ᐅ Is it advisable to lay tiles over existing tiles when using underfloor heating?
Created on: 5 Jan 2017 07:26
T
thesit27Hello,
we have the opportunity to buy a house.
There is underfloor heating installed on the ground floor, but the tiles are old and not very appealing.
We would like to replace them.
What would be the best approach? Remove the old tiles or lay new tiles on top of the existing ones?
We would definitely prefer the second option. Has anyone done this at home?
Will the heat still be distributed effectively?
Additional information:
- The build-up height is not critical, as we would replace the doors.
- Our preferred tiles measure 600 x 300 x 10 millimeters (24 x 12 x 0.4 inches).
I would appreciate any advice.
Thank you
we have the opportunity to buy a house.
There is underfloor heating installed on the ground floor, but the tiles are old and not very appealing.
We would like to replace them.
What would be the best approach? Remove the old tiles or lay new tiles on top of the existing ones?
We would definitely prefer the second option. Has anyone done this at home?
Will the heat still be distributed effectively?
Additional information:
- The build-up height is not critical, as we would replace the doors.
- Our preferred tiles measure 600 x 300 x 10 millimeters (24 x 12 x 0.4 inches).
I would appreciate any advice.
Thank you
H
HilfeHilfe5 Jan 2017 07:33But then it would be colder at the feet. The additional tile layer acts more as insulation.
thesit27 schrieb:
What is the most practical option? Removing the old tiles or laying new tiles over the existing ones? In my opinion, the best approach is to remove the old tiles first and then install the new ones. That’s what I did myself. Otherwise, what happens if renovations are needed again in 20 years?
I also don’t recommend just wallpapering over existing wallpaper. That only postpones the problem. It’s better to do it properly right away.
With underfloor heating, laying tiles over the existing ones will probably make the system even less responsive because there is more material to heat up. I think that can only be a temporary solution.
Hello "thesit27".
Every building material has a so-called thermal resistance.
We are talking here about a warm water underfloor heating system and ceramic tiles. As the thickness of the material (the tiles plus tile adhesive) increases, this thermal resistance also increases.
Depending on whether the underfloor heating system was designed with tight limits or not, doubling the layers with a second tile level may result in the rooms no longer heating adequately.
Doubling the layers is therefore risky, and I would not recommend it.
I suggest the following solution:
Have the old tile layer ground down with a diamond blade, vacuumed, primed, and then filled with a smoothing compound at least 2mm (0.08 inches) thick. While the smoothing compound is still fresh, embed a load-distributing glass fiber mesh into it, press it in using a spiked roller, and apply another layer of smoothing compound over it. This setup prevents the grout pattern of the old tile layer from later showing through the new surface.
After sanding the cured smoothing compound again, have a design floor covering fully bonded over the entire surface using an adhesive method installed.
By design floor covering, I mean PVC planks with convincingly realistic wood or stone patterns.
This results in a reduced total build-up height of approximately 7mm (0.3 inches).
With a 10mm (0.4 inches) thick ceramic tile, plus about 2mm (0.08 inches) for the adhesive bed, the total build-up would be roughly 12mm (0.5 inches).
----------------
Another solution (without removing the old tiles) would be to grind the old tiles with a diamond blade, vacuum, and perform a scratch coat over the grout lines using a reaction resin mortar.
Then prime the entire surface with an epoxy resin while still in its wet phase, broadcast it with fire-dried quartz sand 0.3/1.2mm (0.01/0.05 inches), allow it to cure, sweep off the excess sand, lightly sand with a rotary floor sander, vacuum, apply a 2mm (0.08 inches) smoothing compound layer, and then bond a PVC design floor covering onto this.
This method results in approximately 4–6mm (0.16–0.24 inches) total build-up height.
The required heat transfer would definitely be ensured with this approach.
----------------------
Good luck with your project: KlaRa
Every building material has a so-called thermal resistance.
We are talking here about a warm water underfloor heating system and ceramic tiles. As the thickness of the material (the tiles plus tile adhesive) increases, this thermal resistance also increases.
Depending on whether the underfloor heating system was designed with tight limits or not, doubling the layers with a second tile level may result in the rooms no longer heating adequately.
Doubling the layers is therefore risky, and I would not recommend it.
I suggest the following solution:
Have the old tile layer ground down with a diamond blade, vacuumed, primed, and then filled with a smoothing compound at least 2mm (0.08 inches) thick. While the smoothing compound is still fresh, embed a load-distributing glass fiber mesh into it, press it in using a spiked roller, and apply another layer of smoothing compound over it. This setup prevents the grout pattern of the old tile layer from later showing through the new surface.
After sanding the cured smoothing compound again, have a design floor covering fully bonded over the entire surface using an adhesive method installed.
By design floor covering, I mean PVC planks with convincingly realistic wood or stone patterns.
This results in a reduced total build-up height of approximately 7mm (0.3 inches).
With a 10mm (0.4 inches) thick ceramic tile, plus about 2mm (0.08 inches) for the adhesive bed, the total build-up would be roughly 12mm (0.5 inches).
----------------
Another solution (without removing the old tiles) would be to grind the old tiles with a diamond blade, vacuum, and perform a scratch coat over the grout lines using a reaction resin mortar.
Then prime the entire surface with an epoxy resin while still in its wet phase, broadcast it with fire-dried quartz sand 0.3/1.2mm (0.01/0.05 inches), allow it to cure, sweep off the excess sand, lightly sand with a rotary floor sander, vacuum, apply a 2mm (0.08 inches) smoothing compound layer, and then bond a PVC design floor covering onto this.
This method results in approximately 4–6mm (0.16–0.24 inches) total build-up height.
The required heat transfer would definitely be ensured with this approach.
----------------------
Good luck with your project: KlaRa
@ "77.willo":
1. There is no such thing as THE thermal resistance value, and
2. the overall thermal resistance depends on the material-specific thermal transmittance coefficient (U-value) and the thickness of the material, as well as the interface resistances between different layer sequences (which we do have in this case).
The topic of thermal transmittance in relation to the energy needed to heat a room is highly complex and cannot or should not be reduced to empirical values (of thermal resistance).
After all, the person asking the question ultimately bears the cost (figuratively speaking) for a floor structure that is incorrectly dimensioned based on legally non-binding advice given in a public forum.
My statements, as outlined above, are professionally sound (since they relate to my area of expertise) and at least guide the questioner in the right direction. However, the final decision always remains with them.
------------------
Regards: KlaRa
1. There is no such thing as THE thermal resistance value, and
2. the overall thermal resistance depends on the material-specific thermal transmittance coefficient (U-value) and the thickness of the material, as well as the interface resistances between different layer sequences (which we do have in this case).
The topic of thermal transmittance in relation to the energy needed to heat a room is highly complex and cannot or should not be reduced to empirical values (of thermal resistance).
After all, the person asking the question ultimately bears the cost (figuratively speaking) for a floor structure that is incorrectly dimensioned based on legally non-binding advice given in a public forum.
My statements, as outlined above, are professionally sound (since they relate to my area of expertise) and at least guide the questioner in the right direction. However, the final decision always remains with them.
------------------
Regards: KlaRa
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