Building control, England

Building control, explained — and handled.

Everything a London homeowner needs to know about the Building Regulations for a loft, an extension, a renovation or a new build. The exact rules, the inspection stages, and the figures that will come up on your job — every one cited to its clause. And when you build with us, we run the whole process for you.

The 30-second answer. If you are extending, converting a loft, taking out a structural wall, underpinning, changing the use of a building, insulating a cavity, or altering a controlled service — heating, drainage, ventilation, electrics, windows or doors — the Building Regulations apply and building control has to be involved. A loft conversion and a new build always need it. An extension almost always does. A renovation depends entirely on what you touch.

2 working daysnotice before work may start

8 stageswhere an inspector must be called

12 monthsthe council's window to serve a s.36 notice

Unlimitedthe fine on prosecution

First, the thing most people get wrong

Planning permission and building control are two different things.

They are separate consents, tested by different people against completely different questions. Having one never implies the other — and this single misunderstanding causes more trouble than any other on a domestic project.

Planning permission

Asks: may you build this thing at all, here, looking like that?

Decided by: your local planning authority.

Cares about: size, siting, appearance, impact on neighbours, conservation area and listed status, overlooking, daylight.

Not needed when the work falls within permitted development — but that changes nothing about building control.

Building control

Asks: is it structurally safe, fire safe, warm, healthy and properly built?

Decided by: the council’s building control team or a private approved inspector.

Cares about: foundations, structure, fire escape, insulation, ventilation, drainage, electrics, glazing, stairs.

Needed even when planning is not. Permitted development is not an exemption from the Building Regulations.

Worth knowing: the Building Regulations 2010 are the law. The Approved Documents — Part A, Part B, Part L and so on — are statutory guidance showing one way of meeting the law. You can meet the law another way if you can demonstrate it, and your building control body has the final word on your specific building.

Your job, specifically

What applies to your project.

Pick the job you are planning. Each one gives you the verdict, the parts of the Building Regulations that will actually bite, the inspections that will happen, what you need to decide, and the figures that will come up in conversation with your builder.

Always

A loft conversion always needs building control. It changes the structure, it adds a storey, and it changes how everyone escapes the building in a fire. Many rear dormers are permitted development and need no planning permission at all — that makes no difference here.

What actually bites

Fire escape. Once a storey sits more than 4.5m above ground level, the stair becomes a protected escape route — fire-resisting construction to REI 30 and fire doorsets to E 30.AD B §2.5–2.6
Structure. New floor joists and steels, with padstones sized by a structural engineer.AD A, Req. A1
Stairs. Rise, going, pitch and headroom — the numbers below.AD K §1.2–1.13
Insulation. New roof elements to 0.15 W/(m²·K); retained elements upgraded where feasible.AD L Tables 4.2–4.3
Ventilation to the new rooms, and the cold roof must still breathe.AD F · BS 5250

What you need to do

Appoint a structural engineer — this is not optional and not something a builder can substitute for.
Serve Party Wall notices if you are cutting into or bearing on a party wall — 2 months' notice under s.2.
Decide the stair position early. It is the single hardest thing to change later, and it eats the room below.
Book an asbestos check if the house predates 2000, before anything is disturbed.
Expect the escape route to change how doors and the landing work on every floor, not just the new one.

Inspections on your job

Structural openings and beam bearings, before they are covered.
Floor structure and joist hangers.
Fire-stopping and fire-rated plasterboard, at first fix.
Insulation and ventilation paths, before boarding.
Stair, guarding and escape window on completion.

Loft conversion — the figures, and where each comes from
The figure	What it means on site	Source
Headroom 2m	Minimum over the stair. Where that is impossible in a loft, 1.9m at the centre of the stair reducing to 1.8m at the side is accepted.	AD K §1.11, §1.13
Rise ≤220mm · going ≥220mm	Private stair limits. Maximum pitch 42°. Twice the rise plus the going should be between 550mm and 700mm.	AD K Table 1.1
Escape window 0.33m²	At least 450mm high and 450mm wide, with the bottom of the opening no more than 1100mm above floor level.	AD B §2.10
REI 30 / E 30	Thirty minutes of fire resistance to the stair enclosure, and FD30 doors onto it.	AD B Vol 1
Roof 0.15 W/(m²·K)	The insulation standard for a new roof element. Rooflights 2.2; windows and doors 1.4.	AD L Table 4.2
Eaves ventilation 10mm	Continuous gap on a cold roof pitched over 15° (25mm at 15° or less), plus 5mm at the ridge over 35° pitch or 10m span.	BS 5250
Guarding 900mm	To stairs and landings. A 100mm sphere must not pass through any opening in it.	AD K §1.38–1.40

