Structural engineering is mostly priced by scope, not by time on site - and for domestic work, reputable practices quote fixed fees up front. Rather than quote misleading national averages, here's what actually determines the price, and how to get a real number for your job.
What drives the cost
- Scope - a single beam calculation sits at the bottom of the range; a full structural design for a large extension or new build sits much higher
- Whether a site visit is needed - many calculation jobs can be done from drawings and photos; surveys always involve inspection
- The building - older, altered or unusual structures take more investigation than a standard semi
- Approvals involvement - whether the engineer is also handling Building Control submission and queries
- Urgency - purchase-deadline surveys are prioritised, which some practices charge for
The honest way to buy engineering
Send the engineer your drawings (or photos and a description for a survey), get a fixed fee in writing, and check what it includes - calculations only, or calculations plus details plus Building Control queries? The cheapest quote that excludes approval support is often the most expensive by the end. We quote fixed fees for all domestic work, with Building Control responses included on design packages.
For context on the value side: a correctly sized beam saves over-ordered steel; a foundation designed for the actual ground can save serious dig and concrete cost; and a purchase-survey that finds (or rules out) a real problem moves thousands in negotiation either way.