House extensions are a popular solution to the growing need for more living space. Whether to create new rooms, extend existing ones or improve the functionality of the house, there are various technical solutions available to make this project a reality. However, one of the key questions in any renovation project is financing. What’s the best budget for a home extension?
How is the price of a house extension calculated?
Factors such as the type of extension, its surface area and its design (contemporary or traditional) are all taken into account in the calculation. Similarly, the number of rooms to be created, the materials used and the level of finish have a direct influence on the cost of the extension.
The choice of rooms to be created in the extension also plays a role in the overall budget. Indeed, the cost will be different if the owner wishes to add a dry room (bedroom, study, dining room…) or a wet room (bathroom, master suite, kitchen…).
What is the price for each type of home extension?
There is no single best solution for building a house extension. First, specific needs are taken into account. Then, depending on any technical, administrative or budgetary constraints, certain options will be more suitable than others. For example, building a garage will be less expensive than raising the height of the house or converting the attic space.
The price of a home extension also depends on other factors that influence the overall cost of the project. Here are just a few examples, although the list is not exhaustive:
- nature of the land ;
- location of the house ;
- dimensions ;
- type of architecture;
- respect for certain historical features.
The materials used, as well as complementary elements such as the heating system, electricity and taxes, must also be considered.
When it comes to extending a house, it’s almost unavoidable, if not compulsory, to call on the services of an architect or other project manager. On average, these professionals charge between 10% and 16% of the cost of the work.
What’s more, it’s virtually impossible to establish a precise price for a house extension without taking into account all the variables that make each project unique. That’s why an in-depth study by a building professional is essential.
How much does a horizontal home extension cost?
Horizontal extensions are still the most common solution today, where floor space permits. Prices for a traditional extension start from 1,800 euros per m² and can reach 3,800 euros per m².
Some homeowners opt for a resolutely contemporary construction to extend a recent bungalow or an older house. For these, a flat-roofed extension is the ideal solution. The cost of a flat-roof extension is between 1,900 and 3,800 euros per m².
The budget for a horizontal extension will be influenced in particular by a number of structural works such as earthworks and the pouring of foundations. The budget estimate also needs to take into account the cost of the work required to create the opening from the existing building.
Attic conversion: what’s the budget?
Among the preferred solutions for extending a house, attic conversion is often mentioned. When the house has lost attic space and the roof pitch is greater than 30°, attic conversion is an option.
The budget for this work varies according to the choices made by the homeowner during implementation.
Once again, the cost can double depending on the surface area to be converted and the features to be integrated (master suite, bathroom, games room, etc.). Attic conversion is a project that can require a budget of between €1,500 and €4,000 per m².
What can I say about the price per square metre for raising a house?
If the ceiling height of the attic does not allow it to be used without modification, it is possible to raise the roof. Raising the roof is a more complex and costly operation than simple attic conversion. The cost of raising the roof varies considerably according to the work involved. It’s important to allow around 1,800 euros per square meter (for the structure). This cost can rise to over 4,000 euros per square meter for a complete conversion.
In some cases, the structure of the roof structure or the slope of the roof may not be suitable for conventional attic conversion. In such cases, you’ll need to consider modifying the roof pitch to create a habitable space under the roof. This is generally the most expensive option. It requires expenditure of between 1,000 and 2,000 euros per square meter to modify the roof pitch and make the attic space suitable for conversion.
If the homeowner wants to extend their living space and benefit from an opening onto their garden, the construction of a veranda can be an excellent solution. For full integration, the veranda should be designed as a complete extension of the house. It should not, however, be separated from the rest of the house by an existing façade and openings.
For a custom-built PVC veranda of around 15 to 20 m², the cost ranges from €22,500 to €20,000, depending on the model and color chosen. For an aluminum or aluminum-wood veranda, prices tend to range from €20,000 to €52,500.
The cost of building a veranda will also depend on how it will be used. In addition to the unavoidable electrical work, you’ll need to plan for the installation of a heating system. The latter is necessary if the owner intends to use the veranda all year round, not just during the summer months.
In conclusion
A house extension is an excellent project for optimizing living comfort. However, it requires a substantial budget, depending on the type of extension required.
