Prep for wooden laminate on screed

[saveasteading]

I'm getting conflicting info re preparing the screed for timber flooring.

In other words, people like spending my money.

 

Where there is tiling, we have no issues. The screed has not been ground back to remove ripples or laitence. Dips and ridges disappear using the tiler's skill and some double buttering.

 In the other rooms we will have oak faced  multi ply planks, t and g, 12mm thick.

I can't see what is different in laying this instead of tiles. 

But someone says the screed needs to be ground to remove ripples and laitance.

Someone else says it needs latex at any dips.

 

The floor planks are very high quality and won't be bending or slapping in use unless the gap is significant.

I'm about to survey all the floors using a 3m straightedge, and will consider the 3mm rule as a pass.  Any thoughts on that?

Does anyone know how thick the adhesive is as standard, or what might be considered acceptable at any dips?

 

Then the laitance thing.  These floors only receive downwards loading and won't be flying up in a draught.

But is the screed surface so soft that it comes off if the floor moves?

 

I was thinking that a coat of primer would suffice. And if it's a blue colour then everyone will be happy to see it.

 

Any very big dips or ridges will be dealt with on their demerits... I will soon know the significance.

 

[-rick-]

22 minutes ago, saveasteading said:

The screed has not been ground back to remove ripples or laitence.

 

Forgive me for not answering your question and asking another but I thought you always wanted to remove laitence because it was a weaker layer so if you bond on top you risk separation later. If your tiler isn't bothered by it then I'm probably wrong, but would appreciate to know what I've got wrong.

[saveasteading]

30 minutes ago, -rick- said:

always wanted to remove laitence because it was a weaker layer

That's the theory. But most warehouse floors are left as they are. And structures likewise.

So I think it's overstated, unless the laitance ("fat" to concretors) is very severely overworked and is a paste of very wet gypsum.

Even then I am not convinced it's an issue in a domestic situation.

[saveasteading]

Done that, using a 3m drywall stud which is nicely straight and is stiff enough.

2mm under the straightedge  is generally the worst so that is not significant.

2 areas of about .5m2 are a little worse  so I'm going to try the old fashioned 'rub it with a brick' first.

I'm still keen to find how thick the adhesive is generally applied.

Also any recommendations on brands for primer. As often, the wickes price sets a target.. less 10% and including vat.

 

And of course I am open to being told that I'm wrong on any of the above.