Adding an external porch to the front or back door can stop draughts entering the house. It also provides useful space for coats and shoes - so mud and dirt is not trodden through the house - and can double as a mini-greenhouse for delicate or even tropical plants. A part-glazed porch will allow you to keep the outer access locked until you have identified callers. Planning permission is not needed unless the floor area exceeds 2m sq. or any part is more than 3m (9ft) high, or less than 2m (6ft) from a boundary adjoining a public highway or foot-path. Ready-made porches are available in kit form in a range of styles that are easy to erect, and don't require masonry foundations or supporting walls. You will of course need a solid foundation for any such work.

1 Erecting the side panels

Offer up the first panel to the wall and mark the position of the fixing holes. You may need help to hold the panel in place while you check its vertical levels with a spirit level. Use a masonry bit on a low speed to drill into the wall. Avoid drilling into mortar joints. Then plug the holes.

2 Attaching additional panels

Subsequent panels of the porch are joined using the manufacturer's fittings; some systems simply 'slot and lock' together. It will be useful to have someone to support the panels while they are being positioned and secured, paying particular care to any glazed sections so you don't break them.

3 Adding the door

Before you buy your porch, make sure you check whether the new front door is to open in or outwards and whether it is to be hung on the left or right-hand side. Also ensure that it locks securely and that there is a letterbox.

4 Securing to the base

Many modern porches are constructed so that the panels slot into a grooved channel at the base and are then secured with the supplied fixings. Follow the instructions regarding number and spacing so that panels are well secured.

5 Adding the seals

To make the joins between the panels neat and weatherproof, strips of plastic or plastic-coated sealant are inserted into the grooves. Depending on the system you have chosen, these may require pinning to secure them.

6 Adding the roof

While porches may appear to have flat roofs, they are actually designed to slope away from the neighbouring walls so that rain-water doesn't collect on the roof but is channelled and shed off away from the walls. Use a spirit level to ensure that the required angle of fall is present.

7 Securing the roof

The roof, the fascia boards and the internal supporting cross-members of the roof are secured to the panels, often through pre-drilled holes. Finish with roofing felt or transparent PVC roofing, depending on your choice of porch and the instructions supplied.