BUILDING WITH EARTH

New Zealand Listener, Volume 19, Issue 470, 25 June 1948, Page 5

BUILDING WITH EARTH

Sir,-Having built two places approximately 20ft. by 30ft by the pisé de terre method, I* was interested in the two articles by R. Ammer. My limited experience may be of interest to others. All my information for my building came from a book written by Clough Williams-Ellis, Cottage Building in Cob, Pisé, Chalk and Clay. The book is well written and illustrated in a simple enough style for any average person to follow. The author holds that pisé is undoubtedly the best method of building in earth. Pisé de terre means rammed earth. R. Ammer says the minimum width of wall would be six inches of best quality pisé, but I am rather sceptical. With the best quality this might do for internal walls, but I should say emphatically that unless the builder had had a lot of experience 12 inches was the minimum, and that for internal walls only. Outside walls should be at least 15 inches, but preferably 18. That is the opinion of Williams-Ellis also. I think my first place is very good for a beginner, but the second not so good. With the first I went to particular trouble to-follow instructions. I took care the earth was free from lumps, and had sufficient moisture to bind it properly. I put in the necessary’ amount of work. With the second I wasn’t. so careful. I skimped the work a bit, and there were too many lumps of clay mixed in. I wasn’t careful enough with the foundation ground, with the result that the ground sank and one of my walls fell over. I say, don’t use clay unless it has been reduced to a powder, and then mixed with sand. Don’t skimp the ramming, and take care that the water content is right. If a ball of earth is pressed in the hand and no wet earth adheres, or appears on the, surface, and the ball retains its shape without crumbling, then the water will be about right. If the earth is too wet, it won’t settle under the blows of the rammer. If it’s too dry it won’t bind. The ramming work required is tremendous, and unless the builder is strong he shouldn’t undertake the job. I recommend fine earth, preferably _ silt, rammed hard between forms, 10 feet long two feet high, and at least one-and-a-half inches thick, with end pieces. The forms are held in place with bars going through the walls nd pinned on the outside. This method of building is

not for anyone with a quarter of an acre section unless supplies of earth are handy. There are a good many cubic yards of earth in a building, and contrary to the usual experience of getting earth back into a hole, if the ramming is done as it ought to be done, the earth goes into a smaller compass.

W.

A.

(Auckland).

(This letter has been abridged.-Ed.)

Sir,-In the article on pisé in the issue of May 28 an error has occurred in which the would-be builder is told to "next ram the forms." Ramming the forms will not consolidate the earth in them, The advice should have been "ram next the forms," the idea being to get a smooth surface on the wall by the use of the rammer mentioned. Perhaps I was in error in trying to condense by using "next" instead of "nearest"; a poet would have got away with it, but an earthy individual must mind his pisé

and queues.

R.

AMMER

(Wellington).