THE shed described is a portable building, made in four main units, erected on a concrete or wooden base and bolted together. It can be dismantled in about half an hour. The principal members of the four frames should be mortised and tenoned together, but half-lap joints, carefully cut, and fitted, may be substituted. The roof is of corrugated asbestos-cement sheets, screwed to timbers resting on the tops of the end frames. The sheets are fixed separately, after the four units of the building have been set up and bolted together. Corrugated iron sheets may be substituted if desired. Timber, etc.
The outside members of the front and back units are of 3 in. x 2 in. deal, with the narrow side to front. In the case of the front unit the members that frame and support the window opening also are of 3 in. x zin. Material; all the rest of the timber is 2 in. x 2 in. section. It is assumed that the timber has been purchased to rough size, I.e., not planed. A ledged and braced door of simple construction can be made by the worker, and covered with matching or good weatherboard nailed on vertically. It is quite possible that a light door (half-glass would be an advantage) may be picked up by the reader at second-hand prices, or bought new. In that event the dimension of the door opening will, of course, be adapted to suit. A simple window frame and sash is easily made. The standard types, generally obtainable from a builder’s merchant, will be too heavy for the job. The sides of the shed should be covered with good quality matching or weatherboard. The matching must be nailed vertically. Weatherboard must be nailed in horizontal lengths, each thick edge overlapping the previous board.
A concrete floor is probably the best. But if a wood floor is preferred it should be made up of lin. Floorboards, with a plain edge, nailed to 3 in. x 2 in. joists, the latter spaced at i8in. Intervals, measured from the centre lines.
Clear and level the site first. The joists, when laid, will run from front to back of the shed, and if it is considered advisable to lift the floor a little higher, three lengths of timber, 3 in. x 2 in. can be laid down first, running from side to side of the shed, one at the front, one at the back, and the third midway between. These are known as sleepers. Spike the joists to the sleepers at the proper spacing, then nail on the boards, which will run from side to side of the shed. Make the floor surface about 6in. Longer and wider than the overall dimensions of the building, giving a 3 in. projection on all sides.
The overall dimensions of this unit are 7ft. 6in. High and 9ft. Ioin. Long. The outside members and the other stout ones marked with a cross in.
Cut and joint the outside members; next deal with the 3in. X 2 in. horizontal members. These posts are tenoned into the sill (bottom member) and the head (top member). Where they cross the horizontals they are halved to these latter, since the horizontals themselves are tenoned to the outside posts. The remaining studs (vertical and horizontal) are cut where they meet other members, and are tightly fitted and nailed (butt jointed). The short cross members are shown staggered, so that the ends of adjacent pieces are accessible for nailing through the uprights. Be careful, in finally fitting the studs after the main members have been put together, not to drive these tenoned joints asunder by using too long studs elsewhere. The tenoned joints should be pinned with Ain. Dowel rod.
The length is the same as in the front unit but the height is a foot less, namely 6ft. 6in. Overall. Only the outside members are of 3in. X 2 in. in this case. Besides tenoning these together, the central upright should be jointed in the same manner, all the rest of the members being butt jointed. Prepare and fit the outside and central pieces, and pin the joints. Next cut and insert the two diagonal braces, which run right through as shown . Lay a piece of 2 in. x 2 in. in position, an assistant holding one end, and carefully mark at the top and bottom for the angles at which the material is to be cut; a tight fit is necessary. This done, cut and fit the four uprights that remain, breaking joint at the intersection with the diagonal braces, and nailing obliquely to these diagonals at the intersection. Finally, fix the eight short horizontal pieces that stiffen the unit.
In height, the two end units are two inches less than the front and back units, sloping off from 7ft. 4-in. At the front to 6ft. 4-in. At the back. This is to allow for the depth of the 2 in. x 2 in. purlins (mentioned above) on which the roof sheets rest. These purlins are spiked to the tops of the side frames, and the boarding on the outside of the sides is notched to let the purlin ends pass. Mortise and tenon the outside members and the post that forms one side of the door frame. The cross piece that acts as the head of the latter frame should be tenoned.
Care is needed in cutting the top of the posts to the proper bevel, according to the angle of slope for the roof; also, ensure that the angle of slope for both end frames is identical. The width overall is 6ft., which with 3in. For each of the front and back frames makes a total end width of 6ft. 6in. If these dimensions are varied, take care to get the width identical in both end units. These latter stand between the front and back units, so that the outside dimensions of the shed are 9ft. Ioin. By 6ft. 6in.
In a larger building the ends would normally be braced by a single diagonal, but since the width here is only 6ft. It can be dispensed with. The centre upright, as well as the outside members, should be mortised and tenoned; the rest of the joints may be nailed.
The boarding of the four frames is a simple matter, but in the case of the end units the position of the roof purlins must be settled, and the tops of the boards cut where they encounter the ends of the roof timbers. These boards will project 2 in. above the top members of the unit and be cut off level to the proper slope, the notching for the purlins being done later. If horizontal boarding is adopted (I.e. weatherboarding), this projection will not be needed; the top board will be cut off level with the top member of the unit. After the purlins have been fixed and the corrugated sheets screwed down, a barge board consisting of a piece of 6in. X 1 in. plain board is nailed to the ends of the purlins to cover the gap.
