Casting a slab on the slab?

[jeppeknaster]

Hello
I have a large garage (70 m2) on the lower floor that I plan to convert into a laundry room/bathroom/sauna/toilet and a large living room. The part where the bathroom/laundry room is (about 25 m2) I want to have underfloor heating.
I have a height of 3.10, so I was simply thinking of casting a 30 cm block of leca on the existing (painted) floor and then laying out 20-30 cm of foam insulation, reinforcing it, laying underfloor heating pipes, and casting. Possibly I cast with eps cement or similar, and then I lay the loops on top and level them with self-leveling compound. What do you think, will it work?
I should add that I will break up the old drains and run new ones through the foam insulation.
Should the boards be glued to the floor/each other if using the lighter eps cement?
Thanks for your response.

 

[jeppeknaster]

No one?

 

[Mats]

Search a bit and you will find, among other things, mathias project where he made a similar variant.

 

[jeppeknaster]

I have looked at the basement threads but haven't seen anyone doing what I plan to do. Mattias digs up the whole thing and pours it again with regular concrete, but I was planning to build directly on the slab. Unlike most of the other basement trolls, I have plenty of ceiling height and therefore won't have to break up everything. Hopefully...

 

[ppalm]

epc cemet means that you can take twice the thickness compared to regular foam insulation. You can do so, but the risk is that you get a small “lake” under the insulation against the old floor. I have personally considered this and concluded that the floor should be removed.

 

[jeppeknaster]

I will not use EPScement but regular concrete. Now the problem is that there is a slope on the old floor that I need to fill before laying out the cellplast. How can I fill it the easiest and cheapest way? Is it possible to fill the slope with something like stenmjöl or something similar, or do I have to cast with concrete?

 

[Krawk]

You can fill (and insulate) with leca balls and then cast the slab with underfloor heating on top of this otherwise. More expensive than cell plastic and somewhat less insulating, but it has its advantages.

 

[Eddi Thomason]

You can fill (and insulate) with lecakulor and then cast the slab with underfloor heating on top of this otherwise.
More expensive than cellplast and somewhat less insulating, but it has its advantages.

Which are...?

 

[Krawk]

Which is...?

->

Now the problem is that today there is a slope on the old floor that I need to fill up before laying out the cellular plastic. How do you fill it in the simplest and cheapest way? Is it possible to fill the slope with, for example, stone dust or something similar, or do you have to cast with concrete?

So he skips the step of first leveling the floor and fitting the insulation boards.
It is also a dimensionally stable, inert material.

 

[jeppeknaster]

Krawk, do you think you can fill the case with lecakulor and then place the foam on top?

 

[Krawk]

Of course it's possible.
However, Leca doesn't work well in thin layers, which is why the foam layer ends up being thin. In other words, little benefit, but another step in the process.

Edit: The advantage is that it's easier to pour on foam than on Leca, which risks shifting if too much concrete is poured in one spot. Geotextile or slurry coating the Leca before pouring reduces that problem.

 

[jeppeknaster]

Now the problem is that today there is a slope on the old floor that I need to fill before laying out the foam. How do you fill it most simply and cheaply? Can the slope be filled with, for example, stone dust or something similar, or does it have to be cast with concrete?

In the living room area:
Can the slope be filled by gluing foam boards directly onto the old concrete floor and then using self-leveling compound on top of that? This way, you don't use as much of the expensive self-leveling compound. What do you think?

On top, there will be 50mm grooved foam with loops > parquet floor.

New idea...
Maybe it would work to fill with gravel or crushed stone (like 8-16) and then self-level on top of that? I suppose clay pellets would float up if you use self-leveling compound, right?

 

[jeppeknaster]

http://www.byggahus.se/forum/golv/75422-lecakulor-och.html

Found a thread where they used leca and leveling compound. Seems to be the way to go.

Or with cement:
http://forum.byggahus.se/499431-post7.html

 

[jeppeknaster]

Now I am on a roll. I've cast a reinforced base using half fast-setting concrete and half leca 8-14mm. Here, a non-load-bearing leca wall will be built later. Tomorrow, I'll pour the slope towards the floor drain (about 10-12 cm at most) with cement-bound leca in size 8-14mm. Where it's the thickest, I'll glue 20 and 30 mm s80 foam boards to the floor and then pour the cement-leca on top. I just hope I can remove the form tomorrow. I poured the fast-setting concrete/leca today at 4 PM, can I remove the form in the morning tomorrow? Anyone know?

Regarding the mixing with the tumbler, for some reason I rinsed it out after each batch, do you really need to do that or can you just keep pouring until everything is done and then clean?

As you can see in the first picture, the casting becomes very rough but I'll fix that with leveling compound.

 

[jeppeknaster]

Now I have cast with cement-bound leca. Unfortunately, I had too few pellets (used more than I thought) so the entire floor wasn't cast. It also didn't become completely even.

Does it matter if the base is a bit uneven when laying the insulation (20 cm) and then a 10 cm concrete layer?

One more question; since it gets a bit messy when mixing indoors, I'm wondering if it's okay to mix everything outside (around -5 degrees) and carry it in? Should be possible to just use slightly warmer water.