The four categories, defined properly
India uses four terms, and only two of them are used consistently. What matters is not the label on the term sheet but the scope matrix attached to it — the line-by-line table of who provides what. Ask for it before you sign, and price your fit-out from it rather than from the adjective.
| Provided by the landlord | Bare shell | Shell & core | Warm shell | Plug & play |
|---|---|---|---|---|
| Structure, facade, core walls | Yes | Yes | Yes | Yes |
| Common lifts, lobbies, toilets | Sometimes | Yes | Yes | Yes |
| Power to the floor with a meter | To the riser only | Yes, capped | Yes, with a floor DB | Yes, distributed |
| Fire detection and sprinklers on the floor | No | Main loop only | Yes, to a standard grid | Yes, to your layout |
| HVAC to the floor | No | Riser and shaft only | Yes, usually AHU + main duct | Yes, fully distributed |
| Ceiling grid and tiles | No | No | Yes | Yes |
| Basic lighting | No | No | Yes | Yes |
| Flooring | Raw slab | Screed | Vitrified or raised floor | Carpet and vinyl |
| Partitions, rooms, furniture | No | No | No | Yes |
These are the common Mumbai conventions, not a standard. Individual landlords vary considerably — especially on HVAC and sprinklers.
What the difference is worth
Here is the same 6,000 sq ft floor priced from each starting point, to a standard 2026 specification with eight enclosed rooms. The fit-out specification is identical in all four cases; only the starting condition changes.
| Starting condition | Your fit-out scope | ₹ per sq ft, ex-GST | Total, 6,000 sq ft | Programme |
|---|---|---|---|---|
| Bare shell | Everything, including screed, sprinkler grid, full HVAC distribution | ₹2,550–₹3,350 | ₹1.53–₹2.01 Cr | 12–16 wks |
| Shell and core | Everything above the slab; main services exist at the riser | ₹2,350–₹3,100 | ₹1.41–₹1.86 Cr | 11–14 wks |
| Warm shell | Partitions, rooms, finishes, modification of existing services | ₹2,050–₹2,800 | ₹1.23–₹1.68 Cr | 8–11 wks |
| Plug and play | Furniture, branding, minor reconfiguration | ₹450–₹1,100 | ₹27–₹66 L | 3–5 wks |
Add 18% GST. Plug-and-play carries a higher rent per sq ft that usually recovers the landlord's spend within 30–40 months.
The warm shell trap
A warm shell is cheaper to fit out, but the services it contains were laid out for an empty floor plate on a uniform grid — not for your partitions. The moment you draw eight rooms, some of those sprinkler heads are in the wrong place, some diffusers serve two rooms at once, and the lighting grid cuts across a partition line. Modification is normal and it is not free.
| Modification | Typical quantity on 6,000 sq ft with 8 rooms | Rate each | Total |
|---|---|---|---|
| Sprinkler head relocation | 35–60 nos. | ₹2,200–₹4,500 | ₹0.8–₹2.7 L |
| Diffuser and flexible duct relocation | 18–30 nos. | ₹3,500–₹7,000 | ₹0.6–₹2.1 L |
| Light fitting relocation | 40–70 nos. | ₹800–₹1,800 | ₹0.3–₹1.3 L |
| Smoke detector relocation | 20–35 nos. | ₹1,800–₹3,200 | ₹0.4–₹1.1 L |
| Ceiling tile cut and make good | Throughout | ₹45–₹110 / sq ft | ₹2.7–₹6.6 L |
| Return air path for enclosed rooms | 8 rooms | ₹12,000–₹28,000 each | ₹1.0–₹2.2 L |
Budget ₹110–₹230 per sq ft for modification on a warm shell. It is still cheaper than installing the services from scratch.
Three items that swing the number more than anything else
Across the fit-outs we price, the gap between two 'warm shells' almost always comes down to the same three lines. Find these in the scope matrix before you compare rents.
- HVAC. The single biggest variable. A floor with an AHU, main duct and a tapped-off spine is a genuinely different proposition from one with a capped chilled-water pipe at the shaft. Installing distribution from scratch is ₹220–₹420 per sq ft; modifying an existing spine is ₹60–₹140.
