How to make a chimney through cast floor

[Haagbard]

I have an idea for a future extension with a basement and a concrete slab, with the thought of having, among other things, a boiler room and a wood-fired sauna in the basement....

How should one appropriately build the chimney and the concrete slab? Do you build the chimney past the floor level and then pour the slab around the chimney, or do you create some form of support for the slab to rest on?

Or perhaps should the slab and chimney not even be connected in case they move relative to each other? :-?

 

[Eld]

I don't know how it "should" be done, but in my house which is built in -42, the chimney is also made of concrete up to and including the concrete floor between the basement and the ground floor.

 

[zankan]

The easiest way is to make a recess in the floor structure when casting and later build up the chimney...You can also build up the chimney and dock the arch form against it, that works too...

 

[Per_B]

Make a recess that you fill with cellplast. Then you can cast a thin layer on top and use the surface until you know how to proceed!