Make sure that your chosen structure fits the house wall without obstructing any windows or doors. Pay special attention to the gas flue (if any). In general you must leave 150mm clearance between the conservatory/extension and a fan assisted flue. For peace of mind contact the boiler manufacturer and / or a Corgi registered gas installer.
It is usually possible to move if necessary any overflow pipes, rainwater downpipes, outside taps or kitchen extractor vents that obstruct the conservatory/extension.
Special attention needs to be given when considering aconservatory/extension for a bungalow or single storey extension as there is usually a height restriction for the conservatory roof. Edwardian back hipped or Victorian back hipped models are ideal for such restrictions.
Complications in the base area can include manholes, roding eyes, drain outlets and drain runs. All these complications can usually be overcome by a competent builder or DIYer.
Some thought also needs to be given to site access for delivery of building materials and the components, plus for the removal of spoils and rubbish.