Building Construction Handbook, Eighth Edition

This drawing should be read in conjunction with page 215 †

Foundation Beds.

A domestic solid ground floor consists of three components:-

1. Hardcore † a suitable filling material to make up the top soil
   removal and reduced level excavations. It should have a top
   surface which can be rolled out to ensure that cement grout
   is not lost from the concrete. It may be necessary to blind
   the top surface with a layer of sand especially if the damp-
   proof membrane is to be placed under the concrete bed.


2. Damp-proof Membrane † an impervious layer such as heavy
   duty polythene sheeting to prevent moisture passing through
   the floor to the interior of the building.


3. Concrete Bed † the component providing the solid level surface
   to which screeds and finishes can be applied.
   Typical Details ~

external wall

insulated screed

a damp-proof membrane in this

position is easier to incorporate

in the floor but gives no protection

to the concrete bed against ingress

of moisture

a damp-proof membrane in this

position protects the concrete bed

from the ingress of moisture and

harmful salts ... risk of damage to

dpm when concrete is being placed

dpc dpc

225 min.

below

lowest

dpc, or

dpc

stepped

hardcore

DPM PLACED BELOW

CONCRETE BED

DPM PLACED ABOVE

CONCRETE BED

15 N/mm^2 (1 : 3 : 6)

mass concrete

foundations

150 min.

NB. a compromise to the above methods is to place the dpm in the

middle of the concrete bed but this needs two concrete pouring

operations.

Domestic Solid Ground Floors