Loft
conversions
in Amersham, HP6
Designers, Architects, Engineers & Builders Under One Roof.
One Studio. One Contract. One Team.
Whether an Amersham loft can be converted without a planning application depends first on whether the house stands in one of the town's four conservation areas. We establish that, then design the stair, the escape route and the roof together.
Pitched-roof houses are the norm. The 2021 Census found 957 households in semi-detached houses and 1,673 in detached ones in the Amersham and Chesham Bois ward, with 890 and 2,235 in Penn Wood and Old Amersham, and many of the semis on the hill came from the inter-war estates.
Roof coverings tell the age. The Historic Towns Assessment finds handmade clay tile, machine-made clay tile and natural slate in the market and borough zone, and machine clay tile on the twentieth-century streets of the hill.
Sources: ONS/Nomis: Census 2021 TS044 Accommodation type, 2022 ward Amersham and Chesham Bois (E05013121); ONS/Nomis: Census 2021 TS044 Accommodation type, 2022 ward Penn Wood and Old Amersham (E05013154); Buckinghamshire Council (Chiltern and South Bucks District Councils): Chiltern & South Bucks Townscape Character Study Part 3, Chiltern Settlements (Chris Blandford Associates, November 2017); Buckinghamshire County Council with English Heritage: Amersham, Buckinghamshire Historic Towns Assessment Report (2009)
Permitted development and Amersham's conservation areas
Class B of the householder order permits an addition or alteration to a roof, but not on article 2(3) land, which includes conservation areas. In Amersham Old Town, Shardeloes Parkland, Elm Close and the Weller Estate a dormer or other roof enlargement therefore needs planning permission.
Rooflights are handled under Class C, which carries no article 2(3) exclusion; it allows other alterations to a roof as long as nothing stands more than 0.15 metres proud of the original roof slope.
Outside the conservation areas, Class B caps the added roof space at 40 cubic metres for a terrace house and 50 for others, bars any enlargement beyond the principal roof slope facing a highway, and asks for exterior materials of similar appearance and side windows obscure-glazed.
The enlargement must also stand at least 0.2 metres back from the eaves, measured along the slope, except for a hip-to-gable change or one joining the main roof to that of an extension. A Lawful Development Certificate gives certainty that a scheme falls within these limits.
Sources: legislation.gov.uk: GPDO 2015 (SI 2015/596), Schedule 2 Part 1, development within the curtilage of a dwellinghouse (latest available revised); legislation.gov.uk: Town and Country Planning (General Permitted Development) (England) Order 2015 (SI 2015/596), article 2 (latest available revised); Chiltern District Council: Chiltern District Local Plan, adopted 1 September 1997 (alterations 29 May 2001; consolidated September 2007 and November 2011); GOV.UK (MHCLG): Permitted development rights for householders: technical guidance (September 2019)
Dormers on Old Town, Arts and Crafts and Green Belt houses
In the conservation areas the application is judged under Policy CA1 on bulk, height, design and external appearance, with natural materials matching the existing roof expected and synthetic ones refused. Old Town roofs of handmade clay tile or natural slate are matched in kind.
On the estates built round greens, Elm Close's thirty Kennard semis and Highfield Close's matching pairs, the roofs were designed as a set, so a dormer on one is drawn against the whole group.
A listed house adds a second consent: listed building consent may be required for works to a listed building, and Amersham has 183 of them, including the Art Deco High and Over House and Sun Houses on the hill.
For a house in the Green Belt beyond the built-up edge, we treat a roof enlargement as an extension under GB13, which asks that extensions stay subordinate to the original dwelling and takes earlier extensions into account. The full wording is on our Chiltern page.
Sources: Chiltern District Council: Chiltern District Local Plan, adopted 1 September 1997 (alterations 29 May 2001; consolidated September 2007 and November 2011); Buckinghamshire County Council with English Heritage: Amersham, Buckinghamshire Historic Towns Assessment Report (2009); GOV.UK (Planning Practice Guidance): When is permission required?
