Contact local authority building control to confirm need for approval/warrant for work. Establish the part(s) of the current building code relevant for your proposal. Consider any additional implications of your measure (e.g. insulation may imply improving air tightness and affect ventilation; work to floors may allow for the inclusion of Radon barrier in risk areas). Draw up detail plans and specification and submit in advance to local authority building control or approved inspector for approval. Negotiate and alter design details in response to the inspector

Establish programme of building inspector visits to site during works. On completion, obtain completion certificate from building inspector or certificate by competent installer.