What subfloor for a parquet floor

[Lower]

We have a 1920's build house with a solid floor in the hall. The floor was originally a terrazzo floor but the previous owners have laid a slate tiled floor over the top which we want to remove.

We would like to lay a reclaimed or engineered parquet floor, but what subfloor is required. The would the original terrazzo floor be good enough or do we need to dig it out and put in a proper solid floor with DPM?

The existing Terrazzo is not recoverable unfortunately. Big trenches have been hacked in it for central heating pipes.

Thanks in advance.

 

[blup]

Plywood direct to floor or on battens?

Blup

 

[Deleted member 174758]

Liquid DPM then SLC? I'd certainly consider some form of DPM just to be on the safe side unless you are absolutely certain what is underneath the terrazzo (they didn't have DPMs as we know them in the 1920s)

 

[Lower]

I assume that the old method of laying parquet on tar provided a dpm.

We want to avoid raising the floor height if possible, so battons and then a floating ply floor wouldn't work.

I guess i need to dig out some of the terrazzo and see what's underneath.

 

[blup]

Fair enough, unless you can fill the existing chases and seal.

Blup

 

[blup]

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[blup]

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[Lower]

Chases have already been filled in with concrete. Looks like there is some kind of DPM that has been put into the chases but it might just be something to keep the concrete off the copper pipes.

What is the ideal substrate for parquet? Screed over the top of a DPM?

 

[Deleted member 174758]

I assume that the old method of laying parquet on tar provided a dpm.

Not tar (too soft and likely to move over time) but bitumen which needs to be heated-up to get it liquid - but it does form a DPM. Modern plywood-backed oor recycled parquet are often put down with a special parquet adhesive. Whilst AFAIK this is semi-waterproof, it isn't a DPM. That's why you paint (roller) the floor with a couple of coats of a liquid DPM (such as Mapei Mapeproof ESM, Sika Liquid DPM, Ardex DPM 1C, etc) then screed the top with a thin layer of self-levelling compound and fix to that - thinner and less work than plywood and battens. Provinding you've filled the holes in the terazzo level there should be no need to dig anything out

What is the ideal substrate for parquet? Screed over the top of a DPM?

Yes, which I've now stated twice

 

[Lower]

From the question mark at the end of your first sentence I wasn't sure if your first response was from a position of knowledge or an educated guess. Your second post was much more definitive and exactly the info i was after, so thank you.

The slate that's down at the moment is about 15-20mm thick with adhesive. If i can get away with just painting the existing terrazzo to create a dpm and then levelling any holes, the extra 10-15mm thickness from modern parquet will be relatively insignificant.

My second question was about what the preferred substrate for parquet was if you were fitting it on a new build and what the ideal surface would be. If the terrazzo is badly damaged when i lift the slate, it might be easier to just dig the floor and put down the ideal surface rather than try to make a silk purse out of a sow's ear.

 

[Deleted member 174758]

My second question was about what the preferred substrate for parquet was if you were fitting it on a new build and what the ideal surface would be. If the terrazzo is badly damaged when i lift the slate, it might be easier to just dig the floor and put down the ideal surface rather than try to make a silk purse out of a sow's ear.

In my own experience in both new builds, where so-called "recycled" parquet (actually recut old parquet mounted onto a plywood backer - sometimes called engineered parquet) is installed, as well as refurbs where recycled traditional parquet is being installed, the flooring was cement screed or concrete, topped (in some cases, where there were doubts about the quality of DPM) with a liquid DPM and finally (but not always, as parquet adhesive is quite forgiving of minor discrepancies) some form of levelling compound. It's almost certainly easier to effect some form of repair to the terrazzo in order to get a fairly level surface then DPM that than rip the lot out, put in a full DPM and concrete/screed. The choice is yours. Only thing I'd say is that the terrazzo may need to be roughed-up a little to increase the mechanical bond of the DPM to it - talk to the technical department of the supplier first