Any works to the fabric of the building fall under Part A of the Building Regulations. If you are extending the flank wall to form a gable you will need to consider the following:
• The new wall will require a level base to be constructed from
• The load from the new wall will need to be checked to establish the strength of the existing wall under the new works.
• The new wall will require adequate lateral restraint at ceiling level and at roof level in the form of straps
• Thermal properties of the new wall will need to be compliant with the current Building Regulation.