Without adequate insulation a shed can get very cold during the winter -- and very expensive if artificially heated. While you will need an initial outlay to purchase the materials for insulation, reduced heating bills and the creation of a more conducive environment in which to work will offset this . Bear in mind that because heat rises, you need to focus most attention on insulating the shed's roof.
Measure the surface area of the shed’s interior walls and roof. Purchase this amount of breathable lining membrane from a builder's merchants.
Tack the membrane to the interior cladding of the shed’s walls and ceiling. The membrane will provide an extra barrier to keep water out. While heavyweight polythene sheeting or bubble wrap are cheaper options, their inability to breath means that moisture won’t be able to escape from the shed.
Measure the thickness of the shed’s frame. Buy an insulation material, such as fibreglass wool, that is roughly the same thickness. Use the surface measurement area from step 1 to calculate the amount needed.
Tack this material so that it sits within the shed’s frame.
Nail plywood boards over the insulation material to further hold it in place. Be careful not to compress the insulation material as it is the air within it that provides the insulation. Although plasterboard is easier to work with than plywood, it can become damp in moist environments.
Cover the floor of the shed with sheets of laminate, plywood or carpet. Identify and seal any holes around doors, windows and panel joints. You can fill hard-to-access gaps using expandable polyurethane foam.