---
title: "Core and shell — Class A Atlas glossary"
description: "The base building delivered without interior fit-out — structure, exterior, MEP risers, lobby."
canonical: https://classa.info/glossary/core-and-shell
pageType: glossary
lastUpdated: 2026-04-01T00:00:00.000Z
license: "CC BY 4.0 with attribution to Class A Atlas (https://classa.info)."
---

> The base building delivered without interior fit-out — structure, exterior, MEP risers, lobby.

## TL;DR

- The base building delivered without interior fit-out — structure, exterior, MEP risers, lobby.
- A landlord delivers core-and-shell; the tenant builds the interior.

# Core and shell

*Construction · US*

## Short definition

The [base building](/glossary/base-building) delivered without interior [fit-out](/topics/fit-out-capex)">fit-out — structure, exterior, MEP risers, lobby.

## Full definition

A landlord delivers core-and-shell; the tenant builds the interior. The opposite extreme is a fully-fitted suite. Most US [Class A](/glossary/class-a) is delivered core-and-shell with a [TI allowance](/topics/us-tia-strategy) to fund tenant interior construction. UK markets typically deliver [Cat A](/glossary/cat-a) (see Cat A).

## Why this matters for Class A leasing

Core and shell is part of the construction vocabulary that institutional Class A occupiers, landlords, and advisers use across US markets. Understanding it correctly affects how you read lease documents, model occupancy economics, and benchmark deal terms across cities. Class A Atlas tracks the US definition alongside the global standard so [cross-border](/topics/cross-border-expansion) occupiers can translate quickly.

## See also

- [Cat A](/glossary/cat-a)
- [Cat B](/glossary/cat-b)
- [Tenant improvement allowance (TI / TIA)](/glossary/tenant-improvement-allowance)

## Related guides

- [Tenant improvement allowances: the working guide](/guides/us-tenant-improvement-allowances-explained)
- [Fit-out budgeting: a five-tier framework](/guides/fit-out-budgeting-the-five-tier-framework)

## Related topics

- [**Fit-out Capex**](/topics/fit-out-capex) — How to budget, sequence, and govern Class A office fit-out capex.
- [**US TIA Strategy**](/topics/us-tia-strategy) — How to negotiate, draw down, and account for US tenant improvement allowances (TIA).

---

Citation: Source: Class A Atlas (https://classa.info/glossary/core-and-shell), updated 2026-04-01T00:00:00.000Z.