Building regulations drawings London: what the set contains and which route to use
Planning drawings show a council what you will build. Building regulations drawings show a builder and building control how it will stand up, keep warm, resist fire and drain. This page lists what goes in the set for each project type, compares a full plans application with a building notice, and links every Approved Document.
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(£625 if you supply measured drawings)
Building regulations drawings
Fixed in writing after a free assessment of your property. Council planning fees are separate.
Details building control approves and builders can price
Every price is the total you pay. Checked 24 October 2026.
What goes in a building regulations drawing set, by project type?
The Approved Documents that apply depend on the scheme, so the table shows the usual ones for each project type, not a complete list. Each Part links to its page on GOV.UK.
Project
Drawings in the set
Approved Documents usually engaged
Often added
Single-storey rear extension
Foundation and ground floor plan; roof plan; 1:20 wall, floor and roof sections; steel layout; drainage layout; electrics and heating notes
Planning permission for the change of use, as a separate application
Source: GOV.UK Approved Documents collection, read 14 October 2026. 'Usually engaged' is our working summary: building control decides what a particular scheme needs. Drawing lists describe our own sets.
Full plans or building notice: which should you choose?
Full plans gives you approval before work starts. A building notice does not. For anything structural, near a drain or involving a loft, full plans is the safer route, and for some work it is the only one.
Question
Full plans application
Building notice
What you send
Plans and information showing the construction details (Planning Portal); the application contents are listed in regulation 14
A description of the work, location and, for an extension, a 1:1250 plan, storeys and drainage details (regulation 13). Detailed drawings are not needed in most cases (Planning Portal)
Approval before work
Yes. If the plans comply you receive a notice of approval
No. The Planning Portal says you do not have the protection provided by the approval of full plans
Time to decision
Five weeks from receipt, or a longer period agreed in writing (regulation 14A(6)). The Planning Portal gives five weeks, or a maximum of two months if you agree. Failure to notify is neither a grant nor a rejection
No decision. You must give notice of intention to start and wait at least two days after the end of the day you gave it (regulation 16(1)). The Planning Portal says work can begin 2 days after the notice
Where it is required
Required for work in buildings the Fire Safety Order applies to, a new building fronting a private street, and work where Part H4 imposes a requirement, which covers building over or near a drain or sewer shown on the sewer map (regulation 12(3) to (5))
Not available for the cases in the left-hand column
Risk to the owner
Problems surface on paper before the builder prices or digs
An inspector can ask for opening up and changes on site. You risk having to correct work, and who pays depends on your building contract
How long it stays valid
Approval lapses if the work is not commenced within three years from the end of the day the application was made (Building Act 1984 s.32). Commenced means a defined stage under regulation 46A
The notice ceases to have effect after three years from the date given unless work has commenced (regulation 13(5))
Sources: Building Regulations 2010, regulations 12 to 14A, 16; Building Act 1984 s.32; Planning Portal full plans and building notice pages; all read 14 October 2026. Discrepancy: the Planning Portal full plans page gives a two-month maximum 'if you agree', which matches the former section 16 of the Building Act 1984 (omitted in England from 1 October 2023), and says approval is valid for three years from the date the plans were deposited, after which the council may declare it of no effect. The current regulation 14A(6) reads 'five weeks ... or such longer period as ... agreed in writing', and under section 32 approval lapses if work has not commenced within three years from the end of the day the application was made. We follow the legislation and report the difference.
Who gives approval: the council or a registered approver?
Building control work in England can be done by local authority building control or by a registered building control approver. The Planning Portal's building notice page describes a notice as an application to local authority building control, and GOV.UK says private businesses doing building control work in England must register with the Building Safety Regulator. If you choose a private approver, the old term 'approved inspector' no longer applies, and the route and paperwork differ from a building notice or a full plans application to the council.
Our drawing set is the same either way. It is written to the Approved Documents for England, so any building control body in England can check it against the same guidance.
Which numbers appear on construction drawings?
A building regulations set stands or falls on its figures. These are the standards a typical London loft or extension drawing is checked against, with the edition date shown, because the documents change.
Part
What the drawing must show
Figure
Edition
L: new roof and wall elements
Thermal performance of new elements in an existing dwelling (Table 4.2)
Roof 0.15 and wall 0.18 W/m2K, maximum
2021 edition incorporating 2023 amendments. A 2026 edition takes effect on 24 March 2027, subject to transitional arrangements
L: renovated retained roof
Thermal performance where an existing roof is renovated (Table 4.3)
0.16 W/m2K maximum (a lesser standard may be accepted where it would limit headroom)
As above
B: new loft floor
Fire resistance of a new floor in the loft conversion (para 5.4)
Minimum REI 30 minutes; integrity and insulation may be reduced where one storey with no more than two habitable rooms and 50 m2 is added
2019 edition incorporating amendments to 2026; updated on GOV.UK 16 September 2026
K: private stair
Pitch, rise and going (Table 1.1)
Pitch 42 degrees at most; rise 220 mm at most; going 220 mm at least (Table 1.1); headroom at least 2 m (para 1.11)
2013 edition
F: bathroom extract
Intermittent extract rate (Table 1.1)
At least 15 litres per second
2021 edition. A 2026 edition takes effect on 24 March 2027
Sources: Approved Documents L, B, K and F, read 13 October 2026 for the loft guide and re-checked against GOV.UK on 14 October 2026. Loft-specific figures, including reduced headroom in Diagram 1.4 of Approved Document K, are covered in our loft conversion building regulations guide.
Where do I read each Approved Document, and when was it updated?
