A warm shell is a commercial space the landlord delivers with the core infrastructure already built out: a working HVAC system, finished exterior walls, a dropped ceiling with lighting, basic electrical service, and at least one functional restroom. It sits between a cold shell, which is essentially a bare box, and a turnkey space, which is move-in ready. You take over a usable starting point and build out the finishes, interior partitions, and anything specialized your business needs. Done right, it balances cost against control. Done without attention to the lease, it can produce five- and six-figure surprises.
What’s Actually Included
The word “warm” refers to climate control. An operational HVAC system, typically a rooftop unit feeding ductwork and wall-mounted thermostats, is the feature that separates a warm shell from a cold one. Beyond that, the delivery condition generally includes:
- Exterior walls finished with drywall, taped and sanded, ready for paint.
- A dropped ceiling grid with standard acoustic tiles and recessed lighting.
- A level concrete floor the tenant can later cover with carpet, vinyl, or hardwood.
- A dedicated electrical sub-panel, commonly 100 to 200 amps, with perimeter outlets.
- At least one finished restroom with running water, sewer connections, and working fixtures.
The restroom must meet federal accessibility standards under the 2010 ADA Standards for Accessible Design, which govern water closet placement, clearances, grab bars, and seat heights.1ADA.gov. 2010 ADA Standards for Accessible Design A warm shell delivered with a non-compliant restroom hasn’t met its delivery condition, and that belongs on your punch list.
Warm Shell Compared to Cold Shell and Turnkey
A cold shell (also called a cold dark shell or grey shell) is the stripped-down version: exterior walls, roof, unfinished floor, no HVAC, no ceiling, no plumbing, no interior walls. You get maximum flexibility and often lower base rent, but you’ll need a larger tenant improvement allowance and more time before you can open.
A turnkey space is the opposite. The landlord delivers finished walls, flooring, lighting, restrooms, sometimes furniture. You trade customization for speed. The landlord’s construction costs are built into your rent, and you live with someone else’s design choices.
A warm shell is the middle option. The expensive, slow infrastructure work is done. What remains is finish work: partition walls, flooring, paint, fixtures, and any specialized build-out. For most office and retail tenants, this is where the math works best.
The Work Letter Controls What You Actually Get
The single most important exhibit in a warm shell lease is the work letter, sometimes called a work exhibit or construction rider. It defines exactly what the landlord will deliver and what the tenant must build. “Warm shell condition” as a phrase guarantees nothing specific; the work letter is where the delivery condition becomes enforceable.
A well-drafted work letter includes a site plan showing the premises layout, access, and parking; a floor plan with restroom locations, stairwells, and lobby areas; a utility plan showing where electrical, plumbing, gas, and telecom lines terminate; detailed specifications for materials and construction standards; and a construction schedule with deadlines for both the landlord’s base building work and the tenant’s improvement work.2U.S. Securities and Exchange Commission (SEC.gov). Exhibit 10.3 Work Letter
Most delivery disputes trace back to vague specs. “HVAC system” without tonnage, zoning, or ductwork density can leave you with a unit that technically runs but can’t handle your actual occupancy load. A law office with a server closet draws very different power than a yoga studio. Pin the numbers down before you sign.
Who Pays for the Build-Out
The tenant improvement (TI) allowance is the dollar amount per square foot the landlord contributes toward your custom build-out. Warm shell allowances typically run lower than cold shell allowances because the landlord has already paid for the ceiling, HVAC, electrical, and restrooms. Current office TI allowances generally range from $15 to $60 per square foot depending on building class, location, and lease length. Class A space in competitive markets pushes toward the top end for creditworthy tenants on long leases. Class B space in secondary markets commonly falls in the $15 to $30 range. Retail allowances tend to run lower, often $10 to $30 per square foot for inline space.
The allowance covers hard costs (labor and materials) and soft costs (architect and engineering fees, permits, project management). It rarely covers everything a tenant wants to do, so budget for out-of-pocket spending above the allowance.
How the Money Is Disbursed
Landlords don’t cut a check at signing. The allowance is typically disbursed one of three ways: monthly draws against construction invoices, reimbursement after the tenant submits paid invoices and lien waivers, or direct payment from the landlord to the contractors. Most leases require unconditional mechanics’ lien releases with each payment request, which protects the landlord from contractor claims against the property.
Two traps to watch for. Many leases include a “use it or lose it” clause requiring the full allowance to be spent within a specific window, often 12 to 18 months after lease execution; unspent funds revert to the landlord. And if you fall behind on rent or otherwise default, the landlord can freeze disbursements. A permitting delay that pushes you past both of those deadlines can cascade into a real financial problem.
Fixturing Period and Rent Commencement
Separate from the allowance, most warm shell leases include a fixturing period: a stretch of time after delivery when you have access to build out the space but don’t yet owe rent. The rent commencement date typically falls the day after fixturing ends. Build-outs of two to four months are common for moderate construction, so the fixturing period should realistically match your contractor’s schedule. Rent abatement, a negotiated period of free or reduced rent, is a separate concession that begins after fixturing.
Delivery, Punch List, Acceptance
Three dates get confused and shouldn’t be. The delivery date is when the landlord hands over the keys after completing base building work; it usually triggers the fixturing period. The lease commencement date formally starts the lease term. The rent commencement date is when payment obligations kick in. Treat them as three separate items in the lease, because conflating them is a reliable way to pay rent on a space you can’t use.
