Most new sheds are made of pressure-treated or resinous softwood, clad with shiplap, feather-edged or tongue-and-groove weatherboarding, and with a ridged or nearly flat roof protected with felt. Hot-dipped galvanized steel sheds are durable and secure, but unattractive.
FOUNDATIONS Any shed will need a sound, dry foundation. All but the cheapest will be supplied with a floor and instructions for constructing a firm, damp-proof foundation. Site rules often specify how this should be constructed, or give alternative ways to stabilize the structure – for example, sitting the shed on a damp-proof membrane and anchoring it by sinking metal or wooden piles to which it may be fastened.
One reliable method is to remove enough soil over the base area to accommodate a shingle, sand and slab floor. Consolidate the exposed soil firmly, spread a 5cm (2in) deep layer of shingle and firm this in turn. Top with a 2.5cm (1in) layer of sharp sand, then lay paving slabs to finish. Extending this arrangement beyond the floor area would provide a surface for seating and for standing containers or equipment.
An alternative (and also simpler) arrangement is to dig out trenches one-spit deep where the floor bearers rest, fill these with gravel and position the bearers on these: make sure the bearers and the floor are made of treated timber, and that the floor itself sits clear of the ground.
FITTING OUT YOUR SHED
You can adapt or equip the outside of your shed for a number of working purposes or use it to extend your growing space in various ways. Furnishing the shed depends on its proposed use and the amount of room inside. You could simply stack and store materials in a small building, but tools and equipment soon accumulate and it will be much easier to find what you want with a little organization.
▸ Walls can be used to extend the potential storage space if you construct shelves for small tools, gloves, seeds and tins. Attach these to the main framework (not the boarding) with brackets. Screw an old bookcase or wooden frame to the wall for storing pots and seed trays out of the way. You might also find a small cupboard, tool box or old chest of drawers useful, but make sure it is securely fastened to the shed frame or floor to prevent easy removal by thieves.
▸ Suspend gardening tools from hooks or clips on the wall or roof braces to free floor space for larger items like rolls of netting, a wheelbarrow, boxes of stored root crops. Hang up empty paint tins or small buckets to hold string, cloths, gloves, plant labels and hand tools, and have a large hook or bracket for coiled hoses. A rack or simple timber hangers attached to roof members will keep canes and poles tidy and off the floor.
▸ A bulldog clip on the back of the door gives instant access to gloves. A nail keeps keys in a safe place.
▸ Old mats, a chair, tea-making facilities, even a small camp stove can help transform a functional shed into a welcoming haven where you can rest, admire or plan your work or shelter from the rain. (Make sure you check with your site manager what the regulations are concerning the use of flammable equipment.)
▴ Window boxes (whether your shed has windows or not) can accommodate flowering plants and crops like herbs, trailing tomatoes or leaf salads at a convenient height. Attach trellis to the walls for growing sweet peas, climbing annual crops or fruit such as trained figs, grapes, cordon apples and pears, or thornless brambles.
▸ Use overhanging eaves to support strings for climbing crops like runner beans and outdoor cucumbers, growing in the ground or in troughs of compost.
▸ Build a bench for sitting in the sun, with useful storage space beneath it.
▸ Attach a collapsible table-top or work surface to the outside for potting and sowing activities, especially if space is restricted inside the shed. You might want an old table or home-made work surface within for various jobs and as extra storage. If you make your own, consider a drop-down top hinged to the inside wall, supported by folding brackets.
SECURITY
The risks of forcible entry and theft from an unattended shed are high, and exempt from many association insurance schemes, but guidelines have been issued by police forces and site committees to help prevent loss.
▸ Provide a strong door and a large lock or padlock.
▸ Cover any windows with rigid wire mesh or grilles.
▸ Conceal screw fittings with metal plates.
▸ Use clutch head or ‘one-way’ screws because they are hard to remove.
▸ Fit a battery-operated alarm.
▸ Mark tools with barcodes or postcodes.
▸ Anchor the shed to piles so it is hard to topple over.
▸ Cover walls with trellis and plants for disguise and stability.
The greenhouse Adding a greenhouse to the site can enhance your growing options by offering a protected environment for tender crops and those at sensitive stages of growth, especially early and late in the season. Some gardeners consider a cold frame more essential and versatile (see pages 48–9), but the two structures can work hand in hand, and it is always an advantage to have an all-weather place with enough headroom for working comfortably. A greenhouse can accommodate larger plants, though, including permanent fruiting climbers such as a grapevine or trained apricots.
The minimum useful size is considered to be 2.4m (8ft) long by 1.8m (6ft) wide, or 1.2m (4ft) for a lean-to model, but even the smallest house can be an asset in a limited area, especially if you arrange the internal layout to exclude a permanent central pathway. Although a great variety of shapes is possible, the most serviceable is the traditional span design, with sides that are upright or gently inclining inwards, and glazed to ground level. Some kinds need a foundation similar to that used for sheds (see page 41), while many aluminium models can be pegged down into level ground.
MATERIALS Greenhouse frames usually come in softwood or aluminium, while the glazing is either glass or plastic.
Softwood is cheap, but the construction needs to be strong and this can reduce the total glazed area. Regular maintenance, even of comparatively durable cedar models, is essential for long life.
Aluminium-framed greenhouses are virtually indestructible and maintenance-free, and have thin glazing bars that maximize light transmission. They are more expensive than timber models, though, and need a very firm base to ensure rigidity.
Glass is the best glazing material because of its good light transmission and heat retention. It is, however, expensive, heavy and easily broken – a possible risk on allotments where vandalism is a problem, but if treated with care, it will last indefinitely.
CHECK POINTS
▸ Check if a base is included with your chosen model, and whether this creates a step or barrier in the doorway.
▸ The door should fit tightly and include a kick panel at the bottom for safety; sliding doors make it easier to adjust the ventilation.
▸ Make sure the height at the ridge provides adequate headroom.
▸ Most greenhouses come with a single ventilator, which provides insufficient ventilation: add another on the opposite side of the roof, and at least one (possibly a louvred type) in the side for a free flow of air.
Plastic is lighter and cheaper than glass, but has a limited life according to its type. Flat and corrugated polyester rigid panels are the most expensive. They are almost as clear as glass, but difficult to keep clean. Polycarbonate, especially if double or triple-walled, is more serviceable and affordable. Cheapest of all is flexible plastic sheeting, with a useful life of five years or more, after which it turns yellow