Posted By Jerry Lucey The procedure for carrying out structural alterations would have to include a sign off by a structural engineer prior to commencement of works on the existing structure and on completion of the works. It is important to assess the competence of the contractor to carry out the works. For this you could look at whether the contractor has sucessfully undertaken such projects in the past i.e. size, complexity etc. You could ask for references from previous clients. I would usually ask for sample risk assessments/ method statements, procedures and safety plans developed on previous projects etc. It is worth stressing though that the Contractor may not be competent to determine structural integrity of structures and a structural engineer may need to be consulted for works involving structural alterations.