Businesses specialising in timber frame buildings design, manufacture and assemble structures using timber as the main structural material. Their work can include homes, extensions, garden buildings and buildings for commercial or agricultural use. Some provide a complete service, from initial design and structural calculations through to fabrication and erection, while others supply prefabricated wall panels, floor cassettes, roof trusses or frame kits for installation by a separate building contractor. Typical services include preparing drawings, constructing the frame, fitting sheathing and structural components, and coordinating openings for doors, windows and services. Depending on the project, firms may also install insulation, membranes and external cladding, or advise on how these elements fit with the frame. Customers may need to arrange foundations, internal finishes and utility connections separately.