Building Regulations for Hampshire Extensions (2026)

Key Takeaway

Understand building regulations for Hampshire extensions, from drawings and structural information to energy, fire safety and drainage checks before work starts.

Building Regulations for Hampshire Extensions: What You Need & What We Produce

What Are Building Regulations?

Building regulations set out the minimum standards for how a building must be constructed. Where planning permission governs what you can build — its size, appearance and location — building regulations govern how you build it: structural safety, fire protection, insulation, drainage, ventilation and more.

Planning permission and building regulations are entirely separate processes with separate applications and fees. You may need both, or just one, depending on your project. Building regulations approval is required for the vast majority of extensions, including most that fall within permitted development rights.

The Two Routes to Building Regulations Approval

There are two ways to obtain building regulations approval in England. Both are equally valid — the right choice depends on your project, your builder, and your circumstances.

Route 1 — Building Notice (standard route)

A simple notification submitted to your Local Authority Building Control before work starts. No drawings are reviewed upfront — a Building Control Officer inspects the work at key stages during construction.

• Notification submitted before work starts
• Inspector visits at each key stage
• Fastest, most cost-effective route
• Ideal for straightforward extensions with an experienced builder
• Completion certificate issued on final sign-off

Route 2 — Full Plans Application

A detailed set of technical drawings submitted to Building Control before work starts. They review and formally approve before construction begins.

• Full drawings submitted and reviewed upfront
• Formal written approval issued before work starts
• Takes 4–6 weeks for decision
• Higher drawing cost and admin overhead
• Suited to complex projects or where a lender requires pre-approval

Local Authority or Private Approved Inspector?

Whichever application route you choose, you can also choose who carries out the building control function. The traditional route is your Local Authority Building Control (LABC) — the council's own team. The alternative is a Private Approved Inspector, a CICAIR-authorised private company that carries out the same statutory function.

Factor	Local Authority Building Control	Private Approved Inspector
Cost	Council fee schedule — typically the current published fee	Quoted per project — typically the current published fee+
Speed	Standard council timescales	Often faster, more flexible on inspection times
Local knowledge	Strong — know local soil, site and planning context	Variable
Completion cert	Completion certificate issued	Initial notice + final certificate — equally valid

Both routes are entirely valid and recognised by mortgage lenders and conveyancers. Your builder will often have a preferred contact — worth discussing with them early.

What Hampshire Build Produces

Our building regulation drawings are prepared for Building Notice submission and set out project-specific details such as:

• Floor plans, elevations and sections showing the proposed extension
• Key construction details — wall build-ups, roof junction, DPC, lintels over openings
• Compliance annotation covering the relevant Parts (A, B, C, F, L, M as applicable)
• Dimensioned and annotated to communicate the design to your contractor
• Information for Building Control review at relevant inspection stages

These are design drawings for Building Notice submission; they do not replace the contractor's construction method or site decisions. Building Control determines compliance.

Our Pre-Build Package (£1,950 + VAT), Premium (£2,950 + VAT) and Premium Plus (£3,950 + VAT) include building regulation drawings prepared for Building Notice submission, with required structural calculations prepared by an independent qualified structural engineer.

Who Submits the Building Notice?

Hampshire Build produces the drawings. Submission of the Building Notice is typically handled by your builder — most experienced contractors include this as a matter of course. Alternatively, it is a straightforward online process via your council's portal that you can complete yourself as the homeowner. If you need help with submission as a standalone service, this is available separately — just ask us.

The Key Building Regulations Parts

Building regulations are split into Approved Documents, each covering a different aspect of construction. The Parts most relevant to home extensions are:

Building Control Inspection Stages

Whether you go Building Notice or Full Plans, Building Control will inspect the work at defined stages. Your builder is responsible for giving 48 hours' notice before each stage:

1. Commencement notice — submitted 48 hours before work starts
2. Foundation excavation — before concrete is poured
3. Foundation concrete — after pour, before backfill
4. Oversite and DPC — ground floor slab and damp-proof course in position
5. Drainage — before covering pipes and trenches
6. Structural steelwork — before beams are encased
7. Pre-plasterboard — insulation and services visible before lining out
8. Final inspection — completion certificate issued

Building Regulations Fees in Hampshire 2026

Building Control fees are paid directly by you or your builder — they are not part of Hampshire Build's fixed-fee packages. Approximate fees by council:

Council	Building Notice	Full Plans
Winchester City Council	£450–£650 + VAT	£550–£800 + VAT
Basingstoke & Deane	£500–£700 + VAT	£600–£850 + VAT
Southampton City Council	£480–£680 + VAT	£580–£800 + VAT
Test Valley / NFNPA	£420–£620 + VAT	£520–£780 + VAT

Fees are approximate and vary by extension size. Check current rates directly with your council or Approved Inspector before budgeting.

Learn more about our building regulations drawings service, or compare our fixed-fee packages — building regulations drawings included in Pre-Build Package (£1,950 + VAT) and Premium Package (£2,950 + VAT).

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