Lowering an internal floor can transform a property.
It may provide greater ceiling height, improve a basement conversion or help create a level connection between different parts of a building.
But lowering a floor can also involve significant excavation and structural work.
Where the property shares walls or structures with a neighbour, Party Wall considerations should be reviewed before works begin.
Why can lowering a floor affect a neighbour?
Excavating an existing floor often means going below the level of the original foundations.
That can potentially affect the stability of walls around the excavation.
If those walls are party walls, or the works are close to neighbouring structures, the Party Wall etc. Act 1996 may apply.
Basement and lower-ground-floor projects
This is particularly relevant to basement and lower-ground-floor works.
Projects may involve:
- underpinning;
- excavation below existing foundations;
- new retaining structures;
- structural alterations to party walls; and
- waterproofing systems.
These are considerably more involved than simply replacing a floor finish.
Engineering information will normally be important
Before the Party Wall position can be properly assessed, structural details may be required.
A structural engineer may need to specify:
- excavation depths;
- temporary works;
- underpinning arrangements;
- sequencing;
- retaining walls; and
- safeguarding measures.
Neighbours are understandably cautious
Deep excavation close to an adjoining property can cause concern.
Clear drawings and a properly prepared Party Wall Award can help explain exactly how the work will be carried out and what protections will be in place.
Do not leave this until excavation starts
Party Wall issues should be dealt with before contractors begin removing floors or exposing foundations.
Once excavation is underway, resolving procedural problems becomes much more difficult.
Simple Survey can assist
If you are proposing to lower an internal floor or undertake basement excavation, Simple Survey can review the project and guide you through the Party Wall process.
Contact us at the design stage so we can help identify the relevant notices and keep the project moving.