The Approved Documents are lettered Part A to Part T, with no Part I and no Part N, plus the separate Approved Document 7 on materials and workmanship. The dates are the 'last updated' dates GOV.UK shows against each document.
Source: GOV.UK Approved Documents collection, dates read from the listing on 14 October 2026. The collection page's own update note is older than some of the item dates and GOV.UK does not explain the difference, so check the edition on the document page before you rely on a figure.
What mistakes make building control send drawings back?
Most queries are about missing information, not the design. These are the gaps we close before a set goes in.
Beam and padstone positions with no calculation behind them, so the structural design and the drawings disagree
A loft stair and escape route drawn without the protected-route and door details Part B needs
Wall, floor and roof build-ups drawn without thicknesses or U-values, so Part L cannot be checked
No drainage layout, or no note that a public sewer lies close, which can turn a building notice into a full plans job (regulation 12(5))
A set that cites an old edition of an Approved Document without saying which edition applies
Work started without a notice of intention to start: regulation 16(1) requires the notice and at least two days before work starts, and regulation 16(3C) requires a commencement notice within five days of work being regarded as commenced
What about work already built without approval?
Where unauthorised building work was carried out on or after 11 November 1985, the owner can apply to the council for a regularisation certificate under regulation 18 of the Building Regulations 2010. The application needs a description of the work and, so far as practicable, plans of the unauthorised work and of any additional work needed to make it comply with the requirements that applied when it was built. The council can require the work to be opened up for inspection.
We prepare those as-built and remedial drawings. The comparison between planning permission and building regulations, including enforcement time limits, is in our planning permission vs building regulations guide.
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.
Detailed enough to build from, written to the Approved Documents
Our building regulations drawings are written to the national Approved Documents, so builders can price them like for like and any building control body can check them.
7 days drawing turnaround
Parts A–T approved documents, where they apply
Free revisions until sign-off
From planning approval to a decision on your drawings
The same four steps apply to an extension, a loft or a conversion.
1
Scope and survey
We review your approved planning drawings, whoever drew them, and confirm the structural scope and the Approved Documents your project engages.
2
Construction drawings
We produce plans, sections and details specifying structure, insulation, fire safety, ventilation and drainage.
3
Structural coordination
We coordinate calculations for beams, steels, padstones and foundations so the engineering is built into the drawings.
4
Submission and queries
We submit the full plans application to your council's building control, or the plans and initial notice paperwork to your registered building control approver if you use one, answer queries and revise the drawings free until a decision.
Frequently asked questions
What are building regulations drawings?
Building regulations drawings are construction-level plans, sections and details showing how work complies with the Approved Documents: structure, fire safety, insulation, ventilation, drainage and electrical safety. They differ from planning drawings, which show size and appearance. Builders price from them and building control checks them, so they carry wall build-ups, steel positions and drainage runs.
Do I need building regulations drawings if I have planning permission?
Yes, for most building work. Planning permission and building regulations approval are separate regimes. Planning approves what you build. Building control approves how it is built. Work that is permitted development, so needs no planning permission, still needs building regulations approval where the regulations apply.
Should I choose full plans or a building notice?
Full plans gives approval before work starts, so problems surface on paper. A building notice needs less detail but gives no approval in advance, and an inspector can ask for changes on site. Regulation 12 requires full plans for some work, including work near a drain that Part H4 covers. For lofts and structural work we recommend full plans.
How long does building control take to decide a full plans application?
Regulation 14A(6) requires the authority to notify you of the outcome within five weeks of receipt, or a longer period you agree in writing. The Planning Portal describes a two-month maximum if you agree. A late decision is not treated as a grant or a rejection, so you cannot rely on silence. Plan the programme around the decision, not the deadline.
How long is building regulations approval valid?
Under section 32 of the Building Act 1984, approval lapses if the work is not commenced within three years from the end of the day the application was made. Regulation 46A defines commencement: for a new building or a horizontal extension, when all foundations, any basement and the ground-floor structure are complete; for other work, when the 15% of the work set out in the application is complete. A building notice also ceases after three years unless work has commenced.
What drawings are in a building regulations set for a rear extension?
A set for a rear extension normally has a foundation and ground floor plan, roof plan, 1:20 sections of the wall, floor and roof, a steel layout with calculations, a drainage layout, and notes on electrics and heating. Parts A, C, F, H, L and P are the usual engaged documents. Building control may ask for more.
Can I use the same drawings for planning permission and building regulations?
Not usually. Planning drawings show the size and look of the scheme at 1:50 or 1:100. Building regulations drawings add construction detail, often at 1:20, with specifications and calculations. We prepare the building regulations set from the approved planning drawings so the two sets agree, and we amend the building set if the planning drawings change.
Do I need an architect or an engineer for building regulations drawings?
Regulation 14 lists what a full plans application must include and names no professional qualification for whoever prepares it. Structural alterations need calculations, which an engineer produces. We coordinate the calculations with the drawings so the set is consistent. A set for an extension or loft is typically drawn by a technician and checked against the Approved Documents before submission.
What if the work was built without building regulations approval?
For unauthorised work carried out on or after 11 November 1985, regulation 18 allows the owner to apply for a regularisation certificate. The council may require the work to be opened up for inspection and may ask for additional work to make it comply with the rules that applied when it was built. We prepare as-built and remedial drawings for it.
Which Approved Documents apply to a London loft conversion?
Usually Part A for the floor and steel, Part B for escape and fire separation, Part F for ventilation, Part K for the stair and Part L for insulation, with Part P if wiring is added and, for new floors and bedroom walls, Part E. Part B was updated on GOV.UK on 16 September 2026, so check the edition. Our loft guide goes through each requirement.
Building regulations drawings by London borough
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