed of mortar. Don’t tap bricks too hard when laying.

Further, by using the plough and scoop, excavations can be made quickly and the soil mixed in a small area. The convenient practice of making large mud heaps that can be left overnight to percolate can be followed, and the material will be ready for bricks the next day. By such methods four-fifths of the human labor can be transferred to machines.

If the labor of making and laying mud bricks is undertaken by an amateur home builder he must not think that it costs nothing except his time. Before the venture is undertaken a cold appraisal must be made of costs and of the long physical effort required of those who consider doing all the work themselves. Failure to do this at the outset has been responsible for many unfinished mud buildings.

Amateur bricklayers should take extreme care to work to a line if they want even, straight walls. Surplus mortar is struck off after a line (course) of bricks is laid, before mud hardens.

It should also be realised that when a family does all the work themselves they don’t get a free house. The walls of a house account for about one-sixth of the total cost of the completed and equipped structure.

I never use cement for rendering mud brick walls. Internal walls are rendered with mud or merely bagged down on paint. External walls are pointed up where necessary with mud and bagged down so that all gaps are filled. They are then painted with oil paint, Cementone, or any similar water-proofing material which will not destroy the homely character of the mud bricks.

If reinforced concrete lintels are used above them, the spaces for doors and windows can be of any width. Lintels should be same width as the bricks and thickness varies according to the span, but is preferably equal to one, two or three “courses” of bricks (and don’t forget to allow for the thickness of mortar between the courses). Best tip for your reinforced concrete - be guided by somebody really experienced in this work.

It is not possible in one article to go fully into all the technicalities of mud building, but a useful outline has been given for those embarking on mud-brick building. They should not fail to study the Commonwealth Experimental Building Station’s publication on Earth Wall Construction. (See review, page 13).

Perhaps what I have written may inspire readers who have been toying with the idea of building something of mud bricks to “give it a go.” If so, I wish them all the best of luck. There’ll be hard work in plenty—for there is no easy method of building—but there is a lot of satisfaction in co-operating with Mother Earth in making a building grow.