The structure determines the possibilities
An extra storey changes the loads on the lower structure and foundations. Have the supporting structure assessed first. An existing extension is not automatically suitable for another floor.
The connection to your house, stability, roof shape and openings are also part of the design. The standard single-storey estimate cannot be used for this project.
Think about the entire house
Upstairs space works only when access, daylight and layout are right. This may require changes to the existing upper floor. Design both levels together.
Views from the garden and street may change. Discuss height, privacy and local rules early, before developing a plan that is unsuitable for the address.
A quotation based on investigation
- Collect existing drawings and foundation information.
- Investigate structural possibilities and connections.
- Develop both floors and their access together.
- Identify permits, installation needs and temporary measures.
Design both floors as one project
If you are adding an extension now and considering another floor later, raise that plan early. It may change foundations, structure, access and connections. Stairs also take space on both levels and affect the existing layout. Have options with and without an upper floor designed and costed separately. The single-storey configurator excludes a second floor, stairs and reinforcement, so its total is not a budget for this project.
Assess a future upper floor now
Planning one storey now and possibly another later? Have that assessed now. A lighter ground-floor design may rule out an upper floor. Ask what allowances are needed in the foundations, structure and connections and what must be built immediately. A statement that the roof is strong is insufficient to plan another storey.
Two-storey extension in your area
Choose your municipality or district for housing figures, access and considerations for this home idea. The links open the relevant explanation on the local page.