Core and Shell: What It Means and What You Get

Core and shell (also called shell and core) is a building delivered with its structure, envelope, central core and common areas finished, while the tenant's own floor space is left empty and unfinished. The landlord builds the "base building". The tenant, or the landlord under a separate agreement, then fits out the interior. If you are leasing or buying commercial space in Slovenia, the term decides what you pay for on day one, what you pay for later, and how soon you can move in.

TL;DR

• Core and shell means the base building is complete (structure, cladding, main plant, common areas), but the tenant floor is delivered raw.
• It is a delivery condition, not a fixed technical standard, so the same label can hide very different scope. The handover specification matters more than the name.
• Rent or price is usually lower at the start, but the fit-out is a separate budget and a separate schedule.
• In Slovenia, write the scope into the lease. The old Business Premises Act is repealed, so the contract carries most of the weight.
• Ask for a room-by-room handover list before you sign, not after.

Table of Contents

• What core and shell means
• Shell and core: the two halves
• What is usually included, and what is not
• Core and shell vs fit-out: Cat A, Cat B and turnkey
• Why landlords and developers choose core and shell
• What it means for your budget and timeline
• Core and shell in Slovenia
• What to check before you sign
• Our perspective
• How HOOF can help
• FAQ
• Sources

What core and shell means

The idea is simple. A developer constructs the building fabric and the parts every occupier shares. Everything an individual occupier would want to configure differently is left for later. Designing Buildings describes it as the stage where the base building is built and the tenant's internal workplace fit-out remains to be completed, with the tenant area delivered as a blank or largely unfinished floor plate.

The same idea appears under several names: shell and core, base build, bare shell, cold shell. The order of the words changes by country. "Core and shell" is the common phrasing in North America and in green-building rating schemes. "Shell and core" is the usual British form. Both mean the same thing in practice.

A more precise definition comes from the New Zealand Green Building Council. It treats a cold shell as an unfinished tenancy with no finishes or services beyond the riser or core, and no lighting, plumbing, ceilings, floor finishes or internal partitions. That is a useful benchmark for the strictest reading of the term.

Shell and core: the two halves

The shell

The shell is the outer and structural part of the building: foundations, frame, floors, roof, facade and windows. Its job is to make the building weathertight and stable. Think of it as everything you would see if you stripped a finished office back to the concrete and the glass.

The core

The core is the vertical spine of the building. According to Designing Buildings' entry on the core, it aids structural stability, provides access and escape through lifts and stairs, and clusters services such as toilets, storage and fire services. It is usually a reinforced concrete tube inside the building, often placed centrally with usable space arranged around it, though it can be offset to use the floor more efficiently.

So when someone asks what a "core building" is, the answer depends on context. In a structural sense, it is the central tube holding lifts, stairs and risers. In a leasing sense, "core building" is simply shorthand for a core and shell building. A core is not the same thing as a shell and core space: the core is one component, and a shell and core unit is a whole delivery condition that includes the core.

What is usually included, and what is not

Practice varies, but the typical split looks like this. Designing Buildings says shell and core typically comprises the structure, cladding, base plant, completed common areas and external works.

External works matter for larger sites. Designing Buildings lists roads, paths, pavements, lighting, security, fencing, drainage, incoming services, landscaping and signage as typical examples. If you are looking at a warehouse or a business park, those are part of the base build as well.

A practical way to read this table: anything that serves the whole building belongs to the landlord. Anything that makes the floor usable for one business belongs to the tenant.

Core and shell vs fit-out: Cat A, Cat B and turnkey

Core and shell is the first stage of a sequence. Fit-out follows in one or two steps.

1. Core and shell. The base building, as above.
2. Category A fit-out. The basic office finish: ceilings, lighting, floor finish, air distribution, basic electrical and data containment. It makes the floor lettable.
3. Category B fit-out. The tenant's own layout and look: partitions, furniture, kitchens, branding, specialist IT and audio-visual.

The UK fit-out firm Area describes shell and core as the stage before Category A: the structural fabric is complete, while tenant floors, ceilings and internal walls remain unfinished. It adds that communal areas, reception, lifts and toilets may be delivered, but individual floor plates are generally left raw.

The Cat A and Cat B vocabulary is British. In Slovenia you will rarely see the labels in a listing. You are more likely to meet descriptions such as a space handed over "in raw condition" or "fully fitted and ready to move in". When a listing uses English terms for an international audience, ask the agent to translate them into a written list of what is installed.

