Heated floor in old house

[Bardal]

Just on two points:

- you can also include the pipes of the PC in the mortar laying tiles, which decreases a little the total thickness (6 cm laying mortar + tile or stone) ...

- A pc will have a lot of inertia, especially in these thicknesses, certainly. But this does not add to the inertia of the walls (one is inert with respect to the production of heat, the other is inert with respect to the atmosphere), on the contrary, the inertia of the walls will attenuate largely the disadvantages of the inertia of the heat emitting pc, if at least the house is heated permanently and not sequentially. The only drawback will be that it will take a long time to warm up after a shutdown and a general cooling ...

[florid]

It is true Bardal the inertia of the walls and that of the floor do not add up directly, nevertheless the walls make a lot of mass and I wanted to have a greater reactivity in slimming the coping on the cork. Relative reactivity, I am aware, since obviously, I will not heat sequentially but by modulating the speed of circulation and / or the temperature of the water. The trickiest thing is to find the regulation that goes well.

in any case thank you for your help guys / girls

[Bardal]

I understand your concern, but the thickness of the screed including the pipes has little to do with the nature of the insulation; with a lime screed, which can not be armed with a steel trellis, it is almost obligatory to be a little thicker than with reinforced cement; but 6 cm of screed, including mortar laying stone facing, that's not much ...

On the inertia, it is necessary to see that these are two different processes for the pc and for the walls: suppose a house stabilized with 20 ° C; walls will tend to be close to 20 ° (maybe 15 or 16) and will tend to stay that way; they will stabilize the temperature of the house in case of temperature variations due to heating or external; their inertia will thus constitute an element of stable comfort ...
For this same situation, the pc will rather be at higher temperature, allowing a heat input covering the losses; in the event of an increase or decrease in external inputs, the inertia of this floor will prevent it from following the new needs (which should be its role) and will lead to overheating or under-heating situations, unlike to the inertia of the walls which will tend to stabilize the temperature. The ideal would even be that you could make an external insulation to optimize this inertia of the walls ...

Last but not least, there is an idea that comes to my mind: there are ultra-thin floor heating solutions, consisting of a fermacel plate placed on the pipes and insulation and supporting the surface coating; on the other hand, I do not know if the fermacel (which is fiber-reinforced plaster) can properly accommodate a lime tile seal; the manufacturer must be able to respond; in which case, you would have a thickness of 4 or 5 cm screed, including the laying mortar ...

Good thinking, and good luck ...

[florid]

uh yes, but I think I misspoke. I wanted to say that having the insulation just under the screed + stone paving above, allowed to "return" the heat more directly / quickly than if I put my pipes directly in the 10cm slab with an insulation below which will be less fast / responsive. Now with regard to inertia, you are right. The walls will stabilize the temperature and the PC will have to compensate for the losses, but as it will be "slow" there is a risk of overheating. This is the reason why I want a room thermostat and an exterior, so as to limit this phenomenon. After that, I didn't expect to have 25 ° C in the house but rather to be around 19/20. And yes, three times yes, I should do an insulation from the outside, but the stones were repointed very cleanly and frankly that would make it lose a lot of its cachet.

Regarding the screed, I read that 4cm with the paving laid in advance (without adding mortar, by laying as the screed is pulled) was sufficient if under the cork there is had a very "rigid" slab (for lime, we understand) of 10cm placed on a very stable hedgehog made of large stones. I specify that I do not have a Norman cupboard or a 500kg chest. The only point where there will be weight is under the 1000l or 1500l balloon, but no cork insulation, only lime concrete. in terms of fiberizing the slab, I read everything and its opposite, that it must be done, that it is useless ... that it is necessary to use natural fibers, plastic mesh ... Finally , what is your opinion on the subject?

PS: you look good in all this, what is your path? Finally you answer if you want, it's pretty indiscreet as a question.

[LOGIC12]

hello, The soil, as it is wet. It is possible that there is rising damp, but also that the air that is wet near the sea, condenses on a cold floor.

Some external photos of the house would give an idea. and not taken too closely.

[Bardal]

My journey ? None, if not a physics training, and self-build houses 4, with a particular interest for heated floors and insulation issues ...

As for the laying of a stone pavement (or terracotta tiles), in traditional one sealed (with 4 cm about lime mortar) directly on the clay, or on a layer of sand ... It can also be sealed directly on cork (or pse) itself placed on a stabilized ground; it's more or less what you proposed in your first post. A hedgehog (a little more modern technique) allows to drain more effectively, but adds about twenty cm to the thickness. A thick slab is not necessary if the soil is well stabilized, which is the case in old houses ...

In your case, you have several constraints to respect:
- do not go below the foundations under penalty of serious risks; be careful, in old houses, it is often very shallow (about twenty cm).
- you want consistent isolation
- you want a "breathable" set (and you are absolutely right)

This is why I offered you a "hedgehog" made of breathable insulating material, such as pozzolana, expanded clay or vermiculite (expanded mica), which saves you a good ten cm. The 10 cm slab is not mandatory if your laying mortar is thick enough to accommodate the underfloor heating pipes. Introducing fibers is only an additional precaution; traditionally, we "arm" lime with vegetable fibers (reeds, straw, ...), today, we can use glass fibers, polyethylene, or other high-performance plastics (this is easily found at merchants of materials); the only thing to avoid is steel, incompatible with lime ...

With such an assembly, your "slab" would be no more than a few cm, and its inertia would not be greater than a conventional heated floor.

One more point; with such walls, and a solar heat source + wood, in my opinion, the only relevant regulation is a motorized three-way valve, controlled by an external thermal probe associated with a water law. A room thermostat will necessarily be out of phase with the changes in the outside temperature and will be uncomfortable. Obviously, an important buffer tank will be essential (at least 1 m3, 2 m3 would be better), this in order to store the solar heat and that of the wood ...

Last thing: a floor heating, if you want to stay within the limits of comfort and current rules) can develop a maximum heat flow of about 120-130 Watts per m2. Make sure it covers your losses ...

[LOGIC12]

hello, Would not it be possible to drain around the house to clean it up, and channel so that the water goes farther and lower.

One can also, and in addition make injections of resin in the walls.

It is important to insulate under a floor heating, for better efficiency and lower consumption.

Note that a small PAC AIR / AIR for the bottom, would tend to sanitize, and if the ground was not cold, (even without underfloor heating) the house could be nice, especially in the Hérault, where this Heating is well suited and economical.

But to have a soil that is not cold, it is necessary that the moisture does not rise from the ground, and to put joists and styrodur of same thickness between, and of the true vitrified floor over it. Just at the entrance, you can put a little tiling to avoid damaging the floor.