Shoreham-by-Sea at a glance
- Postcode districts
- BN42, BN43
- Population
- about 19,175 (GeoNames)
- Council area
- Adur District Council
- Building approval
- Adur District Council building control, or a registered building control approver
- Nearest main town
- Worthing, about 5 miles
- Guide price region
- South East (+10% on West Midlands rates)
What makes a good extension roof in Shoreham-by-Sea?
Extension roofs in Shoreham-by-Sea are often replaced because the original was built cheaply: thin chipboard decks, little or no insulation and felt turned up the wall without a proper flashing. Twenty or thirty years on, those weaknesses show up as leaks at the back wall and a cold, damp ceiling.
Around Shoreham-by-Sea, flat roofs are common on low-rise post-war blocks of flats and on lock-up garage blocks on estates. Much of the South East sits in the drier Thames catchment at roughly 730 mm of rain a year, so the usual failures are at joints, upstands and outlets rather than from sheer volume of rain.
How much does a new extension roof cost in Shoreham-by-Sea?
Guide price in Shoreham-by-Sea: £3,100–£5,350 for a 20 m² extension roof in EPDM with a new deck and insulation, including VAT at South East rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM, new deck + insulation | £3,100–£5,350 |
| Extension (20 m²), GRP, new deck + insulation | £3,300–£5,900 |
| Extension (20 m²), EPDM, insulation + 1 rooflight upstand | £3,300–£5,750 |
| Single garage (18 m²), EPDM rubber | £1,750–£3,100 |
Which flat roof system suits a kitchen extension?
On a plain rectangular extension, EPDM rubber is a strong, quiet choice that can often be laid in one sheet. It handles the slight movement between an extension and the house well.
Where the roof has a lantern, several rooflights or an internal corner, GRP fibreglass forms neat, rigid details around each one. Torch-on felt is a proven layered system and keeps costs down, though near timber cladding or at fragile junctions we may prefer a cold-applied method. If the extension is overlooked from upstairs windows, a sedum green roof is worth considering, provided the structure can take the extra load.
Whatever the membrane, the insulation sits above the deck as a warm roof. Our warm vs cold roof guide explains why.
What's included?
- Staged strip-out so the room stays weathertight
- Falls set away from the house wall
- Building control handled where needed, and a written workmanship guarantee
- Free survey of the roof, abutment and room below
Building regulations in England
Replacing more than half of a flat roof over a heated room usually counts as renovating a thermal element, so the roof is insulated to around 0.16 W/m²K where that's technically and economically feasible, and the work is notified to building control: the council or a registered building control approver, unless a registered competent person self-certifies it. A roof on a new extension is built to 0.15 W/m²K. Patch repairs, and most unheated detached garages, don't trigger the upgrade. Structural changes, or a new covering that adds 15% or more to the roof's weight, also need approval. More on the rules.
Which nearby areas do we also cover?
Extension and kitchen roofs in Shoreham-by-Sea: questions
Do you cover Shoreham-by-Sea?
Yes. Shoreham-by-Sea is part of our West Sussex coverage, including postcode districts BN42, BN43. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building regulations for a flat roof in Shoreham-by-Sea?
Where the work needs approval it goes to Adur District Council building control, or a registered building control approver. We tell you at the survey whether your job needs it and deal with the paperwork as part of the quote.
How much does a new extension roof cost in Shoreham-by-Sea?
£3,100–£5,350 for a 20 m² extension roof in EPDM with a new deck and insulation, at South East guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
How do I know my extension roof needs replacing rather than repairing?
Repeated leaks, a soft deck, wet insulation or widespread cracking point to replacement. A single defect on a dry, sound roof can usually be repaired.
Is EPDM or GRP better for a kitchen extension?
Neither is better in every case. EPDM suits simple rectangular roofs with few details, while GRP is often chosen where there are rooflights, corners or occasional foot traffic.