A turnkey space sits at the other end: the landlord delivers a finished, furnished or near-furnished office. You pay more per month or per square meter, and you save time and project management.

Why landlords and developers choose core and shell

There are three reasons, and each matters to you as a tenant.

Flexibility. Leaving the floor unfinished lets each occupier configure the workplace for its own operations. A law firm and a software team do not want the same floor. Area presents this as the main strategic argument for shell-and-core delivery.

Speed to market. A developer can finish and let the base building without guessing the end user's needs. A tenant can sometimes begin its own works before the base building is completely done. According to Designing Buildings, a tenant may start fitting out its demised area before the landlord's shell-and-core works are complete, and the rent-free period for Category A works is triggered by practical completion.

Cost allocation. The landlord avoids paying for finishes that a tenant would rip out. The tenant pays only for what it uses. Sometimes the landlord contributes through a fit-out allowance or a rent-free period, which is negotiable.

What it means for your budget and timeline

Core and shell lowers the entry cost, not the total cost. One industry comparison of turnkey and core-and-shell finishes claims fit-outs can add 15 to 40 percent later, but treat any single percentage as a rough pointer: the real figure depends on layout density, technical systems and the quality you choose. Get a quote from a fit-out contractor against your actual plan before comparing offers.

Here is a worked way to compare two spaces of equal size:

• Space A, core and shell. Lower monthly rent. Add fit-out cost, design fees, permits if needed, project management and the months you pay rent while the works run.
• Space B, fitted. Higher monthly rent. No capital outlay, a near-immediate move-in, but less control over layout and finishes.

Spread the fit-out cost over the lease term and add it to Space A's rent. Then compare the effective monthly cost. If the lease is short, Space B often wins. If you plan ten years or more and need specialist layouts, Space A often wins. A break right inside the term changes the arithmetic, so read our guide to the break clause in a commercial lease before you commit to a heavy fit-out.

Timeline matters just as much. Plan for design, any approvals, procurement, construction and move-in. Rent-free periods during the fit-out are common to negotiate, and they are worth asking for early. Our practical guide to commercial lease negotiation in Slovenia covers how to raise them.

Core and shell in Slovenia

Slovenia does not have a single statutory definition of core and shell for leasing. The label is a commercial convention, so what counts is the contract and the handover list. Corven & Ashby make the same point in a US context: the label is a delivery condition, so identical wording can conceal materially different scope and cost.

Some Slovenian reference points help you judge what a finished office should look like:

• The Ministry of Public Administration's criteria for government office premises state that for new or acquired office premises, working areas should generally represent about 70 to 100 percent of usable office area, and down to 50 percent in existing premises. They are written for government budget users, not private tenants, but they show how the state thinks about space efficiency. The same document treats office planning as a coordinated issue covering space standards, design, construction, energy, procurement, fire safety and occupational safety.
• Construction-related duties are listed on the PIS portal, including project documentation, construction-start notifications and building legalization. Ask who is responsible for each step on your fit-out.

In practice, a large fit-out in Ljubljana or Maribor may need project documentation and notifications. Decide in writing whether the landlord or the tenant coordinates them, and who pays.

The lease framework

SPOT's guidance on business premises leases, dated 19 October 2023, states that the former Business Premises Act was repealed in 2021 and that leases signed afterward are governed by the lease provisions of the Obligations Code. It also advises a written lease, even though the Code generally does not require a special form for validity. For a core and shell space, a written lease with a detailed technical annex is not optional in practice. The same source notes the basic split: the landlord maintains and repairs the premises as needed, and the tenant pays rent and uses the premises as agreed.

That default split does not tell you who builds what at the start. Your lease must.

Taxes also shape the economics. Whether VAT applies to rent affects your cash flow during a long fit-out, which we explain in VAT on commercial leases in Slovenia.

What to check before you sign

Use this list when you view a core and shell office, retail unit or warehouse.

