What are the costs of a roof extension?

A roof extension (also called roof raising or topping) is a major renovation in which extra living space is created by placing a floor on the existing roof. This intervention is more complex and more expensive than placing a dormer, but provides significantly more living space.

1. Price range in 2025

The costs for a roof extension in 2025 average between € 25,000 and € 70,000, depending on:

• The type of roof extension (prefab or traditional)
• The dimensions and construction
• The chosen materials
• Finishing and installations

Via jeofferte.nl specialized contractors issue quotations in which these components are accurately broken down.

2. Target prices per type of roof extension

* Excluding any permit costs, architect, interior finishing and installations.

3. Main cost factors

a. Size and shape

The larger the roof extension, the higher the price.
A simple rectangular structure is cheaper than a complex shape with corners or multiple rooms.

b. Prefab or traditional

• Prefab: Built in the factory, one day installation. Often cheaper due to fewer labor hours.
• Traditional: Built on location, more flexibility and customization, but also more labor hours and costs.

c. Materials

Wood is often cheaper, plastic and polyester are more maintenance-friendly and more durable.

d. Permit and preparation

A roof extension almost always requires a building permit and a structural calculation.
Costs: € 2,000 – € 5,000 (including drawings and calculations).

e. Internal finishing

• Basic finish: walls closed and delivered as shell
• Luxury finish: stucco, painting, floor, electricity and plumbing (surcharge € 5,000 – € 20,000)

4. Examples of total costs

1. Prefab roof extension of 25 m² (shell):
   Total: ± € 35,000 – € 40,000
2. Traditional roof extension of 25 m², luxuriously finished:
   Total: ± € 45,000 – € 55,000
3. Full topping (50 m²) including luxury finish and installations:
   Total: € 60,000 – € 70,000

5. Appreciation and planning

A roof extension not only increases living comfort, but can also significantly increase the value of the home.
Because this is a major intervention, contractors often plan months in advance. Via jeofferte.nl you can compare multiple quotes in time to coordinate the planning and the budget.

Conclusion

In 2025 you should expect to pay € 30,000 to € 70,000 for a roof extension, depending on dimensions, finish and complexity.
Anyone who requests multiple quotes via a platform such as jeofferte.nl can make a well-considered choice for the right type, material and planning.

A roof extension comes in various types and designs. The chosen type has a major impact on the costs. Below you will find the most common variants with target prices as they will be applied in 2025.

1. Prefab roof extension

Characteristics:

• Produced in the factory, fully prepared.
• Placed on the house in one day with a crane.
• Fast construction time, less nuisance and usually competitively priced.

Target price 2025:

• 20 – 25 m²: € 30,000 – € 45,000 (shell)
• Luxury finishing can increase the price by € 10,000 – € 20,000.

Advantage:
Low labor costs and short construction time.

2. Traditional roof construction (built on site)

Characteristics:

• Completely built on location.
• Flexible in terms of dimensions and layout.
• More labor hours, longer lead time.

Target price 2025:

• 20 – 25 m²: € 35,000 – € 50,000 (shell)
• Luxury finish: € 50,000 – € 65,000.

Advantage:
Fully customized and tailored to specific living requirements.

3. Full Top-Up (extra floor over the entire house)

Characteristics:

• Creates a full extra living layer.
• Large impact on home, value and budget.
• Architect, permit and structural calculations always required.

Target price 2025:

• 40 – 50 m²: € 50,000 – € 70,000 (shell)
• Luxury finish: € 70,000 – € 90,000.

Advantage:
Maximum living space and a significant increase in the value of the home.

4. Special shapes and customization

Some homeowners opt for a special shape or extra options, such as:

• Roof terrace integrated into the roof structure.
• Large glass sections or sliding doors.
• Extra insulation or sustainable installations (solar panels, heat pump).

These choices are custom-made and can significantly increase the price.

5. Comparison and quote request

The prices mentioned are guidelines and may vary by region, material choice and finish.
Via a platform such as jeofferte.nl, several contractors submit a quote without obligation, giving you a good idea of the costs and the possibilities per type of roof structure.

Conclusion

The costs of a roof extension in 2025 range from € 30,000 for a simple prefab structure to € 90,000 for a fully luxuriously finished extra floor. The choice for prefab or traditional construction and the desired finish are decisive here.

When realizing extra living space in the attic – whether it concerns a dormer or a roof extension – several factors play a role in determining the final costs. The points below provide an overview of the most important price determinants that specialists also include in their quotations.

1. Dimensions and surface area

The width and height of a dormer or roof extension are the biggest cost factor.

• The wider and higher the construction, the more materials and labor hours are needed.
• With a roof extension, every extra square meter directly affects the budget.