Escape from a new top storey
Adding a storey through conversion that puts a floor above 4.5m triggers Approved Document B's loft provisions. The whole escape route has to be addressed, and fire-resisting doors and partitions provided along it, upgrading existing doors where needed.
Where old doors have historical or architectural merit, the guidance asks for retaining and upgrading them to be investigated before replacement, so we survey each door before the fire strategy is fixed.
New floors in a third storey added to a two-storey house need REI 30 fire resistance, smoke alarms should be mains-powered to BS EN 14604, and an open-plan ground floor needs new partitions to enclose the escape route or the guidance's alternative of sprinklers and a separated kitchen.
We plan the new stair over the existing one wherever the headroom allows, so the protected route runs straight from the loft room to the front door.
Structure, neighbours and sign-off for an Amersham loft
Our London team converts lofts in Amersham with its own architects, designers and structural engineers, and Hampstead Chartered Surveyors & Building Consultancy survey the existing roof. Where a planning application is needed it goes to Buckinghamshire Council; building control comes from Buckinghamshire Council's building control service or a private registered building control approver.
Loft steels commonly sit on the wall shared with next door, and the government's booklet on the 1996 Act lists cutting into a party wall to take the bearing of a beam, for example for a loft conversion, as work needing notice. Removing chimney breasts from a party wall needs notice too.
Re-covering the roof can need building regulations approval in its own right, so on a conversion we price and specify the tiles, battens and underlay together with the structure.
Our engineers check the existing rafters, purlins and ceiling joists from inside the roof before the design is fixed, and the dormer is set out from those measurements rather than from the original drawings of the house.
Outside Amersham, and in London rather than Buckinghamshire: Project example: Belsize Park, NW3. That project of ours included a loft conversion, sympathetic to the house, on a Victorian townhouse of five storeys, with its basement and rear extension alongside, as its case study describes.
Sources: Buckinghamshire Council: Building regulations and control; GOV.UK: Building regulations approval - when you need approval; GOV.UK: The Party Wall etc. Act 1996 explanatory booklet; GOV.UK: Party walls and building work - work you must tell your neighbour about; Hampstead Renovations: Belsize Park Gardens, NW3 case study
Loft Conversions in Amersham: Questions
Can I convert my Amersham loft under permitted development inside one of Amersham's conservation areas?
Not if the roof is to be enlarged. Class B roof additions are not permitted on article 2(3) land, which includes the Old Town, Shardeloes Parkland, Elm Close and Weller Estate conservation areas, so a dormer there needs planning permission. Rooflights that project no more than 0.15 metres beyond the slope come under Class C, which has no conservation area exclusion.
What fire safety work does a loft conversion in an Amersham house need?
Where the new storey sits more than 4.5m up, the whole escape route must be addressed, with fire-resisting doors and partitions and existing doors upgraded or replaced. New floors need REI 30 fire resistance and smoke alarms should be mains-powered. An open-plan ground floor needs partitions round the escape route, or the alternative of sprinklers and a separated cooking area.
Do I need a party wall notice for a loft conversion in Amersham?
In a semi or terrace, usually yes. Cutting into a party wall to take the bearing of a beam for a loft conversion is notifiable, as is removing a chimney from a party wall. Party wall agreements are separate from planning permission and building regulations approval.
Who signs off building regulations for a loft conversion in Amersham?
Buckinghamshire Council's building control service, or a private registered building control approver who notifies the council with an initial notice. You must check whether approval is needed before changing a building, and a loft conversion always involves structure, fire escape and insulation that are inspected.
What do you look at first when visiting an Amersham loft?
Headroom under the ridge, the direction of the ceiling joists, the purlins and any chimney stacks, and where the new stair can land on the floor below. We also confirm the conservation area and listing position, since that decides whether a dormer can be built without a planning application.
Does a loft conversion count against the Green Belt for an Amersham house?
Only for houses outside the built-up area of Amersham, which is excluded from the Green Belt. For those, we treat a roof enlargement as an extension under GB13, which permits extensions subordinate to the size and scale of the original dwelling and counts the cumulative effect of earlier ones.
Book a feasibility visit
Request a visit
Completed renovation project example