Almost always

An extension needs building control — with two narrow exceptions. A ground-level conservatory, porch, covered way or carport with a floor area not exceeding 30m², open on at least two sides where a carport, is exempt under Schedule 2 Class 7. Even then, safety glazing still applies, and it must not block access to a boiler or restrict escape.

What actually bites

Foundations. Depth set by the soil and confirmed in the open trench.AD A §2E4
Damp. Damp-proof course height, cavity trays and weep holes.AD C §5.5
Drainage. Gradients, and whether you are building over a sewer.AD H
Insulation. Every new element to the Table 4.2 limits.AD L Table 4.2
Fire. Distance to the boundary governs how much of the wall may be unprotected.AD B B4
Overheating on new habitable space, and EV charging where there is parking.AD O · AD S

What you need to do

Get trial holes dug before anyone prices the job. It converts the biggest unknown into a number.
Serve Party Wall notices — s.6 if excavating within 3m deeper than a neighbour's foundations, or within 6m cutting the 45° line. One month's notice.
Check for a public sewer crossing the site. Building over one needs the sewerage undertaker's agreement.
Hold a ring-fenced foundation contingency and programme float — depth is the most common genuine variation.
Decide glazing and heating early: they drive the insulation and the 55°C heating design.

Inspections on your job

Excavation, at bearing level, before concrete.
Foundation concrete.
Damp-proof course and oversite.
Drains before backfilling, then again on test.
Steel beams and padstones before covering.
Insulation, cavity trays and fire-stopping at first fix.
Completion.

Extension — the figures, and where each comes from
The figure	What it means on site	Source
Foundation 0.45m	Minimum depth to the underside, for frost. On shrinkable clay — most of London — 0.75m, 0.9m or 1.0m for low, medium and high shrinkage, deeper near trees.	AD A §2E4
DPC 150mm	The damp-proof course sits at least 150mm above the outside ground. The cavity goes at least 225mm below the lowest DPC.	AD C §5.5
Weep holes 900mm	Above a cavity tray. Where the tray stops — above every window and door — stop ends and at least two weep holes.	AD C §5.5(c)
Wall ties 900 × 450mm	Or at least 2.5 ties/m², with extra ties every 300mm vertically within 225mm of openings.	AD A §2C8
Lintel bearing 150mm	Each end. May reduce to 100mm where the clear span is 1200mm or less.	AD A §2C24(a)
Drain fall 1:40	For a 100mm foul drain at peak flow under 1 l/s. At higher flow, 1:80 with at least one WC.	AD H Table 6
U-values 0.18 / 0.15 / 1.4	Wall 0.18, roof 0.15, floor 0.18, windows and doors 1.4 W/(m²·K), rooflights 2.2.	AD L Table 4.2
Heating flow 55°C	A new or fully replaced wet heating system must be sized to work at a maximum flow temperature of 55°C — which is what makes the house heat-pump ready.	AD L §5.10

It depends

A renovation needs building control only for the parts that are controlled work — but that list is longer than most people expect, and some of it can be self-certified by your installer rather than going to the council.

What actually bites

Removing or altering a structural wall — including a chimney breast.reg. 3(1)(c)
Underpinning. Always notifiable, without exception.reg. 3(1)(f)
Cavity wall insulation. Always notifiable.reg. 3(1)(e)
Renovating a thermal element — re-roofing, re-rendering or re-plastering more than 50% of its surface.reg. 23
Converting a garage into habitable space — a material change of use.reg. 5
Forming a flat, or changing the number of dwellings.reg. 5

What you need to do

Establish early which parts of your scope are controlled work — the answer changes the programme, not just the paperwork.
Use installers registered with a competent person scheme for windows, boilers, solid fuel and electrics, and keep every certificate they issue.
Book an asbestos check if the house predates 2000, before anything is disturbed.
Remember only three electrical jobs are notifiable at all: a new circuit, a consumer unit replacement, and any addition or alteration to a circuit inside a special location.
Ask what a new bathroom or kitchen actually touches — drainage and structure are what turn it into controlled work.

