Waterborne floor heating on uninsulated slab - which materials should be used?
Hello,
we have a house from 1974 with a larger basement that is now due for renovation. In part of the basement (about 40 m2), the concrete slab is poured about 10 cm lower than in the other rooms. In this approximately 40 m2 room, the floor is framed and insulated, consequently a so-called risk construction. Now everything is being taken out, including the drywall of the walls and insulation, and it will be plastered instead. I do not know if the base plate can have any form of insulation, but since one part is even "deeper," I assume there is none. The house is a Myresjöhus.
Our idea is to install waterborne floor heating combined with tile in parts of the basement, totaling about 70 m2. In the part where the slab is lower, it is possible to lay 10 cm of cell plastic without "messing up" the ceiling height. In the remaining 30 m2, it is a bit worse since there is no room for a significant amount of insulation.
I have tried to read up on which materials should be used, and cell plastic (isn't that the same as Styrofoam?) seems to be the best choice. Somewhere it is mentioned that one should also lay a Platon mat under the cell plastic against the concrete?
Are there any tips on what we can do with the other spaces? There is a bathroom of about 5 m2 and the intended children's TV room of about 25 m2. The floors do not feel cold at all today, but the main risk is that waterborne floor heating without underlying insulation may go straight into the ground?
It would be great if there are some tips. What types of materials, suppliers, etc., are good? Ideally, there would have been an insulated base plate from the start, but now we have to work with what we have...
Buggaren
we have a house from 1974 with a larger basement that is now due for renovation. In part of the basement (about 40 m2), the concrete slab is poured about 10 cm lower than in the other rooms. In this approximately 40 m2 room, the floor is framed and insulated, consequently a so-called risk construction. Now everything is being taken out, including the drywall of the walls and insulation, and it will be plastered instead. I do not know if the base plate can have any form of insulation, but since one part is even "deeper," I assume there is none. The house is a Myresjöhus.
Our idea is to install waterborne floor heating combined with tile in parts of the basement, totaling about 70 m2. In the part where the slab is lower, it is possible to lay 10 cm of cell plastic without "messing up" the ceiling height. In the remaining 30 m2, it is a bit worse since there is no room for a significant amount of insulation.
I have tried to read up on which materials should be used, and cell plastic (isn't that the same as Styrofoam?) seems to be the best choice. Somewhere it is mentioned that one should also lay a Platon mat under the cell plastic against the concrete?
Are there any tips on what we can do with the other spaces? There is a bathroom of about 5 m2 and the intended children's TV room of about 25 m2. The floors do not feel cold at all today, but the main risk is that waterborne floor heating without underlying insulation may go straight into the ground?
It would be great if there are some tips. What types of materials, suppliers, etc., are good? Ideally, there would have been an insulated base plate from the start, but now we have to work with what we have...
Buggaren
Hello,
the time when I must decide on a solution is approaching rapidly... I've tried reading old posts and also googling, but it feels like there are no really clear guidelines anywhere... in some places, they talk about connecting fans to create airflow under the floor? But if I put a Platon membrane directly on the concrete, can I then put insulation on top of this (and then underfloor heating, leveling compound, and tiles)? And would there be ventilation under the floor in that case? Or do I need a fan system?
Should I paint the concrete? Put a vapor barrier in the form of plastic? before the Platon membrane? or skip Platon completely? or choose another solution...?
It would be really great if any of you have experience with this.
Buggaren
the time when I must decide on a solution is approaching rapidly... I've tried reading old posts and also googling, but it feels like there are no really clear guidelines anywhere... in some places, they talk about connecting fans to create airflow under the floor? But if I put a Platon membrane directly on the concrete, can I then put insulation on top of this (and then underfloor heating, leveling compound, and tiles)? And would there be ventilation under the floor in that case? Or do I need a fan system?
Should I paint the concrete? Put a vapor barrier in the form of plastic? before the Platon membrane? or skip Platon completely? or choose another solution...?
It would be really great if any of you have experience with this.
Buggaren
I can share the experiences I have from acquaintances. They had similar conditions and wanted underfloor heating in the basement. They dug up and made a new slab following today's method with geotextile, capillary-breaking material, and cell plastic insulation. A lot of effort, expensive but with good results. However, they only did parts of the basement. I don't know enough to advise you on alternative methods but want cell plastic insulation on top of the slab and then a raised floor in an extension and the inspector assessed it as a risk construction.sepani said:
In our basement, we laid foam directly on the floor. These were already tracked for plates and hoses. On top of this, we laid plastic followed by 10mm chipboard, paper, and then click flooring. We then folded the plastic over the floor and installed the skirting boards with spacers. After that, we cut off the excess plastic.
We never turn off the underfloor heating.
We have a dehumidifier for laundry and when it gets too humid.
We never turn off the underfloor heating.
We have a dehumidifier for laundry and when it gets too humid.
I have almost exactly the same conditions. In the lower part, I've considered filling with EPS cement and then using self-leveling compound on top of it to embed the underfloor heating. After that, a tiled floor. In the low part, I don't have a good answer, but if the floor is straight and nice and not like mine, which varies almost a decimeter between the highest and lowest points, you can embed the pipe there too.
I think there's little information on what to do when it's not a feasible alternative to break up the basement floor.
