Cold frames are most commonly constructed using a metal framework, with glass (or clear plastic) sides and 'lights' (the top of the frame). Frames made using aluminium alloy are relatively inexpensive to buy and let in a great deal of light. However, they generally do not have good insulating qualities and may not be particularly sturdy. Wood and brick can be used to form a warm and draught-proof solid base; although these are not as easily available to buy as metal framed versions, they can be made cheaply at home.

A frame with sliding lights and front panels will allow you to easily access your plants and provide additional ventilation. Hinged lights are also available; these may be wedged open, not only providing fresh air inside, but also protection from heavy rain.

The best glazing material for cold frames is horticultural glass, which transmits light well and retains heat better than most plastic materials. Any cracked or broken frames should be replaced straightaway, so it is best to choose a frame that allows the individual panes to be replaced easily. Alternatively, plastic glazing material may be used as a cheaper option, or for where glass may present a hazard for children or animals.

An effective cold frame should be well insulated and draught-proof, with no gaps around the glass or framework. Frames with glass or plastic sides may be insulated using expanded polystyrene sheets during the winter; simply position them inside of the frame to reduce heat loss. On particularly cold or frosty nights, protect the cold frame using old carpet or layers of hessian to cover the top. Hold these in place with pieces of wood and remove in the day time so that the plants can receive adequate light. Alternatively, use several layers of thick, clear plastic sheeting; this has the added benefit that it allows in light, and so may be left in place during the day.

Lightweight frames may be moved around the garden so that they receive the best light during different times of the year. Permanent frames should be built where they will get the maximum amount of light in winter and spring.

In addition to housing pots of plants, you can also grow plants directly in the frame itself. Cover the base with a thick layer of drainage material, such as coarse gravel or broken crocks, then add in a 15 cm (6 in) layer of compost or good garden soil.