Hi all, first timer so be gentle. I have bought an old house that has a damp concrete floor (almost 100 year old house) the previous owner laid a floating floor, DPM membrane with 20mm polystyrene and 18mm chipboard over 25 years ago, it's not failed and the house is dry but he didn't level anything off and the chipboard is sagging and perishing so I've had to lift it a room at a time and remove the old bitumen/asphalt layer right back to the concrete. I'm thinking of laying ardex na followed by arditex dpm1c then redo his previous method of another mechanical 1200g membrane, 20mm cellotex then finishing off with 22mm structural tongue and groove ply. Would this then be ok to glue solid wood flooring to? Any suggestions would be great thank you all!
Nope I have 2.8m heigh ceilings (even with the old floating floor in situ) and above each door there's a 30mm gap to lintel so frames can be raised with minimal loss
On a concrete base of that age especially you’ll need to check the actual Rh% in the concrete, the compressive and flexural strength too before thinking about putting a solid wood down, if the readings all come back within tolerances I would grind everything back and smooth them DPM 1C, prime, K11 or similar high compression strength screed and bond direct to it. NA is soft as anything I would personally never bond any wood to it or use it in an area that’ll have heavy furniture. Sent from my iPhone using Tapatalk
Thanks for the reply. I wanted to put a floating floor in so there was at least a bit of insulation in there. If I were to screed it couldn't I just lay a mechanical DPM then screed (I've got just over 50mm to play with)
You’ll need to bring the Rh% below 65% so even if you use a mechanical dpm then screed you’ll still need to epoxy over your screed, plus you’ll be looking at roughly 4 weeks before you can even do a moisture test. Sent from my iPhone using Tapatalk
I only say to use a mechanical DPM as the DPC is actually higher than the slab in some places and I didn't want moisture/vapour mitigating to the edges and rising. Sounds like an unbonded screed might be my best option but does it really matter not having any insulation in the slab/screed? Just want the best option for the oak floor at a later date. Thanks for the reply btw
You can’t fix solid oak to a floating floor. You would be better off with a engineered board. Personally I think a new unbonded screed with mechanical dpm is the safest bet. Unless you really need insulation. Sent from my iPhone using Tapatalk
Yeah thinking I may have to bite the bullet, rip it all up and lay a mechanical DPM with 60mm of reinforced screed. Probably still lay a liquid DPM on top and level lay, any recommendations as to what brands? (I will get a RH% test done to ensure the screeds dry just going full belts and braces with this as it's my forever home) thanks for the info so far chaps.
Uzin PE404 moisture suppressant Then smoothing compound of NC150 or Ardex DPM1c K39 smoothing compound
Thanks very much chaps, any experience with a35 screeds? Thinking this may reduce my drying times and form a stronger screed, need to live there even when this is going on.
A company I do a lot of work for use A35 for the screed in showers. We lay vinyl over them after 24hrs with no dpm, and had never had a problem. Its expensive though.
Well I'm back again! Been advised screeding isn't possible as it'll come higher than the walls DPC, even if a mechanical membrane is down and unbonded screed used it'll cause thermal bridging and eventually rising damp which no one wants. Do the next question is what level lay can I use (20-30mm in some places) on concrete that has no DPM, I'll then lay a floating floor on that as previously described and glue the engineered oak to the tongue and groove ply board, can this be done and is it suitable to glue the oak to a floating floor? Thanks guys