The dimensions of the actual roof, measured over the front, back and end units, are something larger than the plan dimensions measured at floor level, for the slope of the roof adds to the length of the sides. But the shed has been designed to take 7ft. Lengths of corrugated asbestos-cement, and this length will give a sufficient overlap at back and front. If, however, the pitch of the roof is to be altered, the length will be changed proportionately.
The sheeting will run in a single piece from front to back; as the effective cover of a 2ft. 6in. Sheet is 2ft. Tjin., we shall need five sheets in the length of the shed. The minimum satisfactory overlap at the sides of the sheets is one and a half corrugations, equal approximately to 4.½ in.
The asbestos-cement sheets should be drilled for the screws, using a twist drill with a square taper shank, in a carpenter’s brace, or an ordinary round-shank drill in a wheel brace. Holes are made at the tops of the corrugations, not in the valleys, since water would run through in the latter position. Galvanized round head screws should be used, and one of the bent washers, specially supplied for this work, placed under the head of each screw. The hole must be an easy fit. These sheets are very satisfactory, but must not be subjected to jars or knocks.
The purlins on which the sheets are fixed will rest on the tops of the end frames, which are sloping, of course, whereas the tops of the front and back frames are square across. These latter timbers should be shaped by jack plane to make a bevel which will correspond to the slope of the sides. The bevel should be marked first at each end of the top rail; then a line should be carried along the inside face of the front rail, and along the outside face of the back rail, to mark where the slope should finish.
This should be done before the frames are boarded. With care the proper angle can be taken, and transferred by an adjustable bevel to the timber. Failing this operation, the operator may plane down the lowest edge of both front and back frame members so as to get an approximately correct seating for the corrugated sheets. These sheets, the operator must note, are screwed direct to the tops of the front and back frames. Two purlins will be sufficient, placed on the top of the shed so as to divide the span into three approximately equal spaces. A shallow notch can be cut in the sloping rails of the end frames to let the purlins drop in a trifle, and so keep them from sliding. But the notching must not be so deep as to cause the ends of the sheets to foul the tops of the front and back frames. The purlins are spiked down to the end top rails to keep them in place. The frame timbers should be creosoted before putting on the boarding.
A light zinc gutter with a down pipe can be fixed at the back of the shed, under the projecting eaves, the pipe discharging into a butt below. The gutter must slope a little down towards the outlet. After assembly, the boarding should have two good coats of creosote or some similar preservative.
It is advisable, after cutting and fitting the boarding, to leave the first three boards loose at each end of each frame. Tack them in position, not driving the nails right home; follow on with the rest of the boards, properly nailed on, until the three at the opposite end are reached, leaving these off after fitting. Stand the back frame in proper position on the shed floor, assuming that a wood floor has been laid, and hold it temporarily by two struts of quartering, one at the back and another at the front.
An assistant should be available during this operation. When the back frame is Ipcated in the correct position, bore two holes in the sill, near the ends, to take a ¾ in. coach screw; bore a little way into the floor with a smaller bit, so that the worm of the screw can bite. The proper place for the screws is over a joist, but this cannot always be managed when assembling the parts.
Now the worker will see why the end boards were left off, since the opening here gives elbow-room to use a brace and bit. The coach screws are knocked down lightly until the screw bites, then a suitable spanner is put on the squared head, and the screw is turned home.
A washer should be placed under the head of the screw. With the back frame thus partly fastened down, put one of the end frames in place, abutting against the back properly; get an assistant to hold this steady while a hole is bored for one of the fixing bolts, at a point about i8in. Up from the floor line. Mushroom-head bolts (often called coach bolts) are to be used, of suitable length to go through the 3in. Thickness of the corresponding posts of the end unit, plus the thickness of the boarding of the shed sides.
Gently fix the end boards of the back frame, which were left off, tapping in the nails enough to hold the boards in place. Now bore through, from board to inside of shed, going through the post of the end unit; tap the bolt through with light blows, the head at the outer side. The square on the bolt, just under the head, will need to be driven in, and will hold the bolt tight against turning. Put on a nut and washer at the inside, and turn up finger-tight. Mount a step ladder (do not rest it against the job), and put in another bolt about i8in. From the top. Test the angle made by back frame and end frame, to see that they are square; insert two bolts in the sill as before. Proceed in the same way with the remaining end frame. Take down the two struts first put up, but nail a couple of pieces across the top of the side frames, to hold these steady.
Now offer up the front frame to the job, getting it in line with the posts of the end frames. If necessary, withdraw the screws holding the end frames to the floor, and adjust these frames for width. If all is satisfactory, bore for bolts, insert them, and then tighten all bolts. A third bolt at each corner can be put through now, for extra security. With an old brush, paint all the bolt ends with grease against rusting, slacking back one nut at a time and re-tightening it; this is a cleaner method than greasing the bolt end first, before insertion, and can be done when they are being finally tightened with the spanner.
All that remains is to nail on the loose boards firmly, and to put on the roof.
When erecting a shed on a concrete floor, the two frames first put up can be held together by a pair of large G-cramps over the adjacent posts. More strutting is advisable, since the frames cannot in this case be held down temporarily to the floor. The coach screws used with a wooden floor help to hold the shed against wind pressure, which might otherwise cause the shed to shift or slide on the floor.
With a concrete floor, the same result can be obtained by setting four bricks on the base at each angle, outside the shed and firmly cemented down to the base concrete or foundations.