Engineer's calculations for a Wiltshire project — steel beams sized, padstones and load paths worked out and a signed calculations package your builder and Wiltshire Council's building control can build from, delivered in days and revised free until it is approved.
Wiltshire Council granted 96% of the householder planning decisions it made in its latest published year — 9 points above the 87% England-wide householder average. Wiltshire contains ALDBOURNE, ALDERTON, ALL CANNINGS conservation areas (ALDBOURNE designated 1973), so materials, fenestration and roof form are assessed against the appraisal, which is where a policy-literate drawing pack earns its keep. Its dominant Victorian (1837–1901) and postwar (1945–1970) housing stock sets the design brief on most streets.
The permitted-development ceilings are fixed: 40m³ of new roof volume for a terraced loft and 50m³ for a semi or detached house under Class B, plus a 3m single-storey rear extension on a terrace or 4m on a detached house under Class A. Wiltshire carries at least one Article 4 direction, and conservation areas including ALDBOURNE, ALDERTON and ALL CANNINGS remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Wiltshire is determined against an 8-week statutory target.
ALDBOURNE (conservation area designated in 1973), ALDERTON (conservation area designated in 1974), ALL CANNINGS (conservation area designated in 1974), ALTON (conservation area designated in 1992), AMESBURY (conservation area designated in 1980), ANSTY (conservation area designated in 1975), ASHLEY (designated conservation area), ASHTON KEYNES (conservation area designated in 1974), Aldbourne & Ramsbury (ward of Wiltshire), Amesbury West (ward of Wiltshire), Avon Valley (ward of Wiltshire), Box & Colerne (ward of Wiltshire), By Brook (ward of Wiltshire), Corsham Ladbrook (ward of Wiltshire), Corsham Pickwick (ward of Wiltshire) and Corsham Without (ward of Wiltshire) — these are the Wiltshire pockets our drawings cover most. Heritage designations here include ALDBOURNE, ALDERTON, ALL CANNINGS, ALTON, AMESBURY, ANSTY, ASHLEY and ASHTON KEYNES. Wiltshire Council weighs each proposal against the adopted Wiltshire local plan and Wiltshire Council's design guidance for householder work, where the 92,640 homes here are 24% pre-1900, 7% 1965-1972, 7% 1955-1964, which is what sets the realistic roof and rear-projection options. On roofs the borough is steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building and shallow-pitched roofs and integral garages typical of that period's building, over Victorian and earlier houses (24% of 92,640 homes), late-1960s and early-1970s houses (7%) and late-1950s and early-1960s houses (7%).
Before anything is drawn we check your address against the designations that apply in Wiltshire: ALDBOURNE (conservation area designated in 1973), ALDERTON (conservation area designated in 1974), ALL CANNINGS (conservation area designated in 1974), ALTON (conservation area designated in 1992), AMESBURY (conservation area designated in 1980), ANSTY (conservation area designated in 1975), ASHLEY (designated conservation area) and ASHTON KEYNES (conservation area designated in 1974). Inside those boundaries permitted development is curtailed and Wiltshire Council assesses materials, window detail and roof form against the area's own appraisal, so a scheme that would be waved through two streets away can need a full application here.
Beyond the designated areas, Wiltshire takes in Aldbourne & Ramsbury, Amesbury West, Avon Valley, Box & Colerne, By Brook, Corsham Ladbrook, Corsham Pickwick and Corsham Without. Wiltshire Council has 48 recorded Article 4 directions, removing permitted development for rear and side extensions and other roof alterations, including rooflights — check the address before assuming PD applies in the district.
On stock, Wiltshire is Victorian and earlier houses (24% of 92,640 homes), late-1960s and early-1970s houses (7%) and late-1950s and early-1960s houses (7%) — which is why steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building and shallow-pitched roofs and integral garages typical of that period's building govern what a loft or rear projection can realistically be. Wiltshire Council decided 1,779 householder applications in the latest published year and granted 96%, with 53% issued inside the eight-week target. That decision record, not a national figure, is what we design to.
The full build-period split for Wiltshire runs pre-1900 3% (190 homes), 1900-1918 0% (30 homes), 1919-1929 0% (10 homes), 1930-1939 6% (350 homes), 1945-1954 3% (170 homes), 1955-1964 30% (1,850 homes), 1965-1972 33% (1,990 homes), 1973-1982 4% (260 homes), 1983-1992 5% (310 homes), 1993-1999 4% (220 homes) and 2000-2008 3% (170 homes). That distribution is why pre-1900 detailing dominates the drawings here, and it is measured from council-tax records rather than assumed from the street name.