I'm hesitant to trap moisture under plastic, etc.
I think there's little information on what to do when it's not a feasible alternative to break up the basement floor.
I'm hesitant to trap moisture under plastic, etc.
I am in exactly the same situation and have been debating back and forth about this. In the lower part, I already have leveled wood flooring with ventilation underneath. I have no problems there. The problem is in the higher part, which is currently concrete with cheap laminate click flooring, where I want to have tiles and comfort floor heating instead.
My idea was to lay Platon at the bottom (possibly a ground cloth under the Platon to eliminate any clicking sounds), then lay low-profile floor heating boards ready with grooves and heating plates, then tiles on top. Around it, ventilated baseboards for the Platon mat.
The low-profile boards do not insulate much; I'm just after comfort heating, and the heat that goes downward should warm the air gap in the Platon mat, which might even start some upward air circulation underneath.
This solution should prevent trapped moisture and large heat losses. It should not build up more than 20-30 millimeters plus tiles. Ideally, that's too much for me, but breaking it up, insulating, and casting a new slab is out-of-the-question.
I don't know if this method will work, but if I can't come up with a better solution, this is probably what I'll do.
Feel free to share how you did it and how it turned out!
My idea was to lay Platon at the bottom (possibly a ground cloth under the Platon to eliminate any clicking sounds), then lay low-profile floor heating boards ready with grooves and heating plates, then tiles on top. Around it, ventilated baseboards for the Platon mat.
The low-profile boards do not insulate much; I'm just after comfort heating, and the heat that goes downward should warm the air gap in the Platon mat, which might even start some upward air circulation underneath.
This solution should prevent trapped moisture and large heat losses. It should not build up more than 20-30 millimeters plus tiles. Ideally, that's too much for me, but breaking it up, insulating, and casting a new slab is out-of-the-question.
I don't know if this method will work, but if I can't come up with a better solution, this is probably what I'll do.
Feel free to share how you did it and how it turned out!
I should start by pointing out that I’m definitely not an expert on this. I've had similar considerations for part of our basement.
I am very skeptical about using such a thin layer of insulation as 20 - 30mm. There are two aspects to producing "spill heat" into the ground. The obvious one is that it’s (very) poor heat economy. But there is also a risk of increased moisture migration up through the slab.
It took me a while to understand what was meant, but as I understood the argument, heating the ground under the house increases evaporation from the clay or whatever is under the house due to the heat. While the water vapor is indeed pushed downward away from the "warm" concrete slab, if you have adjacent rooms without underfloor heating, the vapor pressure against the slab there increases, resulting in increased moisture migration. Even in the summer when the underfloor heating is turned off, the ground underneath remains warm, increasing the vapor pressure up towards the concrete slab.
I am very skeptical about using such a thin layer of insulation as 20 - 30mm. There are two aspects to producing "spill heat" into the ground. The obvious one is that it’s (very) poor heat economy. But there is also a risk of increased moisture migration up through the slab.
It took me a while to understand what was meant, but as I understood the argument, heating the ground under the house increases evaporation from the clay or whatever is under the house due to the heat. While the water vapor is indeed pushed downward away from the "warm" concrete slab, if you have adjacent rooms without underfloor heating, the vapor pressure against the slab there increases, resulting in increased moisture migration. Even in the summer when the underfloor heating is turned off, the ground underneath remains warm, increasing the vapor pressure up towards the concrete slab.
Absolutely not an expert on the subject either 
. I've thought about it like this in my own case; I only want comfort heat so that the tiles aren't cold to walk on. It might require 3-4 degrees warmer than room temperature for it to feel okay. Additionally, if you have an air gap (with Platon) under the underfloor heating plates and the tiles, I get the feeling that so much heat can't really sink down into the base slab.
If you have a 10-degree base slab and typically have 18 degrees as room temperature in the basement, and then with underfloor heating instead have 22 degrees in the air gap - how much extra disappears then down into the slab? And if heat disappears that way, I've only seen theoretical warnings about it in forums, never seen anyone who've actually had problems.
I also have a bathroom in the basement where those who renovated it in the '90s embedded a floor coil from the radiator coil (considerably higher temperature in it) directly on the base slab. As far as I know, I have no moisture problems in any rooms or walls. However, a lot of energy probably disappears that way.
Again, not an expert on this. Just feel like all warnings about moisture migration are general and theoretical.
. I've thought about it like this in my own case; I only want comfort heat so that the tiles aren't cold to walk on. It might require 3-4 degrees warmer than room temperature for it to feel okay. Additionally, if you have an air gap (with Platon) under the underfloor heating plates and the tiles, I get the feeling that so much heat can't really sink down into the base slab.If you have a 10-degree base slab and typically have 18 degrees as room temperature in the basement, and then with underfloor heating instead have 22 degrees in the air gap - how much extra disappears then down into the slab? And if heat disappears that way, I've only seen theoretical warnings about it in forums, never seen anyone who've actually had problems.
I also have a bathroom in the basement where those who renovated it in the '90s embedded a floor coil from the radiator coil (considerably higher temperature in it) directly on the base slab. As far as I know, I have no moisture problems in any rooms or walls. However, a lot of energy probably disappears that way.
Again, not an expert on this. Just feel like all warnings about moisture migration are general and theoretical.