Bring both floors and the connection to the house together in the design.
More than two separate extensions
The floors, walls and foundation of a two-storey extension work together. The design must also take into account stability and the connection to the existing building.
Coordinate dimensions and use
Indicate where large openings, heavy walls and installations will be located. Discuss the available space for beams and columns early, so that the architectural and structural design support each other.
Describe both floors as one design
An extension with a floor requires coherence between floors, roof, walls and foundation. Indicate how the spaces are used and where large openings are desired. The bottom floor must be able to receive and dissipate the forces of the superstructure. This can influence the column positions and foundation layout. Therefore, do not only have the bottom extension calculated if the floor is already part of the plan.
Adjust the connection to the existing home
New floor heights, breakthroughs and facade connections must match the actual height existing condition. Differences in deformation or foundation behavior can have consequences for the detailing. Collect cross-sections of the existing house and identify uncertain ones sizing. Ask what connections or separations are being designed and what information the contractor needs to implement them.
Your preparation in four steps
- Design of both floors
- Cross-sections and facade connection
- Foundation and soil data
- Desired material composition
Frequently asked questions on this topic
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.
View the associated structural calculation, create your preparation list or take the guides and checklists along to the consultation.