Potters Bar at a glance
- Postcode districts
- EN6
- Population
- about 22,639 (GeoNames)
- Council area
- Hertsmere Borough Council
- Building approval
- Hertsmere Borough Council building control, or a registered building control approver
- Nearest main town
- St Albans, about 8 miles
- Guide price region
- East of England (+5% on West Midlands rates)
What makes a good extension roof in Potters Bar?
Ponding against the house wall is a common reason for replacing an extension roof in Potters Bar. When the deck dips near the wall or the fall runs the wrong way, water sits against the abutment and eventually gets in. A new roof with corrected falls moves the water to the gutter.
Potters Bar's flat roofs are mostly on low-rise post-war blocks of flats, with plenty on newer estates where the first extension roofs are now being replaced too. The East of England is the driest part of Britain, with parts of the Anglian region around 630 mm a year, so summer heat and UV, not rainfall, do most of the ageing on a felt roof.
How much does a new extension roof cost in Potters Bar?
At East of England guide rates, a 20 m² extension roof in EPDM with a new deck and insulation comes to £2,950–£5,150 including VAT. 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 | £2,950–£5,150 |
| Extension (20 m²), GRP, new deck + insulation | £3,150–£5,650 |
| Extension (20 m²), EPDM, insulation + 1 rooflight upstand | £3,150–£5,500 |
| Single garage (18 m²), EPDM rubber | £1,700–£2,950 |
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?
- 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
- New deck, vapour control layer and warm-roof insulation
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?
- Borehamwood · 5 mi
- Hatfield · 5 mi
- Cheshunt · 6 mi
- Waltham Abbey · 7 mi
- Welwyn Garden City · 8 mi
- St Albans · 8 mi
Extension and kitchen roofs in Potters Bar: questions
Do you cover Potters Bar?
Yes. Potters Bar is part of our Hertfordshire coverage, including postcode districts EN6. 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 Potters Bar?
Where the work needs approval it goes to Hertsmere Borough 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 Potters Bar?
£2,950–£5,150 for a 20 m² extension roof in EPDM with a new deck and insulation, at East of England guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
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.
Can you keep my existing roof lantern?
Often, if the lantern itself is sound. We lift it, rebuild the kerb, dress the new membrane up the upstand and refit the lantern.