Tomannsbolig

A tomannsbolig (semi-detached house) is a home with two independent dwelling units under the same roof, divided either vertically or horizontally.

Vertically divided means each unit sits in its own half of the building with a shared wall. Horizontally divided means one unit sits above the other. In the matrikkel, a tomannsbolig is classified as building type 121 (vertically divided) or 122 (horizontally divided) under the building classification from Statistisk sentralbyrå.

Both dwelling units must be approved dwelling units under the technical building regulations TEK17, with their own kitchen, bathroom, entrance and escape routes. This independence is what separates a tomannsbolig from a detached house with a basement flat or a bedsit: in a tomannsbolig, both units are primarily intended as independent homes, not as a main home plus a rental part. In practice the line is blurred, but the building type in the matrikkel is the formal distinction, and the municipality decides the classification in the building application or change of use.

The ownership form is decided independently of the building type. A tomannsbolig can be owned as a freehold unit (each unit is a section with a notional share of the plot and the common areas), as a co-ownership without sectioning (both parties own a notional fraction of the whole property), as two separate bruksnumre where the plot is physically divided, or as a housing co-operative with two shares. The most common modern form is the freehold unit: each owner has exclusive rights to their dwelling unit, and shared areas are registered in the cadaster as common areas. The co-ownership fraction determines how shared costs and voting weight at the co-owners' meeting are distributed.

Tomannsboliger are one of the oldest forms of densification in Norwegian detached-house areas and are often set out in zoning plans as a permitted housing type alongside detached houses. The zoning provisions can set requirements for the number of dwelling units per plot, development density measured as BYA or UFA, building lines, parking provision per dwelling unit and minimum outdoor amenity space. The fire separation between the two units must be built as its own fire compartment under TEK17 § 11-8, in practice with fire resistance EI 60 for non-load-bearing walls and REI 60 for load-bearing walls and floors.

Building a new tomannsbolig requires an application under the Planning and Building Act § 20-1 and needs a responsible applicant, neighbour notification, building permit, permit to start work and finally a completion certificate. A change of use from a detached house to a tomannsbolig (typically by converting a basement flat into an independent dwelling unit with its own entrance and independent access) also requires an application, as work that needs authorisation of responsibility.

For tax purposes, a tomannsbolig is normally treated as each owner's primary home in the unit that owner lives in, while the other unit is typically a secondary home or a rental object. Property Tax, taxable value and document duty are calculated per unit or section where the property is sectioned. When a seller owns one half of a sectioned tomannsbolig, document duty of 2.5% is paid only on the purchase price for that one section, not for the whole building. Each section owner can mortgage their unit independently, and shared costs and maintenance responsibility are distributed according to the co-ownership fraction set when the sectioning was carried out.

In Placepoint you can see the building type, the number of dwelling units and which sections are registered on the property in the building panel. That makes it quick to verify whether an advertised "half of a tomannsbolig" really is a sectioned tomannsbolig or something else.

How this looks in Placepoint

In Placepoint you find this in the Building panel:

From Placepoint's glossary: Tomannsbolig

More information: SSB: Bygningstypekoder, DiBK: TEK17 § 11-8 on fire sectioning, Store norske leksikon: tomannsbolig

English: Two-family house (duplex or semi-detached).

Frequently asked questions

What is a tomannsbolig?

A home with two independent dwelling units under the same roof, divided either vertically or horizontally. Both units have their own kitchen, bathroom and entrance.

What is the difference between a vertically divided and a horizontally divided tomannsbolig?

Vertically divided means the two units sit side by side with a shared wall (matrikkel building type 121). Horizontally divided means one unit sits above the other (building type 122).

How is a tomannsbolig usually owned?

As two freehold units with a shared plot, as two separate bruksnumre where the plot is physically divided, or as a notional co-ownership without sectioning. The housing co-operative form also occurs.

What separates a tomannsbolig from a detached house with a basement flat?

Both units in a tomannsbolig are equal, independent dwelling units. In a detached house with a basement flat, the main home is primary and the basement flat is secondary. The building type in the matrikkel gives the formal distinction.

Do I need a building application to build a tomannsbolig?

Yes. Construction and change of use to a tomannsbolig require an application under the Planning and Building Act § 20-1 and need a responsible applicant, building permit and completion certificate.