Inspections on your job

Structural openings and beam bearings, where a wall is removed.
Any underpinning excavation, before concrete.
Drainage alterations before backfilling, and again on test.
Insulation and fire-stopping at first fix.
Completion, with the competent-person certificates collected.

Renovation — the figures, and where each comes from
The figure	What it means on site	Source
Special location 2.25m	In a room with a bath or shower, the notifiable zone runs from floor level to 2.25m — or to the shower head if higher.	reg. 12(9)(a)(i)
0.6m / 1.2m	And horizontally 0.6m from the edge of the bath or tray — or 1.2m from the shower head centre where there is no tray.	reg. 12(9)(a)(ii)
Sockets 3m	Socket outlets should not be within 3m of a bath tub or shower tray.	AD P Diagram 2
Bathroom extract 15 l/s	Minimum intermittent extract. Kitchen 30 l/s with a hood to outside, 60 l/s without. WC only, 6 l/s.	AD F Table 1.1
Bath water 48°C	Hot water to a bath must be limited to a maximum of 48°C by a blending valve.	AD G §3.65
Replacement glazing 1.4	New and replacement windows and doors: maximum 1.4 W/(m²·K). Heritage route where character must be kept: centre pane 1.2, or secondary glazing.	AD L Table 4.2, §4.10
Safety glazing 800 / 1500mm	Critical locations: glazing below 800mm in a wall, and below 1500mm in a door or a side panel within 300mm of the door edge.	AD K §5.1
Pre-2000 asbestos	Any home built or refurbished before 2000 must be treated as potentially containing asbestos until shown otherwise, and identified before anything is disturbed.	CAR 2012 reg. 5

Always

Every part of the Building Regulations applies to a new dwelling, and several parts apply only to new build. Go the full plans route — you get a formal decision on the drawings before you build, which is the only sensible position when the whole building is being judged.

What actually bites

Part O — overheating. Limit solar gain and provide a means of removing heat. New residential only.Req. O1
Part Q — security. Doors and easily accessible windows tested to PAS 24. New dwellings only.Req. Q1
Part R — broadband. Gigabit-ready infrastructure and a connection where one can be secured within a £2,000 cap.reg. 44ZA
Part S — EV charging. A charge point for each dwelling with an associated parking space.Req. S1
Water efficiency. Not more than 125 litres/person/day, or 110 where planning imposes it.reg. 36

What you need to do

Go full plans, not a building notice. You get a decision before you build.
Commission a proper site investigation — soil, trees, drainage records, contamination.
Appoint the dutyholders in writing: client, principal designer, principal contractor. A statutory duty on all building work since October 2023.
Budget for air permeability testing and SAP calculations.
From 1 October 2026, factor in the Building Safety Levy — developments of fewer than 10 units are exempt.

Inspections on your job

Commencement, with at least two clear working days' notice.
Excavation and foundation concrete, before covering.
Damp-proof course and oversite.
Drains before backfilling, then again on test.
First fix before plasterboard — structure, fire-stopping, cavity barriers, insulation and services.
Air permeability testing and commissioning.
Completion.

New build — the figures, and where each comes from
The figure	What it means on site	Source
125 l/person/day	The water efficiency cap for a new dwelling. 110 where the planning permission imposes the optional requirement.	reg. 36
£2,000 broadband cap	A new dwelling must be connected to a gigabit-capable network where a connection can be secured within this cost per dwelling.	reg. 44ZA
18m / 7 storeys	The higher-risk building threshold, where the Building Safety Regulator takes over building control entirely.	Building Safety Act 2022
10 units	Developments of fewer than 10 units are exempt from the Building Safety Levy from 1 October 2026.	BSA 2022, Part 4
Overheating glazing limits	In moderate-risk locations, maximum glazing the greater of 9% of floor area or 55% of the glazing area as free area; bedrooms minimum 4%.	AD O Table 1.1
EV charge point space	Wall-mounted at 700–1000mm with 800 × 800mm free space; floor-mounted needs 1500 × 1500mm.	AD S Diagram 6.4

See how we build: loft conversions, extensions, new builds. Or read why foundation depth changes on site and why cracks appear over openings. Every figure on this page comes from our full regulations reference — all 295 rules, each with its clause.

