Metal framed greenhouses are usually delivered in sections (base, sides, gable ends, and roof), each of which need to be assembled and then bolted together in turn.

The Base

The base should be put together first, making sure that it is absolutely level and square. Check this by measuring from each corner to the one diagonally opposite - these measurements should be exactly the same, otherwise the frame may warp or twist.

Fix the base frame securely into concrete foundations or paving slabs using anchor bolts. Small greenhouses (less than 2 m wide and 2.5 m long or 6 x 8 ft) may be fixed using ground anchors. See Preparing the Base for more details on both methods.

The Framework

In general, the sides are usually put together first, followed by the gable ends and then the roof sections. However, this may vary, so check the sequence recommended by the manufacturer in the instruction sheet.

Lay out all the pieces for each section in their correct relative positions and check that everything is there. Loosely bolt the pieces for the sides and gable ends, leaving gaps for ventilators as necessary. When all the sections have been assembled, tighten the nuts securely. Bolt the sections together, and then to the base. Finally, bolt on the roof bars and ridge bar.

Ventilators

Assemble any ventilator frames and then bolt them onto the sides or roof as required. The hinges of roof ventilators usually slide in a groove in the moulding.

Glazing

You will then need to glaze the greenhouse. This is usually carried out by completing the sides first, followed by the gable ends and then finally, the roof. The door should be left until later - see below.

Cut the supplied glazing strips to the right length and then press them firmly into the grooves in the glazing bars. Wearing gloves, gently place the top edge of the glass squarely between the glazing bars. Leave approximately 3 mm (1/8 in) clearance on either side of the glass panes to attach the glazing clips. If you have any overlapping glass, the upper pane should overlap the lower one by about 1 cm (1/2 in) and then held securely in place using overlap glazing clips. These are "S" shaped pieces of metal that clip onto the bottom of the upper pane before hooking onto the top edge of the lower pane. Once all the glass is in position, secure it with glazing clips, pressing them gently into place between the glazing bars and panes until they slot into position.

The Door

Finally, fix the door into position. The majority of steel or aluminium greenhouses have sliding doors that can be bolted together and slotted into the runners provided in the end frame. Remember to fix the stop; this will prevent the door from coming off the runners if it is opened too quickly. When the door is in place, complete the glazing.