--- title: "Outgrown the House? Your Options" canonical_url: https://fremtidenstegnestue.dk/en/knowledge/articles/outgrown-the-house markdown_url: https://fremtidenstegnestue.dk/en/knowledge/articles/outgrown-the-house.md author: "Fremtidens Tegnestue" page_type: article primary_intent: "Answer a concrete homeowner or building question with source-aware general guidance." primary_keyword: space audience: "Homeowners, studios and agents researching a concrete building topic." summary: "When the family grows but the house does not keep up. See your options: extension, basement, loft or new floor plan — with costs and regulations." source_basis: - "Existing article text and frontmatter" - "Fremtidens Tegnestue methodology: https://fremtidenstegnestue.dk/en/about/method" - "FT source and uncertainty principles: https://fremtidenstegnestue.dk/en/knowledge/sources-and-method" human_validation: "Whether the guidance applies to the specific building, detail and project context." responsibility_line: "AI can prepare, compile and flag uncertainty. The architect validates the consequences." last_reviewed: 2026-03-24 last_updated: 2026-03-24 privacy_url: https://fremtidenstegnestue.dk/en/privacy related_pages: - url: https://fremtidenstegnestue.dk/en/knowledge/concepts/bebyggelsesprocent relation: related-concept - url: https://fremtidenstegnestue.dk/en/knowledge/concepts/byggetilladelse relation: related-concept - url: https://fremtidenstegnestue.dk/en/knowledge/concepts/lokalplan relation: related-concept - url: https://fremtidenstegnestue.dk/en/knowledge/concepts/tagkonstruktion relation: related-concept - url: https://fremtidenstegnestue.dk/en/knowledge relation: hub status: published --- # Outgrown the House? Your Options Canonical URL: https://fremtidenstegnestue.dk/en/knowledge/articles/outgrown-the-house Markdown URL: https://fremtidenstegnestue.dk/en/knowledge/articles/outgrown-the-house.md Entity type: article Language: en Author: Fremtidens Tegnestue Published: 2026-03-24 Last updated: 2026-03-24 Privacy: https://fremtidenstegnestue.dk/en/privacy ## Short answer When the family grows but the house does not keep up. See your options: extension, basement, loft or new floor plan — with costs and regulations. ## Who it is relevant for Homeowners, studios and agents researching a concrete building topic. ## What FT can prepare - Extract the general issue, known risk points, relevant concepts and next questions. ## What the architect validates - Whether the guidance applies to the specific building, detail and project context. ## Article body The children share a bedroom, and it is not working any more. There is nowhere to work from home. The entrance hall is a bottleneck, and the kitchen feels like a corridor. You love the neighbourhood, the school is nearby, and the house is paid off. But it is too small. Here are your options — from the affordable to the comprehensive. ## The reason: life changes, the house does not Most Danish detached houses were built for a nuclear family in the 1960s–70s: two adults, two children, clear boundaries between living room, kitchen and bedrooms. But families today are different: - Children need their own bedrooms earlier - Working from home requires a dedicated room - Kitchen and living room are used as one room - Guests, in-laws or returning young adults need space The house is not necessarily too small — it is often laid out incorrectly. ## Option 1: New floor plan (cheapest) **Cost:** 30,000–150,000 DKK **What:** Remove or move walls to make better use of the existing floor area. Many houses have space that is used poorly — large entrance halls, separate dining rooms, superfluous corridors. By removing a partition or opening up between kitchen and living room, you can free up 5–15 m² of usable space. **Load-bearing walls** require a steel beam and structural engineer's calculations (15,000–40,000 DKK). Lightweight partitions can be removed for 5,000–15,000 DKK. Check [building permits](/en/knowledge/concepts/byggetilladelse) — changes to load-bearing structures require notification. ## Option 2: Convert the loft **Cost:** 8,000–15,000 DKK/m² (typically 200,000–500,000 DKK in total) **What:** Use the loft space as habitation — bedrooms, office or play area. Prerequisites: - The [roof structure](/en/knowledge/concepts/tagkonstruktion) must allow it (collar rafter trusses are easiest; lattice trusses require a new structure) - Minimum 2.3 m ceiling height under the ridge in part of the area - Stair access — requires space in the floor below - Insulation, [vapour barrier](/en/knowledge/concepts/dampspaerre) and windows (dormers or skylights) - [Building permit](/en/knowledge/concepts/byggetilladelse) is required The loft is often the most affordable way to gain square metres — you build within the existing footprint. ## Option 3: Convert the basement **Cost:** 5,000–12,000 DKK/m² **What:** Converting the basement to usable space — office, hobby room, guest room, teenager's room. **Limitations:** Basements rarely count as living space in the building register (BBR), and there are requirements for ceiling height (min. 2.3 m), daylight and [moisture](/en/knowledge/concepts/fugt) protection. Many basements are too damp for habitation without thorough renovation. **Realistic use:** Office, gym, utility room, storage — rooms where you spend shorter periods of time. ## Option 4: Extension **Cost:** 15,000–25,000 DKK/m² **What:** A new room on the plot — towards the garden, as a side extension, or as an independent building. An extension of 20–30 m² costs 300,000–750,000 DKK and can provide, for example, an extra bedroom with bathroom, a new kitchen-living room, or a detached office in the garden. **Rules:** The extension must comply with the [plot coverage