Office Refurbishment
& Fit-Out Contractors
in London

A Cat A fit-out is the base-level finish a landlord delivers when a space is ready to let: clean walls, basic lighting, mechanical and electrical services, and bare floors. It gives the incoming tenant a blank canvas. A Cat B fit-out is everything the tenant adds to make that space their own, including office partitioning, branded finishes, meeting rooms, a kitchenette, data infrastructure, and staff areas.

Most London SME refurbishment projects are Cat B works carried out on an existing Cat A space. Soraiz handles the Cat B construction. You bring the design drawings or layout plan, and we build to them. If the space is already occupied and you are upgrading rather than starting from a shell, that is typically classed as a refurbishment rather than a fit-out, though the physical trades involved are similar.

Most internal office refurbishments in London do not require planning permission. Partition installation, suspended ceiling works, new flooring, redecoration, and electrical upgrades all fall under permitted development for commercial premises. Planning permission is required only if your project involves structural changes to the building, external alterations such as new windows or cladding, a change of use, or if the building is listed.

A licence to alter from your landlord is a separate requirement and is almost always needed for Cat B works under a commercial lease, regardless of whether planning permission is required. Building regulations apply to certain elements of the work, particularly electrical installations and fire safety measures. CDM 2015 regulations apply to all construction projects, whatever their size. Soraiz checks all of these at Step 3 of the process before a single trade goes on site.

A cosmetic refresh, covering new flooring, redecoration, and lighting on a 1,000 sq ft office, typically takes 4 to 6 weeks on site. A full Cat B fit-out on the same space, including partitioning, suspended ceilings, electrical work, and a kitchenette, runs 8 to 14 weeks. Large-scale Cat B schemes on 3,000 sq ft and above, or projects in listed buildings and conservation areas, can take 4 to 6 months.

Phased programmes in occupied offices take longer per sq ft than the equivalent empty-office programme because trades must work around live areas. That additional time is the cost of keeping your business trading throughout. Timeline is also affected by London building-specific factors: freight lift availability, loading restrictions around the Old Street area EC1 and the Southwark riverside SE1, and lead times for specialist materials like acoustic glazing or bespoke joinery.

Yes, in most cases. Soraiz programmes works by zone, one area at a time, so staff continue to operate in the areas not yet under construction. A temporary hoarding or dust screen divides the active zone from the live workspace. This is standard practice for occupied office refurbishments across London and works well in open-plan spaces from 500 sq ft upwards.

Noise-generating trades, including strip-out, core drilling, and plastering, are scheduled out of hours or at weekends where the building management permits it. Your named contact at Soraiz sends a written weekly update so your team always knows what is happening and where, and what to expect the following week. For very small offices below 300 sq ft, a full vacate-and-return programme is sometimes quicker and cheaper overall.

Office refurbishment in London costs between £45 and £165 per sq ft for construction works, depending on scope and specification. A cosmetic refresh runs £45 to £65 per sq ft. A mid-level refurbishment covering partitioning, upgraded electrics, and new finishes runs £65 to £100 per sq ft. A full Cat B fit-out, covering all trades and joinery, runs £100 to £165 per sq ft. These figures are for construction only and exclude furniture, AV and IT integration, professional fees, and VAT. Source: Fusion Office Design 2025 cost data, Savills Cat B benchmarks, RICS guidance.

Central London projects typically cost 15 to 20 per cent more than the same specification in outer boroughs due to delivery logistics, restricted access, and higher contractor rates. The most accurate budget for your project comes from a site visit, not an online benchmark. Soraiz provides a fixed-price written quote after visiting the building.

Soraiz is the trades contractor. We execute the physical build. We do not originate interior design or produce space planning drawings. If you already have a designer, an architect, or a landlord’s specification, we work directly to those documents and quote from them. If you are starting without a design, we can recommend London-based commercial space planners who work regularly with SME businesses at the 500 to 4,000 sq ft scale. Once the layout is agreed and drawn, we take over the build.

This is an honest distinction that most contractors in this market blur. We think it matters because the right designer for your project is not necessarily the one attached to a building contractor. Separating the roles means you can choose both independently.

Soraiz covers all 32 London boroughs for office refurbishment and commercial fit-out work. We are particularly active in the inner London boroughs where the concentration of SME office space is highest: the City of London EC1 to EC4, Tower Hamlets E14 and E1, Hackney E8 and N1, Southwark SE1 and SE16, Westminster W1 and WC1, Islington EC1 and N1, Camden NW1, and Hammersmith and Fulham W6. We know the access constraints, building stock characteristics, and relevant planning portals for each of these areas.

For outer London boroughs including Croydon CR0, Ealing W5, Brent HA9, and Barnet N3, we work on the same terms with the same programme disciplines. The logistics planning is different, but the quality of the build is not.

A fit-out typically starts from a Cat A shell, an empty space with basic services in place, and builds a complete working environment from scratch. A refurbishment upgrades and reconfigures an existing occupied or recently vacated space: new finishes, adjusted layout, M&E improvements, without a full strip-out. In practice, most projects contain elements of both, and the terms are used interchangeably by landlords, agents, and contractors across London.

The distinction matters most for budgeting. A true Cat B fit-out of an empty shell runs higher per sq ft than a targeted refurbishment of an existing space because the extent of strip-out, new first-fix mechanical and electrical work, and reinstatement is greater. Soraiz handles both under one contract. We assess which category applies during the site survey and build the quote accordingly.