What is causing the various colours on barn floor?

[wtr]

I don't know if there was some oil spoiled on the barn floor or if there is moisture problem or a drip from the roof.

I expanded a hole so see the floor structure.

It looks like sand with aggregatet and cement layer above.

Where the floor joins the wall there is a step up.

Finally here is a picture of the roof above.

So the question is.
What is causing the color variations in the floor?
Can I spray foam the join by wall and place rigid foam board and then place OSB board or just directly pour a self leveling compound. Should i place a foil barrier before or after Ridgid foam.

I'm concerned that those colour patches mean something sinister.
Wes

 

[Swwils]

its a barn why is it even a concern

 

[Mr Chibs]

Lay a clear plastic sheet on the floor, weigh down at the edges, check it tomorrow, if there is condensation under the sheet, then it could be damp making it's way up through the slab. Could be condensation dripping from the roof, when it's cold and thawing/warming up.

As above, why worry?

 

[wtr]

I'm concerned because I want to make an insulted room within the barn. For working ... As office / workshop.

I'll do the sheet thing tonight

 

[Mr Chibs]

I'm concerned because I want to make an insulted room within the barn. For working ... As office / workshop.

I'll do the sheet thing tonight

Insulted room... hahaha

For an insulated room, lay a DPM then insulation. You could then screed or float a floor.
Obviously this will increase the floor height and might affect door threshold etc.

Is the sheeting metal or cement board?

 

[wtr]

Insulted room... hahaha

For an insulated room, lay a DPM then insulation. You could then screed or float a floor.
Obviously this will increase the floor height and might affect door threshold etc.

Is the sheeting metal or cement board?

I did a plastic sheet as you suggested earlier. There was no condensation or water on it in the morning when there was dew on the grass outside. I guess the colours are due to oil stains.

Does DPM mean damp proof material?
I was thinking of using https://www.jemogfix.dk/bewi-gulvisoleringsplade-g60-150-mm/4181/9814366/
With a reflective foil and then screed.

 

[Mr Chibs]

Morning Wes

You were close. Damp Proof Membrane.

Is the insulation worth the cost... depends on what you are going to use the barn for? You can use the one in your link.
I suspect there is a DPM sheet under your slab already.
If you wanted to be sure, you could put another DPM on top of your slab (be careful not to puncture it), then insulation, then screed.

You will need around 75mm of screed as a minimum.

It looks in good condition, difficult to tell, but it could be thin layer of concrete, hard to tell from the photo.

What is the barn made from, steel sheet or fibre cement?

Chibs

 

[wtr]

In the second picture I looked into a hole in the floor.
It appears to be concrete poured onto sand. It's not deep. Only an inch or two.

My plan is to convert the barn to an office/workshop. In future I can see it being a granny annex, to escape the kids.