Flat Conversions Borehamwood

A flat conversion in Borehamwood starts from the stock the town has: the 2021 Census recorded 4,468 terraced and 4,077 semi detached households across the four Borehamwood wards, and only 2% of homes predate 1919. Post-war plans make floor area the first test, because Hertsmere's July 2016 note says it intends to apply the Nationally Described Space Standard. Each new flat has to be measured before it is drawn. We build the separating floors, protected stair, new kitchens and bathrooms and separate services to the approved drawings.

For Borehamwood, converting a house into two or three flats is published at £50,000 to £120,000 including professional and council fees, and an England-wide guide puts a straightforward two-flat split at £40,000 to £80,000 in construction alone, which is the part a builder prices (Architectural Drawings and Mayfair Studio, 2026); a Hertfordshire price follows a site visit. GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Borehamwood: we build the conversion to the approved drawings, building control inspects the fire and sound separation, and a registered electrician certifies each flat's electrics.

Which Borehamwood houses have room to become two flats

A Borehamwood house split into two flats is judged on whether each flat meets the space standard, so the tape measure comes before the planning drawings. Hertsmere's July 2016 note states that the council intends to apply the Nationally Described Space Standard by reference to it in its updated Design Guide SPD Part D. A two storey post-war semi split floor by floor gives each flat roughly half the house, less the new stair enclosure, and that stair takes more room than people expect. Measure the gross internal area of each proposed flat against the standard before paying for full drawings.

Cowley Hill ward recorded 1,275 semi detached households at the 2021 Census, the highest of the four Borehamwood wards, and a semi with an existing side or rear extension has the best chance of giving two flats that pass. The ground floor flat takes the garden and the original front door; the upper flat needs its own entrance, either a new door into a protected hall or a separate external stair. Where the house only just fits, a one bedroom flat above a two bedroom flat may be the arrangement that works.

Housing in Borehamwood

Borehamwood's housing, as the Council Tax list records it, is about 15,090 homes: 63% houses, 36% flats, with 2% pre-1919, 8% interwar and 90% built since 1945. Terraced houses make up 38% of homes here, and a converted terrace in Borehamwood has two party walls to consider for sound.

Planning permission for a Borehamwood conversion

Splitting a Borehamwood house into self contained flats always needs planning permission from Hertsmere Borough Council, because creating new dwellings is development in its own right. Hertsmere requires application plans to be drawn to a recognised metric scale, to include a scale bar and to be supplied in PDF format, so measured drawings of the existing house come first. Hertsmere also states that where new housing only just meets its minimum design standards, it will assess whether to remove permitted development rights, so a scheme drawn right at the minimum can come with a condition restricting later changes.

Hertsmere's Core Strategy states that up to 60 per cent of new housing in the period to 2027 may be developed in Borehamwood, and conversions add to that supply on a smaller scale. The policy picture is moving: Hertsmere must submit its new Local Plan for examination by 31 December 2026. A conversion is also a material change of use under the Building Regulations, so the building control application runs alongside the planning one, and the design should satisfy both before any walls come down.

Fire and sound separation between Borehamwood flats

The build between two flats is fire and sound separation first. Building Regulations Part B asks for a fire resisting floor between the flats, a protected stair or escape route, fire doors to the flat entrances and linked smoke detection. Part E asks for separating floors and walls that resist airborne and impact sound, and flats formed by conversion are sound tested before completion. In a post-war Borehamwood house the existing timber floor is unlikely to meet either on its own, so we lift or overboard it and add resilient bars, insulation and extra plasterboard as specified.

Hertfordshire Building Control handles the inspections for Borehamwood conversions, because Hertsmere does not run its own building control service, unless you appoint a registered approver. Its checks cover foundations, damp proofing and structural issues, among other aspects of construction. We book the visits before the separating floor and the stair enclosure are boarded over. The pre-completion sound test is arranged with a tester once the flats are finished but before they are decorated, so any weak junction can be put right.

Meters, party walls and turning Borehamwood flats back into a house

Each new flat needs its own services. That means a separate electricity supply and meter, a separate gas meter or an electric heating system, its own water supply or a shared supply agreed in the leases, and a separate consumer unit certified by a registered electrician. The new flats also need postal addresses, which the council's street naming and numbering service issues. With 4,468 terraced households across the four Borehamwood wards, a conversion often shares a wall with a neighbour, and cutting into it brings in the Party Wall Act.

Under that Act the building owner serves the notices on the neighbours before work to the party wall starts, and the work goes ahead on their written consent or under an award the surveyors make. The reverse job can also come up in Borehamwood: two flats combined back into one house. The building work is usually simpler than the original split, since the second kitchen comes out and the stair enclosure can be opened up. Merging flats can still need planning permission where a home is lost, so ask Hertsmere before starting.

• House to flat conversions into two or more self-contained units
• Insulation to the walls, roof and floors the conversion touches
• Fire stopping round every pipe and cable through a separating floor

VOA Council Tax stock of properties, March 2025, for Borehamwood Cowley Hill, Borehamwood Brookmeadow, Borehamwood Kenilworth and Borehamwood Hillside. Counts rounded by the VOA.

Next steps that tend to follow flat conversions in Borehamwood: structural alterations in Borehamwood, flat conversions in Radlett, a building contractor for the whole conversion, the Party Wall Act when a conversion cuts a shared wall, flat conversions anywhere in London and Central Heating Installation Cost.

Trusted Flat Conversions in Borehamwood

GS Renovation builds Borehamwood flat conversions to the consented drawings, with one point of contact for the whole job. The structural engineer we appoint designs any new openings and the trimming for the stair, we build the separating floors and walls, and we coordinate the electrics, plumbing and meters for each flat. A registered electrician certifies the electrical work. At handover you get the certificates and sound test results that building control, a lender or a buyer will ask for, and the owner or their designer keeps hold of the planning consent.

• Each flat numbered and supplied before the keys are handed over
• One point of contact from first survey to handover
• Each flat's new electrics signed off by a registered electrician for Part P

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.