Adding underfloor heating will add ??? to the height of the floor!!!

[Aspesim]

Hi

I have floor joists first (with extra noggins) then 18mm WBP plywood going down which will be screwed down, then 6mm Hardie Backer Board before the tiles go on. With the current set up it would be approx 17mm above the currnet level. There is approx 15mm dip from the hallway into the bathroom so it would ballance itself out...

Question is now "The Boss" is thinking about underfloor heating as well. How much more would it add to the levels? Do you need a special board to reflect the heat upwards, or is it just a mat?

Thanks for you help and advise as always

[timeless john]

It would add only about 3/5mm for the wires and straight onto the Hardie boards.
If it were my job I'd 100per cent have it. In the winter it makes all the difference.

[blocko]

I agree with John, fit and not regret. Approx 5mm addition in height

[kendo1]

Remember the size of the sensor.

[Mike]

i 'sink' the sensor into the cement board so it doesn't add any height to the floor . you could use insulation boards instead of cement boards to enhance the performance of the ufh and it's highly advisable to cover the ufh cables with slc (self levelling compound) to prevent damage to the cable and prevents any cable not being covered. i always use mapei renovation screed which is flexible and usable over wood.

[Dave]

Hi.

Plywood is a good insulator , so IMO you will be ok to put the UFH straight
on the hardibacker.

Then cover over with min 5mm fibre enhanced SLC.

Extra height ? 5mm.

But check with SLC spec for min thickness with UFH on timber.

[blocko]

Remember the size of the sensor.

As Mike....I always sink the sensor so it is level with the UFH cable

Dont forget to fit the sensor in the enclosed sensor tube (or make one yourself) so it can be replaced if it ever fails. I have mounted two sensors before and left the tails of the wires taped to the inside of the dry-lining box just in case.

Here is a useful post.... sensor tube

[paulpa]

Get it.
This gives an idea of what you need.
Underfloor Heating | Underfloor Heating Systems

[Aspesim]

Hi guys

Thanks for the advice. I have purchased Warmup loose cable and 6mm Warmup insulation boards.

With everything within these help forums too much info can be dangerous, overwelming or in my case confusing...

Would this installation be wrong?
Bal Prime all sides of the plywood
18mm WBP then screwed into the joists
Tank plywood with Bal Tanking system
Using tile addy install Hardie Backer Boards and mecanically fix
Using tile addy Install insulation boards
Install warmup cable
Using tile addy install tiles

I would avoid slc like the plaque if I can (You'll think it would be a simple job but not for me... I don't know why!!!!)

Cheers
Simon

[blocko]

Would this installation be wrong?

Bal Prime all sides of the plywood
18mm WBP then screwed into the joists
Tank plywood with Bal Tanking system
Using tile addy install Hardie Backer Boards and mecanically fix
Using tile addy Install insulation boards
Install warmup cable
Using tile addy install tiles
I would avoid slc like the plaque if I can (You'll think it would be a simple job but not for me... I don't know why!!!!)

I would do it this way.......

1. Bal Prime all sides of the plywood
2. 18mm WBP then screwed into the joists
3. Using tile addy Install insulation boards and mecanically fix (feel free to tape joints to make floor fully waterproof)
4. Install warmup cable
5. Cover cable with SLC (it really isnt as scary as you may think!)
6. Using tile addy install tiles

You do not need hardibacker & Marmox...... if it is a tanked floor you are trying to acheive, then I would forget the hardi and BAL tanking and opt straight for the Marmox with joints taped. This will be 100% waterproof, will serve as an excellent backer board and result in quick warmup times. Oh, and Marmox is lighter, easier to cut and less hassle to use