Inspection Chambers ~ these provide a means of access to drainage
systems where the depth to invert level does not exceed 1„000.
Manholes ~ these are also a means of access to the drains and
sewers, and are so called if the depth to invert level exceeds 1„000.
These means of access should be positioned in accordance with the
requirements of part H of the Building Regulations. In domestic
work inspection chambers can be of brick, precast concrete or
preformed in plastic for use with patent drainage systems. The size
of an inspection chamber depends on the depth to invert level,
drain diameter and number of branch drains to be accommodated
within the chamber. Ref. BS EN 752: Drain and sewer systems
outside buildings.
Typical Details ~
brick levelling course
one brick wall in
dense engineering
quality bricks
bedded in cm. mt.
(1:3) and laid in
English bond
branch drain
150 mm thick
mass concrete
(1:3:6) base
brick levelling course
precast concrete
cover slab
precast concrete
chamber sections
to BS 5911- 4, circular
or rectangular
shapes available
precast concrete
base unit with main
channel and branch
channel(s) cast in as
required
branch drain
step irons required for invert levels over 1„200 deep
600 × 450 light duty cover and frame
bedded in cm. mt.
600 × 450 c.i. cover and frame
600 minimum
1:6 fall
main
drainage
channel
100 mm thick
precast concrete
slab
150 mm mass
concrete
encasing
required in wet
subsoils
25 mm thick (1:1)
cement/sand
topping to 1:6
fall over mass
concrete benching
main
drainage
channel
arch or
lintel
over pipe
Simple Drainage---Inspection Chambers