Where extending pays in Jersey
One comparison decides whether a build is worth doing: what a square metre sells for locally against what a square metre costs to build. Island-wide, properties currently for sale that publish a floor area sit at a midpoint of £7,438/m² across 484 listings.
The £4,000–£6,000/m² new-build and £2,000–£4,000/m² refurbishment figures below are Guernsey's own build rates, carried across because no Jersey-specific equivalent could be sourced (web search, 21-Aug-2026) — they have not been confirmed against Jersey merchants, labour rates or shipping costs, which plausibly differ from Guernsey's. The sale-value side (per-m² asking prices) is genuinely Jersey's own data.
By parish: sale value per m² against build cost
| Parish | Sells for | Margin vs new build | vs mid refurb | Verdict |
|---|---|---|---|---|
| St Mary (5) | £9,139/m² | +£5,139 to +£3,139 | +£6,139 | Works at any build quality |
| St Lawrence (33) | £8,889/m² | +£4,889 to +£2,889 | +£5,889 | Works at any build quality |
| St Peter (20) | £8,611/m² | +£4,611 to +£2,611 | +£5,611 | Works at any build quality |
| St Martin (21) | £8,500/m² | +£4,500 to +£2,500 | +£5,500 | Works at any build quality |
| Grouville (21) | £8,380/m² | +£4,380 to +£2,380 | +£5,380 | Works at any build quality |
| St Brelade (60) | £8,287/m² | +£4,287 to +£2,287 | +£5,287 | Works at any build quality |
| Trinity (15) | £7,644/m² | +£3,644 to +£1,644 | +£4,644 | Works at any build quality |
| St Clement (10) | £7,609/m² | +£3,609 to +£1,609 | +£4,609 | Works at any build quality |
| St John (14) | £7,241/m² | +£3,241 to +£1,241 | +£4,241 | Works at any build quality |
| St Helier (219) | £6,818/m² | +£2,818 to +£818 | +£3,818 | Works at any build quality |
| St Saviour (49) | £6,703/m² | +£2,703 to +£703 | +£3,703 | Works at any build quality |
| St Ouen (17) | £6,441/m² | +£2,441 to +£441 | +£3,441 | Works at any build quality |
Margin is local value per m² minus build cost per m². The new-build column runs best case (£4,000/m²) to worst (£6,000/m²) — Guernsey rates, see the note above. Parishes with fewer than 5 floor-area listings are left out rather than shown on a sample that can't carry a conclusion.
Under-improved stock: asking well below its parish rate
Properties currently for sale asking at least 20% less per m² than the midpoint for their parish. That gap is where refurbishment or extension has the most room — though it can equally mean a small flat, a short lease, an awkward site or something structural. This is a shortlist to go and look at, not a valuation of any of them.
| Property | Asking per m² | Parish midpoint | Gap |
|---|---|---|---|
| 3 BED DETACHED HOUSE, La Verte Rue, St Brelade St Brelade · 300 m² · £825,000 |
£2,750/m² | £8,287/m² | -67% |
| Le Boulivot De Bas, Grouville Grouville · 285 m² · £825,000 |
£2,895/m² | £8,380/m² | -65% |
| Rue Des Buttes, St. Mary St Mary · 126 m² · £510,000 |
£4,048/m² | £9,139/m² | -56% |
| Vauxhall Street, St. Helier St Helier · 205 m² · £495,000 |
£2,415/m² | £6,818/m² | -65% |
| Le Mont Du Rocher, St. Lawrence St Lawrence · 334.5 m² · £1,595,000 |
£4,768/m² | £8,889/m² | -46% |
| 15 Netherby Court St Peter · 139.4 m² · £629,000 |
£4,512/m² | £8,611/m² | -48% |
| High Street (La Rue Du Crocquet), St. Brelade St Brelade · 203 m² · £875,000 |
£4,310/m² | £8,287/m² | -48% |
| Le Vier Mont, Grouville Grouville · 180 m² · £799,000 |
£4,439/m² | £8,380/m² | -47% |
| La Rue Du Crocquet, St. Brelade St Brelade · 201 m² · £875,000 |
