Everything About Installing a 5-Meter Dormer Window

A 5-meter wide dormer offers a lot of extra space and light.
This format almost always falls into the customization category and is suitable to transform a complete attic into several usable rooms.

1. Price indication (including placement and VAT)

Prefab dormer – 5 meters wide

Prefab dormers larger than 4 meters are less common, but some manufacturers offer this width.

• Wood: € 8,500 – € 11,000
• Plastic: € 9,000 – € 12,000
• Polyester: € 9,500 – € 13,000

Traditional (custom) dormer – 5 meters wide

Often the preferred method for 5 meters due to flexibility and sturdiness.

• Wood: € 10,000 – € 13,000
• Plastic: € 10,500 – € 14,000

2. What is included in this guide price?

• Construction and placement
• HR++ glass
• Basic insulation and standard exterior finish
• VAT and labor costs for placement

3. Not included (optional)

• Shutters or screens
• Interior finishing (plaster, painting, electricity)
• Luxury cladding (trespa, zinc)
• Permit costs and construction drawings
• Possible adjustments to the roof construction

4. Extra options and additional costs

A 5-meter wide dormer with luxury options and full finishing can rise to € 14,000 – € 16,000.

5. Example projects

Example 1 – Prefab plastic 5 meter

• Back of house
• Including HR++ glass and standard finish
• Total costs: approx. € 10,000 – € 11,000

Example 2 – Traditional wooden dormer with permit

• Front of house
• Including permit, painting and finishing
• Total costs: approx. € 12,000 – € 13,000

Example 3 – Luxury polyester with shutters

• Width: 5 meters
• Shutters and high-quality insulation
• Total costs: approx. € 14,500 – € 16,000

6. Key cost drivers

1. Placement method: prefab is still possible at 5 meters, but custom work is more common.
2. Material: wood is cheaper, plastic and polyester require less maintenance.
3. Location: front means permit and extra costs.
4. Extra options: shutters, screens, ventilation and finishing influence the total price.
5. Accessibility: large format requires a sturdy crane and sufficient workspace.

Conclusion

In 2025, a dormer window of 5 meters wide will cost on average:

• Prefab: € 8,500 – € 13,000
• Traditional customisation: € 10,000 – € 14,000

With extra options, this can increase to approximately € 16,000.

Jeofferte.nl advice:
With a width of 5 meters, customisation is usually the best choice. Always request a specified quote and have the roof construction assessed in advance.

A dormer is an investment that adds a lot of value and comfort to a home.
The costs depend on, among other things, width, material, construction method (prefab or custom) and extra options.

1. Average costs per type (standard width 3 meters)

Prefab dormer

• Wood: € 4,500 – € 6,500
• Plastic: € 4,800 – € 7,500
• Polyester: € 5,500 – € 8,000

Traditional (custom) dormer

• Wood: € 5,500 – € 8,500
• Plastic: € 6,000 – € 9,000

2. Costs for wider dormers

• 4 meters wide: + € 1,200 – € 1,800 per extra meter
  Indicative price: € 8,000 – € 11,000 (prefab) or € 9,000 – € 13,000 (traditional).
• 5 meters wide: almost always custom work
  Indicative price: € 10,000 – € 14,000, depending on material and options.

3. Extra options (additional costs)

4. Other costs

• Environmental permit: € 200 – € 600 (depending on the municipality)
• Drawings and structural calculations: € 300 – € 700
• Adjustments roof construction: price depending on situation

5. Influence of material and construction method

• Prefab: faster placed (usually in 1 day) and cheaper.
• Traditional: more expensive, but custom-made and suitable for complex situations.
• Material:
• Wood: more affordable, but more maintenance.
• Plastic: low-maintenance and durable.
• Polyester: highest purchase, but seamless and very maintenance-free.

6. Example total costs (3 m wide, prefab plastic)

• Standard prefab plastic dormer: € 6,000
• Including HR++ glass and installation
• Possible extras (shutters, finishing): € 1,500 – € 2,500 extra
• Total: approx. € 6,000 – € 8,500

Conclusion

Average price range in 2025:

• Standard dormer (3 meters wide): € 4,500 – € 9,000
• Wide dormer (4 – 5 meters): € 8,000 – € 14,000
• Luxury version with extra options: up to € 16,000

Jeofferte.nl advice:
Request multiple customized quotes, including specified items for material, assembly and extra options.

The material is one of the most important factors determining the price of a dormer.
Below you will find the average target prices per type of material.

1. Wooden dormer

• Prefab: € 4,500 – € 6,500
• Traditional customisation: € 5,500 – € 8,500

Characteristics:

• Natural appearance, suitable for classic homes.
• Regular painting required.
• Lifespan: 20 – 30 years with good maintenance.

2. Plastic dormer

• Prefab: € 4,800 – € 7,500
• Traditional customisation: € 6,000 – € 9,000

Characteristics:

• Low maintenance and colourfast.
• Durable and well insulating.
• Lifespan: 30 – 50 years.
• Most chosen material in 2025.

3. Polyester dormer

• Prefab: € 5,500 – € 8,000
  (Polyester is almost always delivered as prefab, customisation is limited.)

Characteristics:

• Completely seamlessly cast in one piece.
• Very low-maintenance and waterproof.
• Lifespan: 40 – 50 years.

Comparison per material

Important price differences

• Wood: cheaper to purchase, more expensive to maintain.
• Plastic: higher purchase, but saves maintenance costs.
• Polyester: highest purchase, but extremely maintenance-friendly and long lifespan.

Conclusion

In 2025:

• Wood is attractive if the lowest investment is desired.
• Plastic is the most popular due to the balance between price, maintenance and lifespan.
• Polyester is the best choice for those who want little maintenance and a very long lifespan, but falls into the higher price range.

Jeofferte.nl advice:
Choose the material not only on price, but also based on maintenance and the appearance of the home.