A commercial fit-out is one of the most significant investments a business makes. Get it right and you have a workspace that supports productivity, reflects your brand, and holds its value. Get it wrong and you are looking at cost overruns, programme delays, and a defects list that drags on for months after you move in.
Most of the problems we see on commercial fit-outs are not caused by bad contractors or poor materials. They come from a lack of clarity about what happens at each stage — who is responsible for what, when decisions need to be made, and what the consequences are of leaving things too late.
This guide walks through the eight stages of a commercial fit-out as TCM runs them, with honest notes on the points where projects most often go wrong. Whether you are fitting out a new office, refurbishing a retail unit, or taking on a shell-and-core space, the process is broadly the same — though the timescales and complexity vary considerably.
What this guide covers
CAT A and CAT B fit-outs for offices, retail units, and mixed-use commercial premises in Hertfordshire and North London. If you are planning a commercial refurbishment of an existing occupied space, see our guide to commercial refurbishment services.
CAT A vs CAT B: Understanding the Starting Point
Before we get into the stages, it is worth clarifying the terminology, because it causes confusion on almost every project.
A CAT A fit-out brings a shell-and-core space to a basic functional standard. Think raised floors, suspended ceilings, M&E distribution to floor and ceiling level, and perimeter trunking. It is typically the landlord's responsibility and creates a blank canvas for the tenant.
A CAT B fit-out is the tenant's fit-out. This is where the space becomes yours: partitioning, kitchen and welfare, reception, branding, specialist lighting, furniture, IT and AV infrastructure. Most commercial clients engage TCM for CAT B works, though we also carry out combined CAT A and CAT B programmes where the landlord has not completed the base build to the required standard.
| Element | CAT A (Landlord) | CAT B (Tenant) |
|---|---|---|
| Raised floors / screeds | ✓ | — |
| Suspended ceilings | ✓ | — |
| M&E distribution | ✓ | — |
| Partitioning | — | ✓ |
| Kitchen / welfare | — | ✓ |
| Reception / branding | — | ✓ |
| Specialist lighting | — | ✓ |
| IT / AV infrastructure | — | ✓ |
| Furniture | — | ✓ |
The Eight Stages of a Commercial Fit-Out
Initial Survey and Brief
Project-specificStart by defining the intended use, starting condition, occupancy requirements, access, available drawings and known landlord or building-management constraints. Further measured, M&E, structural or specialist surveys may be needed depending on the premises.
From Our Experience
Landlord requirements can affect the critical path, so establish early whether a Licence to Alter or other landlord submission is required. The review period is controlled by the lease, landlord and quality of the submitted information rather than a universal number of weeks.
Design and Specification
Project-specificThe responsible designers develop the space plan, finishes and relevant building-services information to the level needed for approvals and pricing. The project specification should identify what is retained, altered, supplied by the client and delivered by each contractor or specialist.
From Our Experience
M&E interfaces should be resolved before quotations are treated as comparable. Existing capacity, HVAC distribution, power, data, fire systems and specialist equipment can materially change the scope.
Regulatory Approvals and Landlord Consent
Project-specificConfirm the applicable planning, Building Regulations, landlord and other consent routes for the actual work. Responsibility for drawings, submissions, notices, inspections and responses should be stated in the project appointments.
From Our Experience
Landlord consent and statutory approvals are separate processes. Neither their timing nor outcome is guaranteed by TCM; the project programme should show the relevant dependencies and hold points.
Quotation and Contract
Project-specificOnce enough information is available, compare quotations on the same scope and specification. The selected contract or agreement should record the parties, price basis, payment arrangements, programme, responsibilities, changes, completion and dispute terms appropriate to the project.
From Our Experience
Where design or site information remains unresolved, identify it as an assumption, allowance, provisional item or exclusion rather than presenting an incomplete scope as a guaranteed fixed price.
Pre-Construction and Mobilisation
Project-specificBefore site work starts, confirm relevant CDM dutyholders and construction-phase arrangements, procurement, access, deliveries, welfare, temporary protection, waste handling and any building-management rules. Long-lead products and specialist packages should be tracked against the agreed programme.
From Our Experience
Out-of-hours or phased working is only used where the premises and project constraints allow it. Permitted hours, access and any cost or programme impact should be agreed before mobilisation.
Construction Phase
Project-specificThe sequence depends on the design, but can include enabling or strip-out work, structural alterations, first-fix services, partitions and ceilings, second-fix services, joinery, floor finishes and decoration. TCM can undertake building work directly and coordinate specialist contractors where required by the agreed scope.
From Our Experience
Progress reporting, site-management arrangements and the frequency of updates are project-specific. They should be stated in the agreed delivery plan rather than assumed from this guide.
Commissioning and Testing
Project-specificInstalled systems are tested or commissioned as required by their design and responsible provider. Building-control or other inspections take place through the applicable route, with defects and incomplete information recorded before handover.
