Cavity wall or ceiling cistern?

[Ahearsum]

I'm planning a wetroom in a very small space 1m x 2m (see attached). I want to maximise the space by having a cistern entirely in the stud wall including the waste . Two questions really
1. Is there a cavity wall cistern that fits completely inside a100mm cavity?
2. Is there such a thing as a cavity ceiling cistern? I would have around 160mm space above the lowered ceiling.

Thanks

 

[ShaunCorbs]

Yes toilet frame

 

[Ahearsum]

Yes toilet frame

Thanks Shaun for replying. I'm aware of various brands that do a cavity wall cistern with or without a frame but any that I have found exceed the 100mm I have available. Do you have a particular one in mind that fits the space?

 

[ShaunCorbs]

Soil goes underground?

 

[Basher]

Thanks Shaun for replying. I'm aware of various brands that do a cavity wall cistern with or without a frame but any that I have found exceed the 100mm I have available. Do you have a particular one in mind that fits the space?

Concealed Cisterns & Frames

Wall mounted, slimline and concealed toilet cisterns are ideal for small spaces. We sell leading brands at great prices. Easy to install and lengthy guarantees.

www.drench.co.uk

Are you mounting the toilet on the floor, with the soil pipe straight down?

 

[ShaunCorbs]

https://catalog.geberit.co.uk/en-GB/Geberit-Sigma-concealed-cistern-8-cm,-6-/-3-litres/PRO_168869.html

 

[Ahearsum]

Concealed Cisterns & Frames

Wall mounted, slimline and concealed toilet cisterns are ideal for small spaces. We sell leading brands at great prices. Easy to install and lengthy guarantees.

www.drench.co.uk

Are you mounting the toilet on the floor, with the soil pipe straight down?

Thanks for that. I'm not sure yet what is under the floor so uncertain. Ideally a wall hung pan I think

 

[Ahearsum]

https://catalog.geberit.co.uk/en-GB/Geberit-Sigma-concealed-cistern-8-cm,-6-/-3-litres/PRO_168869.html

Hi Shaun thanks for that. The link didn't work for me but I think it was probably the same product as this maybe? Geberit Duofix WC Frame 1.14m With Sigma Cistern 8cm - 111.799.00.1 - https://www.tradingdepot.co.uk/geberit-duofix-wc-frame-1-14m-with-sigma-cistern-8cm

 

[Basher]

Thanks for that. I'm not sure yet what is under the floor so uncertain. Ideally a wall hung pan I think

How will you get the 140mm waste pipe in the 100mm cavity?
If you use a frame at the front of the wall, you'll have to find more space at the back to accommodate the waste?
I don't understand your design 🤔

 

[Ahearsum]

How will you get the 140mm waste pipe in the 100mm cavity?
If you use a frame at the front of the wall, you'll have to find more space at the back to accommodate the waste?
I don't understand your design 🤔

I'm not 100% sure but this model seems to suggest the waste is a smaller diameter until it goes below the floor. Do you think I'm correct in inferring that from the last diagram? Geberit Duofix frame for wall-hung WC, 114 cm, with Sigma concealed cistern 8 cm - https://catalog.geberit.co.uk/en-GB/products/PRO_168879.html. The tech drawings of this alternative cistern also suggests that the soil pipe is stepped down in size inside the cavity wall: 748-5805-01 - Vitra 8cm Slim Wall Hung Toilet Frame : Bathroom Planet - https://www.bathroomplanet.com/product/vitra-concealed-cistern.html?vid=14977&gclid=CjwKCAiA55mPBhBOEiwANmzoQj8N0Autn6xSN6ry_0X0GUCi17_txDVdUqnQg2yo4m1fRUGtZlRMlRoClGYQAvD_BwE. Am I misreading these drawings?

 

[Ahearsum]

I'm just now beginning to wonder about the condensation issue with stud wall cisterns. Does anyone have a view in that? The condensation on the outside of a normal exposed ceramic cistern in a warm bathroom is pretty copious.

 

[ShaunCorbs]

Yes or

Geberit 109.792.00.1 Sigma Concealed Flush Cistern 8cm 6/3 L

The Geberit Sigma Concealed Flush Cistern 8cm 6/3 Litre Including Flush Pipe is a high quality well designed cistern that offers good value. It's been designed for use with Sigma Flush Plates that are sold separately.Application PurposeFor drywall constructionFor installation in part- or...

www.builderdepot.co.uk

Depending on waste pipe

 

[Basher]

I'm not 100% sure but this model seems to suggest the waste is a smaller diameter until it goes below the floor. Do you think I'm correct in inferring that from the last diagram?

I think you are correct - 90mm dia. Looks like what you are after, as long as the soil pipe can go straight down, or you relieve the wall behind for the pipe.
Also, re your following posting, the spec says the cistern is insulated against condensation!

I don't think you are misreading the drawings. Either look like a possible solution for your plan.
Now I understand!