Shell & Core Fit-Out

What Is Shell and Core Fit-Out?

This is the bare bones of a building’s interior space and is often how the developers provide the building. The building may be complete on the outside, but on the inside, the office space is just a shell, looking like a bare construction site, with concrete floors and walls, but with no lighting or facilities.

Although the office space is a bare shell, the common areas shared between tenants will have been completed; for example, the lifts, toilets and building reception. Unlike the shell, these core areas are usually finished to a high standard and will be ready for incoming tenants.

The concept of shell and core (or base build) is that the developer’s scope of work is the design and construction of the base building. A range of other construction and fit-out works are left to be completed before the building is occupied.

The concept originated in the USA, where it was applied to office buildings built by developers for rent. American developers initially fitted out offices, installing access floors, carpet tiles, ceilings, air conditioning and lighting based on a notional layout for prospective tenants.

However, the actual tenant’s ideas often differed from the developer’s notional layouts, and so money was wasted taking down ceilings and taking up floors, while mechanical and electrical services had to be altered to accommodate partition layouts.

‘Core and shell’ is undoubtedly a technical term that you will come across during a real estate project. Here is a little bit on what ‘core and shell’ really mean and why it should definitely be on your real estate project checklist of questions to ask your project manager, architect or landlord. 

Core and shell is a design method commonly used in commercial office buildings today. The method originated in the United States and has become the preferred method of design and construction for commercial office buildings today, especially buildings with multiple tenants and multiple fit-outs.

The method refers to a process where the interior core structure of the building and the exterior building envelope are fully designed as the first phase of the project. The core (inside) of the building is covered by the shell (outside) as the first part of the construction. Once the core and shell structures are built, the internal architectural elements and tenant fit-out can be integrated throughout building occupancy.

The alternative to the core and shell method is to fit out tenant space with ceilings, flooring, lighting, HVAC, etc., before a tenant occupies the space. However, oftentimes these items are altered to accommodate a tenant’s ideas and requirements for space. The result is a great deal of wasted time spent altering a space that just had new fittings installed.

There are several benefits to the core and shell method. Firstly, it speeds up the design and builds process. Defining the core and shell elements of the building first allows for progress to be made in the design of other portions of the building while the long-lead items of the core and shell can be implemented. Once those elements have been planned, work can proceed without having to wait on the interior details.

This method typically provides a better finish for the end user since the end user is able to work from a blank canvas and create a space that suits their specific needs rather than altering an existing fit-out. There is also more time to develop the internal fit-out allowing for a more careful and specific fit-out design. Be sure that this is a topic on your real estate project checklist to discuss with the professionals you have on your team.

The “shell and core” building concept involves the building owner or landlord planning and constructing the core or inside, of a building surrounded by the exterior shell. This creates a blank canvas for a tenant to come in and outfit the space to fit their needs with flooring, equipment, furnishings and so forth.

Shell & Core Fit-Out

What’s Involved in the Fit-Out Construction Process?

The term fit-out refers to everything you need to outfit the interior of a building, such as furnishings, decorations, and other interiors. It also includes flooring, walls, woodwork, and anything related to main services and utilities. The goal of a complete fit-out is to create a building that is ready to be occupied. A shell and core build-out is ready to be occupied, but first, the furnishings and interiors must be added by the tenant.

This type of construction is a long-lead item, meaning it takes to most time to build. A developer can get ahead by building the shell of a building while marketing for tenants.

The word ‘shell’ is exactly as it sounds, a hard or protective covering. In construction, this is the supportive exterior of a building’s structure. The predetermined shape and size of the building are constructed using wood, engineered wood or structural steel erected vertically on a defined base plant.

Doors and windows are inserted according to the specific design, along with egress or exit lighting, and sometimes a minimum number of restrooms are also added. Once this stage is completed, it is enclosed with a chosen siding such as wood, aluminium, brick, stucco, etc. Note: This is not mass wall construction where horizontal layers are stacked one on the other using logs, masonry, rammed earth, adobe or other natural materials.

Sometimes included in this type of construction are paved pathways and roads, boundary walls, drainage and fencing, along with soft and hard landscaping. The above-referenced base plant can also include mechanical, electrical, and fire detection systems. The structure can be completely fire-clad on a solid foundation with defined floor heights. Working elevators, basements, and more can also be defined in the scope of the construction.

