The majority of gardening that needs to be carried out under glass can take place in a conventional greenhouse. These designs are usually built using a timber or metal framework, with part-solid or all-glass walls.

Traditional Span

This style of greenhouse is shaped like a traditional house with an even span roof. The sides may be fully glazed or part-solid. The panes of glass on the roof are usually set so that they overlap slightly to increase rigidity and keep out rain. However, if they overlap too loosely, they may lose heat.

This design is the most practical choice for most gardeners as it offers plenty of growing space and headroom - the best use of space for the least cost.

Dutch Light

A Dutch light greenhouse is shaped in the same way as a Dutch barn, with slightly sloping all-glass sides meeting an even span roof. This design, along with its large sheets of glass, lets in the maximum amount of sunlight making it particularly useful for growing low-growing crops such as lettuces. However, as the panes of glass are very big (normally 145x77 cm or 59x30 3/4 in), they can be very expensive to replace.

Lean-To

If your garden does not have enough room for a free-standing greenhouse, you will probably need to consider a lean-to structure. These are usually vertical sided, with a sloping roof that meets the sides in a curve - similar to a conservatory. Alternatively, a shape more like the traditional span may be used, with the span backing on to the wall being half the width of the other side. This is termed a three-quarter span.

Lean-to's are best sited against beside a sunny house wall; the bricks will retain heat from the sun (and the house heating), which will then be released into the greenhouse. The brick will also provide excellent insulation, which will reduce the amount of escaped heat in comparison to other styles.

Mansard

Each layer of glazing in a Mansard greenhouse is slightly more slanted than the previous layer, resulting in a greenhouse that is shaped like a tunnel. This allows the maximum amount of sunlight to enter, making this style particularly useful for plants that need plenty of winter light.