Homeowners often ask whether architectural drawings are 'enough', or whether they also need structural calculations. They do different jobs, and many projects need both. Here's the difference, when calculations are usually required, and how the two work together.
In short
Architectural drawings show the design and how the work is built; structural calculations are a structural engineer's evidence that load-bearing elements are strong enough. Many projects need both — calculations are common for beams, widened openings and loft floors. SC Design prepares and coordinates the drawings; calculations come from a structural engineer.
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Reviewed by Sean Corser, SC Design & Construction. Sean Corser helps Wirral homeowners with architectural design and drawing packs for extensions, loft conversions, planning and building regulations.
Last reviewed June 2026
Architectural drawings set out the design: layout, appearance, dimensions and — at building-regulations stage — how the work is constructed, including junctions, insulation, fire safety and drainage.
They tell the story of the whole project and give building control and your builder the information they need to assess and build it.
Structural calculations are specialist engineering evidence that the load-bearing parts of the work are strong enough and stable. They size beams, lintels and other members and demonstrate the structure performs safely.
They're a different discipline from design drawing, which is why a structural engineer usually prepares them.
Calculations are commonly required for steel or timber beams, widening or forming openings (for example removing a wall or knocking through), new loft floors, roof alterations, and changes to foundations or other significant structural work.
Planning Portal guidance notes that wider openings may need beams and padstones, and that calculations may be required — so it's worth establishing early whether your project triggers them.
The two are coordinated: the engineer's calculations confirm the structure, and the drawings show how it all fits into the design and construction. Building control may ask to see the calculations alongside the drawings.
We prepare the architectural and building-regulations drawings and coordinate with a structural engineer so the two sets line up. We don't present ourselves as the structural engineer unless that's expressly confirmed — the calculations are the engineer's specialist work.
A few details are enough for an honest first view — with no obligation:
Need building regulations drawings? We can prepare them — clear, coordinated and ready for builders and building control.
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Send Sean a few photos and a short description of what you'd like to do. You'll get an honest first view with no obligation.