Structural appraisal for change of use

Appraising a building you did not design means working out how it actually stands up, which is rarely as tidy as a new-build calculation. We review any available drawings, but we do not take them on trust, because buildings are altered over their lives and the drawings often lag behind. A site survey establishes the real structural form, the spans, the members and their condition, and where the structure is hidden we identify what needs opening up or investigating before firm conclusions can be drawn. Following the principles in the guidance on structural appraisal, we build a clear picture of the load paths and the condition before we assess capacity.

Older materials need judgement, not just a formula. Cast iron, wrought iron, early steel, lime-mortared masonry and historic timber all behave differently from modern materials and are assessed on their own terms, allowing for corrosion, decay and past alterations. Where the original design standard is unknown, we assess the members against current codes and, where justified, use testing or established assessment methods to establish real capacity. The aim is an honest statement of what the building can and cannot do, not an optimistic one that unravels on site.

The output is a report that answers the practical question the client is actually asking: can this building take the change of use, and if not, what has to happen to make it work. We set out the existing structure, the loads for the proposed use, where the structure is adequate and where it is not, and outline strengthening or alteration where it is needed, with enough detail to inform the budget and the design that follows. Where the change of use needs planning or Building Control approval, the appraisal gives them the structural evidence they will look for.

An appraisal is also a risk tool for a purchase or a development appraisal, because it tells a buyer or developer what they are taking on before they commit. We keep the report clear and specific, flag anything that needs further investigation rather than glossing over it, and give a defensible position rather than a reassuring one. We agree a single fixed fee agreed before we begin, and we work with clients across the UK, delivering reports remotely and arranging site visits by region.