Generally speaking, greenhouses and conservatories can supply the same sort of facilities as each other, the main difference being that conservatories have a wider range of building materials in their construction, and often, if they have been added to a property as a sun-room extension, they may have a solid roof, which cuts down the available light. Modern conservatories are also double-glazed.
Although you may not need planning permission or building consent to erect a free-standing or conservatory-type structure if it does not exceed a certain area, it is advisable to check first.
Greenhouses are usually purchased these days as ready-to-assemble units, which can either be bought for do-it-yourself erection, or in many cases, an erection service is available as an optional extra from the stockist.
They are mostly made nowadays from either aluminium, which is by far the most popular, or timber, but occasionally iron-framed ones are seen. One or two firms are now selling PVC-U greenhouses, which combine the low maintenance attributes of aluminium with the good looks of painted timber. Aluminium greenhouses are light and easy to assemble and require no further maintenance to the constructional materials once erected but they tend to look a little austere in the surroundings of traditional architecture. Timber greenhouses are usually made of cedar wood. They blend considerably better into the garden scene but the timber requires periodic treatment with a cedarwood preservative. They also require slightly more skill in their erection.
Sometimes softwood greenhouses are available – these also have to be treated, or preferably painted, which increases the time required for regular maintenance considerably.
Galvanized iron-framed greenhouses are less common and are generally used in connection with semi-rigid plastic sheeting or polythene. These are much cheaper but also much less permanent and can have problems associated with the polythene or plastic deteriorating and also with ventilation. They tend not to look as attractive, either.
Conservatories are usually made from PVC-U, aluminium or timber, often incorporating other building materials, such as brick and stone. Timber has a better appearance than aluminium and plastic, but requires more maintenance.
Greenhouses are obtainable in a variety of shapes: Rectangular ones are the most common and perhaps the most useful for the majority of gardeners. Some firms make extension modules which can be added to a smaller greenhouse. Mini-greenhouses, similar in all respects except for the size, are also available. In very tight spots, they can be useful, but it is better perhaps to look on them more as a large, vertical garden frame.