Wiltshire Council also decides for Aldbourne & Ramsbury, Amesbury West, Avon Valley, Box & Colerne, By Brook, Corsham Ladbrook, Corsham Pickwick and Corsham Without, so a decision in Wiltshire sits inside a wider pattern of decisions we track across the same authority — useful when an officer cites a precedent from the next area over.
The Article 4 directions recorded for this council include Ashley, Avebury, Baydon 1 and Baydon 2. Each removes a specific permitted-development right inside its own boundary, which is why the check is done on the address rather than on the town.
Published figures for Wiltshire and Wiltshire Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | Wiltshire |
|---|---|
| Dwellings recorded | 92,640 |
| Built pre-1900 | 190 (3%) |
| Built 1900-1918 | 30 (0%) |
| Built 1919-1929 | 10 (0%) |
| Built 1930-1939 | 350 (6%) |
| Built 1945-1954 | 170 (3%) |
| Built 1955-1964 | 1,850 (30%) |
| Built 1965-1972 | 1,990 (33%) |
| Built 1973-1982 | 260 (4%) |
| Built 1983-1992 | 310 (5%) |
| Built 1993-1999 | 220 (4%) |
| Built 2000-2008 | 170 (3%) |
| Built before 1919 | 27% |
| Built 1919–1939 | 6% |
| Built 1945–2008 | 55% |
| Conservation areas in Wiltshire | 8 (ALDBOURNE, ALDERTON…) |
| Conservation areas district-wide | 245 |
| Article 4 directions recorded | 48 |
| Householder applications decided | 1,779 |
| Householder applications granted | 96% |
| Decided within 8 weeks | 53% |
Dwelling stock from VOA council-tax data at 31 March 2025; conservation-area and Article 4 counts from planning.data.gov.uk (MHCLG); decision figures are Wiltshire Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
The moment a wall comes out or a new floor goes in, something has to carry the load that wall or floor was holding — and building control will not accept "it looks strong enough". The engineer traces the load path: the weight of the roof, floors and walls above is gathered into a beam, the beam is sized in steel or timber to carry it within safe deflection, and that load is passed through padstones into the masonry and down to the ground. On Wiltshire's Victorian and earlier houses (24% of 92,640 homes), late-1960s and early-1970s houses (7%) and late-1950s and early-1960s houses (7%), the spans and loads differ house to house, so every calculation is specific to the property.
The deliverable is two things that work together: the calculations, which show the maths an approved inspector can check, and the structural drawings, which turn that maths into something a builder can order and fit — a beam schedule with sizes and lengths, bearing and padstone details, and connection notes. Wiltshire contains ALDBOURNE, ALDERTON, ALL CANNINGS conservation areas (ALDBOURNE designated 1973), so materials, fenestration and roof form are assessed against the appraisal, and the calculations are drawn to sit alongside the architectural set rather than contradict it. Everything is signed by a chartered or incorporated engineer carrying professional indemnity insurance.
Older Wiltshire stock — the kind found across ALDBOURNE, ALDERTON, ALL CANNINGS, ALTON, AMESBURY, ANSTY, ASHLEY and ASHTON KEYNES — often hides the real structural question: shallow Victorian foundations, timber that has been notched by past work, or a wall that turns out to be load-bearing when the drawings assumed otherwise. Wiltshire Council has 48 recorded Article 4 directions, removing permitted development for rear and side extensions and other roof alterations, including rooflights — check the address before assuming PD applies in the district. A survey-based calculation catches this before the wall is opened, not after.
Building control needs an engineer's calculations whenever you change how the building carries load. On a typical Wiltshire project that means any of these:
We size the steel, work the padstones and bearings, trace the load to the foundations and issue a signed calculations package and a beam schedule for Wiltshire Council's building control — coordinated with your architectural drawings so the beam that is calculated is the beam that is drawn and the beam that is ordered.
Below is Wiltshire Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Wiltshire Council granted 96% of 1,779 householder decisions in the year to 31 March 2026, 53% of them inside eight weeks. Structural calculations sit behind building control rather than planning, but the same wave of loft, extension and knock-through work that drives these decisions is exactly what needs an engineer's package.
Source: MHCLG planning application statistics (householder decisions, England, 1 April 2025 - 31 March 2026). Compare every borough on our London approval-rate league table.
Tell us about your project and get a fixed, no-obligation quote back within one working day. If you don't need planning permission at all, we'll tell you that too — for free.
Building control approves structural work by checking the numbers, not by looking at the finished steel. Wiltshire Council's inspector, or an approved inspector acting for you, reads the calculations to confirm the beam is deep enough for its span, that deflection stays within limits so ceilings do not crack, that the bearing length and padstones spread the point load into masonry that can take it, and that the load has somewhere to go all the way to the ground. Across ALDBOURNE, ALDERTON and ALL CANNINGS, the recurring issue is a beam sized off a rule of thumb that the actual span will not support.
