Cottage Building in Cob Pise Chalk and Clay Part 11

The floors are boarded save for the back kitchen, which is tiled. The inner part.i.tions are of 2-in. breeze blocks, the ceilings are plastered, and the cas.e.m.e.nt windows are of steel.

There are two good lofts for storage, one entered from the barn, which is an extension of the house proper.

The pillars of the barn and the part.i.tion wall between scullery and veranda are of 18 in. by 9 in. by 9 in. rammed earth blocks; the angle pillar to the veranda is of similar blocks made from soft chalk.

The rest of the structure is of monolithic pise, built up _in situ_ without joints of any kind, either horizontally or vertically.

_Cost._--The total cost of the whole of the outer walling of the house (in pise) amounted to less than 20. Had the walls been built in brickwork the cost would, according to estimate, have been about 200.

[Headnote: The Newlands Specification]

_Specification._--The following is an abridged extract from the specification so far as it affects the pise-builder:

(1) Excavate to a depth of 9 in. over the site, dumping the turf and surface humus where directed.

This soil is not to be used for building.

(2) Lay a 6-in. bed of cement and flint concrete 3 ft. wide under outer walls. Centrally on this, lay two courses of brickwork in cement, to a width of 18 in., or build up to the same extent in concrete.

Lay on this an approved damp-proof course; if of slates, having a further course of brickwork or concrete above it to prevent fracture when ramming.

[Ill.u.s.tration: +The Newlands Corner Pise Demonstration Building.+]

[Ill.u.s.tration: +Newlands. The Cottage from the South-east.+]

[Ill.u.s.tration: +Newlands. The Garden Court.+]

(3) Erect the walls according to the plan on the bases thus formed, carrying them up plumb and true and properly bonded by working round the building course by course, using the special angle-pieces at the corners to keep the work continuous and h.o.m.ogeneous.

(4) All stones and flints above a walnut size to be removed by riddling and reserved for concrete.

All sticks, leaves, roots, and other vegetable matter to be eliminated.

(5) The soil immediately on the site to be used without admixture of any sort and to be thrown direct into the shutterings.

No water to be added without the express permission of the architect.

(6) The boxes are to be filled in thin layers of not more than 4 in. at a time, and well rammed until solid. The workmen are not to use their rammers in unison.

(7) Rammed earth at box ends to be shaved down to a 45 degrees slope so as to splice in with new span of pise adjoining it.

Where door and window openings occur, the special "stops" to be adjusted and firmly secured so as to withstand hard ramming. Two 4 in. by 2 in.

by 9 in. plugs to be built in to each window jamb for the securing of the frames and three to each door jamb.

Special care to be taken in the thorough ramming at the corners and along the box edges.

(8) Insert below floor level, where directed, 24 3-in. field drainage pipes to act as ventilators through the thickness of the wall. Insert wire mesh stops to exclude vermin.

(9) Set all frames square and plumb, and where in outer walls, flush with finished exterior plaster-face, the joint being covered by a 2-in.

by -in. fillet.

Where lintels occur, they are to be tailed in at least 9 in. on each side the opening.

Provide plain picture-rail round all rooms at window-head level, providing plugs for fixing where necessary.

Secure to floor round all boarded rooms a 2-in. by 1-in. angle fillet as skirting.

(10) The smooth surface of the pise walling to be hammer-chipped to give good key to the plaster.

Before rendering or plastering walls, any loose earth or dust to be removed with a stiff brush and the wall surface evenly wetted.

[Ill.u.s.tration: NEWLANDS CORNER PISe HOUSE. THE PLAN.]

The rendering to be carried evenly round the walls--the minor square angles being roughly chipped down first so as to obviate sharp corners.

The main corners of the house are ready-rounded off to a 9-in. radius by the special corner mould.

(11) Bond brick and slab work to pise walls by driving iron spikes into the latter every few courses at joint level and bedding in.

(12) Colour-wash walls with tallow lime-whiting tinted with ochre.

Provide 2 ft. skirting of pitch, applied hot, to form base-course round exterior of building.

[Ill.u.s.tration: +Newlands. The Backyard, showing Barn with Pise Pillars.+]

[Ill.u.s.tration: +Newlands. Framing the Roof.+]

[Ill.u.s.tration: +Newlands. An Interior, showing Fire-brick Hearth Fire.+]

N.B.--The exterior of the walls of the Newlands Corner house have been finished in several different ways with a view to determining the most durable and economical form of epidermis.

A trial pise-building adjoining has stood for four years without any external protection whatever. It has suffered no damage and grows continually harder. For the sake of appearances, however, and for the better preservation of the wall from chance injury whilst still "green,"

a coating of some sort may be deemed necessary.

