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To check whether construction follows the approved plan, first establish exactly which drawing set is current and approved. Then compare the same locations and elements on site, measure observable differences, record evidence against drawing revisions, and ask the responsible designer, contractor and building-control authority how any material discrepancy must be handled. A planning illustration, tender drawing, superseded revision or informal markup is not proof of what may be built.
The legal process depends on your country, local authority, building category and approval route. The steps below provide a disciplined comparison method, while examples from England, Scotland and New York City show why you must confirm the project-specific rules before altering, covering or accepting work.
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What counts as the approved drawing set?
Start with the documents that have authority for this project, not with the first PDF someone sends you. Ask the client, principal designer, contractor or building-control authority for the current approved or agreed drawings, specifications and formally issued revisions. Keep the drawing index, issue register or transmittal with the files so you can show how the set was identified.
Check the identity of every sheet
- Project address and, where relevant, building or plot reference.
- Drawing number, title and sheet description.
- Revision letter or number and issue date.
- Status, such as approved, agreed, construction issue or information only.
- Author, approving organisation and any approval reference.
England’s Building Safety Regulator (BSR) says drawings should be clearly labelled and accompanied by a reference file identifying each file and its contents. For an approved higher-risk building application, the uploaded documents are the “agreed documents.” Those labels matter because a drawing can be technically detailed yet have no authority for the work being inspected.
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Separate approval routes
Planning drawings, building-regulations drawings, structural calculations, fire strategies and construction details may be issued at different stages. A planning approval does not automatically approve every construction detail, and a tender package may be replaced before work starts. Identify which document controls the particular question you are checking: for example, a planning-approved footprint, a building-control wall build-up or a structural engineer’s beam detail.
How do I make sure the site team is using the same revision?
Ask the contractor or site manager to show the controlled copy available to the people setting out and building the work. Compare its revision and issue date with your reference set. Remove or mark superseded copies so they cannot be mistaken for live information.
New York City Department of Buildings guidance tells owners and contractors to check that completed work matches the most current approved drawings and that those drawings are on site before scheduling required inspections. The practical lesson applies more broadly: a comparison against an old revision can produce either a false non-compliance finding or, worse, acceptance of work that was never approved.
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- An early planning illustration when a later technical drawing governs.
- A tender or pricing drawing marked “not for construction.”
- A scanned print with handwritten changes but no formal issue or approval.
- A contractor’s shop drawing that has not been accepted through the project’s document-control process.
- A screenshot or cropped detail that omits the title block and revision.
When a revision is missing, pause the conclusion rather than guessing. Record which sheet you received, request the issue register and ask who is authorised to confirm the current requirement.
How can I compare the building with the drawings?
Compare like with like: stand at a known part of the building, identify the corresponding plan, section or elevation, and work through one element at a time. The checklist below is a practical synthesis for owners and site teams, not a universal inspection standard.
1. Confirm orientation and reference points
Use the drawing’s north arrow, grid lines, survey coordinates, setting-out points, levels and fixed features such as the site boundary or an existing wall. A room can appear reversed if a plan is viewed from the wrong direction. Establish a baseline before taking dimensions.
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2. Check location and overall dimensions
Compare the building footprint, offsets to boundaries, floor-to-floor levels, ridge or parapet heights and the position of extensions. Measure from stable reference points rather than from a finish that may move. Note whether the drawing dimension is to a structural face, finished face or centreline; mixing those conventions can create an apparent error.
3. Check layout and openings
Walk each floor and compare walls, partitions, doors, windows, stairs, ramps, shafts and service penetrations. Check opening widths, sill and head heights where shown, door swing and the relationship to escape routes or accessible routes. A wall in the right room but on the wrong line can affect structure, fire separation, ventilation or usable area.
4. Check structural and safety-critical elements
Look for columns, beams, load-bearing walls, foundations, retaining structures, fire compartments, protected stairs, cavity barriers and smoke-control features where they are represented. Do not infer concealed construction from a finished surface. A visible plasterboard face cannot establish the studs, fixings, fire stopping or insulation behind it.
5. Check materials and systems shown
Where the approved information specifies a wall build-up, roof covering, insulation, window type, fire door rating, cladding system or mechanical and electrical arrangement, compare the installed product or system evidence. A colour or surface appearance alone is not sufficient to identify performance. Ask for product data, delivery records, certificates or inspection evidence where the project requires them.
