Sandwich elements as garage foundation??

[m800sweden]

Bought a house with a cold garage a few months ago. The previous owner created a foundation with sandwich elements and placed an old military storage unit on top. Can these elements be used for base insulation and to pour a slab on?

Planning to embed underfloor heating if so, thinking that the sheet metal acts somewhat as a barrier and doesn't let much heat through to the ground. What do you think? There are underfloor heating plates intended precisely for this purpose—anyone knowledgeable on the topic?

 

[m800sweden]

It is "frigolit" between the sheets and not stone wool.. Maybe it's not called sandwich elements then?

 

[Rabbithole]

Yes, it does, anything with a core with two enclosing materials or different density can be called a sandwich element.

The sheet will not act as a barrier to stop the heat downwards, that is misunderstood. The sheets used in floor heating on top of, for example, grooved boards are to distribute the heat more evenly across the floor.

 

[m800sweden]

Ok. But do you think it can handle the weight of a concrete slab about 10cm thick? The walls are on leca-block (which are on the elements) so I will need to cast against the leca-block if so (build a frame around it so it doesn't push out the blocks). The elements are about 15cm thick and I do not know what strength class they have. Will it be extremely uneconomical to maintain a base temperature of about 5 degrees Celsius with the underfloor heating, with 15cm base insulation?

 

[Rabbithole]

Can't you add a bit more insulation then?

You can use the Leca elements as a form and just cast directly against it. Just make sure there's no hole where the concrete can flow out.

If the foam is supported against the ground underneath, it will hold up without issue. Do you have any pictures of how it looks so we can understand the situation better?

 

[m800sweden]

Would prefer not to add more insulation, because if I pour as it looks now, it will mean making a 10cm high ramp up to the doors, on asphalt. The elements are currently at ground level (asphalted) at the doors now. I'll take some pictures tomorrow after work while it's still light if I remember.

 

[m800sweden]

This is how it looks on the outside now, a bit messy and cluttered but you get the idea. Of course, I will freshen up the facade with maybe sheet metal if it becomes relevant.

 

[Rabbithole]

I think it will work, but it seems to be a bit uneven surface?
Maybe go over the inside of the leca with some mortar/concrete and seal before casting.
Also saw off what sticks out of the elements on the outside and smooth it, and it will look good.