THE construction of a span-roof greenhouse of the type usually favoured by amateur gardeners is not a difficult undertaking. The house described is built in sections, which makes for greater strength and has the advantage that the structure can be easily assembled and taken apart.

Throughout the construction an endeavour has been made to specify material of standard size which is normally easily procurable. The precise dimensions of the house are largely determined by these sizes. For instance, it is intended that 21 oz. horticultural glass 24 ins. by 12 ins. should be used, and the exact length of the roof frames is found by allowing 1 ft. 0 1/8 in. between the bars plus the widths of the roof timbers. The width of each roof frame ends, allowance should be made in their lengths for the thickness of these ends, also the inch hang-over of the roof frames. The bars should be positioned similarly to those of the top frames, the side ventilator openings being arranged accordingly. The members of each frame are tenoned together, open mortise and tenon joints being used at the corners.

Referring to Fig. 2, it will be seen that the centre rails are bevelled slightly, and it is necessary to cut the shoulders of the lower tenons to suit this bevel. Some of the members are ploughed to take the glass. Care should be taken to position the grooves so that they agree with the rebates on the bars. Before assembling each frame 1/2 in. holes for the securing bolts should be bored in the positions is ascertained in a similar way, but in this case 1/2 in. should be allowed for the overlap of the glass panes and 1 in. where the lower panes overlap each bottom rail.

SPAN-ROOF GREENHOUSE BUILT IN SECTIONS. SIZE (AS SHOWN) 10 FT. BY 6 FT.

Dimensions may be modified as required. Height to eaves is 5 ft. Ridge height 7 ft. 6 ins.

The nominal sizes of the timbers are given, but if prepared stuff is obtained (which is to be preferred) it will, of course, be slightly less in size. The roof frames when in position should overhang the gable ends by 1 in. Before commencing construction it is advisable to determine the precise size of the roof frames as the other sections are dependent on these dimensions.

Side Frames (Fig. 1).—As these butt against the gable indicated on the drawings. The joints are put together with thick white lead paint and secured with dowels where indicated. Finally each frame should be given a coat of red lead priming.

Gable Ends (Fig. 3).—The pitch of the end frames may be found by setting out on two rods a length corresponding to the width of a roof frame, plus half the thickness of the ridge plate. The two rods are then nailed together with a cross member equal in length to the estimated width of the gable end. The rods when put together will have the form of a triangle. The position of the eaves should correspond with the height of the side frames. Similar joints are employed to those described in connection with the side frames.

KEEP YOUR GREENHOUSE WELL PAINTED

Certain

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GARDEN CARPENTRY SPAN-ROOF GREENHOUSE, 10 FT. by 6 FT.

GARDEN CARPENTRY

SPAN-ROOF

GREENHOUSE, 10 FT. by 6 FT.