I'm looking for advice on how the drainage would most likely be installed/altered from existing to proposed layouts below. I'm hoping to get an idea of the extent of the work involved. I understand the floor will have to be cut and dug up then made good once the drainage has been installed. Thanks in advance.
Welcome to the Bunnings Workshop community @GC9114. It's great to have you join us and we are looking forward to seeing how you can transform your bathroom. Can I ask what is your aim for this project?
Apologies for the delay in getting back to you. Let me tag one of our resident Bunnings D.I.Y. experts in @EricL as well as experienced members @Vis-á-vis and @redbournreno to help kick off the discussion.
We trust you'll get loads of helpful advice and inspiration for all your projects from our wonderful community.
When you say the floor cut then I assume you are on a concrete slab?
Ultimately a plumber will need to advise you but most of what you have seems like not much of a change. Falls in the waste pipe from your shower and vanities can have a fair bit of variance so long as they meet a minimum. Falls from the WC are not so flexible - you need a minimum amount of fall to take the water away but too much and the water will run too fast leaving solids behind.
Everything will really depend on where your current waste pipes fall to and how far away they are from the proposed WC.
Most things are possible these days. You just need to be flexible to a degree and have a good plumber on hand.
@Jason thanks for the reply, aim of the project is to make better use of such a large bathroom that is attached to a guest room. The changes will add a grnd floor wc that has its own access rather than entry through the laundry. Also there will be much needed modernisation of the room.
@Vis-á-vis thanks for the comments. I understand the falls etc being in construction most of my life. How would the the plumber determine where the drains ran? Service locator with attack wire? Camera?
If I understood plumbing wizardry then I too would have a couple of boats and a choice of vehicles to tow them.
More seriosuly.. start off with an educated guess. Look at you property and then check on dial before you dig to see where the main sewer lines run. Is your new plumbing upstream or downstream of existing plumbing? How far away? If you are downstream then it should be fairly easy to plumb in to the existing pipe. If you are upstream then measure from your new WC to roughly where the outlet for the old one is, work out a minimum fall of 1 in 40 and a max of 1 in 100 and see what that gives you in overall drop in height. Is that number within the thickness of your slab? If so then you are probably fine, if not call a plumber.
There doesn't appear to be an incredible amount of drainage that needs to be installed here. The shower stays the same, and the corner bath is being replaced with a standard one. So, it's just the two vanities that need the wastes connected and a toilet on the external wall. Hopefully, the sewer runs outside, and the plumber can connect the new toilet to it without cutting across the slab. As @Vis-á-vis mentioned, it really depends on where that sewer line runs. I believe there are options out there for the vanities to run the wastes through a cavity wall's thickness. This depends once again on where the sewer line is.
Ultimately it's going to be the plumber you've contracted that dictates how they'll connect up the wastes. I'd suggest getting a couple of quotes to gauge the extent of the work involved.
Please let us know if you have further questions.
@MitchellMc thanks for the comments. If the sewer line does run down the outside of the property, hope it does, would the toilet waste be likely to go through the wall and then dig down on the sewer to connect. Haven't engaged a plumber as yet just trying to get my head around it so I don't get given any bull. Thanks again
@Vis-á-vis thanks for the comments. New wc is downstream of existing, so here's hoping the sewer is outside the building.