When construction is complete, the client has an enclosed weathertight shell that is ready for a tenant to take this blank canvas – this clean, bare space – and outfit it to meet the needs of the business that will occupy the building. Our experienced team can progress the project through design and build to the Certificate of Occupancy.

What Does ‘Shell and Core’ Include? 

Shell and core, also known as base build, is a technique that started in the US and has since spread to the UK and other parts of the world. It involves developing the core or shell of a building, including walls and windows but does not include flooring, furniture or other interior elements. In other words, building owners create a basic shell for renters to outfit as they, please. This approach allows more time to finish internal fit-outs and gives the renter more options to customise the space to their specific style or business needs.

Shell & Core Fit-Out

Most Shell and Core Provisions Include:

  • The structure of the building
  • The cladding on the building
  • The base plant of the building

In Other Cases, it May Also Include:

  • Roads and paved pathways around the property, including fencing, drainage, and boundary walls.
  • Hard and soft landscaping
  • Base plant, including mechanical and electrical systems that meet local regulations and building codes.
  • Fire-clad structure complete with a solid foundation and “clear structural floor heights defined,” as well as basements, working elevators, etc.

Fire Detection Systems

There’s no way to know for sure what is included without looking at the lease agreement and conducting a formal meeting. Keep in mind that you can always negotiate before signing a lease.

Does the Landlord or Building Owner Pay for Additional Fit-Out Expenses?

The landlord covers the cost of the base structure and external elements but is not necessarily responsible for carpeting, flooring, furniture, lighting, AC, etc. This allows every new tenant that comes in a chance to outfit the space as they see fit.

It is common for landlords or developers to buy materials necessary for the fit-out and then leave them stacked in the building without installing them. Some landlords do not provide free materials but may instead offer free rent for X number of months to compensate for costs to outfit the space.

Why is this a popular construction process? Every tenant requires different furnishings and layouts, which makes it impossible for landlords to guess what their future tenants may need. As a result, landlords can end up wasting a lot of money outfitting spaces one way, only to tear things down and redo them based on a new tenant’s needs. That’s why it’s more cost-effective to leave the space blank until a tenant moves in.

Normal shell and core provision for a high-spec city office. Shell and core will typically comprise the structure and it is cladding, its base plant completed common areas and external works. More specifically, it will generally include the following:

  • Roads, paths, pavements, external lighting, security systems, fencing and boundary walls, drainage systems, incoming services, hard and soft landscaping, signage and all statutory requirements relevant to the site.
  • Foundations and fire-clad structure with column grid and clear structural floor heights defined.
  • The building envelope, including insulation, external walls, glazing, balustrade and roofs.
  • Completely finished circulation and common areas, including main reception, lobbies, staircases, toilets, plant rooms, riser shafts, lift shafts, basements, loading bays and car parking. Fire compartmentation should also be part of the shell and core provision.
  • All base plant, mechanical and electrical systems to plant rooms and services in shafts with air capped off by a fire damper to each tenant leased zone, electrical services connected to tenant’s zone switch panels and water and sprinkler services taken to each tenancy where they are capped off. 

The Base Plant Will Generally Include :

  • High and low voltage switchgear.
  • Transformers.
  • Lift systems.
  • A standby generator.
  • Boilers.
  • Chillers.
  • Cooling towers.
  • Water and fuel tanks.
  • Sprinkler plant.
  • Building control systems.
  • Air conditioning chambers and fans.
  • Water and fuel pumps.
  • Dry risers.
  • Fire detection, alarm and hose reel systems.

Scope of Work

The lease agreement between the landlord and tenant must clearly define the following aspects:

  • Scope of the shell and core built by the developer. This includes spaces in common areas for tenant appliances such as generators or chillers.
  • Does the landlord include a type A fit-out?
  • Which tenant equipment will be located in common areas?
  • The landlord’s contract should define practical completion of the shell and core works, and this includes all the requirements under the building regulations for occupation other than those what will be completed by tenants.

Fit-Out Expenses

The landlords are responsible for paying the cost of the base structure and external elements of the building. Still, they are not necessarily responsible for carpeting, flooring, lighting, air conditioning, furniture, and other indoor elements. All charges will be established in the lease agreement beforehand.

There are two common ways to complete the fit-out. One involves the landlord, who buys the materials and then leaves them stacked in the tenant spaces to be used as necessary. On the other hand, some landlords don’t provide the materials but offer free rent during the fit-out.