From Our Experience
Commissioning scope depends on what has actually been installed. The responsible M&E, fire, data, controls or other specialists provide the relevant records where their systems are in scope.
Snagging and Handover
Project-specificHandover should compare the completed work with the agreed specification and record any remaining snagging. The project documents should state which completion records, certificates, O&M information, as-built information and warranties are due and from whom.
From Our Experience
Do not assume every fit-out produces the same handover pack. The required records depend on the installed work, statutory routes, product systems and specialist appointments.
Typical Programme by Fit-Out Type
Programme depends on scope, size, starting condition, approvals, procurement and specialist interfaces. The table below therefore shows the information that should drive the programme rather than publishing unsupported fixed durations by fit-out type.
| Fit-Out Type | Scope / starting condition | Overall programme | Construction programme |
|---|---|---|---|
| Office fit-out | Confirm actual Cat A / Cat B starting condition | Project-specific | Project-specific |
| Retail fit-out | Existing retail unit / shell / change of use as applicable | Project-specific | Project-specific |
| Hospitality fit-out | Kitchen, extraction, fire-safety and services interfaces | Project-specific | Project-specific |
| Occupied-premises refurbishment | Phasing, access and business-continuity constraints | Project-specific | Project-specific |
| Higher-specification fit-out | Bespoke finishes and specialist systems | Project-specific | Project-specific |
| Combined landlord + occupier works | Define responsibility split and dependencies | Project-specific | Project-specific |
The Most Common Causes of Programme Delay
Commercial fit-out programmes can be affected by the same broad categories of dependency across many projects. The actual impact is project-specific and this page does not present them as measured TCM frequencies or fixed delay periods.
Licence to alter delays
Landlord review can affect the critical path where a Licence to Alter or other consent is required. Establish the submission requirements and responsible party early, and record the landlord-review dependency in the programme rather than assuming a fixed saving.
Incomplete specification at tender
An incomplete specification can create allowances, exclusions and later changes. Make unresolved information explicit in the quotation and change process instead of representing an incomplete scope as a guaranteed fixed price.
Long-lead item ordering
Bespoke joinery, specialist lighting, floor systems, HVAC equipment and other products can have significant procurement lead times. Identify actual suppliers and current lead times for the selected products and track them against the project programme.
IT and AV scope creep
IT and AV requirements often expand during construction as the client's team gets more involved. Agreeing the IT and AV specification in full before construction begins avoids late changes that affect the M&E programme.
Building control delays
Where building-control inspections or information are required, agree the notification and inspection arrangements with the relevant building-control body and project team. Sequence the work around the actual inspection requirements rather than a generic timetable.
Frequently Asked Questions
How long does a commercial fit-out take?+
There is no reliable universal duration. Programme depends on the starting condition, design information, landlord and statutory approvals, M&E and specialist interfaces, procurement, access, occupation constraints and changes to the agreed scope. Use a project-specific programme with stated assumptions and dependencies.
What is the difference between CAT A and CAT B fit-out?+
Cat A and Cat B are market descriptions rather than fixed statutory specifications. Cat A commonly describes a more neutral landlord or base-build condition, while Cat B commonly describes occupier-specific work. The lease, landlord specification and project documents determine what is actually included and who is responsible.
Do I need planning permission for a commercial fit-out?+
It depends on the premises and proposed work. Internal alterations, external changes, signage, plant, listed-building constraints and changes of use can follow different planning or consent routes. Building Regulations and landlord consent are separate questions and should also be checked for the project.
Can the fit-out be carried out while we are still trading?+
Phased or out-of-hours work may be possible where the premises, lease, landlord rules, neighbours, access and safety controls allow it. The work areas, temporary separation, permitted hours and any programme or cost effect should be agreed for the individual project.
What should I check at the handover inspection?+
Check the agreed scope against the completed work, record snagging items, and confirm which commissioning records, certificates, O&M information, as-built information, manufacturer documents and warranties are due from the responsible parties. The exact handover pack depends on the installed systems and project responsibilities.
Related Services and Guides
Commercial Fit-Out Services
Commercial fit-out building work with project-specific coverage, phasing and specialist responsibilities
Office Fit-Out
Bespoke office fit-outs from survey to handover
Retail Shop Fit-Out
Retail fit-outs for Hertfordshire and North London businesses
Commercial Refurbishment
Refurbishment of occupied commercial premises
Commercial Fit-Out Cost Guide
Commercial fit-out budget and quotation-scope guidance
Commercial Maintenance
Ongoing maintenance contracts after your fit-out
Commercial Fit-Out Contact Route Status
TCM Building & Maintenance can undertake commercial fit-out building work from its Borehamwood base and coordinate specialist contractors where required. Project coverage, CDM roles, access arrangements, quotation basis and programme are confirmed for the individual premises.