£4,353/m² | £8,287/m² | -47% |
| Winchester Street, St. Helier St Helier · 167.2 m² · £495,000 |
£2,961/m² | £6,818/m² | -57% |
| For Sale/To Let – Warehouse Unit St Clement · 363 m² · £1,375,000 |
£3,788/m² | £7,609/m² | -50% |
| Le Clos Alexandra St Lawrence · 161.9 m² · £825,000 |
£5,096/m² | £8,889/m² | -43% |
| La Rue Du Crocquet, St. Brelade St Brelade · 187 m² · £875,000 |
£4,679/m² | £8,287/m² | -44% |
| The Farmhouse, 1 La Porte St Saviour · 410 m² · £1,295,000 |
£3,159/m² | £6,703/m² | -53% |
| Devonshire Place, St. Helier St Helier · 177 m² · £580,000 |
£3,277/m² | £6,818/m² | -52% |
| Victoria Street, St Helier St Helier · 120.8 m² · £399,000 |
£3,303/m² | £6,818/m² | -52% |
| Vue Du Pre, St Martin, St. Martin St Martin · 577.9 m² · £2,995,000 |
£5,183/m² | £8,500/m² | -39% |
| Beach Road, St Saviour St Saviour · 137.4 m² · £498,000 |
£3,624/m² | £6,703/m² | -46% |
| Dicq Road, St. Saviour St Saviour · 170 m² · £625,000 |
£3,676/m² | £6,703/m² | -45% |
| Simon Cottage St Peter · 213.7 m² · £1,195,000 |
£5,592/m² | £8,611/m² | -35% |
| La Rue De Samares, St. Clement St Clement · 215 m² · £995,000 |
£4,628/m² | £7,609/m² | -39% |
| La Rue Du Bocage, St. Brelade St Brelade · 348 m² · £1,850,000 |
£5,316/m² | £8,287/m² | -36% |
| La Grande Route Des Sablons, Grouville Grouville · 235 m² · £1,275,000 |
£5,426/m² | £8,380/m² | -35% |
| Fabulous 3/4 Bed Family Home, Trinity Hill, St Trinity · 148.6 m² · £699,000 |
£4,704/m² | £7,644/m² | -38% |
| 52 Don Street, St. Helier St Helier · 77 m² · £299,000 |
£3,883/m² | £6,818/m² | -43% |
| DETACHED 4 BED 2 BATH HOME, Le Clos Du Roncher St Brelade · 185.8 m² · £999,500 |
£5,379/m² | £8,287/m² | -35% |
| DETACHED 3 BED 2 BATH, La Route De St Jean, St St Lawrence · 130.1 m² · £779,000 |
£5,988/m² | £8,889/m² | -33% |
| La Rue Du Bocage, St. Brelade St Brelade · 342 m² · £1,850,000 |
£5,409/m² | £8,287/m² | -35% |
| 1 Isla Villas, St. Saviors Hill, St. Saviour, St Saviour · 336 m² · £1,299,000 |
£3,866/m² | £6,703/m² | -42% |
| La Rue Du Nord, St. Ouen St Ouen · 412 m² · £1,500,000 |
£3,641/m² | £6,441/m² | -43% |
| La Rue De La Blanche Pierre, St. Lawrence St Lawrence · 529 m² · £3,250,000 |
£6,144/m² | £8,889/m² | -31% |
| Hope Lodge, 20 Chevalier Road, St Helier, St. St Helier · 106.8 m² · £439,000 |
£4,110/m² | £6,818/m² | -40% |
| Le Mont Cambrai, St. Lawrence St Lawrence · 202 m² · £1,250,000 |
£6,188/m² | £8,889/m² | -30% |
| Le Grande Route De Faldouet, St. Martin St Martin · 469 m² · £2,750,000 |
£5,864/m² | £8,500/m² | -31% |
| Apartment 4, Thornton Hall, Upper Kings Cliff, St Helier · 399 m² · £1,675,000 |
£4,198/m² | £6,818/m² | -38% |
| Agincourt St Lawrence · 127.4 m² · £799,000 |
£6,272/m² | £8,889/m² | -29% |
| La Rue De Fauvic, Grouville Grouville · 467 m² · £2,697,500 |
£5,776/m² | £8,380/m² | -31% |
| Le Mont Felard, St. Lawrence St Lawrence · 358 m² · £2,250,000 |
£6,285/m² | £8,889/m² | -29% |
| 139 Maisons Les Arches, St. Helier St Helier · 55.9 m² · £236,250 |
£4,226/m² | £6,818/m² | -38% |
| Edgefield Barn La Route De Vinchelez St. Ouen, St Ouen · 465 m² · £1,795,000 |
£3,860/m² | £6,441/m² | -40% |
Sale values here come from properties that state a floor area — a minority of Jersey's live stock, so treat this as directional rather than exhaustive. Nothing here accounts for whether a site can physically take an extension, whether a street has a ceiling price, or the condition behind the asking price. Check what actually gets approved and the approval rate by type of work before committing.