Leveling a concrete floor with floor boards

[CrazeUK]

Hi all.
A friend bought a flat and one of her rooms seems to have a bit of an issue.
The carpet showed that some floorboards where slightly concave with some high ridges at the joins.

Wr pulled the carpet up, to find floorboards that where sat on what looks like very crumbly screed over concrete.

I need to help her level it for when the laminate comes in.

Unfortunately she is on a very tight budget due to unforseen costs on the property.

Originally my plan was to just screw down then sand the boards. Given their condition not sure its an option.

So i THINK some options are:
1. Put ply over it all.
2. Remove the original wood, scrape if the crumble then use a deep bed screed at around 10mm. Although we are talking £150 for 6 bags of deep fill. Which does 2.2m2 at 5 nn.
Are there any other cheqp options?

Thanks in advance

 

[Deleted member 174758]

Go for 12mm plywood. It will be a lot less work and far easier to get a level surface. Screw down every 150mm/6in

 

[CrazeUK]

Quick update. Let's hope I don't have too many typos like my first post.

I took some of the floor boards up and noticed them crumble. Evidently rotten, so I decided to rip them all up exposing the original concrete base. Worked put a quarter of the cost of the ply.

I covered it in a single sheet of damp proof membrane, then added a layer of concrete with a slightly coarse balast and leveled against the existing skirts.

The floor is now covered in a thick underlay and carpet. Seems to have done the trick. My only regret is the screed that was initially wasted by the worker on the original floor and not screening the concrete to smoothen it for the underlay.

I hope the concrete doesn't act as a heat sink.

Thank you again for your response

 

[dazlight]

How thick did you put the concrete ‘ screed down ?