Units of Flats vs Apartment in Nigeria: Which One Are You Actually Building?

Quick answer: "Units of Flats" describes a building where every unit is identical — if it's a block of 3-bedroom flats, every single unit is a 3-bedroom flat, regardless of which floor it sits on. "Apartment" (in the sense this article and our Estimator use it) describes a building with a genuine mix of unit types — some 2-bedroom, some 3-bedroom, maybe a penthouse unit, all under one roof. The two look similar from the street but need different inputs to cost correctly, because one is "one room program, repeated," and the other is "several different room programs, combined."

What "Units of Flats" Actually Means

A block of Units of Flats is built around repetition. Every unit shares the same room program — the same bedroom count, the same living room, the same kitchen and toilet arrangement — and floor tier only affects how many units sit there, never what kind of unit they are. A 4-storey building of "2 units of 3-bedroom flats per floor" has 8 identical 3-bedroom units total; the ground floor and the third floor are functionally the same unit, just stacked. This is genuinely the most common form of multi-unit residential construction in Nigeria, and it is also the simplest to cost correctly once you know the one thing that trips people up: a block of 4 units doesn't cost 4× one unit's price — party walls between neighbouring units add real cost that a standalone unit never has, while shared foundation and roof economies claw some of that back.

What "Apartment" Actually Means

An Apartment building, by contrast, is defined by genuine variety. It might have six 2-bedroom units, four 3-bedroom units, and two larger penthouse-style units, all sharing the same building envelope, structure, and common areas, but each unit type has its own distinct room count and floor area. This is the mental model behind terms like "mixed-use residential" or "mixed-unit apartment block" — the defining feature is that no single room program describes the whole building, because there isn't just one.

This distinction matters immediately once you try to price the building: a Units of Flats estimate only ever needs one room program and a unit count. An Apartment estimate needs a list of room programs, one per unit type, each with its own count — a structurally different input, not just a bigger version of the same input.

Why the Distinction Matters for Costing

Treating a genuinely mixed-unit apartment building as if it were a Units of Flats building (by, say, averaging the unit sizes into one "typical" unit and multiplying) understates the truth in a specific way: larger units use disproportionately more of the expensive line items — more floor area for finishes, more fixtures for extra bathrooms, more roofing and ceiling per unit — while smaller units use less. Averaging smooths over that difference and tends to under-price a building that's actually weighted toward its larger units, or over-price one weighted toward its smaller ones, depending on which way the mix leans. The only way to avoid this is to actually cost each unit type separately and combine the results, rather than force-fitting the whole building through a single "typical unit" number.

The reverse mistake also happens: treating a building of genuinely identical units as if it needed unit-type-by-unit-type tracking, when a single room program and a unit count would have described it perfectly well and been far faster to fill in. If every unit in your building really is the same, you're building Units of Flats, not an Apartment, no matter how the building is marketed or what the developer calls it.

A Worked Example

Consider a 3-floor building with 10 total units: 6 units are 2-bedroom (2 bed, 1 living, 1 kitchen, 1 toilet each) and 4 units are 3-bedroom (3 bed, 1 living, 1 kitchen, 2 toilets each). Priced correctly as an Apartment, each unit type's room program is costed on its own terms — the 2-bedroom units contribute their real, smaller floor area and fixture count, the 3-bedroom units contribute their real, larger ones — and the two are combined into one total floor area, spread evenly across the building's 3 floors, with party walls added based on how many units actually sit on each floor.

Priced incorrectly as "10 units of an averaged 2.4-bedroom flat," the building gets one blended room program applied 10 times — a number that happens to land somewhere between the true cost of a small unit and a large one, but doesn't correctly reflect either, and doesn't reflect the building's actual unit mix on any single floor. For a bank valuation, a contractor's bid comparison, or your own budgeting, that gap is exactly the kind of thing that surfaces later as a disputed variation, not before.

Units of Flats vs Apartment: Side-by-Side Comparison

How to Estimate Either One Correctly

For Units of Flats: describe one unit's room program honestly (remembering that "3 bedroom flat" in Nigeria implies a living room too, not just three bedrooms), then state how many units sit on the ground floor and how many sit on each upper floor — our Professional Estimator's Units of Flats building type takes exactly these two inputs and handles the party-wall and fixture-scaling math for you.

For a genuinely mixed-unit building, use the Estimator's dedicated Apartment building type instead: add one entry per unit type, give each its own room program and count, and the calculator combines them into one accurate total floor area, distributes it evenly across your stated number of floors, and derives party wall length from the real combined unit count — the same underlying engine as Units of Flats, just fed a list of room programs instead of one.

Frequently Asked Questions

What if my building has mostly identical units but one or two different penthouse units?

That's still genuinely an Apartment building, not Units of Flats — the defining test is whether every single unit shares one room program, not whether most of them do. Even one differently-sized unit type means you need to track it separately to get an accurate total.

Does floor placement matter for an Apartment building's cost?

Not directly for the total cost — the Estimator's Apartment type tracks total unit counts per type, not which floor each specific unit sits on, since total buildable area (not floor placement) is what drives most of the cost. This is a deliberate simplification: floor-by-floor tracking adds real input complexity for very little costing accuracy gain in practice.

Is a Terrace the same as an Apartment building?

No. A Terrace is a row of attached, multi-floor townhouses that share side walls — each unit spans every floor of the building, the way a normal detached house would, just attached to its neighbours. An Apartment building's units, like a Units of Flats building's, sit entirely on one floor each and never span floors internally. The two building types answer different questions on a room-program input, which is why our Estimator treats them separately.

Can a Units of Flats building have different unit counts on different floors?

Yes — that part is independent of the identical-unit-type question. A block can have 2 units on the ground floor and 3 on each upper floor while every one of those units is still the same 3-bedroom room program; it's Units of Flats either way, since what makes it "Units of Flats" rather than "Apartment" is that the units themselves are identical, not how many sit on each floor.