Cost of a synthetic dormer
Synthetic cladding (often made of Trespa or polyester) is the best-selling exterior finish for dormers in the Netherlands. The reason: low maintenance, colourfast, lighter than zinc, and affordable. But "synthetic" is a collective term — quality and price vary greatly. On this page, we explain where the difference lies, what a good quote should mention, and which items you do not want to overlook.
We don't quote rates — we explain how the price is structured.
What is a 'synthetic' dormer exactly?
In practice, a "synthetic dormer" means a dormer where the exterior cladding is synthetic. The internal construction is almost always wood or steel — synthetic is only the finishing layer.
Two main types:
- Trespa panel: dense panel with an extra hard, pressed top layer. Sleek appearance, colourfast, high-quality.
- Polyester sandwich panel: insulated panel with polyester on the outside. More economical, lighter, but the appearance is slightly less sleek.
The choice between these two explains a large part of the price difference between "synthetic" quotes.
What determines the price?
Panel choice and colour
Trespa is more expensive than polyester. Standard colours (anthracite, white, black) are always more affordable than custom colours (RAL number).
Window frame type
There is often more difference here than in the panel material itself. Synthetic window frames with HR++ glazing are standard; wooden or aluminium frames significantly increase the price.
Sandwich or build-up
A prefab synthetic sandwich element with integrated insulation is installed faster than separate panels on a wooden frame. The price is comparable; the difference in time and construction nuisance is not.
Warranty
A shorter warranty = often a lower price but more risk. Ten years on the panel and five years on sealant and connection work is a reasonable lower limit.
Advantages and disadvantages of synthetic materials
Advantages:
- Virtually maintenance-free — no painting.
- Colourfast if high quality (UV-stable pigment).
- Lighter than zinc — smaller crane suffices.
- Short production time with prefab suppliers.
Disadvantages:
- In case of damage, the entire panel often needs replacing.
- Any shrinkage/expansion requires good sealant quality.
- Not always welcome in protected views of the townscape or historical neighbourhoods.
- Cheap polyester can yellow — pay attention to the manufacturer's warranty on colourfastness.
Comparing: what should you pay attention to?
Ask every supplier:
- Panel material: brand and type (e.g., "Trespa Meteon" or "Polyester sandwich panel 6 mm").
- Warranty on panel: minimum 10 years.
- Warranty on colourfastness: separate clause, often 5–10 years.
- Sealant and connection work: type of sealant, warranty period.
- Window frame type: synthetic / wood / aluminium, brand.
- Glazing: HR++ glazing standard, triple optional.
- Internal insulation: Rc-waarde and insulation type.
- Roofing: EPDM class III is the most durable.
Two quotes with identical specs and equal warranties are the only fair comparison.
Sustainability and lifespan
A well-executed synthetic dormer lasts 25–40 years, provided the sealant and connection work are checked periodically. The panel itself generally lasts longer than the sealant; count on renewing the sealant around year 10–15.
The insulation inside (PIR, mineral wool) has a comparable or longer lifespan than the panel. Under normal circumstances, the entire dormer only requires large-scale renovation after 30–40 years.
Comparison table
| Aspect | Trespa panel | Polyester sandwich |
|---|---|---|
| Appearance | Sleek, high-quality | Smooth, slightly less sleek |
| Price | Higher | Lower |
| Maintenance | Virtually zero | Virtually zero |
| Colourfastness | Very high | Depends on quality |
| Repair | Replace panel | Replace panel |
| Warranty | 10–15 years | 10 years |
Frequently asked questions
Short, honest answers to recurring questions.
- What does a synthetic dormer cost?
- We do not mention rates. The price depends on panel material (Trespa vs polyester), window frame type, glazing, insulation, dimensions, and accessibility.
- Is synthetic material cheaper than wood?
- Usually yes, especially in the long run because painting is eliminated.
- Which synthetic material is best?
- A Trespa panel provides the sleekest appearance and highest warranty. A polyester sandwich is more economical and installed faster.
- How long does a synthetic dormer last?
- With good quality and regular maintenance, 25–40 years.
- Do I need to paint?
- No — that is exactly the advantage. You do need to check the sealant periodically.
- Is synthetic cladding permitted in a protected view of the townscape?
- Often not, or only with an aesthetic review (welstand). In such neighbourhoods, wood or zinc are more common.
- What if the panel gets damaged?
- Usually the entire panel must be replaced. Custom colours might require a new order then — keep your production details.
- Do I get a colourfastness warranty?
- With high-quality manufacturers, yes. Request a separate clause.
- Which colour is popular?
- Anthracite (RAL 7016), black, and white are the most requested and almost always standard stock — thus more economical.
- Is synthetic material recyclable?
- Trespa is partially recycled. Polyester is less sustainable at the end of its lifespan. Ask a supplier about their recycling policy.
Summary
Synthetic cladding is the standard choice because it is low-maintenance, colourfast, and affordable. The difference between a Trespa panel and a polyester sandwich explains a large part of the price differences between providers. A warranty on the panel and colourfastness says a lot about quality; ask specifically for the brand and type. Window frame and glazing selection remain at least as decisive as the panel choice — always compare based on complete specifications.