Advantages of the Shell and Core Method

Every tenant requires a specific layout for working spaces, which makes it almost impossible for landlords to predict their needs. As a consequence, landlords can waste large amounts of money on tenant spaces, which will often be torn down and rebuilt. It is more cost-effective to leave the space empty until a tenant moves in. The main advantages of the shell and core method are the following:

  • The design and construction process becomes faster while reducing costs and waste.
  • Tenants can complete indoor spaces as needed.
  • Common energy efficiency elements can be built into the project, offering their benefits to all tenants.
  • Design flexibility

There Are Several Advantages to the Shell and Core Methods:

  • It can speed up the design and build process considerably, which can generate cost savings. It allows progress to be made in the design of portions of the building, which will be fitted out later, while the items of the shell and core that have a longer lead time (i.e. structures, façade and so on) are being constructed. This allows work to proceed without delays waiting for details of the interiors to be finalised.
  • It creates a blank canvas for occupants, making it more flexible without impacting the main fabric of the building.
  • It avoids waste as it is less necessary for occupants to strip out existing fittings.
  • It can result in more energy-efficient buildings, as the typically concrete core creates a thermal mass that enhances the heat storage potential of the building.
  • From the perspective of the end-user, shell and core is particularly beneficial as they can result in a finish more suited to their needs. The ‘blank canvas’ of the building enables the end-user to align it to their requirements better, and there can be more time to develop a proposal.
  • The underlying flexibility of the design means it is generally more straightforward for subsequent occupants to change the interior fit-out.

Property developers and building owners frequently commission these sorts of improvements. It is a standard practice in the design of commercial office buildings, especially those that house several different businesses in their various spaces.

In shell and core construction, both the interior core structure and the exterior structure are designed in their entirety before any construction begins. In this method of building, the shell is placed over the structure’s core first. interior architectural essentials and tenant fit-out can be merged during building occupancy once the shell interior and core structure are complete.

A shell, in the context of architecture, is an outer covering that is both hard and protective. Wood, engineered wood, or structural steel is used to erect the building vertically on a specified foundation in a predetermined shape and size. It’s possible to add doors and windows at a later date if desired. Doors and windows are installed, as well as emergency lights and a set number of restrooms.

In addition to drainage and fencing, boundary walls, and soft and hard landscaping, these developments sometimes feature paved pathways and roadways. Construction has various advantages, such as reducing time spent on planning and building. By starting with a blank slate, individuals are able to design a space that perfectly suits their needs.

Although the rent-free period (to allow the tenant to fit-out category A works) will begin upon practical completion of the landlord’s shell and core works, it is not uncommon for a tenant to begin fitting out their demised areas prior to such completion.

The contract administrator for the landlord shall issue a certification upon practical completion of the shell and core works. All items necessary for occupancy per the building codes will be included, save for those pending tenant completion.

Setting up service systems and commissioning activities is best handled by an independent commissioning agency with a duty of care to both landlords and tenants due to the complexity of commissioning landlord and tenant work at the same time.


A Shell and Core fit-out, often abbreviated as ‘Shell & Core’, refers to the initial stage of construction and fit-out in a commercial building project. It’s the process of completing the basic structure of a building, leaving the internal space ready for further customisation based on the specific needs of future tenants.

Key components of a Shell and Core fit-out include:

  1. Building Structure: This involves the construction of the basic structure of the building, including walls, floors, and ceilings.
  2. External Works: The shell and core stage typically includes completing all external works such as facades, roofing, and basic landscaping.
  3. Core Services: The building’s core services are installed, which usually involve main utility connections (water, gas, electricity), lifts, staircases, and basic fire safety systems.
  4. Common Areas: Common areas such as lobbies, reception areas, restrooms, stairwells, and lifts are often completed during this stage.
  5. Building Envelope: The building envelope or shell is completed to protect the interior from weather and provide security.

After the shell and core fit-out is completed, the building is essentially a shell – a blank canvas that tenants can fit out according to their specific requirements. The next stage of fit-out (often a Cat A or Cat B fit-out) then involves the installation of the internal features such as partition walls, flooring, internal doors, suspended ceilings, lighting, HVAC systems, and IT infrastructure.

A shell and core fit-out is advantageous for future tenants because it provides maximum flexibility for customisation. The tenant has the freedom to design the interior space to perfectly align with their brand identity, business needs, and functionality requirements. However, it’s important to note that this also requires a more significant time and financial investment compared to moving into a space that’s already been fitted out.

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