# Fit-Out Timeline Calculator: How Long Will Your Office Take?

> A fit-out timeline estimate adds design, approvals, site works, procurement, installation and handover into one programme. Site works and long-lead procurement run in parallel, so whichever takes longer sets the handover date. That phase is the critical path.

## What it calculates

The estimator builds an indicative fit-out programme in weeks, from the start of design to
handover. It shows:

- the **total programme** in weeks and months;
- the **site works duration**, from mobilisation to finishes;
- which phase sits on the **critical path**, site works or procurement;
- the time **from approval to handover**;
- a simple **bar chart** of the phases, with the critical ones highlighted.

## Inputs

**Carpet area** is the area being fitted out.

**Starting condition** describes what is already there. A bare shell has no ceiling, air
conditioning or lighting. A warm shell has them in place, so less work is needed. An
existing office has to be stripped out before new work starts.

**Working hours allowed by the building** reflects the landlord's rules. In occupied
buildings, noisy work is often limited to nights and weekends.

**Design and drawings** is the time to produce approved working drawings. Enter zero if
they already exist.

**Landlord and authority approvals** is the wait between submitting drawings and receiving
permission to start.

**Longest lead item** is the time from order to delivery for the slowest item on the
project, often imported furniture, specialist glass or HVAC equipment.

The **assumptions** panel holds the weekly site progress, mobilisation, installation and
commissioning, and the handover period.

## Method

The programme runs in five stages. The third stage has two activities in parallel:

1. **Design and drawings**.
2. **Approvals**.
3. **Site works** and **long-lead procurement**, both starting when approval is received.
   Site works = mobilisation + (area ÷ weekly progress) × condition factor × hours factor.
4. **Furniture installation, testing and commissioning**, which starts when both the site
   works and the long-lead delivery are complete.
5. **Snagging and handover**.

Total = design + approvals + the longer of site works and procurement + installation +
handover.

## Assumptions

| Assumption | Default | Notes |
| --- | --- | --- |
| Site progress | 1,500 sq ft a week | Area taken through civil, MEP, ceiling and finishes each week |
| Mobilisation | 1 week | Site set-up, protection, permits to work |
| Bare shell factor | 1.0 | The reference case |
| Warm shell factor | 0.75 | Less ceiling and services work |
| Existing office factor | 0.9 | Strip-out first, but some services may be reused |
| Night and weekend factor | 1.4 | Shorter, less productive shifts |
| Installation, testing and commissioning | 2 weeks | Furniture, then testing of services |
| Snagging and handover | 1 week | Defects list, cleaning, documents |

Weekly progress depends heavily on the specification and the size of the team on site. A
simple open-plan office progresses faster than a floor of cabins, glass partitions and
detailed joinery. Change the figure to suit the project.

## Limitations

- **It assumes approvals arrive in one go.** In practice, landlords often comment and ask
  for resubmission, and each round adds time.
- **It treats site works as one block.** A real programme overlaps trades and tracks dozens
  of activities, some of which depend on deliveries other than the longest one.
- **It assumes the order is placed on approval.** If decisions on furniture or finishes are
  late, procurement starts late and the programme moves with it.
- **It does not allow for client changes.** Changes after work has started are one of the
  most common causes of delay.
- **It ignores external events.** Authority inspections, power connections and building
  works by the landlord can all hold up handover.

## Worked example

A 10,000 sq ft bare-shell office, normal working hours, four weeks of design, three weeks of
approvals and an eight-week lead time on imported furniture:

| Phase | Calculation | Weeks |
| --- | --- | --- |
| Design and drawings | entered | 4 |
| Approvals | entered | 3 |
| Site works | 1 + (10,000 / 1,500) × 1.0 × 1.0 | 7.7 |
| Long-lead procurement | entered | 8 |
| Parallel stage | the longer of 7.7 and 8 | 8 |
| Installation and commissioning | assumed | 2 |
| Snagging and handover | assumed | 1 |
| Total | 4 + 3 + 8 + 2 + 1 | 18 |

The programme is about **18 weeks, a little over four months**. Procurement, not the site,
sets the date: the furniture arrives a few days after site works finish. Placing the order
two weeks earlier, for example by approving the furniture during design, would bring
handover forward by the few days procurement is ahead of the site.

If the same floor can only be worked at nights and weekends, site works stretch to about
10.3 weeks and become the critical path. The programme grows to about 20.3 weeks, and
ordering early no longer helps.

## How engineers use it

A project manager builds the programme in the same way: fix the dates that cannot move,
identify the long-lead items, and find the chain of activities that sets handover. The
difference is detail. A real programme breaks site works into trades and areas, links them
with dependencies, and tracks deliveries item by item.

The most useful output at the early stage is knowing what is on the critical path. If it is
procurement, the decisions that matter are about ordering early. If it is site works, they
are about working hours, labour on site and avoiding changes.

## When a professional design must replace it

Use the estimator to set expectations, to test what a later lease start or a night-only rule
does to the date, and to decide which decisions must be made early. Replace it with a
contractor's detailed programme before you commit to a move-in date, a lease start or a
notice period on your current premises, and keep that programme updated as the project runs.

## Frequently asked questions

### How long does an office fit-out take?

It depends far more on approvals, lead times and working hours than on area alone. A mid-sized office with design still to do can easily take four months or more from appointment to handover, while a small warm-shell refresh with drawings ready can be much quicker. Enter your own figures to see which phase dominates.

### What is the critical path in a fit-out?

It is the chain of activities that sets the finish date. Delay anything on it and handover moves; delay something off it and handover does not, up to a point. In many fit-outs the critical path runs through a long-lead item such as imported furniture or HVAC equipment rather than through site work.

### Why do night-only working hours add so much time?

Many occupied buildings allow noisy or dusty work only at night or at weekends. Shorter shifts, mobilising and clearing up each night, and restrictions on deliveries all reduce how much gets done each week. The calculator applies a factor to site works to reflect that; change it if your building's rules are different.

### Can ordering early shorten the programme?

Only if procurement is on the critical path. If the longest lead item takes more weeks than the site works, placing that order the day the design is approved, or before, brings handover forward. If site works are longer, ordering earlier changes nothing.

### Does this include the time to find and lease a building?

No. The programme starts when the design work starts. Lease negotiation, landlord consents before signing and any rent-free period discussions come before it.

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Source: https://hagerstone.com/calculators/fit-out-timeline-calculator