What actually happens

The inspections, in the order they happen.

Building control does not sit in an office and approve a folder. An inspector attends the site at set stages, and each one closes permanently the moment the work is covered up. Miss one and the only remedy is opening the work back up.

01Commencement. The building control body must have at least two clear working days' notice before work starts. If plans have not yet been approved, the work is formally deemed 'at risk'.
02Excavation for foundations. The inspector attends the open trench and confirms the bearing. This is the one that decides your foundation depth — and it cannot be done retrospectively.
03Foundation concrete. Inspected before it is covered.
04Damp-proof course and oversite. Before anything is laid over them.
05Drains. Before backfilling, and again on testing — air test at 110mm water gauge, or a water test held for 30 minutes.
06First fix, before plasterboard. Structure, fire-stopping, cavity barriers, insulation and services — everything that disappears behind the walls. This is the inspection that separates a good builder from a cheap one.
07Occupation before completion. If you move in before the job is finished, at least five days' notice must be given first.
08Completion. Notice within five days. Where the authority is satisfied, it issues your completion certificate — the document your buyer's solicitor will ask for one day.

If work was done without approval. The council may prosecute in the magistrates’ court, where an unlimited fine may be imposed, and may serve a section 36 notice requiring the work to be pulled down or altered — though not more than 12 months after completion. The bigger problem is usually the sale: no completion certificate means an enquiry you cannot answer. Unauthorised work carried out since 11 November 1985 can be regularised by application, which normally means opening work up so it can be inspected.

How we handle it

We deal with building control. All of it.

When you build with 2VP, building control is our job, not yours. You never submit a form, chase an inspector or wonder whether a stage was signed off. But the part that matters is how we run it — because most of what building control checks is work that disappears within days.

So we built a record system around it. Not because anyone asked us to, but because on a job where everything is photographed, dated and logged, there is nothing to argue about — at the inspection, at handover, or five years later when you sell.

We submit and we front it

We make the application, choose the route with you, and act as the single point of contact with the building control body from first notice to completion certificate.

Every covered element photographed

Foundations at bearing level, steel bearings and padstones, cavity trays and weep holes, fire-stopping at every penetration, insulation, drainage before backfill. Dated, indexed to the drawing, before it is covered.

An inspector visit register

Every visit booked, attended, and logged — who came, when, what stage, what they said, what was signed. You can see the whole chain of sign-offs at any point in the job.

Building control kept current

Progress, photographs and stage data are shared as the job moves rather than assembled at the end. The inspector is never catching up, and neither are you.

A complete handover pack

Completion certificate, Regulation 38 fire safety information, Regulation 40 building information, commissioning records, structural calculations, and every competent-person certificate — Part P, Gas Safe, FENSA. One file, yours to keep.

The other side of it

When you don’t need building control.

We would rather tell you this than let you spend money finding out. Some work is genuinely exempt, some is controlled but self-certified by your installer, and some is not controlled at all.

Exempt buildings — Schedule 2

Class 6. A detached single-storey building with a floor area not exceeding 30m², containing no sleeping accommodation, and either sited more than 1m from the boundary or built substantially of non-combustible material.
Class 7. A ground-level conservatory, porch, covered yard, covered way or carport open on at least two sides, floor area not exceeding 30m².
Class 4. Temporary buildings intended to remain erected for less than 28 days.
Class 3. Greenhouses and agricultural buildings, subject to conditions.

The catch. A garden room with sleeping accommodation is not exempt. A conservatory must still have safety glazing, must not obstruct access to a boiler, and must not restrict escape. And sleeping in it changes everything.

Controlled, but self-certified

Replacement windows and doors — FENSA or CERTASS.
Boiler and heating replacement — Gas Safe (a legal requirement, not just a scheme).
Solid fuel appliances — HETAS. Oil — OFTEC.
Most electrical work — NICEIC, NAPIT, ELECSA, Stroma.

Only three electrical jobs are notifiable at all: a new circuit, a consumer unit replacement, and any addition or alteration to existing circuits inside a special location. The scheme notifies on the installer’s behalf and issues your certificate — keep it.

