Base Building
Base building refers to the core structure and systems that a landlord delivers as part of the leased space, separate from any tenant-specific improvements. What's included in the 'base building' is defined in the lease and varies significantly — some landlords include a fully conditioned vanilla shell, others deliver only a structural cold shell with utilities stubbed in. Understanding exactly what the base building includes is critical to accurately estimating buildout costs before signing.
Updated July 18, 2026
Key Facts
- 1Base building provisions are defined in the lease's 'work letter' — a critical document that specifies exactly what the landlord delivers vs. what the tenant is responsible for building
- 2In multi-tenant office buildings, the base building typically includes common area HVAC, sprinklers to the ceiling grid, and electrical panels at the suite entry — tenants build out the distribution within the space
- 3In retail and food service, base buildings vary widely: some landlords deliver a vanilla shell (HVAC, electrical, plumbing to the suite), others deliver a cold shell with nothing but the structure
What Base Building Typically Includes vs. Excludes
| Typically Included in Base Building | Typically Tenant Responsibility |
|---|---|
| Structural shell (floors, walls, roof) | Interior framing and drywall |
| Main electrical panel at suite entry | Electrical distribution within suite |
| HVAC capacity stubbed to the suite | HVAC distribution, diffusers, controls |
| Plumbing stubbed to the floor (if applicable) | Plumbing distribution and fixtures |
| Fire suppression main line (if building has it) | Sprinkler head distribution within suite |
| Building-standard restrooms (multi-tenant buildings) | Food service-specific plumbing fixtures |
The Work Letter: Defining Base Building Scope
The lease work letter is the document that defines the boundary between landlord work (base building) and tenant work (tenant improvement). It specifies what the landlord will deliver, to what standard, by what date, and what the tenant is expected to do from that point forward.
Before signing any lease, have your architect or contractor review the work letter alongside the base building drawings. The gap between what the landlord delivers and what your buildout requires is the scope of work you're responsible for — and the number that drives your TIA negotiation and cost estimate.
Frequently Asked Questions
What does 'as-is' mean in a lease?
'As-is' means the landlord is delivering the space in its current condition with no improvements, no TIA, and no warranty on existing systems. The tenant accepts full responsibility for any buildout needed. 'As-is' deals sometimes offer lower rent or other concessions — but the full cost of making the space functional is on the tenant.
Who pays for base building deficiencies discovered during construction?
This is one of the most contentious areas in commercial construction. If a landlord-represented system (HVAC, plumbing, electrical panel) is found to be inadequate or defective after the lease is signed, responsibility depends on the lease language. Leases with 'as-is' provisions typically push this risk to the tenant; leases with delivery warranties give the tenant recourse. Have legal counsel review the work letter before signing.