Key Takeaway
How building regulations work for home extensions in Hampshire. Hampshire Build produces lean, accurate technical drawings calibrated for Building Notice — everything your builder needs, at outstanding value.
Building regulations approval is required for almost all home extensions. Hampshire Build produces lean, accurate technical drawings calibrated for a Building Notice — exactly what your builder and Building Control need, at outstanding value.
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
Hampshire Build's drawings are produced to Building Notice standard. They contain everything needed for a compliant Building Notice and for your builder to work from on site. This is the most common, practical route for Hampshire extensions — and the one we're set up to support efficiently.
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 £400–£800 | Quoted per project — typically £500–£1,000+ |
| 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 regulations drawings are lean, accurate and purposefully value-driven. They contain precisely what's needed for a compliant Building Notice and for your builder to work from on site:
- 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 so your contractor can work from them directly on site
- Sufficient detail for Building Control sign-off at each inspection stage
These are working drawings — not architectural specifications. Calibrated for Building Notice: accurate, compliant, and nothing more than is needed. This is what keeps our Pre-Build Package at £1,950+VAT while others charge considerably more for the same outcome.
Building regulations drawings are included in our Pre-Build Package (£1,950+VAT) and Premium Package (£2,950+VAT). The Essential Package (£1,350+VAT) covers planning drawings only.
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:
Part A — Structural Safety
Foundations, steel beams, load-bearing walls, roof structure and floor loading. Structural calculations are typically commissioned separately through your builder or a structural engineer.
Part B — Fire Safety
Escape routes, fire doors, smoke alarms and fire-resistant construction. Requirements vary depending on whether the extension is single or two-storey.
Part C — Resistance to Moisture
Damp-proof course, cavity trays, weatherproofing and condensation control. Hampshire's chalk and clay soils make DPC detail particularly important.
Part F — Ventilation
Background ventilation (trickle vents), extract fans in kitchens and bathrooms, and whole-house ventilation strategy.
Part L — Energy Efficiency
Thermal performance of walls, roof and floor — U-values, thermal bridging and air tightness. Standards have tightened significantly in recent years.
Part M — Access & Facilities
Level access thresholds, minimum door widths, socket and switch heights. Applies to all new external doors and habitable rooms.
Part G — Drainage & Sanitation
Foul and surface water drainage, connection to main sewer, soakaways and pipe sizing.
Part P — Electrical Safety
All electrical work must be carried out by a certified installer and notified to Building Control. Your builder arranges this with their electrician.
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:
- Commencement notice — submitted 48 hours before work starts
- Foundation excavation — before concrete is poured
- Foundation concrete — after pour, before backfill
- Oversite and DPC — ground floor slab and damp-proof course in position
- Drainage — before covering pipes and trenches
- Structural steelwork — before beams are encased
- Pre-plasterboard — insulation and services visible before lining out
- Final inspection — completion certificate issued
The completion certificate issued at final inspection is an important document — keep it safe. It is required when selling the property and may be requested by your buildings insurer.
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 | £550–£800 |
| Basingstoke & Deane | £500–£700 | £600–£850 |
| Southampton City Council | £480–£680 | £580–£800 |
| Test Valley / NFNPA | £420–£620 | £520–£780 |
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 (£1,950+VAT) and Premium (£2,950+VAT).
