How Long Does an Interior Design Project Take?
Two months for a furnishing scheme, eighteen for a major renovation. What decides the gap is not floor area but the authorisation regime, lead times and how fast approvals come back. Here is what actually happens during that time.
An interior design project takes anywhere from two months to two years depending on its scope. A scheme covering only furniture, textiles and lighting is completed in two to four months. A light renovation takes four to eight months. As soon as a building authorisation is involved, expect ten to eighteen months, and a full restructuring often runs beyond eighteen. This guide sets out what happens during that time, phase by phase, and above all what genuinely stretches a schedule, which is almost never what owners expect.
How long by project type
| Project type | Total duration | Of which design |
|---|---|---|
| Decoration and furnishing, no building work | 2 to 4 months | 4 to 8 weeks |
| Light renovation, partitions unchanged | 4 to 8 months | 6 to 12 weeks |
| Major renovation requiring authorisation | 10 to 18 months | 3 to 5 months |
| Full restructuring or new build | 18 months or more | 5 to 9 months |
These orders of magnitude apply to French-speaking Switzerland and cover the whole journey, from first meeting to handover. They assume a project run without interruption and a client available to make decisions. Every project remains a particular case.
The phases of a project and how long each takes
In Switzerland, construction and conversion projects are structured according to the phase model of the SIA, the Swiss Society of Engineers and Architects. Regulation SIA 102 distinguishes six phases: definition of objectives, preliminary studies, project design, tendering, execution and operation. An interior design project follows the same logic even when it is not formally governed by an SIA mandate, and knowing this breakdown helps you locate where a project actually stands.
Defining objectives and preliminary studies
Two to six weeks. This is where the brief, the uses, the available budget and the constraints of the building are established. You check what the co-ownership permits, survey the existing space, and identify load-bearing walls and service risers. It looks like a formality and it is not: most delays that surface later trace back to a vague brief signed off too quickly.
Concept and detailed design
Four to twelve weeks depending on complexity. The concept stage fixes the spatial approach, the drawings, the volumes and a first cost estimate. The detailed stage then resolves materials, finishes, lighting, joinery details and final selections. This is the phase most dependent on the client's decision-making pace: an approval that drifts for three weeks pushes the entire schedule back three weeks.
Authorisation procedure
Zero to twelve months. This is the harshest variable in any schedule. Some projects need no procedure at all, others go through a waiver of public consultation, others through a full thirty-day consultation followed by cantonal review. A complete file with no objections generally clears in five to seven months in the canton of Vaud; an appeal commonly adds more than a year.
Tendering and award
Three to eight weeks. Contractors are consulted, offers compared, the project adjusted to the real budget and the contracts awarded. This phase often reveals a gap between the estimate and the offers received, which forces a decision: reduce the scope, change a material, or accept the additional cost. That moment of arbitration is routinely left out of schedules.
Execution
Six weeks to twelve months. The building work itself, with site supervision, coordination of trades and quality control. A bathroom takes four to six weeks. A whole apartment with partitions moved and technical installations reworked takes four to eight months. Under SIA 102, this phase alone accounts for roughly half of the architect's services.
Commissioning and handover
Two to six weeks. Acceptance of the works, clearing of snagging items, installation of furniture, hanging of textiles and lighting. Snagging items rarely clear in a single day: there is almost always a part to replace or a finish to redo.
What actually stretches a schedule
Delays rarely come from the design work. Five factors account for most overruns.
- The client's decision-making pace. By far the leading factor, and the only one entirely within the client's control. Every deferred approval pushes back what follows, and those delays accumulate rather than cancel out.
- Lead times. A bespoke kitchen or a sofa made in Italy cannot be improvised. These lead times run in parallel with the works if ordered in good time, and block them if they are not.
- The authorisation procedure. Not compressible, largely unpredictable in its exact duration, and often discovered far too late in the process.
- Third-party approvals. Co-ownership, landlord, managing agent. These are handled in parallel with the municipal steps, never after them, or the waiting time doubles.
- Contractor availability. In French-speaking Switzerland, good trades are booked months ahead. Awarding late means starting late, even when everything else is ready.
Lead times to plan for
The figures below are those commonly seen in the trade. They vary considerably by supplier and time of year, and should be confirmed case by case at the point of order.
| Item | Indicative lead time |
|---|---|
| Bespoke kitchen | 8 to 14 weeks |
| Bespoke joinery, wardrobes, shelving | 8 to 12 weeks |
| Natural stone worktop | 4 to 8 weeks after templating |
| Made-to-order sofa or armchair | 10 to 16 weeks |
| European-manufactured lighting | 6 to 12 weeks |
| Made-to-measure curtains and blinds | 4 to 8 weeks |
| Imported tile or stone | 4 to 10 weeks |
| Wood flooring | 3 to 6 weeks |
On-site templating governs several of these. A stone worktop can only be ordered once the units are installed, which creates an unavoidable wait at the end of the works no matter how carefully the project has been planned.
How to shorten a project without damaging it
- Settle structural questions early. Moving a partition, opening a load-bearing wall or altering service risers determines the authorisation regime. Making that call in week two rather than week twelve changes the schedule by months.
- Group approvals. Signing off in coherent batches, rather than room by room as items arrive, avoids back-and-forth and redrawing.
- Order long-lead items at award. Kitchen, joinery and seating are launched at the start of the works, not once the walls are finished.
- Set a realistic budget before tendering. A significant gap between estimate and offers forces a round of arbitration that costs several weeks.
- Run authorisations in parallel. Co-ownership, landlord and municipality are anticipated together, never one after the other.
One thing cannot usefully be shortened: the design phase. It is the cheapest part of the project and the one that prevents the most errors. A month saved in design is generally repaid twice over during construction.
Frequently asked questions
How long does a full apartment renovation take?
Ten to eighteen months where authorisation is required, of which four to eight months on site. Without moving partitions or relocating sanitary fittings, the same apartment can be handled in four to eight months in total. Whether an authorisation procedure applies is the decisive factor.
How long does the design phase alone take?
Four to eight weeks for a furnishing project, three to five months for a major renovation including preparation of the authorisation file. This duration depends directly on how quickly approvals come back.
Can I live in the property during the works?
It is possible for work limited to one room or to surface finishes, but rarely advisable once the kitchen, bathroom or technical installations are involved. Living on site also slows the works, since contractors then have to work in zones and make good each evening.
When should I contact an interior designer?
As early as possible, ideally before purchase or as soon as contracts are signed. An early visit identifies load-bearing walls, service risers and the applicable authorisation regime, which means knowing what the property actually allows before committing to it.
What happens if a supplier is late?
An isolated delay on a non-blocking item can be absorbed by reordering the sequence of trades. A delay on a blocking item, typically the kitchen or the joinery, pushes back every trade that follows, with a knock-on effect that often exceeds the original delay.
Why do projects so often overrun the schedule given?
Because schedules are built on task durations, while overruns come from the waiting time between tasks: approvals, authorisations, deliveries and contractor availability. A realistic programme puts numbers on that waiting rather than ignoring it.
A schedule is built at the start, not along the way
The duration of a project is largely decided in its first few weeks, when scope, authorisation regime and the level of bespoke work are settled. Those three decisions, made early and held to, are worth more than any attempt to accelerate once the site is open.
Our interior design services build this planning in from the first meeting, and our residential projects give a concrete sense of what these different scales of intervention involve. We work across French-speaking Switzerland, including Lausanne, Geneva, Vevey, Montreux and Nyon.
