Metal sheds are commonly used as outbuildings to store tools, supplies and gardening equipment. They usually aren't heated in winter or equipped with air conditioning in the warmer months. To keep the shed's interior as temperate as possible, proper insulation applied to the walls and ceiling is as important for energy conservation and efficiency as it is in your home. There are several options for insulating a metal shed.
If you hire a contractor to add insulation to your metal shed, the most efficient and least expensive option is to have the walls and ceiling "flocked." In this process, special equipment is used to spray a sticky mix of cellulose insulation onto the interior walls and ceiling. The material dries quickly, leaving a thick, permanent coating of insulation. The cost of the flocking mix is competitive with other materials, but a contractor can insulate your shed in a fraction of the time required with other methods. Be sure you get competitive bids from more than one insulation contractor to ensure a good price.
Fiberglass batting can be attached to the inside walls and ceiling of metal sheds with tape or stapled to wooden posts or rafters. Like flocked cellulose, unless a wall covering is applied on top of the batting, you end up with a soft interior wall that can easily be damaged. Fiberglass batting is the least expensive DIY installation.
Expanded polystyrene (such as Styrofoam) billets and sheets can be glued or otherwise attached to the interior walls of metal buildings to insulate them. The product comes in a variety of thicknesses, yielding different insulation R-values. Installing polystyrene insulation is an easy DIY project since the material is easy to cut and shape as needed.
If you add an interior wall to the inside of your metal shed, it's possible to blow dry cellulose insulation into the space between the interior walls and the metal exterior. You can rent the equipment needed to blow in cellulose insulation or have it done professionally.