Is it necessary to pour concrete screed over a precast floor? (hollowcore)

[MariaD]

Is it necessary to pour a concrete screed over a precast floor made of hollowcore slabs?

Can porcelain tiles be installed directly on the hollowcore slabs without the need for a concrete screed?

[JohnMo]

Where is the insulation going?

[George]

Yes 

 

- you need to bind the slabs together to form a two directional diaphragm. This is similar to the grout on beam and block

 

- hollow core slabs always have an upwards deflection. It's fairly minor on short spans but still too much for tiling. The cost of floor leveller would be eyewatering

[Iceverge]

25 minutes ago, JohnMo said:

Where is the insulation going?

 

I guess if it's the first floor then no insulation will be necessary. 

 

Structurally we would have been ok with just the slabs but they do hump up in the middle so the engineer specced 75mm concrete with a252 mesh in it. Seems like total overkill but probably just as cheap as screed.

[MariaD]

2 hours ago, JohnMo said:

Where is the insulation going?

I don’t plan to install any insulation since it’s the upper floor, and thus, the heat would still remain in the house.

[nod]

Why not just use bagged self leveling Matt it then tile 

I do lots of commercial like that It’s usually only the joints that need sorting out Some companies don’t want to pay for the Matt So we seal and tile directly onto it 

[George]

20 hours ago, Iceverge said:

 

I guess if it's the first floor then no insulation will be necessary. 

 

Structurally we would have been ok with just the slabs but they do hump up in the middle so the engineer specced 75mm concrete with a252 mesh in it. Seems like total overkill but probably just as cheap as screed.

Sounds quite  a lot of mesh but unless there's a good reason not to, I just revert to the hollowcore manufacturer's detail.