A full high-end renovation with complete demolition on an apartment around 150 square meters typically takes 6 to 9 months from the start of demolition to final finishes — assuming permits and designer plans were already finalized before construction began.
The single biggest variable isn't the construction work itself — it's what happens before the first wall comes down. Permit approval, structural engineering review (especially in older buildings), and finalized designer plans can easily add 1–3 months before any physical work starts, and this phase is the one most owners underestimate when mentally budgeting a timeline.
Once construction is underway, the phases that most commonly run long are:
Electrical and plumbing rough-in, especially in older buildings where existing systems need full replacement rather than simple upgrades.
Custom work — aluminum, built-in cabinetry, and imported materials often have longer lead times than owners expect, and ordering late is the most common self-inflicted delay.
Inspection sign-offs, which depend on municipal scheduling, not just contractor readiness.
The renovations that stay closest to their original timeline are the ones where sequencing is actively managed — where the next trade is ready to start the day the previous one finishes, rather than waiting idle for materials or scheduling gaps. Left unmanaged, these small gaps compound: a week lost here, two weeks lost there, and a project quietly extends by months.
If you're planning a renovation and building a timeline, add real buffer for the pre-construction phase specifically — it's the part most likely to be longer than a contractor's initial estimate suggests.