What Happens After Planning Permission? The Steps Before Building Work Can Start

Planning permission settles one question: whether the council accepts what you want to build, and where. It says nothing about whether the structure is safe, whether it meets the Building Regulations, whether your neighbour has been told, or whether you can build over the drain behind the house. Each of those has its own process, and most have to be in place before anyone digs.

None of this is unusual, and none of it is a reason to worry. It is simply the part of a project nobody photographs, and the part where most avoidable delays are made.

Read the decision notice in full, not just the word "granted". The conditions are part of the permission, and so are the approved drawings it lists.

• There is a time limit — a full permission in England normally has to be started within three years of the decision date. Once that passes without a lawful start, the permission is gone and you apply again.
• You build what was approved — the permission covers the drawings it names, at their revision. A smaller window, a different roof pitch or a change of brick can all count as a change.
• Changes have their own route — a genuinely minor change can go through a non-material amendment; a larger one needs an application to vary the approved drawings, or a fresh application. The council decides which side of the line a change sits, not the builder.

Conditions come in two kinds, and the difference matters. Compliance conditions tell you how to build — "materials to match the existing house" is the common one — and you follow them as you go.

Pre-commencement conditions tell you what must be approved before you start. They usually begin "No development shall take place until…" and ask for details such as brick and tile samples, a drainage scheme, tree protection or a construction method statement. You send those details to the council in an application to discharge the condition, and the council has eight weeks to decide unless you agree a longer period.

Planning decides what the building looks like and where it goes. The Building Regulations decide how it is built: structure, foundations, fire safety, insulation, ventilation and drainage. Almost every extension needs Building Regulations approval, whether or not it needed planning permission.

You can choose who checks the work: your council's building control team, or a registered building control approver (until 2024 these were called approved inspectors). Either way there are two main routes.

• Full plans — detailed drawings and structural calculations are checked before work starts. The council has five weeks to decide, or up to two months if you agree, and an approval lasts three years. For most extensions this is the route worth taking, because problems are found on paper rather than on site.
• Building notice — you give notice before starting and the work is checked by inspection as it goes, without approved plans. It suits small, simple jobs. It cannot be used for some work, including building close to or over a public sewer, which needs full plans.

The structural engineer's calculations sit inside the Building Regulations package. They size the foundations, beams and lintels, and building control checks them. Inspections happen at set stages, and a completion certificate is issued at the end. Keep it: a buyer's solicitor will ask for it.

From our work

Single-Storey Rear Extension & Garden, Colchester, Essex

On this Colchester extension we organised the structural engineer and worked with the private building control body through to sign-off.

See the project

The Party Wall etc. Act 1996 does not give your neighbour a veto. It sets out a procedure you must follow before certain work starts, so that both properties are protected and any damage is dealt with properly. It applies to three kinds of work:

• A new wall on the boundary line — for example an extension wall built astride or up to the boundary: at least one month's notice.
• Work to an existing party wall — for example cutting in a steel beam, or raising or thickening the wall: at least two months' notice.
• Excavating near a neighbour's foundations — new foundations within 3 m and deeper than theirs, or within 6 m and below a 45° line from theirs: at least one month's notice.

Your neighbour then has 14 days to respond. If they agree in writing, work can go ahead once the notice period ends, or sooner if they agree to that too. If they do not reply within 14 days, the law treats it as a dispute. That sounds worse than it is: surveyors are appointed — one agreed by both of you, or one each — and they produce a party wall award setting out how the work will be done. The surveyors decide who pays their fees; for work that benefits only you, that is normally you.

A notice lapses if work has not started within twelve months, so time it to the programme. Serve it too early and it may need serving again.

Many rear extensions in Essex are built over or close to a drain. If it is a public sewer — and since 2011 that includes many shared drains serving more than one property — you need the sewerage company's agreement to build over it or within three metres of it. Across most of Essex that is Anglian Water; your water bill names yours. Some small, shallow sewers meet standard criteria and need no separate agreement. Others need an application, and sometimes a CCTV survey.

The question to answer early: is there a manhole or inspection chamber in the footprint of the extension, or within a few metres of it? If so, find out what runs through it before the drawings are finished. Moving a manhole after the slab is down is the expensive way to find out.

• Community Infrastructure Levy — some councils charge a levy on new floor space. New build under 100 m² is exempt unless it creates a new dwelling. Above that, an exemption for extending the home you live in is usually available, but it has to be claimed before work starts. Check with your council first.
• Your insurer and lender — tell your home insurer before work starts, because a house with an open back wall is a different risk. If you have a mortgage, check whether your lender needs to know.
• Health and safety on site — on a domestic job, the client duties under the Construction (Design and Management) Regulations 2015 pass to the contractor. In practice your builder should be planning the work and running the site safely, and should be able to tell you how.

Some of this runs in parallel and some cannot start until something else is finished. A sensible order for a typical extension:

1. Read the decision notice — list every condition and mark the pre-commencement ones.
2. Commission the structural engineer to work from the approved planning drawings.
3. Check the drains — find any manhole or sewer near the footprint and agree a build-over with the sewerage company if one is needed.
4. Prepare and submit the Building Regulations package — full plans for most extensions.
5. Submit the condition details for discharge, at the same time as step 4 where you can.
6. Serve party wall notices, timed so the notice period ends before the start date and the notice will not lapse before work begins.
7. Fix the specification and the price against the approved drawings, and order long-lead items such as steel, glazing and roof lights.
8. Agree the programme and start date once conditions are discharged, Building Regulations approval is in place and any party wall award or agreement is settled.

The order matters more than the speed. Most delays at this stage come from one step being started late, not from any single step taking long.

On our design and build projects this stage is part of the job, not something handed back to you to coordinate. We organise the structural engineer and the Building Regulations submission, and we deal with building control through to sign-off. We go through the conditions with you at the start, and we check for drains before the design is fixed.

Where the Party Wall Act applies, we tell you early and build the notice period into the programme. We do not act as party wall surveyor; the notices and any award are handled by an independent party wall surveyor.

If you already have planning permission and drawings from an architect, we can take the project on from there. We review what has been approved before we price it.