Extension · calculationFrom €659 excl. VAT (business) · €797.39 incl. VAT (private customers)What can be included in your commission?
Your quote specifies the exact elements and documents. The following topics matter for this structural calculation:
Roof and supporting structure
The agreed beams, walls and other load-carrying elements of your extension.
Foundations and connections
The foundations and connection to the existing house, where included in the commission.
Coordination with the wall opening
The relationship between the extension and support of the existing facade when a new opening is proposed.
Calculations, drawings and construction work are separate parts of a project. Your quote defines what is included. Mention any questions about a site visit, temporary support or design changes.
Start with a short description and the information you already have. Sending an enquiry is free of obligation and does not place a paid order.
What is assessed?
With an extension, the new construction and the existing building must fit together. The design takes into account the ground, the existing foundation, the bearing direction of the roof and any opening in the rear facade.
A new foundation can behave differently than the existing home. The structural engineer determines how the connection or separation is carried out and what this means for the superstructure.
What data is needed?
The following information can be used to prepare the assessment. The structural engineer determines whether additional research is necessary.
| Information | What should you send? |
|---|---|
| Drawings of the existing and new situation | Show where the extension connects and which existing walls or openings change. |
| Dimensions and desired materials | State length, width, height and the proposed wall and roof build-up, where known. |
| Available foundation information | Include drawings of the house and earlier extensions, identifying the construction phase of each part. |
| Soil testing when available | Send the complete available report, including the address and investigation date. Tell us if no investigation is available. |
Not everything available yet? Describe what you have and what is missing. You do not need to calculate load capacity yourself. Any survey or additional investigation needed will be discussed for your project.
Materials and drawings
The choice of materials and connections follow from the design. Read more about Concrete and reinforcement and the difference between a architectural drawing and a construction drawing.
How does the process proceed?
You describe your project and share the available data. The assignment, any additional information and planning are then coordinated. Check it out complete step-by-step plan for all phases.
Price and scope: agree these points first
The price above is a starting point. Compare quotations covering the same elements and ask for additional work to be listed separately.
What should be calculated?
Describe the roof, walls, foundations and connection to the house. Explicitly include any rear-wall opening; it is not automatically covered by an extension calculation alone.
What needs a separate agreement?
Discuss ground investigation, measurements, supplier calculations, permit documents and revisions. Materials, excavation and construction are not automatically included in the calculation price.
What affects the schedule?
Changed dimensions, a different roof build-up or missing foundation information can require further coordination. Use one design version with your architect, supplier and structural engineer.
Ask your quotation to identify who prepares the calculations, who provides the drawings and who answers technical questions. State your preferred date; feasibility is agreed for your commission.
Can I already order material?
Order structural parts based on the coordinated and current design data. A preliminary estimate is not a complete basis for this.
Is a site visit necessary?
That depends on the project and the available information. Sometimes drawings and photos are sufficient for the inventory; sometimes an admission or additional examination is necessary.
What happens if my plan changes?
Report changes before they are implemented. The structural engineer assesses whether calculations and drawings need to be adjusted.
Frequently asked questions about extensions
Are the rear facade opening and extension one calculation?
They can be part of one constructive assignment, but that must be agreed. The opening in the existing facade, the new roof and the foundation influence each other. Therefore, describe the complete plan and ask which existing and new parts are included in the quotation.
Can an extension be built without piles?
The choice of foundation is based on building loads, soil and allowable deformations. The situation of the neighbors or a general construction method is not sufficient justification for your own extension. Share available CPTs and foundation data and discuss what additional information is required for the choice.
What must the supplier of my extension provide?
Ask about the structure, weights, support points, connections and the limits of his own calculations. The structural engineer must know which components the supplier is developing and who assesses the connection to the existing home. Use the same design version in both assignments.
Can I add a floor to my extension later?
Discuss that wish before the first draft. A future floor may change the principles for foundation, walls, columns and stability. Make it clear whether and with what principles the later expansion has been included. An extra floor is not automatically possible because the extension is new.
Related structural topics
Your project location
Provide the building address and share available drawings and photographs. Discuss whether a site survey is needed and which travel or investigation costs form part of the commission.