Key facts at a glance
- Full Plans: detailed drawings checked before work starts — maximum certainty
- Building Notice: no drawings submitted — BCO inspects as you build
- Full Plans is recommended for extensions, loft conversions, and any structural work
- Building Notice suits simple, low-risk work (e.g. boiler replacement, internal wall removal)
- Full Plans approval takes 5–8 weeks; Building Notice gives same-day registration
- Building Notice cannot be used for commercial buildings or shops
Full Plans submission explained
A Full Plans submission involves providing detailed technical drawings to the building control body (BCB) before work starts. The BCO checks the drawings against all relevant Approved Documents — structure, insulation, fire safety, drainage, ventilation, accessibility — and issues a decision notice approving or conditionally approving the plans. The builder then works to the approved drawings, and the BCO inspects at key stages.
The main advantage of Full Plans is certainty. Your builder knows exactly what they are building to an approved specification. Any design issues are resolved at drawing stage — before concrete is poured. This is vastly cheaper than resolving problems on site.
Building Notice explained
A Building Notice is a simpler notification route. You give the council 48 hours' notice of intention to start work, paying a fee. No drawings are required — the BCO inspects at key stages and advises on compliance as work progresses. It is faster to initiate but transfers risk to the builder and client.
The risk with Building Notice is that if the BCO requires changes at inspection — a foundation too shallow, insulation below Part L standards, fire stopping inadequate — the builder may need to demolish and redo finished work. This is uncommon on simple projects but a real cost risk on complex ones.
Which route for extensions and loft conversions?
Always use Full Plans for structural extensions and loft conversions. The structural content alone — foundation design, beam sizing, floor structure, roof structure — requires detailed drawings that must be checked against Part A. A Building Notice on a structural project means the BCO is making structural judgements on site without pre-approved calculations — not a position most experienced BCOs or structural engineers are comfortable with.
Our standard building regulations drawings package is designed for Full Plans submission. It includes structural drawings coordinated with an engineer, Part L energy calculations, Part B fire spread details, Part F ventilation, and Part P electrical notes — everything the BCO needs to issue a Full Plans approval.
Approved inspectors vs local authority building control
Both routes — Full Plans and Building Notice — can be administered by either the local authority building control (LABC) or an approved inspector (private sector). Approved inspectors typically offer faster turnaround on Full Plans (3–5 weeks vs 5–8 weeks for LABC) and more flexible inspection scheduling. The choice does not affect the technical standard — both must apply the same Approved Documents.
Verdict
Use Full Plans for any project involving structure, extensions, or loft conversions. The pre-approval certainty is worth the 5–8 week wait. Reserve Building Notice for simple, low-risk works where drawings are not needed.
Frequently asked questions
Can I switch from Building Notice to Full Plans mid-project?
Yes. You can regularise a Building Notice project by submitting Full Plans drawings at any stage. The BCO will assess the work already completed. This is more expensive and disruptive than submitting Full Plans at the start.
Is a completion certificate issued under both routes?
Yes. Both Full Plans and Building Notice result in a final completion certificate once the BCO is satisfied all work complies. The completion certificate is required for sale and for insurance purposes.
How much does building regulations approval cost?
The fee depends on the project type and local authority. For a typical single-storey rear extension, the Full Plans fee is approximately £800–£1,200. This covers all inspections from foundation to completion.
Do building regulations expire?
Building regulations approval does not expire, but work must start within 3 years of the Full Plans approval date. The completion certificate must be issued within a reasonable time after the work is finished.
Can I sell a house without a building regulations completion certificate?
Technically yes, but solicitors and mortgage lenders typically require it. Without a certificate, you may need indemnity insurance, which is cheaper but provides less protection than the certificate itself.