How to use Ground Domain object when insulation is above the slab?

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It is not very uncommon to insulate the ground floor above the slab. But I can only put the insulation below the slab in the Site:GroundDomain:Slab. Does it not really matter where the insulation is location? Or should I not include the slab in the model and just put the insulation material and the screed layer as slab material?

My actual ground floor construction is as followed:

Construction, NPGRFloor, Brick - burned0.11floor, Cast Concrete (Dense)0.075, Extruded polystyrene 25 mm0.025floor, Floor Screed0.012, Ceramic/clay tiles - ceramic floor tiles Dry0.012;

Material, Brick - burned0.11floor,
Rough,
0.11,
0.85,
1500,
840,
0.9,
0.6,
0.6;

Material, Cast Concrete (Dense)_0.075,
Rough,
0.075,
1.13,
2000,
1000,
0.9,
0.6,
0.6;

Material, Extruded polystyrene 25 mm0.025floor, !- Name Rough,
0.025,
0.027,
40,
1450,
0.9,
0.4,
0.4;

Material, Floor Screed_0.012, Rough,
0.012,
0.41,
1200,
840,
0.9,
0.73,
0.73;

Material, Ceramic/clay tiles - ceramic floor tiles Dry_0.012,
Rough,
0.012,
0.8,
1700,
850,
0.9,
0.6,
0.6;