Most offers for terrace roofs mention a single number. What that number includes is rarely specified. This makes comparing two quotes a matter of luck: one includes the foundation, another does not, and a third charges assembly by the hour. Knowing the individual components allows you to check instead of guess.
The five cost blocks
A louvered pergola can be broken down into five parts for calculation. The proportions vary depending on size, but the order remains surprisingly stable.
- Aluminum framework. Posts, beams, frame. The largest single item, usually 35 to 45 percent. The price depends on wall thickness and profile cross-section, not on appearance.
- Louvers and drive. 20 to 30 percent. This determines whether the roof can only close or also open controllably, and whether the motor is inside the beam or outside.
- Foundation and earthworks. 10 to 20 percent, highly dependent on the ground. A frost-free point foundation in natural soil costs many times more than the same work on an existing surface that must be opened.
- Assembly. 15 to 25 percent. The item most often missing or hidden as a flat rate.
- Accessories. Lighting, side elements, heating, control. Often used as a discount item and the block where savings are most likely.
Why the assembly share often gets overlooked
Assembly is the only item without material value. That is exactly why it disappears into flat rates. Anyone wanting to compare should have it listed separately — including what is included: travel, scaffolding or lifting equipment, connection to the facade, electrical connection, acceptance.
The second area where quotes differ is the foundation. An offer assuming a "builder-provided foundation" is not cheaper but incomplete. It shifts a several-thousand-franc item onto the builder, who then has to contract it separately.
What really drives the price
- Span width. The jump from four to six meters of free span costs disproportionately more because profile cross-section and foundation size grow simultaneously.
- Freestanding or attached. An attached version saves two supports and two foundations but requires a load-bearing wall connection.
- Snow load zone. In higher locations, profile and foundation dimensions increase without any change in appearance.
- Ground conditions. Rock, groundwater, or a finished surface affect earthworks more than any equipment option.
- Own labor. Those who assemble themselves save the assembly cost — but must have the foundation plan and dimensions correct, otherwise the savings turn into rework.
How to make two quotes comparable
Usually, three questions suffice:
- Is the foundation included, and what depth and cross-section are calculated?
- How many assembly hours are calculated, and what happens in case of extra effort?
- What load assumptions are used — specifically named snow load zone and wind zone?
With these three answers, you can place two numbers side by side. Without them, you compare different scopes of service.
The same approach is worthwhile for other trades. For example, handwerker-kosten.ch collects cost calculators and guideline prices by work step for Swiss crafts services — helpful to get a sense of scale before requesting a quote.
Where it makes sense to save and where not
Sensible savings can be made on equipment: lighting and side elements can be retrofitted if the preparation is right — an empty conduit costs little, a later cable duct is permanently visible. Own labor is also realistic for assembly, provided the foundation plan and dimensions come from the manufacturer.
You should not save on profile cross-section and foundation. Both cannot be corrected later without dismantling the structure. An undersized foundation shows its weakness after the second winter, and then the question is no longer what it would have cost but what the dismantling costs.
Conclusion
A terrace roof is not a product with a single price but a component with five cost blocks. Those who name them individually recognize which offer is complete — and quickly realize that the cheapest number is often the one with the least included.