- Sprinklers and fire detection. A standard-grid sprinkler layout with a tested main is worth ₹90–₹180 per sq ft against a floor where only the riser exists. Note that either way you will relocate heads once partitions are drawn — the saving is in the main loop, the pump connection and the approvals, not in the heads.
- Flooring. A screed you can lay carpet tile onto directly saves ₹80–₹190 per sq ft against a raw slab needing levelling. Raised access flooring, where a building provides it, saves more but locks your service strategy underfoot.
Two floors quoted at the same rent, one with all three and one with none, differ by roughly ₹370–₹740 per sq ft of fit-out. On 6,000 sq ft that is ₹22 L to ₹44 L, which is worth several months of rent differential and should be part of the leasing comparison rather than discovered afterwards.
Questions to ask before you sign
- Can I have the scope matrix and the base-build drawings? If the landlord cannot produce these, price the floor as a bare shell and negotiate from there.
- What is the sanctioned electrical load per sq ft, and is it available today? 1.0 to 1.5 W per sq ft for lighting and small power, plus HVAC, is the usual figure. A floor with a sanction on paper but no transformer capacity is a bare shell with extra steps.
- Is the HVAC a central chilled-water system, a VRF, or nothing? Central systems charge by the hour beyond building hours, which matters if you run two shifts.
- Who owns the ceiling tiles I damage? On a warm shell you will replace 8 to 15 per cent of them. Agree whose cost that is.
- What is the fit-out period rent-free? Eight to sixteen weeks is standard in Mumbai Grade A. A warm shell needs less of it, which is part of the value.
- What must be reinstated at the end of the lease? Read this clause before you build. Full reinstatement of a heavily partitioned floor can cost ₹250–₹500 per sq ft at exit.
Nobody reads the reinstatement clause on the way in. Everybody reads it on the way out, and by then the number is fixed.
Greenbox commercial fit-out lead
Which to take
For a company with a five-year-plus horizon and a specific spatial requirement, a shell and core or bare shell gives you a floor that is exactly what you designed, with services laid out to your partitions rather than to a generic grid, and no inherited maintenance liability. For a company under three years of visibility, or one taking under 5,000 sq ft, a warm shell or plug-and-play is almost always the better financial decision — the capital saved is worth more than the design compromise, and the shorter programme means you occupy sooner.
Fit-out priced from the scope matrix, not the adjective
Selected work by Greenbox Design Studio. Tap any image to enlarge.
Frequently asked questions
What does warm shell mean in an Indian commercial lease?+
A floor handed over with the ceiling grid and tiles, basic lighting, fire detection and sprinklers to a standard grid, flooring, and usually HVAC distribution to the floor — but no partitions, rooms or furniture. It typically saves ₹180 to ₹400 per sq ft of fit-out and two to four weeks of programme against a shell-and-core handover.
Is warm shell always cheaper than bare shell?+
On fit-out capital, yes — but the rent is usually higher, and the services you inherit were laid out on a generic grid rather than for your partitions. Budget ₹110 to ₹230 per sq ft for relocating sprinkler heads, diffusers, detectors and lights once you draw rooms. Over a five-year lease the two options often land within 5 per cent of each other.
What is the difference between bare shell and shell and core?+
Bare shell is the tenant floor plate as a concrete slab, with services only at the building riser. Shell and core adds the completed common areas — lifts, lobbies, toilets — plus main services brought to the floor and capped, and usually a screed. In Mumbai the two terms are used interchangeably more often than they should be, so read the scope matrix.
How long is a typical rent-free fit-out period in Mumbai?+
Eight to sixteen weeks in Grade A buildings, scaled to the size of the floor and the condition it is handed over in. A bare shell justifies the longer end because the fit-out itself takes 12 to 16 weeks; a warm shell needs 8 to 11. Negotiate the period against your actual programme rather than accepting the building's standard.
What should I check about reinstatement before signing?+
Whether you must return the floor to its handover condition, and what that condition is defined as. Stripping out a heavily partitioned fit-out and reinstating a warm shell can cost ₹250 to ₹500 per sq ft at exit. Where possible, negotiate reinstatement to 'as handed over' with photographs attached to the lease, and get partitions you may leave behind agreed in writing.