Solid floor level / screed problem.

[VvrooomM]

4 months into ownership of 85 year old house with 45 year old flat roof single story extension. Builders start tomorrow and I have pulled up the maple wood flooring we want to try and reuse from the extension to find a solid concrete floor with inlaid battons to which the flooring was directly fixed.

The battons in the extension are sound but will be removed as a completely new orangery structure with underfloor is being built. The house battons are completely wrotten and the bitumen type felt that was laid between the concrete and maple has perished. I assume this is some kind of DPC??

My dilemma and I have no prior experience is what to do now. As the new structure is built over the next few weeks I'll have to decide on a finished floor level but what do I do about the house?? Put a levelling compound down after filling in where the rotten battens are with concrete?? What about a DPC.

Left high and dry by the wife who has abandoned me to get the house ready and deal with builders as well as going to work.

Any advice greatly appreciated.

 

[ree]

Its difficult for me to understand what exists and what you are proposing?
Could you take pics of the work so far and any relevant areas and post them on here?

 

[noseall]

I'm puzzled too.
You would typically leave a proposed floor down low enough (50-75mm or so) in order to be able to fix a suitable thickness batten and whatever thickness finished flooring.
A lot will depend upon how you intend fixing the decor floor and whether it is your intention to have the decor floor at FFL or whether it will sit higher i.e. at carpet/tile height etc.

If, for example, a customer wants an oak finished floor, we would deck the floor out as normal i.e. fit joists, lay floor boards, then fix the decor oak after all plastering has been completed. This oak decor floor is then sitting at carpet/tile level.

 

[VvrooomM]

Will try and take some pictures. I was a little surprised to discover what I did. I knew the engineered maple flooring was underneath the carpet but had been led to believe there was a standard timber floor underneath with joists and boards. I thought the maple would be secured to this.

I guess I'm going to have to lift all the maple which covers lounge , dining and hall. Remove the rotten battons and then screed level to the original maple floor level and put a membrane DPC between existing concrete floor and new screed, this would only be around 20-25mm thick though - is that enough?

I suppose I could replace the battons, add a DPC layer and then fix a new board floor to the battons in place of the maple which we'd then have to discard as it would be above a FFL for the rest of downstairs and doors etc.

One pic for starters.....

 

[ree]

I'm still not clear on what it is you want to do?

From the pic above the dark red cuboidal cracked and segmented wood looks like the beginnings of dry rot - probably caused by a lack of ventilation. And maybe damp coming up thro the concrete - does the concrete have a membrane below it?

You should perhaps lift up all the flooring to expose the concrete sub-floor.
Skip all damaged materials.
Use anti fungal chemicals on the concrete surface.
Then use a liquid damp membrane (DPM) on the concrete surface.
Perhaps then lay a screed to whatever height will allow finished flooring to sit on top of the screed.

Maybe some, or all, of the Elm can be saved?

 

[VvrooomM]

I'm still not clear on what it is you want to do?

From the pic above the dark red cuboidal cracked and segmented wood looks like the beginnings of dry rot - probably caused by a lack of ventilation. And maybe damp coming up thro the concrete - does the concrete have a membrane below it?

You should perhaps lift up all the flooring to expose the concrete sub-floor.
Skip all damaged materials.
Use anti fungal chemicals on the concrete surface.
Then use a liquid damp membrane (DPM) on the concrete surface.
Perhaps then lay a screed to whatever height will allow finished flooring to sit on top of the screed.

Maybe some, or all, of the Elm can be saved?

I've no idea what I need to do. The top of the maple is the FFL throughout the downstairs. We are building an open plan new exstension that will have to meet this old floor across an 11m span. I'm trying to get my head around the best way to bring the two together but also ensure the old floor is sound, level and free of any future damp problems.

Quite surprised a 1930's house has a concrete floor so thrown a little especially given the rotten timber and potential DPC issue.

 

[VvrooomM]

I've no idea yet whether the concrete sub floor has a DPC. May hopefully see that once exstension removed.

Will a 20-25 mm screed on top of liquid or sheet DPC be thick enough?

 

[Nige F]

have a google for specialist screed

 

[noseall]

Will a 20-25 mm screed on top of liquid or sheet DPC be thick enough?

No. It's about 50mm too thin. Un-bonded sand/cement screed needs to be about 75mm thick.