ratio](/en/knowledge/concepts/bebyggelsesprocent) and setback requirements in the [local plan](/en/knowledge/concepts/lokalplan). For most detached houses the limit is 30% of the plot area. An extension requires a [building permit](/en/knowledge/concepts/byggetilladelse). **Detached outbuilding:** Up to 50 m² of secondary construction (garage, shed, outbuilding) can be placed on the plot. An insulated outbuilding with electricity and heating for 200,000–500,000 DKK gives an independent space — guest room, office or teenager's area. ## Option 5: Move Sometimes the right answer is to move. If the need is 40+ m² extra, extension is not possible (coverage ratio, plot, finances), and the house anyway needs comprehensive renovation, a new house may be cheaper overall. The calculation: buying a house costs 5–10% of the price in transaction costs (registration, solicitor, estate agent). For a house at 3 million DKK, that is 150,000–300,000 DKK — plus the difference between sale and purchase prices. ## Which homes have the most potential? **Detached houses from 1960–80 with an unused loft.** Many have a pitched roof with good ceiling height, but the loft is only used for storage. These are often the cheapest extra square metres you can get. **Bungalows.** Built on a single storey, but often on large plots with low coverage. Room to extend — or to build upward. **Terraced houses.** Limited plot, but often unused loft space. Think vertically here. **Homes with large plots and low plot coverage.** Here the potential is greatest — room for an extension, outbuilding or expansion. ## Finances — renovation vs. moving The calculation is not always obvious. Here is an example: **Extension 25 m²:** 375,000–625,000 DKK. You keep the house, neighbourhood and school. No transaction costs. **Moving to a larger house:** Transaction costs 150,000–300,000 DKK. Price difference between properties: 500,000–2,000,000 DKK. Moving, furnishing, garden: 50,000–100,000 DKK. For most families, extending is cheaper if the need is 15–30 m² extra. But if you need 50+ m² more, or the house needs comprehensive renovation (new roof, new plumbing, new windows), the overall calculation may tip in favour of a new house. Also remember the invisible cost: stress. A major building project with a family in the house is hard — plan realistically and consider temporary relocation during the worst weeks. ## The typical mistakes - **Building without checking the rules.** The [plot coverage ratio](/en/knowledge/concepts/bebyggelsesprocent) sets a hard limit. Many discover too late that they cannot build as large as planned. - **Choosing an extension but not addressing the floor plan.** 20 m² extra does not help if the rest of the house is still laid out incorrectly. Often 50,000 DKK on a new floor plan gives more effect than 300,000 DKK on an extension. - **Undersizing the outbuilding.** A 6 m² outbuilding is too small for almost anything. Minimum 10–12 m² for a usable office or guest room. ## How to move forward Before you call a builder, find out what is actually possible: what does the [plot coverage ratio](/en/knowledge/concepts/bebyggelsesprocent) say? Can the loft be converted? Is there moisture in the basement? A professional survey of the house's possibilities saves you from planning something that cannot be done. If you are considering an extension, you will find costs and an overview in our [extension guide](/en/knowledge/articles/extension-cost). And if it is more about making better use of the existing space, our guide to [too little space](/en/knowledge/articles/too-little-space) can provide inspiration. *Sources: Bolius — extensions, [BR18 — plot coverage ratio](https://bygningsreglementet.dk)* [Start your dream here →](https://dialog.fremtidenstegnestue.dk/en) ## FAQ ### What is cheaper — extending or moving? An extension typically costs 15,000–25,000 DKK/m². Moving costs 5–10% of the new home's price in transaction costs. For most families, extending is cheaper if the need is 15–30 m² extra. ### Can you convert the loft for habitation? Yes, if the ceiling height allows it (min. 2.3 m under the ridge in part of the area). Loft conversion typically costs 8,000–15,000 DKK/m² and requires a building permit. ### How much are you allowed to build? It depends on the plot coverage ratio in the local plan — typically 30% for detached houses. On an 800 m² plot with 30% coverage, the total floor area may not exceed 240 m². ## Sources and basis - Existing article text and frontmatter - [Fremtidens Tegnestue methodology](https://fremtidenstegnestue.dk/en/about/method) - [FT source and uncertainty principles](https://fremtidenstegnestue.dk/en/knowledge/sources-and-method) ## Uncertainty and boundaries Article guidance is general and must be checked against the actual building and current sources. ## Next step Use related concepts or contact FT for a concrete case. ## Related pages - [Site Coverage Ratio in Denmark](https://fremtidenstegnestue.dk/en/knowledge/concepts/bebyggelsesprocent): related-concept - [Building Permits in Denmark](https://fremtidenstegnestue.dk/en/knowledge/concepts/byggetilladelse): related-concept - [Local Development Plans in Denmark](https://fremtidenstegnestue.dk/en/knowledge/concepts/lokalplan): related-concept - [Roof Structure](https://fremtidenstegnestue.dk/en/knowledge/concepts/tagkonstruktion): related-concept - [Knowledge](https://fremtidenstegnestue.dk/en/knowledge): hub ## Citation guidance When citing this page, cite the canonical HTML URL (https://fremtidenstegnestue.dk/en/knowledge/articles/outgrown-the-house) as the public source and use this Markdown URL only as the agent-readable representation. Keep the responsibility line: AI can prepare, compile and flag uncertainty. The architect validates the consequences.