West Cornwall · TR26 · Cornwall Council West
Affordable extensions in Carbis Bay — where to spend and where to save
Most "budget" extensions in Carbis Bay go over budget for the same three reasons: ground conditions you didn't survey for, glazing spec creep, and "while we're at it" scope drift. We design to a fixed budget by ranking decisions: structure first, weather-tight envelope second, finishes last. Below is what an honest sub-£50k TR26 extension actually looks like. Extensions are the bread and butter of Cornish homes — adding the kitchen-diner the original layout never had, the bedroom for a growing family, or the light and views the back of the house should always have had. A TR26 site visit comes before a Carbis Bay sketch, every time — Carbis Bay is the residential coastal suburb of St Ives, climbing up the cliffs above one of the calmest beaches on the north coast and built largely between 1900 and 1970, with a building stock that leans toward 1960s estate housing and post-war bungalows.
Carbis Bay sits in West Cornwall — just off the A3074; with Truro the closest city; 1 miles from St Ives.
- Cornwall AONB
- Coastal exposure zone
- ✓ Sub-£50k Carbis Bay extension: realistic for 15–20m²
- ✓ Fixed-fee design + planning from £4,800
- ✓ Staged finishes — save 15–20% by deferring kitchen upgrade
- ✓ Two-tender approach typically saves £6k–£12k
Who this is for
In Carbis Bay the extension brief is almost always a private homeowner improving a forever home — so we lead with feasibility and long-term value, not show-home rhetoric.
Local watch-list
Common Carbis Bay pitfalls we plan around.
Watch #1
AONB ridge-line scrutiny on hillside plots
Watch #2
St Ives Bay long-view protection
Watch #3
Sloped sites driving split-level slab design
Watch #4
Coastal exposure on north-facing facades
Local proof — We typically have one or two extension jobs live in the TR26 area at any time, so the local planning officers know our drawings on sight.
Get a free feasibility viewFAQs
Carbis Bay Extensions — local questions answered.
- What's a realistic budget for a small extension in Carbis Bay?
- £35k–£55k for 15–20m² including basic kitchen, standard glazing and one bathroom touch-up. Push under £35k and you're trimming the wrong things; over £55k and you've moved into mid-spec territory.
- Where should I spend the budget?
- Structure, foundations, weather-tight envelope and glazing — in that order. Kitchen and finishes can be staged later. Heating distribution gets locked in at build stage so design around it from day one.
- Where can I save without regretting it?
- Worktops, splashbacks, sanitaryware brands and external paving — all upgradeable later. Insulation, glazing and electrics — never.
- Will my house be liveable during the build?
- For most rear and side extensions, yes — we sequence the works so the kitchen and one bathroom stay functional until the new build is watertight and connected. In Carbis Bay specifically, we'd start by checking AONB landscape sensitivity before committing to a direction.
- How long does the whole process take?
- Allow roughly three months for design and approvals, then twelve to twenty weeks on site for a typical single-storey extension. Wraparounds and two-storey add-ons take longer, mostly through approval and groundworks.
- Do I need planning permission for an extension?
- Often no — single-storey rear extensions, side extensions and modest two-storey additions can sit inside permitted development on a typical detached house. Conservation Areas, AONB and Article 4 zones remove some of those rights, so we always check the address first.
Local context
Why Carbis Bay is its own job.
Cornwall Council's lens on Carbis Bay is consistent: aONB designation covers the whole village; coastal views and cumulative cliffside development are weighed in most applications. Carbis Bay sits inside St Ives parish's principal residence policy area. For extension specifically, the surrounding landscape falls inside the Cornwall Area of Outstanding Natural Beauty, so massing, height and landscape impact carry extra weight in any planning decision; coastal salt-laden air around Carbis Bay drives detailing choices — fixings, render systems and timber treatments all need to be specified for exposure. That's why we treat every Carbis Bay project as a TR26-area job first — not a generic Cornwall job with a postcode bolted on. The 1960s estate housing that dominate Carbis Bay (and continue out toward St Ives) set the tone for any extension scheme here.
Planning note
Most extensions in Cornwall are either permitted development or a straightforward householder application — but Conservation Area and AONB sites need a more careful design conversation upfront.
Recent work nearby
Glazed seaward elevation we delivered last summer ran solar shading via fixed louvres.
See more recent West Cornwall work →What we focus on
Extensions considerations specific to Carbis Bay.
01
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
02
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
03
Permitted development for rear extensions runs to four metres on a detached house, three on a semi or terrace — but Article 4 areas remove this in some parishes.
04
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
Our process
How a Carbis Bay extension project runs.
Step 1
Brief
We meet on site, talk through how you live now and what's missing from the current layout.
Step 2
Design
Two or three sketch directions with rough budgets, then refinement of the chosen route.
Step 3
Approvals
Planning or Cert of Lawfulness, then a full building regs package.
Step 4
Build
Either through your own builder with our drawings, or as a full build by our team.
Step 5
Handover
Snag, certify, hand over the keys to your new space.
Typical single-storey rear extensions run twelve to twenty weeks on site; two-storey and wraparound projects sixteen to thirty weeks.
Local fabric
Choosing a extension team that actually knows TR26.
Building stock
Across Carbis Bay (TR26) we work on Edwardian and 1930s detached villas, post-war bungalows, 1960s estate housing, modern coastal architect-designed homes. Each stock type drives a different extension response — 1960s estate housing in particular needs careful detailing here.
Parish & policy
Carbis Bay sits in the parish of St Ives, which matters for how parish-level consultation lands on a extension application.
Coverage
We cover TR26 from our studio, with regular extension jobs also running in St Ives, Lelant. Most Carbis Bay site visits get booked within the same week.
How quickly can you visit a Carbis Bay site?
Usually within the same week. Carbis Bay (TR26) is on our regular West Cornwall run, alongside St Ives, Lelant. First visits are free and you'll get an honest feasibility view inside seven days.
Request a free visitCarbis Bay is the hub for these neighbourhoods
We run extensions across Carbis Bay and the surrounding TR26 neighbourhoods — same studio, same site team.
Other services in Carbis Bay
Nearby places we cover
An affordable extension in Carbis Bay isn't about cutting corners — it's about ranking decisions and protecting the structural and weather-tightness budget above all else.