Before formally accepting delivery, walk the space and build a punch list of deficiencies: HVAC operation across zones, outlet functionality, restroom plumbing, drywall finish, ceiling tile alignment, and every spec in the work letter. The punch list becomes part of the lease record, and the landlord is obligated to correct identified items within the lease’s stated timeframe, commonly 15 to 30 days.
Most warm shell leases include an “as-is” clause: once the landlord finishes its work and you accept delivery, you take the space without further warranty. The punch list walkthrough is your last real chance to hold the landlord accountable for delivery-condition problems. Bring your contractor or architect if you can. They’ll catch things you won’t.
Certificate of Occupancy
Acceptance is often tied to the local building authority issuing a certificate of occupancy, which confirms the space meets safety codes, building codes, and zoning for its intended use. Without one, you cannot legally operate. If your tenant improvements change the use classification or involve significant structural alterations, you’ll likely need a new certificate after your build-out, which adds permitting time. Commercial TI permits can take anywhere from two to twelve weeks depending on jurisdiction and project complexity, before any additional reviews for fire safety, accessibility, or historical districts.
Who Maintains What During the Term
Maintenance allocation depends almost entirely on the lease structure. In a triple-net (NNN) lease, the tenant pays operating expenses on top of base rent: property taxes, insurance, maintenance. That typically means routine HVAC servicing, plumbing repairs, electrical maintenance, and upkeep of systems inside the premises are yours. Annual service contracts, filter replacements, thermostat repairs, minor plumbing fixes.
The landlord usually keeps responsibility for structural components: foundation, exterior walls, roof, common areas. The contested question is who pays when a major system needs full replacement rather than repair. In most standard commercial leases, replacing an entire HVAC unit is treated as a capital expenditure that falls to the landlord, since these systems last 10 to 15 years and the replacement cost dwarfs routine maintenance. Some NNN leases, however, push capital replacement onto the tenant. Read the maintenance clause carefully. The distinction between “repair” and “replace” can be worth tens of thousands over a lease term.
Insurance for Your Improvements
Once you spend your allowance on custom walls, flooring, and fixtures, you have a financial stake in improvements you don’t own. In insurance language these are “tenant improvements and betterments” (TIB): fixtures, alterations, or additions you made at your own expense that become part of the building and can’t legally be removed.
Most commercial leases require tenants to carry property insurance covering TIB at replacement cost. If a fire destroys your build-out, this coverage pays to reconstruct it. Without it, you’re paying out of pocket to rebuild improvements in someone else’s building. Tenants with significant build-outs should also consider ordinance or law coverage, which pays increased construction costs when a rebuild must comply with updated codes, and business income coverage sized for extended code-related downtime. If the lease requires you to insure building components beyond your own improvements, such as HVAC equipment or glass that came with the warm shell, you’ll need endorsements. Read the insurance clause alongside the maintenance clause so you know which systems you both maintain and insure.
What You Owe at Lease End
This is the clause that surprises tenants. Many warm shell leases include a restoration obligation requiring you to remove your custom improvements and return the space to its original delivery condition before the lease expires. Demolish partition walls. Pull up flooring. Repaint back to standard. Leave bare concrete. The cost can be substantial, and it falls entirely on the tenant.
Restoration obligations survive even if you didn’t build the improvements yourself. Take over a lease through an assignment and you may still owe removal of the prior tenant’s build-out. The scope varies with negotiating leverage and local custom, but the default favors the landlord.
Trade Fixtures and Permanent Improvements
Most leases distinguish between trade fixtures (specialized equipment and furnishings you installed for your business) and permanent improvements (walls, flooring, built-in cabinetry). Trade fixtures are typically yours to remove, provided you repair any damage from the removal. Permanent improvements often become the landlord’s property at lease end. Some leases let the landlord choose, at or near expiration, which specific alterations you must remove and which can stay. If the landlord doesn’t affirmatively require removal, the improvements usually remain.
Abandoned property is a separate risk. Fail to remove your belongings within the window the lease specifies (sometimes as short as two days, sometimes up to 30) and the landlord can treat what’s left as abandoned, take title, and dispose of it at your expense. Negotiate the restoration clause before you sign, not during the move-out scramble. Push for a specific list of what you must remove and what can stay. Better still, cap restoration costs or build in a mutual walkthrough that sets expectations early.
Where to Push in Negotiation
Nearly every term in a warm shell lease is negotiable if you know where your leverage sits.
- Landlords often prefer increasing the TI allowance over reducing base rent, because the allowance is a one-time cost while lower rent reduces income across the full term. If your build-out is significant, trade on that preference.
- Negotiate a remedy if the landlord misses the delivery date. Common ones: postponing the fixturing period, pushing back rent commencement, or extending the lease expiration so you keep the full term you bargained for.
- If permitting runs long in your jurisdiction, push the “use it or lose it” allowance deadline further out. Losing unspent dollars because the city took three months to approve plans is avoidable.
- If your business has above-average cooling needs (server rooms, commercial kitchens, high-occupancy spaces), negotiate supplemental HVAC as part of the landlord’s base building work rather than paying for it from your TI allowance.
- Get a specific list of which improvements must be removed at lease end. A blanket “restore to original condition” clause gives the landlord maximum flexibility at your maximum expense.
The fixturing period deserves special attention. A landlord sitting on vacant space has every reason to get you in quickly, which makes fixturing one of the easiest concessions to win. Two to four months of rent-free access for construction can save real money, and it costs the landlord nothing they weren’t already losing to vacancy.