The 92,640 homes here are 24% pre-1900, 7% 1965-1972, 7% 1955-1964, which is what sets the realistic roof and rear-projection options. We issue calculations detailed enough to be signed off without a query, coordinate them with the architect's drawings so nothing conflicts on site, and stay available to revise if the builder finds the Wiltshire property is not quite as the survey assumed — free, until the work is approved.
We calculate beams, openings and floors on the period and modern stock across the borough. A few of the Wiltshire neighbourhoods where structural packages come up most often:
Structural calculations for ALDBOURNE's conservation area designated in 1973 — beams sized, load paths traced and signed for Wiltshire Council's building control.
Structural calculations for ALDERTON's conservation area designated in 1974 — beams sized, load paths traced and signed for Wiltshire Council's building control.
Structural calculations for ALL CANNINGS's conservation area designated in 1974 — beams sized, load paths traced and signed for Wiltshire Council's building control.
Structural calculations for ALTON's conservation area designated in 1992 — beams sized, load paths traced and signed for Wiltshire Council's building control.
Structural calculations for AMESBURY's conservation area designated in 1980 — beams sized, load paths traced and signed for Wiltshire Council's building control.
Structural calculations for ANSTY's conservation area designated in 1975 — beams sized, load paths traced and signed for Wiltshire Council's building control.
Different jobs load the building differently, so each needs its own calculation. This is what the common Wiltshire projects typically require.
| Project | Typical structure | What the calculation proves | Signed off by |
|---|---|---|---|
| Wall knock-through | Steel beam on padstones | Span, deflection and bearing | Building control |
| Loft conversion | New floor beams and ridge/purlin steels | Floor loading and roof support | Building control |
| Rear or side extension | Opening beam plus extension roof and floor | Combined loads and foundations | Building control |
| Basement or underpinning | Retaining and foundation design | Ground and adjacent-building loads | Building control & party wall |
On older Wiltshire stock around ALDBOURNE and ALDERTON, shallow foundations and altered structure often mean the calculation drives the design rather than following it.
A fixed process built around building control rather than planning — most calculation packages are ready within five days of the architectural drawings.
Send us your Wiltshire postcode and the architect's drawings or a sketch. We confirm what structure the project needs, flag any load-bearing wall or foundation question, and tell you exactly what the calculation package will cover.
Where the loads are not obvious — an unknown wall, an old alteration, a deep span — we survey the property so the beam is sized on what is really there, not an assumption.
A chartered or incorporated engineer sizes the steel, works the padstones and load path, and issues the signed calculations and a beam schedule coordinated with your Wiltshire architectural set.
We submit the calculations to Wiltshire Council's building control or your approved inspector, answer queries, and revise free if the build uncovers something the survey could not see.
Whenever you change how the building carries weight — removing or opening a load-bearing wall, converting a loft, building an extension, or inserting a beam or column. Wiltshire Council's building control needs an engineer's calculation to approve any of these before the steel goes in. A Wiltshire project that only redecorates or moves a non-structural partition does not, but almost anything that opens the structure does.
No — they are a separate, later step. Planning permission decides whether Wiltshire Council will allow the change; structural calculations prove the change is safe to build and are submitted to building control, not to the planners. Many Wiltshire projects that need no planning permission at all — an internal knock-through, a permitted-development loft — still need a full engineer's calculation before work can lawfully start.
A chartered or incorporated structural engineer, carrying professional indemnity insurance, who takes responsibility for the numbers. Wiltshire Council's building control, or an approved inspector acting on your behalf, then checks and signs them off. Your builder cannot self-certify a steel beam, and an unsigned calculation will not be accepted — the engineer's signature and insurance are what make the package one building control will approve.
Yes — a beam over a removed wall is the most common calculation we do. We work out the load the wall was carrying, size a steel or timber beam to span the opening within safe deflection, and detail the padstones that spread its weight into the masonry each side. The result is a beam schedule your Wiltshire builder can order and Wiltshire Council's inspector can approve, with the load traced all the way to the foundations.
Sometimes. Where the loads are clear from the drawings we can calculate directly, but Wiltshire's older stock often hides surprises — a wall that turns out to be load-bearing, notched or altered joists, or shallow foundations near ALDBOURNE and ALDERTON. In those cases a short structural survey means the beam is sized on what is really there, which avoids a redesign once the builder opens the wall. Wiltshire Council is the decision-maker.
We price each Wiltshire package on the number of beams and the complexity — a single knock-through is straightforward, a whole-house loft-and-extension scheme has several elements — and send a fixed, no-obligation quote within one working day. It covers the calculations, the beam schedule and free revisions until Wiltshire Council's building control approves. Call 020 7864 7245 to start.
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