How to add a bathroom floor waste?

[BryceBrad]

Hi All,

Curious to how others tackle this problem. I have a combined bathroom and shower upstairs. It came without a floor waste so part of the renovation would be to add one (if possible). The screed would need to be at least 15mm thick and by the time is it tiled the floor level in the bathroom will be about 25mm higher than the floor outside the bathroom(carpet). 

Would like to have that piece of mind in case flooding occurs however, if not possible may have to continue without one.

Thoughts

[EricL]

Hello @BryceBrad

I'm curious why the original builder had to increase the height of the shower base. But here are some of my observations concerning your desire to put in a floor waste. Is your floor solid cement or framed timber? If it is timber, the position of your waste will be based on the direction the timber bearers are facing. If the conditions of your plumbing are favourable the plumber should be able to add an extension pipe. 

The other option of course is to add the extension piece from the waste pipe of the basin. When I say favourable conditions, it means that the conditions are right and that an extension is possible. For example, there is enough room to place a 90-degree elbow in the floor without resorting to using special fittings. There is enough room to place a puddle flange without increasing the floor height. Other plumbing conditions will need to be met before the plumber can say ok.

All these factors will come out once you remove your tiles in the bathroom. But only your plumber will be able to make the decision if a waste can be installed or not. The second option will be that the plumber will tell you how much the floor needs to increase to make putting a waste possible.

Let me call on our experienced members @TedBear, @tom_builds, and @Brad for their thoughts on adding a waste to your floor.

Please keep us updated with your progress, we look forward to seeing the start of your renovation.

Eric

[BryceBrad]

Thanks for the detailed response Eric. It is appreciated. The floor is timber and I suspect the timber joists run across the room(from the camera angle towards the shower base or from door to the shower base). I suspect the base may have been increased to fit a puddle flange (an assumption).

I get your point in relation to shower base, there seems to be minimum clearances needed for AS 3500 for the puddle flange. I guess once demolition occurs and the the plumber has a look he will be able to provide input on the whether we need a screed or we can get away without it. 

Thanks

[Vis-á-vis]

Hi,

Your screed will need to be a minimum of 15mm at the waste. You will then need to work back from the waste allowing a minimum of 1mm increase every 100mm to get your new floor height at the room perimeter and door. You can get as low as 10mm if you use something like Abecrete instead of water to mix your screed. If your waste is 2M from the door then you'll have a 35mm thick screed at the door.

It would be a personal choice but I wouldn't like anything more than a 15mm height difference between rooms. I have rebuilt bathrooms where there was an 18mm height increase but that was always meeting a timber floor so we just popped the edge of that first tile up by 1mm and used some 19mm quad on the outside. It looked ok given the join was under the door.

Ideally, if time and money allow, I always try and reduce the height of the bathroom subfloor if we are trying to get a walk-in or screeded/waterstop shower base. It requires cutting of some joists, checking out the height of others and installing new joists at the correct height.

Another option that may be open to you is to forget about the screed and take up your flooring. Can't say exactly what you have down under the tiles but a good chance it will be either 19mm particle board or 19mm timber. If you replace that with 19mm Scyon cement sheet then your level will remain the same and you will have a much quieter and stronger floor. Sometimes, old bathrooms have tiles glued directly to a particleboard floor, if that has been done then you'll have to put 6mm cement sheet down which will increase the height of the floor. Again the only way around this is to take out the floor and put in 19mm cement sheet which you can tile directly over.

My main concern is having a shower floor higher than the rest of the bathroom. This may of been done as a plumbing necessity or just poor design. Until you rip that floor up you won't know.

[MitchellMc]

Many thanks for taking the time to put such a detailed response together, @Vis-á-vis. I trust @BryceBrad really appreciates your expert knowledge.

Mitchell

[BryceBrad]

Thanks @Vis-á-vis

Appreciate your detailed response. Once the floor is ripped out we should be able to work out what's required. I was trying to plan ahead.