floor wastes in laundries - qld based home and the qdc
Generally, floor wastes in laundries can be dry wastes or wet wastes.
The difference being a dry waste is a non charged waste pipe, that is, no active water flowing through it.
Wet wastes are those charged by other fixtures, as in water flows through them and they have a trap.
Either way, if a dry or wet waste is installed, under the new NCC 2022 fall is required - EXCEPT, there is a performance solution that fall is not required if installing a linear drain or a weir at the entrance to the room.
A weir is a little tile ramp up to the outside of room floor level.
Getting a linear waste installed means that the concretor doing your slab only has to provision a recess (normally they use a bit of LVL timber to do this - dieseled up so it can be removed after pour - or wrapped in plastic) larger than the strip drain that will be inset into the slab to meet the finished floor level of your laundry.
I would make sure if doing the linear drain option that the laundry wastes were charged/wet wastes so they did get flushed from time to time.
The only cost factors to consider here is the supply of the linear drain and floor waste (smart waste) - will be $150 minimum for the linear drain and $50 for the smart waste, the supply of two additional underslab waste points (drainer) (one for the FWG the other for the linear drain) the forming of the recess cost to the concretor (maybe $50 or $75 max) the install of the drain by the tiler, (say $100-$150 to bed and set the drain in place).
When smart wastes are used the slab must be "scooped out" while wet, around the waste to allow for the smart waste to be installed (the depth of the fitting).
Finally, if your concerned about water overflow/exposure from washing machine or sinks etc, get the laundry floor fully waterproofed and make sure that the waterproofing is ABOVE any screed, even through you shouldn't need a screed or falls if you do the linear drain to the door performance solution.
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