This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
These notes are intended for the man who, starting in a small way, finds it necessary to study the expenditure of every penny. Our large horticultural builders can probably put up a large range of houses at a price very little higher than the grower can do it for himself; but when it comes to one or two houses an appreciable saving can be made by doing the work oneself, and if the builder is a handy man the results will bear comparison with the professional work. All the timber can be obtained ready prepared, and the Ventilators and louvre boxes can be got any size the grower likes. The most difficult part of the work is getting a good start.
Houses are best built running north and south for all except the earliest work, when lean-to's facing south are best. A start is made by laying out the footings. A good long garden line is wanted for this purpose; long enough to go all round the proposed house will not be amiss. It is most important to get the corners quite square. A large square can easily be made out of two lengths of l-in.-by-3-in. batten, or the line can be set out square as follows. Stretch the line along what will be the side of the house. Peg out the exact length of the house, inside measurement. Use pieces of stiff thick wire for the pegs, and push them in quite straight and about 18 in. deep, so that they will not be disturbed when the footings are taken out (see fig. 164). af is the line so laid down, and A is one of the corner pegs. Measure off ab 12 ft., and put in a small thin peg. Measure off ac 16 ft., and run a pin through the line at this point. Slip the ring of the tape measure over the peg B. Now hold the tape at 20 ft, and bring the line AC to such a position that the 20-ft. mark on the tape comes right on the pin in the line ac. Then AC will be square with af. Now the width of the house can be measured off along AC, and a long peg put in as before. The performance is repeated at the other end, F, and then the other side line can be laid down between the pegs so found, and the outline of the house will be complete.
VIEW OF MODERN GLASSHOUSES AT Messrs. R. COBLEY & CO.'S NURSERY, CHESHUNT Showing two narrow houses with high gutters between to save waste of space at top, and to economize heat.
Photos. W. Duncan Tucker & Sons.
Before proceeding to take out the footings it will be as well to consider the question of the walls. The simplest and the quickest to put up are wooden walls, but an efficient wooden wall will cost almost as much as concrete and will always be a trouble.
However, if wooden walls must be built, the best way to do it is to get good oak posts, and set their butts in concrete after thoroughly tarring them. As space is limited, the details of only one form of wall can be given. Brick walls can be made in 4 1/2-in. work with 9-in. piers every 6 ft. along the outside, but for strength, durability, cheapness, and ease of erection the concrete wall takes first place, and so this is the wall chosen for description.
For this work a quantity of thick plank and some 3-in.-by-2-in. quartering will be required. The planks must not be thinner than 1 1/4 in., and 1 1/2 in. will be better, though the thinner size will do well enough if it is well supported. This planking will by no means be wasted, as it can be used after to make part of a shed, frames, or may simply be kept for wheeling on till wanted for building again. Enough planking should be got for about a day and a half's work and to make a platform about 12 ft. square to mix concrete on. For two men and a boy this would mean about 1400 ft. run of l 1/4-in.-by-7-in. plank, and about 400 ft. run of 2-in.-by-4-in. scantling. The quantity would vary a little, according to the size of the house. The above quantities were used on a house 140 ft. long, and have since helped to build several more.
A 4-in. wall will be quite thick enough for any ordinary height of greenhouse wall; a lean-to wall would have to be thicker.
To return to the footings. The four pegs are now in position, marking the corners of the inside of the house. Lay down the line 6 in. inside these pegs, and cut all round with a sharp spade. Shift the line outside the pegs 18 in. away from the line just cut, and cut all round as before. Now dig out the trench so marked out, one spit deep, putting the earth on the inner side of the line for use on the borders, or else far enough away from the outside to allow a barrow to be wheeled along between. Stretch lines tightly between the four corner pegs, which should have been left undisturbed, and peg the line down at intervals to make sure it will not get moved. The 4-in.-by-2-in. scantling is now cut into convenient lengths for posts, say 4 ft. for a 2-ft.-by-6-in. wall, and a chisel point is made at one end, making the cuts on the 4-in. side of the wood only. A post is now set up in each corner just so far inside the lines as to allow the planks to be used for the concreting to be set up on edge between the line and the post both ways. Get the posts perfectly upright with a plumb-line, and fix them so by means of two stays made of slating batten driven into the ground behind each post, and nailed to it near the top so as to hold it firm in two directions (see fig. 165). The simplest way to get all the posts the right distance from the line is to make a plumb-board like fig. 166. The board is made exactly the width of the wall, plus twice the thickness of the planking to be used for the concreting: in the case of a 4-in. wall and 1 1/4-in. plank this will be 6 1/2 in. At one bottom corner, A, cut out a little square piece the thickness of the planking, 1 1/4 in. Now if the plumb-board is set up with the point B, as in figure 166, touching the line, the wider part of the board will overhang the line by the correct amount, and if the posts are driven in touching this edge they must all come right. When cutting out the posts it must be remembered that they must be made long enough to allow for the height of the wall at its highest point, plus the depth of the footings and 4 or 5 in. to go into the ground, and about 6 in. extra, so that if the wall is to be say 2 ft. 6 in. high, the posts must be at least 4 ft. high, and if the ground slopes much across the house, they had better be higher by the amount of the slope, so that they can be used for both walls.