Why the sequence has to be owned by one party
On a shell conversion each discipline constrains the next, and a decision made in the wrong order is expensive to reverse. This is the dependency chain we work to, and it is the reason splitting the contract goes wrong more often here than anywhere else.
- 1 · Structural capacityWhat the columns and slab will carry decides whether there is a mezzanine, how big it is, and where the heavy plant can sit. Everything downstream waits on this.
- 2 · Fire strategyThe deck, the enclosures and the occupancy set escape routes and sprinkler coverage. Approved before joinery is released, not after it is installed.
- 3 · Services capacity and routesAvailable power at the compound panel, extract shaft capacity, and where the risers can go. This decides plant selection and ceiling zones.
- 4 · Interior layoutOnly now does the plan get fixed, because the previous three have already constrained it. A layout drawn first will be redrawn.
- 5 · Procurement and constructionLong-lead steel and plant ordered first, joinery and finishes behind them, and all of it inside the compound's delivery window.
Worked example: 5,000 sq ft mill-shell conversion, turnkey
| Package | ₹ lakh | Covers |
|---|---|---|
| Design, structural engineer and fire consultant | 8.4 | Full drawing set, structural certification, approved fire strategy |
| Civil, mezzanine steel, deck and stairs | 14.6 | Deck over 28% of the plate, two stairs, balustrades |
| Fire package — sprinklers, detection, escape, signage | 17.2 | Coverage above and below the deck; certificates retained |
| Electrical, new sub-distribution, UPS and data | 18.9 | New feed from the compound panel; the existing riser was inadequate |
| HVAC for a high-volume shell | 15.8 | Low-level supply, high-level return; stratification managed |
| Furniture, joinery and reception | 33.4 | 64 seats across two levels, breakout, boardroom |
| Ceiling, exposed-services treatment and lighting | 11.6 | Services coordinated and painted rather than concealed |
| Flooring | 8.2 | Original mill floor ground and sealed below; carpet tile on the deck |
| Pantry, washrooms and wellness room | 5.2 | Two in-suite washrooms supplementing the compound's |
| Project management, commissioning and contingency | 4.2 | Includes the fire sign-off pack and as-built set |
| Total, ex-GST | 137.5 | ₹2,750 per sq ft on 5,000 sq ft |
Add 18% GST. Structure and fire together are ₹31.8 lakh, 23% of the contract, and both are gates rather than line items — the project does not proceed past them until they are signed.
Structure, fire and interiors under one contract
The access window, negotiated once
Mill compounds run on a shared delivery regime: height-barriered gates at around 2.5 m, single-file internal lanes, and restaurant loading that overlaps with construction traffic. We negotiate a fixed window with the compound management at mobilisation — on the project above, 6:30am to 9:00am six days a week — and every delivery on the programme is planned into it. A contractor who books ad hoc gets whatever is left, which in a busy compound is very little. This is not a detail; on a twenty-week programme the difference between a held slot and an ad hoc one is roughly three weeks.
Phased handover in an occupied building
A good share of Lower Parel work is done around people who are still working or trading. We price that explicitly rather than absorbing it, because it is real: temporary partitions and dust screens with negative pressure where needed, a separate route for construction traffic, noisy scope confined to agreed bands, a daily clean of any shared route, and a sectional handover so the client can occupy in stages. Expect 12 to 18% above a vacant-possession equivalent, and a programme about a third longer. What you get is trading or operating income through the works, which usually more than covers it.
The other thing worth saying plainly about occupied work here is that the neighbours are commercial tenants with their own customers. A compound where forty operators are trading has no tolerance for a site that spills into the public realm, and the compound management will act quickly. A hoarding built to the compound standard, a named site contact who answers the phone, and a daily clean of the frontage are scope items in our contracts rather than gestures, because they are what keeps the access window open.
Sectional handover also changes the commissioning plan. Each phase is tested, certified and handed over on its own, with its own snag list and its own retention release, rather than everything being held to a single completion date at the end. It is more administration for us and considerably less risk for the occupier.
For the district see interior designers in Lower Parel; for the design side see office interior designers in Lower Parel and commercial interior designers in Lower Parel. Contract terms are on turnkey interior contractors in Mumbai.
Shell conversion work by Greenbox Design Studio.
Frequently asked questions
Why does a mill-shell conversion need a single contract?+
Because the disciplines are sequentially dependent. Structural capacity decides the mezzanine; the mezzanine decides the fire strategy; the fire strategy and the available services capacity decide the ceiling and plant; only then can the layout be fixed. Split across four contracts, each party optimises its own scope and the clashes land on you. We have been called in to unpick exactly that more than once.
What is the fire sign-off gate?+
A point in the programme where the compound's fire consultant approves the revised strategy — sprinkler coverage above and below every deck and enclosure, escape widths and travel distances, lining ratings — before joinery is released for fabrication. It exists because a change to the strategy after joinery is made means remaking joinery. On our worked example it was week seven and it held.
How much does working in an occupied building add?+
Twelve to eighteen per cent, and roughly a third on the programme. That covers temporary partitions and dust screening, a separate construction route, noise confined to agreed bands, a daily clean of shared areas and sectional handover. For a trading business the income through the works normally exceeds the premium comfortably.
Can you guarantee the compound delivery window?+
We negotiate it at mobilisation and hold it for the duration, which is the only reliable way. On our 5,000 sq ft example it was 6:30am to 9:00am, six days a week, for twenty weeks. A contractor booking ad hoc in a busy compound gets what is left over, and across a full programme that is worth about three weeks of slippage.
Does the rate cover both mill shells and tower floors?+
The band does — ₹2,150–₹3,900 per sq ft — but they sit at different points in it. A Grade-A tower floor on Senapati Bapat Marg runs like a BKC project, with a landlord manual and nominated vendors, and lands mid-band. A shell conversion with structural and fire engineering lands higher, and a straightforward fit-out in a 1990s commercial block lands at the bottom.