1. A written scope of the base build. Designing Buildings says the lease should define what comprises the shell and core, what Category A fit-out is installed by the tenant but funded by the landlord, and what tenant equipment is to be installed in common areas. Ask for the same clarity in Slovenia, whatever the labels.
2. Services at the boundary. Where exactly do electricity, water, drainage, ventilation, heating, cooling, fire detection and data stop? "Provided to the floor" and "provided to the riser" are very different promises, and the NZGBC definition above shows how far the strictest version goes.
3. Capacity. Ask for the available electrical load, ventilation capacity and floor loading, in numbers. A server room or a commercial kitchen can exceed a base-build allowance.
4. Handover condition and date. Define practical completion and attach a snag list. This date can trigger rent-free periods and start the clock on your own works.
5. Access for fit-out. Can you start works before the landlord finishes? Which lifts, loading areas and hours are available?
6. Fit-out rules. Does the landlord need to approve your design and contractor? Are there restrictions on penetrations, facades or roof equipment?
7. Allowances and contributions. Is there a landlord contribution or rent-free period? What is it tied to?
8. Restoration at lease end. Must you remove your fit-out and return the space to shell condition? That cost belongs in your budget today.
9. Sustainability and operations. CER Slovenia notes that tenants influence building performance through lease requirements and operating practices, even though they rarely control structural elements. It recommends that commercial leases address shared goals, renewable energy, consumption monitoring, upgrades, water and waste reduction, indoor environmental quality and how costs and benefits are allocated. A core and shell lease is the best moment to write these in.
10. A letter of intent first. Fixing the main terms before drafting saves cost on both sides. See our guide to the letter of intent for a commercial lease.

If a clause is unclear, take it to a lawyer before signing. We explain when that is worth it in do you need a real estate lawyer in Slovenia.

Our perspective

We see the same mistake again and again: a tenant compares two rents without comparing two specifications. A "cheaper" core and shell unit can end up costing more than a fitted one once ceilings, cooling, lighting, cabling and restoration obligations are counted. The reverse also happens: a business with a clear layout and a ten-year horizon wastes money paying for another occupier's finishes.

Our advice is to begin with the plan, not the listing. Decide how many people, which functions, what technical load and how long you will stay. Then ask each landlord for the same handover list and price the gaps. When we represent tenants, that comparison is the first piece of work. When we represent landlords, we advise setting out the base-build scope in plain language, because a clear specification shortens negotiation and avoids disputes at handover.

The Slovenian market is small and relationship-driven. A precise handover annex and a realistic timeline do more for a long-term tenancy than any headline rent.

— Maruša

How HOOF can help

We advise tenants, landlords and investors on commercial space in Slovenia: offices, retail, warehouses and hospitality. For tenants, that means searching the market, comparing specifications on equal terms and negotiating the lease, including fit-out contributions and rent-free periods. For landlords, it means positioning and leasing the space, and managing it afterward.

If you are weighing a core and shell space against a fitted one, start with our office rental in Ljubljana and commercial spaces pages, or contact us through the HOOF homepage and tell us what you need. Owners deciding how to present an unfinished space can read about commercial space leasing for landlords, and those planning a purchase can look at our commercial property valuation and market analysis. After handover, our property management service keeps the building running.

FAQ

What does shell and core mean?

It means the base building is complete, with structure, envelope, main plant and common areas, while the tenant's interior is not. The tenant area is typically a blank floor plate. The exact scope is set by the contract, not by the term.

What is the difference between core and shell and a fit-out?

Core and shell is the base building. A fit-out is the interior work done afterward, often in two stages: a basic Category A finish that makes the floor usable and a Category B finish that adds the occupier's own layout, furniture and branding.

What is a core building?

Structurally, the core is the central tube that holds lifts, stairs, risers and often toilets, and that helps stabilize the building. In leasing, people sometimes use "core building" loosely to mean a core and shell building. Always ask what the speaker means before comparing specifications.

Is core and shell cheaper than a fitted office?

It usually has a lower starting rent or price, but you pay for the fit-out separately and often wait longer to move in. Over a long lease with a specific layout, it can be the better value. Over a short lease, a fitted space often wins.

Who pays for the fit-out in a core and shell lease?

That is negotiated. The tenant normally funds and manages it, sometimes with a landlord contribution or a rent-free period. Write the answer, including restoration at lease end, into the lease.

Sources

• Shell and core, Designing Buildings
• Core, Designing Buildings
• Fitout Scope guidance, New Zealand Green Building Council
• Cat A vs Cat B fit out, Area
• Core and Shell Scope Gaps, Corven & Ashby
• Criteria for government office premises, Ministry of Public Administration
• Graditev objektov, PIS
• Najemna pogodba za poslovni prostor, SPOT
• Sustainable commercial buildings recommendations, CER Slovenia

Recommended

• Facility Condition Assessment: A Guide for Building Owners
• When to Hire a Real Estate Advisor for Business Premises
• Preventive Maintenance for Buildings: A Practical Plan