Live smaller. Live together.

You’ve talked about it for a couple of years. Two families, two couples — or something in between. Someone who wants a house but can’t manage it alone. Someone who’s tired of owning 200 m² for themselves. A house with potential. A garden that’s too good for one family.

The idea isn’t utopian. It’s possible. But it requires you to understand the rules, make decisions in the right order — and have an architect who knows the system.

The building register and local plan: what do the rules say?

The first thing to understand is that “sharing a house” isn’t one legal concept — it’s several.

Simple co-ownership is the minimal solution. Two parties own the house together, but it’s still legally one dwelling. You can both live there. You can have separate rooms. But legally you’re two owners of one property. No planning permission required, but no separate address.

Division into two self-contained dwellings is what most people actually want. Two homes with separate entrances, their own bathroom facilities, their own kitchen, their own heating system. Two separate registered addresses. Two separate entries in the building register.

To divide a detached house into two self-contained dwellings, you need:

1. Planning permission from the local authority for change of use
2. Compliance with technical requirements: fire separation, acoustic separation, ventilation, daylight, separate utilities
3. The local plan must permit it — some local plans prohibit two dwellings on one plot

What does the local plan say? This varies enormously from municipality to municipality and from plan to plan. In many areas it’s permitted. In some it’s prohibited. And in some cases a dispensation can be applied for.

The building register (BBR — Bygnings- og Boligregistret) reflects the legal reality. Before the council approves the division, there’s one dwelling in BBR. Afterwards there are two. This affects everything from property tax to insurance.

Division — what does it require in practice?

A divided dwelling isn’t just “an extra bathroom and a locked door”. It’s a self-contained dwelling unit, and the requirements are real.

Separate entrance is the first requirement. Not necessarily directly from the street — a shared lobby with two front doors is often acceptable. But the two homes must not require passing through each other’s dwelling.

Own sanitary facilities — toilet, bathroom and kitchen in both dwellings. This is typically where the money goes.

Fire separation between the two dwellings. Depending on the construction, this may mean additional fire walls, fire doors and fire-protective coatings.

Separate utility metering for electricity and potentially heat. Not always a legal requirement, but practically necessary for separate billing.

What does the division cost? From 200,000 to 800,000 DKK depending on the starting point. A house that already has two bathrooms, two kitchens and a natural dividing line will cost far less to regularise than one that needs to be fully reconfigured.

Shared areas vs. private spaces — the design challenge

This is where the architect’s work really begins.

The easy solution is to divide the house horizontally: you live downstairs, the others live upstairs. It works. But it’s not necessarily the best arrangement.

The interesting question is: what do you actually want to share? And what do you want to keep to yourselves?

Shared areas that typically work well:

• Garden and terrace — the easiest thing to share, and the best argument for co-ownership over being neighbours
• Utility room / laundry — the logistical heart of the house
• Guest parking

Things that typically create friction:

• A shared entrance that’s too narrow for two families’ prams and bicycles
• Garden tools and responsibility for maintenance
• Noise from the other unit that travels through the structure

We design for what you actually want to use. Not just what’s least complicated to build.

Legal structure: ownership, title and exit scenarios

The most important question you’re avoiding: what happens if one of you wants out?

You need to answer that before you start building. And the answer needs to be in a legal agreement.

Co-ownership means both parties must agree to a sale. That’s difficult if the agreement breaks down.

Subdivision into two separate titles is the cleanest solution. Two properties, two owners, two mortgages. But it requires the plot and building to be large enough, and the municipality to approve it. A new title requires cadastral work, a licensed surveyor and municipal approval.

Company structure — you set up a limited partnership or housing cooperative that owns the property. Each household owns a share. Flexible but complex.

Our recommendation: bring in a lawyer early. We’re happy to work alongside a solicitor who specialises in co-ownership structures.

The architect’s role: from idea to legal home

We work concretely. Not with vague principles.

We look at the house and assess: can it be divided? What does it require technically? What will it cost? What will the council most likely say?

From there we produce a sketch design showing you the options — not just one solution, but a few. So you can make an informed decision.

Then we handle the planning application, liaise with the council and ensure everything is buildable.

From idea to keys in the hands of both parties.

Want to know if your house can become two? Get in touch.