Bathroom renovation: underfloor heating + enlarging bathtub / floor slab opening

  • Erstellt am 2017-01-08 22:32:10

BenjaminJ

2017-01-08 22:32:10
  • #1
Hello forum,

since this is my first post here, a few words about me first:

My name is Benjamin, I turned 30 a few days ago, and the reason I registered here is that my girlfriend and I bought a larger house, which was generously built in 1965 and then just as generously "neglected". In this specific case, the situation is as follows:

We are currently renovating the bathroom. The house already had underfloor heating as well as partial wall heating installed in 1965. The structure appears to be as follows:

- Screed
- Ventilated clay blocks, the steel pipes with aluminum fins are embedded in the clay blocks
- 2cm cork
- Sand layer
- Solid concrete ceiling

In the bathroom, a 170x70 bathtub (corner position) was installed:



As I personally find it reasonable, the tub together with its masonry support did not stand on the screed but on the floor slab, so the screed is recessed accordingly (dimensions can be seen from the black still standing skirting boards in the picture). Now, however, we definitely want to install a 190x90 tub, and logically the recess in the screed is now smaller than the tub itself. It would be possible to place the feet on the floor slab, but the new tub should also be underpinned and this underpinning would now be supported on the screed. I have not been able to find such a configuration anywhere on the internet so far, only either everything on the screed or everything on the floor slab.

The question is now:
I do not know exactly how the heating pipes are laid. Option A would be to carefully enlarge the recess slowly by chipping at one spot in order to find out where the nearest steel pipe lies in the floor. If there is enough distance, enlarge the recess and also build the bathtub support on the floor slab.
Option B would be as described above, to place the tub with the 4 feet on the floor slab and build the support on the screed.

1) Is there anything against Option B if done correctly (here I mainly imagine sealing to be difficult because of the moving screed)?

2) How can I / can I at all create proper protection against water damage in the floor with Option A and B? Especially because of the steel pipes, I am not keen on this, likewise I would gladly avoid a wet workshop ceiling below. But I have read that such sealing is disproportionately difficult to implement with installation on the floor slab.

Please note that the relevant work will also be carried out by professionals. However, I like to inform myself about the topic in advance to ensure that I can identify workers who do not work properly in order to ensure a proper end result.

I would be very happy about suggestions and tips from you and wish you a pleasant start to the working week in advance.

Best regards,
Benjamin
 

Koempy

2017-01-08 23:04:41
  • #2
A 50-year-old underfloor heating system? It has reached the end of its lifespan. In case of water damage, no insurance will pay anymore.

Are you gutting the entire house? If yes, then replace all the water pipes as well. And preferably replace the underfloor heating too.

I think the bathtub is the least of the problems.
 

BenjaminJ

2017-01-09 08:53:02
  • #3
Hello Koepy,

thank you for your reply. Do you have experience with the underfloor heating system? Or what is your statement based on? Both the heating installer and the architect were very quickly in agreement: "This system is indestructible as long as no external corrosion attack occurs, the steel pipes are very robust especially in connection with the boiled heating water."
Yes, water pipes and electrical wiring will be completely redone.

I am still interested in the matter with the bathtub.

Regards,
Benjamin
 

AOLNCM

2017-01-09 12:19:45
  • #4
Option C: If you absolutely want the recess and can borrow a thermal imaging camera. Let the underfloor heating in the bathroom cool down first, then turn it to full power, and mark the course of the underfloor heating pipes with the thermal imaging camera while heating up. Create a predetermined breaking point in the screed with a grinder and separate it with a mallet and chisel.

Option D: Place insulation boards in the existing recess. Close the recess with new screed. Set up the new bathtub on the screed.
 

BenjaminJ

2017-01-09 12:55:29
  • #5
Option C sounds good, I might even be able to borrow a thermal imaging camera from work.

Option D would be a good idea as a last resort, primarily I want to try to place the tub on the floor slab.

Can you say something more about Option B (tub on floor slab, support on screed)?
 

AOLNCM

2017-01-09 13:17:52
  • #6
That depends on the execution. But it is also sometimes done when another shape, e.g. corner bathtub, is to be installed. The bathtubs are often enclosed with aerated concrete blocks. Mosaic is often used as tiles. For corner bathtubs because of the curves, but also in the case of possible transverse loads, cracks are hardly visible in mosaic. Corners and transitions to other materials are provided with expansion joints.
 

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