[Headnote: A Swedish Contribution]

THE THEORY OF PISe

The Swedish scientist, Mr. Karl Ellington, of Nossebro, who is basing a book on pise (in his own tongue) upon the frail foundation of the present volume, has, in the course of a letter to the author, made some exceedingly suggestive "guesses at the truth."

"I am very interested to hear that you are proposing to use an hydraulic rammer for making blocks. I have thought a good deal about this pressure business. I am trying to scrutinise the thing from 'the inside,' so to speak. I am trying to trace out how Nature makes rock. That helps us to understand pise. Nature made all the stratified rocks out of what was once fine loose earth and mud. Rivers carried the mud out to sea. Waves pounded and gnawed the sh.o.r.es and got down some more stuff. The tides went forth and back and shovelled and levelled at the sea-bottom. Some more mud on top of that, and a few hundred or thousand feet of the heavy water on top of that--and Nature's pise was in its making. But why do these mud particles stick together for ever even after that stratum is raised up high above the sea and the pressure is discontinued? That is the counterpoint of the whole problem. What is gravitation? Is it some form of magnetic or electric energy? We don't know. Do particles of mud grip and hold each other if they are forced together close enough to be united by some sort of magnetic or electric energy? Or do the particles only get a 'mechanical' grip on each other? However that may be, we seem to know now that we can make them grip by bringing them closely together. It would seem important, then, that we must bring as much of particle surfaces together within any given cubic s.p.a.ce as we possibly can; that is, we must have as little of 'holes,' 'empty s.p.a.ces,' pores and channels as possible in the ma.s.s, in the pressed wall. This, then, would in turn make it important that plenty of very fine (small) particles must be present in the ma.s.s--and so well distributed among the coa.r.s.er particles as to be on hand close by wherever there can be one more chance for a small particle to fill a little chamber that the coa.r.s.er particles would like to bridge over. We can think of how well Nature was fitted for this work of shuffling over all the particles at the sea-bottom and under great water pressure till she got every particle into the niche where it would exactly fit. She used waves, tides, and gulf streams as shovels and mixers and packers, and the water above as 'hydraulic rammer.' Looking at the pise matter in this way, it would appear that both the _mixing_ and the _shuffling_ are of vital importance. And by 'shuffling' I mean in this connection only that the smaller and larger particles get a chance to shift over a little during the process of pressing the earth together to hardness, so that the pressure may not work only and exclusively in a straight downward direction, but in a sort of wavy zigzag direction as well--much as when a street-roller is working the macadam and gravel a little forth and back at the same time as downward. I have a great respect for old tools which are the outcome of long-time experience and handed-down wisdom.

I suspect the presence of some of that sort of experience in the rammer described in your book, p. 59. That tool would do the necessary shifting while attending to its _main_ intention: hammering the ma.s.s solidly together downwards. Now for your hydraulic rammer--is it advisable to make it blow or press only in a straight line downward? Maybe there ought to be two or three kinds of strokes alternating--one stroke with a rifled or wavy surface under the rammer--and the next stroke with a _plane_ surface... . What sort of witchcraft enters into the effect of _high frequency blows_ as compared with blows with a little longer intervals between? Do the strokes create also some 'magnetic' effect in the pounded earth-ma.s.s which helps to fasten the particles to each other? And does this magnetic charge or friction heat, or whatever it is, act more promptly if one keeps on 'striking the iron while hot,'

instead of letting the charge 'evaporate' and sneak away between strokes? Two or three of my hairs are turning grey over these questions alone. You compliment me by insinuating that I might stumble across some fruitful idea for the forms or boxes if I speculate a little more on the key-problem. Well, the thing won't leave me alone, so I have thought out several foolish variations and rejected them too. But the last one seems to have a little more vitality, so if it will live till I write my next letter I will tell you about it. One is so apt to follow the temptation of 'perfecting' an apparatus--at the cost of getting away from keeping it cheap, simple--and 'fool-proof.' By this time the idea has grown ripe in my mind, so that I ought to write out a little book on the pise problem in Swedish and have it printed before springtime. Something ought to be done... . I have to ask you kindly to permit me to make use of the data contained in your book. To this I will have to add what special precautions we must observe as to foundations in a climate like ours. I intend to treat only the pise method. Cob and chalk methods are not applicable here, as we have such materials only in a few unimportant spots."

Mr. Ellington has long been an admirer and a firm friend of England, and he is good enough to regard his country as indebted to ours for the introduction of pise-building:

"Let me tell you that the help you are giving me now--not me, but my nation--will work as an additional bond that draws us more closely towards each other... . Some of our people here have always looked too much towards the South and too little towards the West."

[Headnote: A Pise-Builder's School]