Retained structures and concrete
House demolition when the new design retains a foundation
Retaining a house foundation for a new design changes the demolition boundary fundamentally. The responsible engineer must establish whether and how the existing construction is suitable. Demolition does not certify that suitability simply because the foundation appears intact.
Planning guidance by MetroPoint Demolition. Illustrative comparisons describe decisions, not completed projects.
Compare three building sections
| Proposed design | Removal question | Professional decision |
|---|---|---|
| Foundation removed | Which above- and below-grade elements are included? | New excavation and foundation design |
| Part of the foundation retained | Where are the reviewed retained and removed limits? | Connections, temporary conditions and receiving inspection |
| Above-grade construction removed | What must remain around the retained foundation? | Suitability and preparation for the new building |
These are illustrative sections, not details for carrying out the work. No local retained-foundation project is being claimed. The actual structure and approved design determine whether MetroPoint can accept the defined removal.
Describe the retained edge precisely
Ask the engineer and rebuilding contractor what condition is required at walls, openings and other interfaces after demolition. A general instruction to leave the foundation can omit slabs, stairs or connections that need separate decisions.
Record information still awaiting review. If the intended reuse changes, revisit the removal scope before treating the old plan as authority. The demolition enquiry should identify the design revision and the person responsible for resolving the retained construction.
Plan the interval before rebuilding
The GC or owner must assign access, temporary protection and site control between the old building leaving and new work starting. Inspection and any further investigation belong in that sequence. Retention does not remove the need to review the exposed condition.
Excavation, underpinning, new concrete and specialist cutting/coring are not automatically included in ordinary removal or concrete breaking. Keep their providers and interfaces explicit if the design requires them.
Enquire against the retention design
Provide the property, existing information, engineer's intended retained elements and rebuilding contractor's requirements. Explain which parts of the foundation decision are settled and which remain conditional. MetroPoint can then assess the demolition contribution without promising reuse suitability or a complete foundation-renewal package.