Want an extension for your home The Mercia 3m x 2m Self Build Garden Room is the perfect solution. The insulated garden pod is suitable for year-round use, boasting a range of features:. *Simple design for easy self-assembly *72mm Thick Double Skinned Walls *Fully insulated roof, floor and walls *Interlocking tongue and groove roof and floor *14mm double-glazed windows *10-year anti-rot guarantee