Not controlled at all

Redecoration, and most cosmetic work.
Replacing like for like on a non-structural, non-controlled item.
Loft insulation on its own, unconnected to other work or a change of use.
Repointing, and general repair.
Replacing a kitchen or bathroom where nothing structural, no drainage run and no controlled service changes — although in practice something usually does.

If you are not sure, ask before you start. A five-minute call to building control, or to us, costs nothing. Finding out afterwards is what costs.

Straight answers

The questions we are actually asked.

Do I need building control approval?

If you are erecting or extending a building, altering it structurally, changing its use, underpinning it, inserting cavity wall insulation, renovating a thermal element, or providing or materially altering a controlled service or fitting — heating, drainage, ventilation, electrics, windows or doors — then the Building Regulations apply and building control must be involved. A loft conversion and a new build always need it. An extension almost always needs it. A renovation depends entirely on what you touch.

Is planning permission the same as building control?

No. They are two completely separate consents with different tests and different bodies. Planning permission decides whether you may build the thing at all and what it may look like. Building control decides whether it is safe and built to the required standard. Having one never implies the other, and permitted development rights do not exempt you from the Building Regulations.

How long does building control approval take?

On the full plans route the local authority must decide within 5 weeks, or 2 months if you agree an extension. On a building notice you can start after two clear working days, but you get no decision on the plans, so all the risk of non-compliance sits with you. With a private approved inspector, the initial notice is presumed accepted if the council does not reject it within five working days.

What are the building control inspection stages?

Commencement with at least two clear working days' notice, then excavation for foundations before it is covered, foundation concrete, damp-proof course, oversite, drains before backfilling and again on testing, first fix before plasterboard, and completion with notice within five days. Each inspection closes permanently once the work is covered — the only remedy for a missed one is opening up.

What happens if work was done without building control?

The local authority may prosecute in the magistrates' court, where an unlimited fine may be imposed, and may serve a section 36 notice requiring the work to be pulled down or altered — though a section 36 notice cannot be served more than 12 months after completion. In practice the bigger problem arrives when you sell: no completion certificate means a conveyancing enquiry you cannot answer. Unauthorised work carried out since 11 November 1985 can be regularised by application, which usually means opening work up for inspection.

Do I need building control for new windows or a new boiler?

Yes, but usually not through the council. Replacement windows and doors, boiler replacements, and most electrical work can be self-certified by an installer registered with a competent person scheme — FENSA or CERTASS for glazing, Gas Safe for gas, HETAS for solid fuel, OFTEC for oil, and NICEIC or NAPIT for electrics. The scheme notifies on the installer's behalf and issues your certificate. Keep that certificate: it is what a buyer's solicitor asks for.

Who pays the building control fee?

The client pays it. The fee goes to the building control body, not to the builder, and it is separate from the build price. 2VP lists it in every quote as a third-party cost, alongside the structural engineer and any party wall surveyors, so the figure on the contract is the figure you actually spend.

Does 2VP deal with building control for me?

Yes. We submit the application, act as the point of contact with the building control body, book and attend every notifiable inspection, keep a dated photographic record of every element before it is covered, log every inspector visit with date and outcome, and hand over the full certificate pack at completion including the completion certificate, Regulation 38 fire safety information and all competent person certificates.

Can I see the record of what was inspected?

You should ask any builder for it. On 2VP projects every covered element is photographed and dated before it disappears, every inspector visit is logged with the date and the outcome, and the whole record is handed over at completion alongside the certificates, the Regulation 38 fire safety information and the structural calculations.

Next step

Know the number. Then know who is handling it.

Get a realistic figure for your project in two minutes, then talk to us about the build. The building control fee is listed in every quote as a third-party cost, so the figure on your contract is the figure you actually spend.

Get my estimate →Send us your drawings

About the information on this page. England only; Wales, Scotland and Northern Ireland have separate regimes. Every figure is taken from the Approved Documents, the Building Regulations 2010 as amended, or the governing British Standard, and cited to its clause. Approved Documents are statutory guidance, not the law — compliance is judged against the Requirements in Schedule 1, and your building control body has the final word on your specific building. Editions change; this page was last reviewed 17 August 2026. It is written to be genuinely useful, but it is not a substitute for a building control body, a structural engineer or a fire engineer.