Greenhouse foundations and bases vary, depending on the type of greenhouse and the manufacturer's specifications. It is important that the foundations are strong enough to support the weight of the structure and that they are level. Often the base comes as part of the kit and is fixed to anchor pins buried in the ground; it should be capable of anchoring the structure in windy conditions and preventing it from lifting. Other greenhouse models will need a concrete or brick plinth.
If the lower part of the greenhouse sides are to be built of brick, you need to construct permanent foundations as for a patio. If you want to accommodate soil borders within the structure, the foundations must correspond exactly to the greenhouse measurements given by the manufacturer. If in any doubt, discuss the requirements with the supplier. At this stage you could also lay down concrete or paving slabs to make the permanent central path, which should be no less than 2 feet (60 cm) wide.
An alternative to having soil beds is to construct an entire solid floor of slabs or concrete over a hardcore foundation, in which case the base should extend beyond the greenhouse on all sides to spread the weight and help to reduce settlement later. Or the floor to either side of the path can be covered with a layer of gravel over a weed-proof membrane.
Although many suppliers offer a construction service, it is not difficult for two people to erect a small greenhouse. Read the instructions before you start, however. Begin by unpacking the sections and check that all items are present and correct. Each section will come as a numbered bundle; lay these out in order of construction and get to work!
The Reader’s Digest Association, Inc./GID
Greenhouse foundations shouldn't be too difficult to build, especially when they come in a kit.
