Engineered wood flooring - concrete floor prep

[Baball]

My 2 pence worth, the plastic looks like Radon membrane/barrier, and shouldn't be compromised, secondly as you are across a threshold it may well be the case that the wall is a supporting wall and as such there will a footing in that line, with block work of some sort bought up to the floor level and leaving the thickness of a mortar joint below the finished floor screed in the adjacent rooms.

Thanks HOJ. You could be right, especially as what is underneath looks like blockwork, and it does run in line with an internal block wall. Seems odd though that maybe it ends half across the doorway at the white tape, as the concrete after that seems very solid like the rest of the floor.

If so, I now have the challenge of re-sealing the membrane. I'm open to any recommendations or experience!

 

[Baball]

It’s quite strange but looking at your photos I’d strongly suspect there is something under that screed or concrete- my reasoning for this is why would the builder not of just screeded the entire floor instead of leaving that part covered in yellow plastic .. so I’d just remove it as it’s not serving any purpose and prime the hard surface with an acrylic primer and just record / photograph and make a note not to drill into that area at any point . Maybe if you could contact the builder and get a better picture of the design and layout of all services and if possible obtain the original plans .. but I don’t think I’d go any further than what you have already exposed. That hard surface looks quite solid and secure so prime / leveling compound and hsppy days with your new flooring.. let us know how you get on and don’t forget pics of the finished floors..

In the meantime, I have asked the builder for plans or information.

 

[HOJ]

If so, I now have the challenge of re-sealing the membrane. I'm open to any recommendations or experience!

In the meantime, I have asked the builder for plans or information.

If you have access to the builder I would advise asking them to make a repair, they may have the double sided tape or some single overlap tape that they use.

 

[Bingy man]

My 2 pence worth, the plastic looks like Radon membrane/barrier, and shouldn't be compromised, secondly as you are across a threshold it may well be the case that the wall is a supporting wall and as such there will a footing in that line, with block work of some sort bought up to the floor level and leaving the thickness of a mortar joint below the finished floor screed in the adjacent rooms.

Just weird that it rises up and over the threshold like that instead of being at a lower level. I think contacting the builder and or the plans should confirm it one way or the other.. if any concerns regarding radon gas then there are alarms to alert you that are relatively cheap

 

[Bingy man]

There are many tapes available at several price points ..this one seems fine for repair work .
Double Sided Jointing Tape
£5.15
+£9.99 delivery
https://www.googleadservices.com/pa...uu0wLaIAxV9ywIHHS2VGscQwg8oAHoFCAcQuAE&adurl=
Straight 2 Site
Apologies didn’t see the delivery charge but as i said above there are several options..

 

[XTiffy]

Radon barrier is normally coloured green, so I don't think that is a barrier. There is a companion tape for joining overlaps of radon barrier.
Coloured tapes to indicate buried pipes or cables would never be that close to the surface (cowboy tradesman excepted). As we live in a low radon area when recently building a new house we had to pay and download a radon map for building control approval. I too would only be happy when I knew what was there, it might well be a way of continuing or protectinga standard dpm (should be under the floor screed) over a dpc.

 

[Bingy man]

I thought the same tbh so I did a quick search and found several yellow radon barriers
https://www.googleadservices.com/pa...5dLg2LiIAxV4UkEAHX47H44Qwg8oAHoECAQQDA&adurl=
Radon Barrier Yellow - 400mu 1600g - 10 Metres - Damp Proofing - Just The Job Supplies
£39.46
+£7.00 delivery
https://www.googleadservices.com/pa...5dLg2LiIAxV4UkEAHX47H44Qwg8oAHoECAQQDA&adurl=
Just The Job Sup

 

[HOJ]

Radon barrier is normally coloured green

Green, Yellow, and Red, that I have seen.

 

[Baball]

So I found this today, the same yellow material and white tape by the front door at the other end of the hallway. It is already split .

 

[Baball]

Radon barrier is normally coloured green, so I don't think that is a barrier. There is a companion tape for joining overlaps of radon barrier.
Coloured tapes to indicate buried pipes or cables would never be that close to the surface (cowboy tradesman excepted). As we live in a low radon area when recently building a new house we had to pay and download a radon map for building control approval. I too would only be happy when I knew what was there, it might well be a way of continuing or protectinga standard dpm (should be under the floor screed) over a dpc.

I checked the radon map of the UK and it seems we are in the lowest rated (<1% affected) area, so some relief if it is in fact a radon barrier!

 

[Bingy man]

It could be as simple as that was used as a dpc - now I could be wrong but you said 6/7 years old so roughly speaking around the 1st Covid outbreak and then the whole seemed to stand still . No food in the shops , no toilet paper and a massive shortage of building materials. If it is a radon barrier and you’re in the < 1% then. Use a suitable tape to make good any damage and make good with acrylic levelling compound and get that flooring down

 

[HOJ]

Ok, spoiler coming, you may well be in an geographical area with a "natural" low Radon risk, but, if the land your house was built on was found to be reclaimed, for what ever reason, (being in South Yorkshire Coal mines, perhaps) then a more local risk/survey/sample bore hole may have been done to analyse for any soil contaminants.

I would suggest, in view of the fact, to my mind it looks like a Radon barrier, check with the local council for the planning files, the Builder, and Building control, after 6 years the records will still be readily available.

With respect @Bingy man, Covid was just short of 5 years ago, and speculation on a forum is not going to give a definitive answer.

The reason I have come back to this is purely based on my experience of working on a house that was built on reclaimed land, (Marlpit) it had to have piled foundations and full Radon mitigation, the house next door was unaffected.

 

[Bingy man]

Ok, spoiler coming, you may well be in an geographical area with a "natural" low Radon risk, but, if the land your house was built on was found to be reclaimed, for what ever reason, (being in South Yorkshire Coal mines, perhaps) then a more local risk/survey/sample bore hole may have been done to analyse for any soil contaminants.

I would suggest, in view of the fact, to my mind it looks like a Radon barrier, check with the local council for the planning files, the Builder, and Building control, after 6 years the records will still be readily available.

With respect @Bingy man, Covid was just short of 5 years ago, and speculation on a forum is not going to give a definitive answer.

The reason I have come back to this is purely based on my experience of working on a house that was built on reclaimed land, (Marlpit) it had to have piled foundations and full Radon mitigation, the house next door was unaffected.

Also with respect - I agreed with your previous post advising that it could be a radon gas barrier and my advice has changed to reflect this . I’m no builder but the method of laying this membrane seems a little strange especially as the op has identified other areas and further problems with this barrier exposed and already split . I did suggest contacting the builder and looking at the original plans to confirm if it is a radon barrier. Shouldn’t these situations not be disclosed by way of the usual surveys ( mine reports / drainage reports and wether or not it was a previous brownfield site etc ?? ) moving forward repairing the membrane and laying the new flooring seems to be the best option. The op can then investigate via building control etc as you have advised should he wish to ..

 

[XTiffy]

With due respect, if that was a radon barier its installation would have been checked by building control and I very much doubt that it would have been approved. i.e correct material, correct overlaps and correct tape on these joins. That is why I believe it is something else more like a dpc or even levelling up a trunking. Most local councils have plans to view online. The buiding regs. plans show construction details which are passed before construction starts, any alterations from those plans have to be approved. The only caverat to that is rogue builders!