Thread: Bathroom Drainage

Fall isnt such a scary thing, if you have a floor waste, you have the floor falling towards it, and since the majority of floors are tiled on a screeded cement bed, its common practice.
And where a LOT of people come unstuck trying to save a buck is leaving out details such as this, which more often than not ends up having to be ripped out and done again, properly.

Is there a fall ratio specified in the Australian Standards or Building codes?

In South Australia there is a recommendation in the Minister’s Specification SA F1.7.


2.0 Floor Drainage
2.1 Floor waste
Notwithstanding the requirements of the Waterworks Act 1932, the Sewerage Act 1929 the
requirements of AS 3500 and the SA Variations and/or Additional Provisions to the National
Plumbing and Drainage Code AS 3500, the following applies;
(a) Drainage of a wet area floor to a floor waste shall be provided to the following
(i) a bathroom; or
(ii) areas adjacent baths and spas (including the floor under a free standing bath);
or a
(iii) room containing a shower; or a
(iv) room containing a sanitary fixture.
(b) A bathroom floor or floor of a room containing a shower, may drain to a shower waste
within a shower area, provided the water can drain from the wet area floor to the
shower waste without ponding.
(c) Drainage of a wet area floor to a floor waste is not required when all the fixtures within
a room are provided with in-built or attached overflow protection, connected to the
sanitary fixture drainage.
2.2 Falls to floors
Unless stated otherwise in this Specification the floor must drain such that water does not pond
on the floor. The recommended ratio of fall in a shower area is between 1:60 and 1:80 and the
recommended ratio of fall in other wet areas that are required to drain to a floor waste is
between 1:80 and 1:100.
NOTES:
Additional requirements for the drainage of wet area floors in sanitary facilities for people with
disabilities are contained in AS 1428. 1.
Generally, at the entry to a shower area there shall be no step down or hob. The following
drainage requirements also apply;
(a) the shower waste shall be as near as practicable to the centre of the shower area; and
(b) the ratio of fall to the shower area shall be between 1:50 and 1:60
(c) the ratio of fall to the room containing a sanitary fixture shall be between 1:70 and 1:80

Clause G.8.1(c) of the South Australian Housing Code (SAHC) provides a concession which dispenses with the requirement to drain the wet area floor
to a floor waste, as long as all sanitary fixtures within the room are provided with in-built overflow
protection.
The definition of sanitary fixture states that for the purpose of the SA Housing Code a shower is not a
sanitary fixture.
Therefore, the concession provided by G.8.1(c) has no effect on a room containing only a shower—
because there are no sanitary fixtures within the room.


Cheers

I am planning to renovate a bathroom which is built on a concrete slab in a Sydney 1950's double brick house. The bathroom is entirely usable and sound, but is the pink colour scheme of the era. I have already replaced all the tapware for basin, bath, shower and will be replacing the gravity hot water heater with a mains pressure water heater.

The floor is mosaic tile with a fall to the drain off centre. The mosaic tiles are on a screed which raises the floor about 20mm above the timber floor in the rest of the house.

I would appreciate some advice on:
- Is it possible to lay new tiles on top of the old?
Pros - No additional work to lift the tiles, the floor fall is in place
Cons - Raises the floor another15-20mm ie almost a real step

- The drains are old style drains leading to terra cotta piping, what is the best drain fitting for the floor that will "fit" into the older pipes?
- I plan to waterproof the shower stall so the floor tiles would need to be lifted