6. Use measuring tools correctly
Use a tape measure for observable site dimensions. A scale ruler is useful only when the drawing scale is known and the sheet has not been resized by printing, scanning or a PDF viewer. The dimension written on the drawing takes precedence over scaling a line. Record the measurement method and uncertainty, especially where access, finishes or tolerances limit accuracy.
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Record observations, not legal conclusions. Write what you saw, where you saw it and how you measured it; leave the determination of approval or compliance to the responsible professionals and authority.
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Minimum discrepancy record
- Date and time of observation.
- Project address, floor, room, grid line or other precise location.
- Drawing number, title, revision and issue date used for comparison.
- Element checked, such as “window W-03” or “north boundary offset.”
- Drawing requirement, including the stated dimension or detail reference.
- Observed condition and measured value.
- Measurement method, access limitation and any tolerance visible in the information.
- Photograph numbers and the person who made the observation.
- Question raised, responsible person notified and response or action due.
Photographs that remain useful later
Take an overall image that identifies the location and a closer image showing the detail. Include a tape measure, ruler, level or other reference when it helps establish scale. Scottish Government verification guidance gives a photograph with a tape measure as an example of evidence. Add the date, location and photo number to your log rather than relying on a camera filename.
A photograph proves only what was visible at that time. It does not establish that the work was approved, identify concealed layers or prove that a product meets a performance requirement. Photograph critical work before it is covered when the project’s inspection arrangements call for that evidence.
How do I know whether a difference is an authorised change?
An apparent mismatch is not automatically defective work. Check the revision register, architect’s instructions, approved substitution, site instruction, building-control comment and any formal change-control record before calling it non-compliant.
England: controlled changes for higher-risk buildings
For an approved higher-risk building application in England, the agreed documents must be followed throughout the build. The BSR states: “You must comply with the agreed documents throughout the build.” A change to those documents is controlled and must be assessed and recorded in the change control log. A major change requires BSR approval before related work is carried out. Ask the project’s accountable and responsible people which category applies and obtain the recorded decision; do not rely on a verbal assurance.
Other projects and jurisdictions
Non-higher-risk projects may use a different amendment, inspection or notice process. The contract may require an architect’s instruction, a revised building-control submission or a new planning decision. Confirm the route with the project’s building-control body and designer. Never assume that the formal higher-risk process in England applies to a house in another country, a different building category or a project using another approval route.
What should I do if the work does not match the plans?
- Stop making the situation harder to inspect. If safe and contractually appropriate, pause covering, enclosing or altering the affected work until the responsible people advise. Do not enter an unsafe area to obtain evidence.
- Complete a discrepancy record. Attach the relevant drawing extract, measurements and photographs, and identify the exact revision.
- Notify the responsible designer and contractor. Send the record through the project’s normal document-control or site-reporting channel so there is a dated trail.
- Ask whether a formal change exists. Request the revision, instruction, approval, change assessment or inspection note that supports the installed condition.
- Ask building control what is required. The authority may require opening-up, additional calculations, remedial work, a revised submission or a targeted inspection.
- Track the response to closure. Record the decision, person responsible, deadline, evidence supplied and final inspection or sign-off. Keep the original observation even if the work is later corrected.
England’s building-control performance standards describe keeping inspection records, communicating contraventions promptly and notifying statutory consultees about significant departures from plans. Westminster guidance also notes that where plans are not formally approved, inspections may identify work requiring further work before a certificate can be issued. The exact consequence depends on the authority and approval route.
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Which differences deserve immediate escalation?
Prioritise a discrepancy when it could affect life safety, structural stability, escape, accessibility, fire resistance, drainage, boundary compliance or the ability to inspect concealed work. Escalate promptly when:
- A load-bearing element, foundation, retaining wall or structural connection is in a different position or size.
- A fire compartment, protected escape route, fire door, cavity barrier or smoke-control feature is missing or altered.
- A stair, guard, ramp, landing or doorway changes a safety-critical dimension.
- An opening, roof height or building footprint affects planning conditions, neighbouring property or the site boundary.
- Specified insulation, cladding, waterproofing or a building-services system has been substituted without supporting information.
- Work is about to be concealed and no inspection or evidence has been obtained.
- The team cannot identify which revision or approval authorises the installed condition.
Minor finish variation may be dealt with through normal quality control, but do not label it minor merely because it is visible. Ask the designer or authority to classify the consequence when the effect is uncertain.
