Where required due to local conditions, an approved barrier membrane can be installed in the under build. Please consult your local building control authority.
Where units share an intermediate bearing wall, a minimum bearing of 100mm should be provided in all instances.
Installation without a void offers considerable savings on the cost of spoil removal.
Where ground conditions permit (unaffected by heave or shrinkage) installation without a void is possible.
An approved damp proof membrane suitably detailed is required to prevent ingress of moisture from the ground.