Flat Conversions Stevenage

A flat conversion in Stevenage starts with the borough's planning position on splitting houses, and every new dwelling is measured against the Nationally Described Space Standard. The stock makes that a real test: the largest single category is the three bedroom terrace, with 13,430 on the valuation list, and splitting one into two flats that each meet the standard is hard. Larger semis and detached houses are the realistic candidates. We build the self-contained flats to the approved layout, with fire and sound separation between them.

For Stevenage, 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 Stevenage: 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 Stevenage houses make workable flat conversions

Larger houses, in locations the plan supports. The 2019 Local Plan permitted converting larger houses into smaller homes, flats or shared accommodation where negative impacts can be mitigated, and expected proposals within walking distance of primary school provision and other community facilities. The Partial Update has since replaced that plan, so your designer checks the adopted wording. The town has 4,680 semi detached houses and, by the Local Plan's count, only one detached home in every eight. A large semi or detached house near a neighbourhood centre fits the policy far better than a small terrace at the edge of an estate.

The plan also warns that converting or subdividing even a modest number of houses in a Stevenage street can tip the balance on parking. Your designer needs to show where the extra cars go, or why they will not arrive. On a New Town estate with shared parking courts and limited kerb space, that question often decides the application before layout or finishes come into it, so test it first.

Housing in Stevenage

Stevenage has around 38,430 homes on the Council Tax list: 96% post-war, 1% interwar and 2% predate 1919, with 24% flats and 76% houses. A converted terrace in Stevenage has two party walls to consider for sound, and 52% of homes here are terraced.

Room sizes and outside space for new Stevenage flats

Stevenage assesses proposals creating new dwellings against the Nationally Described Space Standard set out in Appendix C of the Local Plan. Each flat needs its minimum gross internal area, bedroom sizes and storage, and in a house conversion the existing walls, stair and chimney breasts rarely fall in the right places. The layout is usually won or lost at the stairwell, which has to serve every flat and meet the fire escape rules.

For new flatted developments, the Stevenage Design Guidance SPD asks for at least 50m2 of communal amenity space, or 10m2 per unit above five units. The guidance is written for all new flatted developments, so expect a house conversion to be asked how its garden is shared or divided. We build the bin store, cycle store and garden boundaries shown on the approved plan as part of the same contract.

Fire and sound separation between new Stevenage flats

Every new flat needs fire separation from its neighbours and from the common stair under Part B of the Building Regulations, and the floors between flats need sound insulation under Part E. Where a Stevenage house has a timber first floor, that means a resilient ceiling, acoustic insulation and a floating layer. Flats formed by a change of use need sound testing before completion. Each flat entrance gets a fire door, the stair becomes a protected route, and every service passing between flats is fire stopped.

A conversion is a material change of use, so it needs building regulations approval from Hertfordshire Building Control, the council's service, or a registered approver. A deposit of plans suits this work, because the separating floor, the escape route and the drainage are all agreed before we build. A Building Notice cannot be used if the work is over or within 3 metres of a public sewer, which new soil stacks and connections in a Stevenage garden can be. Each flat also needs its own meters, supplies and a postal address.

The levy on new flats and turning Stevenage flats back into a house

Stevenage's Community Infrastructure Levy is payable on development of any size that results in a new house or flat, not only on schemes of 100 square metres or more. A house split into two flats therefore creates a new dwelling that can attract the levy. The revised schedule, SCIL2, was implemented from 22 July 2026. Your designer or agent handles the CIL forms, and they must be settled before work starts on site, or the exemptions and payment terms can be lost.

The reverse journey also needs planning thought. Under Policy HO6, residential schemes causing a net loss of housing in Stevenage are permitted only where they show demonstrable benefits against the plan's housing policies. Combining two flats back into one house is a net loss, so your designer sets out that case first. Physically the work is simpler than a conversion: removing a second kitchen, reopening the stair as one home, taking out separating partitions and merging the meters into one supply.

• Fire stopping round every pipe and cable through a separating floor
• Fire detection in every flat and the common hall, laid out to the fire strategy
• Separate gas, electricity and water supplies for each flat

VOA Council Tax stock of properties, March 2025, for all 12 statistical areas in Stevenage. Counts rounded by the VOA.

Next steps that tend to follow flat conversions in Stevenage: structural alterations in Stevenage, flat conversions in Hitchin, building control sign-off for a conversion, party walls in a flat conversion, flat conversions across London and Structural Engineer Report Cost.

The GS Renovation Difference in Stevenage

A flat conversion joins structural work, fire separation, acoustic upgrades, new drainage and separate supplies in one building, and the order matters. We run it as a single programme, build to the planning consent and building regulations approval you hold, and book each inspection and the sound test at the right stage. The owner or their agent handles planning and the levy forms, and we supply the programme and drawings they need. A registered electrician certifies the wiring, and a Gas Safe engineer connects any gas.

• Full plans application to building control, never a building notice
• Building control applications and inspections coordinated for you
• Separate meters, supplies and consumer units arranged for every flat

Reviewed jobs near Stevenage

1 MyBuilder review from Stevenage, with each customer's own job title:

• Kitchen worktops, Stevenage, 24 Jun 2021 (5 out of 5)

Read all 31 on our reviews page.

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.