Do I need to clean this concrete before glueing engineered wood?

[jacoscar]

I have a concrete floor that used to have tiles; the tiles have been removed prior to plastering so the concrete is ‘stained’ with plaster; there are also some paint residues due to me spraying some doors in this room
Do I need to clean it before glueing the wood floor to it? What’s the best way?

 

[crazydaze]

Ideally you need to moisture test the floor with a protometer or hydrometer. If all dry, screed the floor with a quality self levelling screed like Ardex NA

If there is residual moisture in the subfloor you will need to apply a Liquid DPM then moisture tolerant screed before installation.

 

[jacoscar]

Why do I need the self levelling? It's quite flat already

 

[crazydaze]

If you check the specification of your wood flooring you will see that 'quite flat' is'nt flat enough for the specification to glue direct to the subfloor.

The Subfloor needs to be properly level (and dry) and clean, a latex screed will give you the level and cleanliness you need to securely fit to.

 

[jacoscar]

If you check the specification of your wood flooring you will see that 'quite flat' is'nt flat enough for the specification to glue direct to the subfloor.

The Subfloor needs to be properly level (and dry) and clean, a latex screed will give you the level and cleanliness you need to securely fit to.

And will the screed adhere to a non clean substrate?

 

[crazydaze]

Depends on the quality of screed, but judging by your photo's, a premium screed like Ardex NA would be fine for your application, provided the floor has been tested for residual moisture.

Some screeds may require priming before application.

 

[jacoscar]

Wouldn't a light grinding be quicker? I've checked for level and it's within the floor specification

 

[crazydaze]

A proffesional floor installer would moisture check the subfloor and then self levelling screed it, if you choose to grind it, that's your choice.

 

[jacoscar]

A proffesional floor installer would moisture check the subfloor and then self levelling screed it, if you choose to grind it, that's your choice.

That’s probably because it takes the same amount of time than grinding and the customer pays for the screed plus a premium for sourcing the material
That is, if the floor is level

 

[crazydaze]

It's because the screed will perfectly level the subfloor and create a clean surface to glue to with no contamination and cause little to zero dust and mess.

 

[jacoscar]

I tried grinding but I found I was just exposing the bitumen from the tile adhesive
I’ll just float the floor; I was able to return the wood adhesive and get some underlay
I couldn’t justify the cost of self levelling compound for something that is already flat