Tiles directly on foam board?

[sepani]

Hello,

We are going to install underfloor heating in the basement, and the choice is a waterborne system from LK. 30 mm thick foam insulation and 20 mm pipe. According to the reseller, you can lay the tiles directly on the foam insulation. But I'm a bit skeptical. Does anyone have experience? I know there is another more expensive variant of foam insulation where you can do it, but it should apparently work with the thicker one as well?

Buggaren

 

[Stew]

I don't think that will work very well. The foam must be quite rigid. Foam does move a bit, in gaps and so on. If you lay tiles on it with hard grout, the grout will probably crack. But sure, with a sufficiently hard foam and very tightly sealed joints, it might work.

I just searched the topic and found an old post. I think you'll get good answers here: http://www.byggahus.se/forum/badrum/141099-lagga-klinker-pa-s80-cellplast.html

 

[largab]

If you read on LK's websites, EPS16 is AL-coated, grooved EPS designed to be glued directly onto concrete and to glue tiles directly onto it. It then builds about 26 mm. You can also have a layer of leveling compound between the EPS and the tiles if you want slope build-up. For their EPS30, direct gluing of tiles is not mentioned, only floating floors....
So please read up on this yourself http://www.lksystems.se/sv/LK-Systems-Sverige/Golvvarme/, or the retailer might be right.
It might be that 16 mm is stiff enough, but not 30.

 

[sepani]

Thanks for the response. I've looked further and concluded that I need about 4m3 of liquid screed if I go for the 30 mm version... apparently, it should be at least 30 mm, and I have quite a large area. So, besides the cost of the liquid screed, there's also the cost of laying it... does anyone know what that might amount to?

If I choose the 16 mm version from LK, it costs about 20,000 kronor more for my 120 m2, but it's probably worth it? 4 m3 of liquid screed + laying it is likely to cost quite a bit?

Buggaren

 

[sepani]

Hello,

If you are going to lay 16 mm cell foam, how even must the surface be to glue the cell foam?

Buggaren

 

[tmarkr]

Hello @sepani
found this thread and have a couple of questions about it as I am also deciding how to lay floor heating in the basement (https://www.byggahus.se/forum/threa...a-liten-isolering-golvvaerme-klinkers.381477/)
- did you have an insulated or non-insulated slab?
- which solution did you ultimately choose?
- are you satisfied?

Thanks in advance
//Mark

 

[sepani]

Hello, I was lucky in that the entire basement except for the "gillestugan" actually had insulation in the slab. However, only 5 cm, but considering the house is from 1974, it's okay. I added 10 cm in the gillestugan and cast up to level with the rest, for a total area of about 150 m2. I then laid LK low build directly on the cement in the grout joint. We distributed the loops on two manifold cabinets. Overall, with 5 people, we have an annual electricity consumption of about 19,000 kWh with about 300 m2 of heated space. The basement, which is partially a sutteräng, feels warm in winter and cool in summer and has a very good climate. We are very satisfied after a total of about 8 years with the solution.

 

[tmarkr]

Hello, I was lucky as the entire basement except for the "gillestugan" actually had insulation in the slab. However, only 5 cm, but considering that the house is from 1974, it's okay. I added 10 cm in the gillestugan and poured it to level with the rest, covering a total area of about 150 m2. I then laid LK low-profile in the screed directly on the cement. We distributed the loops on two distribution cabinets. Overall, with 5 people, we have an annual electricity consumption of about 19,000 kWh with approximately 300 m2 of heated area. The basement floor, which is partly a split-level, feels warm in winter and cool in summer and has a very good climate. We are very satisfied after a total of about 8 years with the solution.

Thanks for the response. We don't have space for that much insulation, but the difference between 30 and 100mm insulation is not that much if you use concrete & tiles if I understood LK's documentation correctly.
I assume you're using geothermal heating?

 

[sepani]

Thanks for the answer. We don't have space for that much insulation, but the difference between 30mm and 100mm insulation isn't much if you're using concrete & tiles, if I understand LK's documentation correctly. I assume you're using geothermal heating?

We're using an air/water heat pump.