Structural drawings answer one question building control cannot take on trust: will it stand up, and by how much margin. They sit alongside the architectural set rather than replacing it, and on a domestic job they are usually the cheapest part of the package and the one most likely to cost you money if it is wrong.
MCIAT chartered drawings for planning, building regs, lofts and extensions — fixed fees 30% below typical London architects. Tell us what you need and we’ll reply the same working day.
A calculation set and the drawings that carry its results: beam and lintel sizes with their reactions, padstone and bearing details, connection details where members meet, foundation type and depth, and any temporary propping sequence needed to get from the existing structure to the new one safely.
Everything traces back to load. Dead load is the permanent weight of the construction, imposed load the variable weight of occupation and contents, and wind and snow are added where relevant. The member is then checked for strength and, usually more critically on a domestic span, for deflection — conventionally limited to span/360 so finishes above do not crack.
Whenever load is removed or redirected: taking out a wall between two rooms, forming an opening for bifolds, cutting a floor for a stair, removing chimney breasts, or building anything that sits on new foundations. Building control will ask for calculations for all of them, and an inspector cannot approve an assumed beam size.
Loft conversions bring their own case. New floor joists usually span between the existing party walls onto new steels, and the roof structure is altered rather than merely opened, so both the floor and the roof need checking. Basements add retaining structure and underpinning, which is why the basement package sits at £1,950 rather than the £840 planning fee.
The chimney breast case is the one homeowners most often get wrong: removing a breast at ground floor leaves the stack above unsupported, and gallows brackets are not universally accepted by London authorities. That is a calculation, not a rule of thumb.
On a London terrace almost every structural intervention touches a shared wall, and the Party Wall etc. Act 1996 then applies. Section 2 works — cutting into a party wall for a beam bearing, raising it, or removing a chimney breast built into it — need two months' notice. Section 6 excavation within 3m of a neighbouring structure to a lower depth than its foundations needs one month, extending to 6m where the excavation cuts a 45° line down from the neighbour's foundation. Section 1 covers building a new wall at the line of junction, again on one month.
The engineer's drawings are what the neighbour's surveyor reads. Vague bearing details produce questions, and questions produce delay — which is why we produce the structural set before serving notice rather than after.
Because the expensive mistakes live at the boundary between the two sets. A beam designed without reference to the insulation zone produces a cold bridge or a dropped ceiling nobody priced. A rooflight positioned without reference to the beam layout meets a steel on site. A stair drawn to Part K geometry that ignores the new floor structure loses its 2m headroom by 40mm.
We produce the architectural and structural sets together from one measured survey, so the beam schedule, the sections and the fire strategy describe a single building. Where a scheme needs a specialist — a basement, a complex frame — we say so and coordinate rather than stretching beyond our own competence.
£350 for structural calculations on a typical domestic scheme, fixed at instruction. Where they are bought as part of the combined planning and building regulations package the total is £1,750. Complex cases — basements, multi-connection frames, underpinning — are quoted individually because the design work genuinely differs.
If the wall carries load, yes, and whether it does is not reliably obvious from tapping it. Building control will require calculations for the replacement beam, sized against actual dead and imposed loads and checked for deflection, normally to span/360. An assumed beam size cannot be approved.
No — they answer different questions. Structural drawings size members and detail connections; the architectural set covers layout, fire strategy, thermal performance, ventilation, drainage and how the whole thing goes together. Building control needs both, and the failures we see most often are at the junction between them.
Deflection is how far a member sags under load. A beam can be strong enough not to fail and still bend enough to crack the plaster and jam the doors above it, which is why domestic design is usually governed by a deflection limit of about span/360 rather than by strength.
We produce the structural drawings your neighbour's surveyor will read, and we set out which sections of the Party Wall etc. Act 1996 apply and when notice must be served — two months for section 2 works, one month for section 1 and section 6. Formal surveyor appointments are a separate service and we will tell you plainly when you need one.
Send the opening width and what sits above it. We will confirm a fixed fee the same working day.
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