5.03(i) Pis6 Pis6 is a rammed-earth technique, formed in shuttering and utilising a dryish loam, free from all organic material. The technique appears to have been developed in France, in the second half of the eigllteenth century, and its use spread quickly. Pis6 may have been introduced to Scotland from a number of sources. Tlie French connection is obvious as claret was still the national drink in the eighteentll century. A great deal of Scottish trade was still througli the Netherlands where the technique was also used and individual lairds such as Lord Gardenstone recortlcd similar techniques on their travels and brought tlie ideas horne to their owvn estates. One of the most complete early tlescriptions of tlie process of erecting pis6 nlalls appears in Corlrs Corilplct d'Agricr~ltl~rc, Tlleriqr~e, Pratique, Eco~lo~niqric ct rlc Alc(!cci~leRrirale ct \7cterinnirc, si~ivid. tirlc Alctlto(1c porlr ctridicr I'Agricrrltrlrc par Prir~cil~cs: or1 Dictiorlrznire U ~ l i ~ e r stl'Agriciilturc el ... in 1786. Tlie translation by Catherine Meyer, originally from Grenoble, France but now living in \.L7ellbankAngus clln 11e stnnmarisecl as follows. A wall or pis6 is an agglo~nerateof lumps of natural earth ... mixed, compacted and hardened on site through tlie skill of the 'piseur' ... There is no earth that is unsuitable for pist., except pure clay or sand ... Earth wliicl~ coagulates easily clln be recognised when the print of a hand remains on tlle lump of earth ... One can successfully use strong earth (clay) mixed with gravel ... Avoid roots and dung ... The eartll used must have approximately the same humidity as fount1 a foot tlowwm ... If the earth is too wet, the volume of water contained makes it unsta1)le preventing co~npression ... Dry earth is also unsuitable as it is porous ant1 full of air. Take earth from below tlie cultiw~atedlevel. It is essential to:
1. hlaintain natural humidity by covering the pit.
2. Break the earth as much as
with a pick, spade and rake to eliminate lumps. If the eartli lacks lmmitlity add water nitli a watering can then mix wvell. If it sticks to the "pisois" it is too wet. If soaked by heawy rain, suspend work. Tlie pit can be (lug in such a way that one part is alwvays dry ~ v l ~ etlie n rest is too wet.
Abundant gravel adds to t l ~ eexcellence of the eartli but di~ninisliestlie strengtli of poorer quality soils. If good earth is in short supply use for the lowwrer sections of wvall. The number of wvorkers required for a nine IT hvelve foot mould is six: three "piseurs" or beaters, hvo earth carriers and one labourer. If the earth is to be carried more than twelve to fifteen 'toises', twvo carriers will not be enough.
Chapter 5 Tempered Earth Structures
The best time to build starts in March and finishes in August. Rainy days must be excluded as parts of the wvalls just finished would not dry quickly enough to take second layers: one good day or night is enough to make it good. The great summer heat is also harmful as accelerated drylng creates cracks ... Avoid frost ... Time varies according to local conditions. The report continues wvith a description of the pine formwork, the 'pison' for consolidating the pis6 and the masonry foundations, bound with lime mortar. The process continues:"The piseur grabs the basket by the twvo handles and spreads the earth in the formwork where he stands and gives the basket back to the carrier who repeats the process of filling and carrying. The piseur levels the earth wvith his feet then tamps with the pison, lifting it up from ten to twelve inches. The first strokes are directed systematically along the shuttering. Tlie second stroke half covering the first and so on. The blade of the pison worked parallel to the shuttering against which it slides so that it reaches the earth at the angle of the formwvork. The piseur will hold the handle tilted towards the opposite shutter. Once he has tamped along one side he repeats the process on the other, then tamps across the formwork keeping the blade of the pison parallel to the end shutter. The piseur tamps the same layer a second time in the same order. If the earth contains a lot of gravel, he must tamp a quarter Inore and beat harder. The second piseur does the same with the second load, the third with the third load each of them tamping the earth as soon as it is poured and not waiting for each other to start and finish a layer ... The piseurs each occupy one third of the mould, timing tliemselves to move back and fonvard without disturbing each other. It is important not to add new earth to a layer that llas not been tamped sufficiently, that is when the pison hardly leaves a print. This sequence continues until the formwork is full. When the formwork is f1111it is dismantled immediately and used to form the next section.". T l ~ edescription then covers the differences in formwvork used in building level walls and inclined malls. It then describes the formation of corners and changes of angle. The walls should be protected from rain during construction ... and covered with wvooden slabs or even tiles ... The render is not applied to the completed wvall until the following year, or even the year after.
\\'ails can be rendered in the usual manner but me
TAN 6