Concrete slab

[Kattisarna]

Hi, I have a space of about 20m2 that has been a standalone conservatory. Now we want to renovate this and install a hot tub and infrared sauna, but the problem is I want underfloor heating. The issue with that is the slab, which is dry and without cracks at the moment, is cast directly on the rock underneath! I'm wondering how to proceed since it won't be possible to break it up and drain under the slab due to the rock. Anyone with suggestions on possible approaches?

 

[mexitegel]

First, you need to decide whether you want to "elda för kråkorna" or not. If you are okay with it costing a small fortune to heat up, you don't insulate and either embed loops on top of the existing slab or jackhammer away and pour a new one with loops, depending on the building height you can accept.

If you want to insulate, you have two options here as well: insulate on top and embed loops, or jackhammer away the slab and blast away the rock to make a new slab with heat in it. A skilled blaster can shoot charges right against the house wall.

 

[topmount]

Is there any particular reason you want underfloor heating? I think a spa bath set up in ten square meters will provide quite a substantial heat addition to the room.

 

[Kattisarna]

First of all, you need to decide whether you want to heat for the birds or not. If you're okay with it costing a small fortune to heat, you won't insulate and either cast loops on top of the existing slab or break away and cast a new one with loops depending on the construction height you can accept.

If you want to insulate, you also have two options: insulate on top and cast loops or break away the slab and blast away the rock and make a new slab with heat in it. A skilled blaster can fire charges right up to the house wall.

First of all, you need to decide whether you want to heat for the birds or not. If you're okay with it costing a small fortune to heat, you won't insulate and either cast loops on top of the existing slab or break away and cast a new one with loops depending on the construction height you can accept.

If you want to insulate, you also have two options: insulate on top and cast loops or break away the slab and blast away the rock and make a new slab with heat in it. A skilled blaster can fire charges right up to the house wall.

I don't think the heating will be so bad in there anyway since the spa bath will also be there. But you mean that it's possible to insulate on top of the slab and then "cast a new slab" with heating pipes on the insulation without there being any complications?

 

[Kattisarna]

Is there any specific reason you want underfloor heating? I think a spa bath set at ten square meters will provide a pretty substantial heat addition to the room.

Just for convenience's sake Plus, if in the future I want to use it as a guest room or just a cozy retreat room, it would be nice to have prepared and functional underfloor heating, I thought.

 

[mexitegel]

I don't think the heating will be so intense in there anyway since the hot tub will also be there.
But you mean that it works to insulate on top of the slab and then "cast a new slab" with the heating pipes in the insulation without any complications?

Yes, the best option is probably a layer of EPS concrete which is insulating, and then you embed the heating loops in self-leveling compound or concrete on top of that.

 

[Kattisarna]

Yes, best is probably a layer of EPS concrete that is insulating and then you embed the heating coils in levelling compound or concrete on top of that.

How thick should the layer of EPS be? Or can I use a layer of isodrän instead and then cast? (I have quite a lot left over)
I was also thinking of having some kind of waterproofing and microcement throughout the room.

 

[mexitegel]

Isodrän should work as well, a tip is to call their support and ask for advice. They are usually very helpful.

 

[Kattisarna]

Isodrän should work too, a tip is to call their support and ask for advice. They are usually very helpful.

Great, I will try calling them tomorrow!
Thanks for the response.