What Information Does a Structural Engineer Need?

The project brief

The brief is the single most valuable item. It does not need to be long: what is being done, why, where, when, and who else is involved is usually sufficient to establish scope.

It is particularly helpful to state what has already been decided and what remains open. An engineer approaches a fixed architectural layout very differently from one that can still be adjusted to suit an efficient structural arrangement.

Existing drawings

Any existing drawing is useful, even if it is old, incomplete or known to be inaccurate. Original architect's drawings, previous extension drawings, estate records, and drawings retrieved from a local authority building control archive all help to establish construction type, spans and previous alterations.

Where nothing exists, a measured survey may be required. Establishing that early avoids programme surprises later.

Architectural proposals

• —Existing and proposed plans, sections and elevations
• —The intended use of each space, and any changes of use
• —Openings, glazing and any areas where structure must be concealed
• —Finished floor levels, ceiling zones and any constraints on structural depth
• —Drawing status — concept, planning, tender or construction

Photographs

For existing buildings, photographs frequently communicate more than drawings. Elevations, the affected rooms, ceilings and floors, the roof space, any cellar, and the ground around the building all help. Photographs of areas of concern should include a scale.

Dimensions

• —Clear spans of floors, roofs and proposed openings
• —Wall thicknesses and construction, including whether walls are solid or cavity
• —Storey heights and available structural depth
• —Joist and rafter sizes, spacings and spans where they can be seen
• —Overall building dimensions and the extent of any extension

Surveys

Measured surveys, topographical surveys, and structural condition surveys each serve different purposes. On sloping or constrained sites, a topographical survey with levels is usually essential before foundations or retaining structures can be designed sensibly.

Where boundaries, party walls or rights of light are involved, the associated survey information is also relevant to the structural design.

Ground investigation

Ground investigation informs foundation design. For small domestic works, trial holes and a knowledge of local ground conditions are often sufficient. For new build, extensions on shrinkable clay, sites with made ground or mining history, and any commercial or industrial development, a formal site investigation report is normally required.

The report should identify soil types and strengths, groundwater, contamination, and recommended allowable bearing pressures or pile capacities.

Drainage

Drainage runs constrain foundations, and defective drainage is a frequent contributor to ground movement. Existing drainage layouts, the position of manholes, and any known history of leaks or blockages are all relevant. Where new foundations pass close to or over existing drains, specific detailing is required.

Equipment and plant loads

On commercial and industrial projects, loading information is the critical input. Weights, footprint, fixing arrangements, dynamic effects, and access routes for installation all influence the structural design.

Manufacturer's data sheets are preferable to estimates. Where equipment is not yet selected, an agreed allowance should be recorded explicitly, together with what happens if the eventual selection exceeds it.

Existing structural information

• —Previous structural calculations and drawings
• —Steelwork fabrication drawings and, where available, mill certificates
• —Records of previous strengthening, repairs or underpinning
• —Asset registers, maintenance records and previous condition reports
• —Details of any known load restrictions currently applied to the structure

Programme, contractor and constraints

• —Key dates: planning submission, building control, tender, start on site and completion
• —Whether a contractor is appointed, and whether they have proposed a construction method
• —Whether the building will remain occupied or operational during the works
• —Access restrictions, craneage limitations and working-hours constraints
• —Budget expectations, which legitimately influence the structural solution
• —Any listed building, conservation area or party wall considerations

How requirements differ by project type

• —Residential — emphasis on existing construction, spans, what is above the area being altered, and foundation depth. Photographs and dimensions often matter more than formal drawings.
• —Commercial — emphasis on change of use, imposed loading, fire and means of escape implications, tenant fit-out constraints and phasing around occupation.
• —Industrial — emphasis on record information for the existing frame, plant loading and dynamics, penetrations, craneage, operational continuity and construction-stage engineering.

Related guidance

• BES-TG-001Do I Need a Structural Engineer?Read →
• BES-TG-004Preparing for a Structural InspectionRead →
• FAQWhat information should I send to a structural engineer?Read →
• FAQWhat information is required for a quotation?Read →
• FAQHow long do structural calculations take?Read →