Existing information needs assessment of reliability
Archive drawings for an existing building may differ from actual conditions. Later openings, changed floor layers and concealed repairs can matter. Ask what needs verification and how missing information will be handled. Ensure assumptions are identifiable in the documents. New builds place a different emphasis on coordinating proposed materials, dimensions and connections as one design for the construction team.
Ask which assessment framework is used
NEN describes the NEN 8700 series for existing structures and alterations in conjunction with the Eurocodes. The responsible adviser must determine and identify the applicable framework, editions and project assumptions. A standard number on a website does not demonstrate complete verification. Where existing and new elements are combined, assessment must address their interaction and clearly define its scope.
Make scope boundaries useful for construction
Ask which elements will be reassessed, which new elements will be designed and which existing parts are outside scope. Discuss what happens if investigation reveals different conditions. An offer may distinguish an initial investigation phase from later design. This keeps uncertainty visible instead of concealing it within a fixed solution. Retain the final assumptions with the drawings for assessment of later changes.
Practical checklist
- Identify existing and new elements
- Ask which information will be verified
- Have the assessment framework identified
- Address uncertainties in the scope
Existing construction is not a reason to ignore unknown material properties or changed loads.
Preparing your own project
Would you like this assessed for your home? See our information about renovation. It explains which information is relevant to that brief. The project check helps you prepare your enquiry.
Unsure about a term? The structural glossary provides plain-language explanations and technical context. To understand how the documents are organised, explore our fictional example project .
Background and sources
Sources checked on 3 October 2026. This guide is not a project-specific assessment.
Editorial guide • updated 3 October 2026. General information; not a project-specific assessment.