2. Material choice

The material not only determines the price, but also the maintenance and the lifespan:

• Wood: often slightly cheaper, but requires maintenance.
• Plastic: low-maintenance, good price-quality ratio.
• Polyester: durable, sleek appearance, higher price range.
• Wooden or plastic constructions are often used for roof extensions.

Jeofferte.nl sees that plastic and prefab elements will be popular in 2025 due to the low maintenance.

3. Prefab or traditional building

• Prefab: Produced in the factory and installed in one day. Fewer labor hours and usually cheaper.
• Traditional: Built on location, offers more customization but costs more time and money.

4. Complexity of the roof

• Adjustments to the roof construction: When the existing roof needs to be reinforced or adjusted, the costs increase.
• Accessibility: Difficult to reach roofs often require a crane and extra safety measures.

5. Finishing and interior

The desired level of finish has a major impact on the price:

• Shell: Only the outer construction, you finish the inside yourself.
• Basic finish: Walls closed, windows and frames placed.
• Luxury finish: Including stucco, painting, electricity and sometimes even a bathroom.

With a roof extension, a luxury finish can increase the costs by € 5,000 to € 20,000.

6. Permits and preparation

• Building permit: Required for almost all roof extensions and some dormer windows.
• Costs for permit, structural calculations and drawings: € 500 – € 5,000, depending on the size.
• Specialists who submit quotes via jeofferte.nl often include guidance on these permits in their proposal.

7. Region and market conditions

• In urban areas, prices are often higher due to higher labor costs.
• Due to price increases in materials and labor costs, rates in 2025 are higher than in previous years.

Summary

The final costs of a dormer or roof extension depend on a combination of:

• Dimensions
• Material choice
• Construction method (prefab or traditional)
• Complexity of the roof
• Finishing
• Permits and preparation

By requesting multiple quotes via a platform such as jeofferte.nl, consumers gain insight into these factors and can make informed choices.

A roof extension is a major renovation that not only provides extra living space but can also significantly increase the value of a home. Because this is a major undertaking, it is important to be well prepared. The step-by-step plan below shows which phases are involved in successfully realizing a roof extension.

1. Inventory wishes and possibilities

• Determine goal: Extra bedroom, office, bathroom or full floor.
• Determine budget: Make a realistic estimate based on target prices (from approx. € 30,000).
• Check the possibilities: Does the roof extension fit within the zoning plan and the construction of your home?

2. Advice and initial orientation

• Consult a contractor, architect or structural engineering firm.
• Collect examples of dimensions and styles.
• Via platforms such as jeofferte.nl you can request quotes without obligation to gain insight into costs and feasibility.

3. Have a design and drawings made

• An architect or drawing office makes a design that suits the house and the requirements of the municipality.
• Structural calculations are drawn up for safety.

4. Apply for an environmental permit

• An environmental permit is almost always required for a roof extension.
• You will need the following for this:
• Construction drawings and structural calculations
• Possibly an aesthetic advice
• The processing by the municipality usually takes 6 to 8 weeks.

5. Compare quotes and select a contractor

• With the approved plans, you can request multiple quotes.
• Platforms such as jeofferte.nl ensure that you receive quotes from specialized contractors who have experience with roof extensions.
• When selecting, pay attention not only to price, but also to planning, guarantees and references.

6. Preparation and planning

• Work with the contractor to draw up a schedule and plan.
• Arrange in time:
• Possible financing
• Temporary storage or accommodation if necessary
• Access for crane and material

7. Execution of the roof construction

The execution proceeds in broad terms as follows:

1. Preparation: Placement of scaffolding, protection of the interior.
2. Demolition: Removal of roof parts.
3. Placement roof construction:
• Prefab: placed in one day with a crane
• Traditional: built on site in 2 to 3 weeks
4. Constructive connections: Make roof and facades waterproof.
5. Interior finishing: Depending on the chosen options (shell or luxury).

8. Completion and aftercare

• The contractor will review everything with you during the completion.
• Any defects will be resolved within an agreed period.
• With a well-executed roof construction, a clear added value to the home is immediately noticeable.

Practical advice

• Start on time with the process: from first idea to permit can quickly take several months.
• Always request multiple quotes to be able to compare costs and quality.
• A platform such as jeofferte.nl helps you to make this process clear and to get in touch with experienced specialists.

Summary

Realizing a roof extension requires a structured approach:

1. Determine wishes
2. Orientation and advice
3. Have design made
4. Arrange permit
5. Request and compare quotes
6. Establish planning
7. Construction phase
8. Delivery and completion

With the right preparation, a roof extension becomes a valuable investment in your home.