How should I check work before it is covered?
Plan hold points around foundations, reinforcement, drainage, membranes, insulation, fire stopping, cavity barriers, service penetrations and other elements that become inaccessible. The hold point should identify who inspects, what drawing or specification is checked, what evidence is retained and whether work may proceed.
Take photographs from more than one angle, include a scale or location reference, and mark the photograph against a plan when necessary. Record concrete pours, pressure tests, insulation continuity or fire-stopping checks only when the responsible person has actually carried them out. A photo of an open cavity is useful evidence of the visible condition, not a substitute for a competent inspection or product certification.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How do jurisdiction and building type change the process?
There is no single worldwide definition of “approved drawings.” Use the project’s own legislation, approval notice and inspection plan.
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|---|---|---|
| England, higher-risk building application | BSR identifies agreed documents, requires clear file labelling and controls changes through assessment and a change control log; a major change needs approval before related work. | Verify the agreed-document revision and change record before accepting a difference. |
| England, building-control practice | Performance standards emphasise inspection records, prompt communication of contraventions and notification of significant departures. | Keep a dated evidence trail and notify the appropriate building-control body. |
| Scotland | Verification guidance uses site evidence such as a photograph with a tape measure; the verification process and building warrant govern the project. | Use photographs and measurements as evidence, while following the verifier’s requested format. |
| New York City | Department of Buildings guidance tells owners and contractors to ensure completed work matches the most current approved drawings and that those drawings are on site before required inspections. | Check the current approved set on site before scheduling an inspection. |
England’s Approved Documents provide guidance on ways to meet building regulations; they do not replace checking the project’s own approved documents. Scotland’s building-warrant and verification arrangements, and New York City’s filing and inspection requirements, are distinct. Ask the local authority or verifier which notice, inspection, amendment and certificate rules apply to your building.
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What scale should a site location plan use?
For the specified higher-risk building application guidance in England, BSR gives a minimum 1:1,250 scale for the site location plan. That figure is not a general scale rule for every drawing, project or jurisdiction. Other plans may use different scales, and a detail sheet may be “not to scale.” Always use written dimensions and the drawing’s stated scale rather than applying 1:1,250 to a floor plan or detail.
Worked example: investigating a moved window
Suppose the approved elevation places window W-03 900 mm from the internal corner, while the installed frame appears 1,150 mm away. First photograph the elevation and measure from the same reference face used by the drawing. Check whether the wall thickness or finish changes the reference. Then verify the sheet revision and search the issue register for a revised window schedule, energy calculation or planning amendment.
If no authorised change is found, issue a discrepancy record stating both dimensions, the measurement method, the drawing reference and the potential effect. Ask the designer whether the move affects structure, fire performance, ventilation, daylight, planning conditions or accessibility. Building control may request a revised detail, calculations, an inspection or remedial repositioning. Do not order demolition solely on the basis of the first visual comparison.
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How can I organise a repeatable inspection?
- Create a register of current drawings and approval documents.
- Divide the building into zones, floors or grid areas.
- For each zone, list walls, openings, levels, structure, services and specified systems shown on the drawings.
- Inspect in a fixed route and give every observation a unique number.
- Attach measurements and photographs immediately, while the location is clear.
- Classify each item as matching, apparent difference, authorised change pending evidence, or unresolved.
- Issue the log to the responsible people and set a response date.
- Update the register when a revision or decision is formally issued; never overwrite the original observation.
A simple spreadsheet can contain columns for item number, location, drawing revision, requirement, observed condition, evidence, responsible person, response, due date and closure reference. Use the same naming convention for photographs, drawings and inspection notes so another person can reconstruct the comparison.
When should I appoint a professional?
Seek a qualified building surveyor, architect, structural engineer, fire specialist or building-control professional when the difference is material, safety-related, concealed, disputed or outside your competence. An owner’s visual check can identify a question; it cannot certify structural adequacy, fire performance or legal compliance. Give the professional the controlled drawing set, revision history, photographs, measurements, inspection records and any change-control documents so the assessment starts from reliable information.
The practical test
A building plan matches the approved drawings only when you can identify the controlling revision, compare the same location and element, document what is actually observable, and trace any difference to an authorised decision or corrective action. Keep checking as work progresses, especially before critical work is covered, and use the applicable authority’s process rather than assuming that a procedure from another jurisdiction applies.
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