Laminate flooring on the concrete ground floor

[SaudisLoveAudis]

Hi All,
I hope you are well.
I have about 90 years old house.
I was trying to asses if the concrete has a membrane but I reckon I would need to drill to find out.
I have taken pictures of the ducting hole, I see some plastic sticking out but not sure if you can consider this a moisture barrier.

Does it mean regardless if the membrane is there or not should I put plastic membrane on top? like this one?

NDC 1000 Gauge Black Damp Proof Membrane 4X12.5m | Wickes.co.uk

NDC 1000 Gauge Black Damp Proof Membrane 4X12.5m

www.wickes.co.uk

and then these wood fibre boards?

Diall 5mm Wood Fibre Underlay Boards 7m² 15 Pack - Screwfix

Order online at Screwfix.com. Environmentally-friendly natural wood fibre underlay designed for use in new build and upgraded floors. Smooths uneven floors up to a 3mm variation. High compression strength of up to 15 tonnes/m². Ideal for click systems. Suitable for use with hard floors. FREE...

www.screwfix.com

this would only be 5mm thick but no insulation value

or is it better to use

Timbershield Wood and Laminate Underlay 3mm

Buy Timbershield Wood and Laminate Underlay 3mm at Carpetright. Improve the comfort and durability of your carpet or flooring. Spread the cost with interest free credit.

www.carpetright.co.uk

with underlay tape https://www.wickes.co.uk/Arbiton-Underlay-Foil-Tape---50mm-x-50m/p/220459
with wood fibre underlay on top, this would be 8mm thick in total

I checked the doors and on the ground floor there is at least 18mm clearance in the dining doom and between 25 and 30mm in the living room.
Upstairs it is at least 22mm clearance but I put the wood fibre underlay boards only.

I aim after 8mm thick laminate boards so I need at least 16mm without cutting doors.

 

[oldbutnotdead]

If you are curious, cut a square of polythene, tape it flat to the floor, leave for a day. If when you lift it there's a damp patch then good odds there's no DPM under the slab.
I'd always use polythene under laminate, usually use those green tiles (they're better IMHO at flatting out slightly uneven slabs).

 

[SaudisLoveAudis]

If you are curious, cut a square of polythene, tape it flat to the floor, leave for a day. If when you lift it there's a damp patch then good odds there's no DPM under the slab.
I'd always use polythene under laminate, usually use those green tiles (they're better IMHO at flatting out slightly uneven slabs).

Thank you. Will try that trick to look for moisture.
Does that mean I should not bother with extra insulation layer, just black DPM then wood fibre underlay?

 

[SaudisLoveAudis]

Ok, I commenced the test. After 24h will see if there is dump collected under this 1000 gauge membrane.
But you say to put it anyway even if there seems to be one under the concrete, right?

 

[dazlight]

If you sub floor is 90 years old it won’t have a proper Dpm under it.

 

[SaudisLoveAudis]

If you sub floor is 90 years old it won’t have a proper Dpm under it.

I know the building is 90 years old but they do big jobs on these building over time.
This concrete does not look like 90 years. I would give it maybe 60 years tops.

 

[SaudisLoveAudis]

is there a point using some aluminium type layer for insulation of the ground floor or 1000 gauge membrane and wood laminate is enough?

 

[SaudisLoveAudis]

I forgot to share the results of my testing

It looks like there is no dump collecting underneath. It's dry as before.

 

[Deleted member 174758]

Sorry to play devil's advocate here, but we are in the middle of an exceptionally dry period when river levels even up here in the Pennines (a notably wet and windy part of the world) are very low. As is the water table. So surely all your test confirms is that the slab is dry now, not necessarilly that it still will be after a wet November when the water table is near to the surface

 

[SaudisLoveAudis]

Ok, I have the 1000 gauge membrane ready but I also plan to put Sonic Gold on top of it.
Does the membrane has to go slightly onto the wall? What is the best practice?

 

[Deleted member 174758]

You normally lap it up to above where the DPC is

 

[SaudisLoveAudis]

You normally lap it up to above where the DPC is

So there is insulation on the outside and there are 2 bricks high that are not insulated ~17cm, the end of insulation is at the ground floor level.
Should I unscrew the skirting boards and lap the DPM up a bit 3-5cm then put them back?

Before there was carpet directly on the concrete.

 

[Deleted member 174758]

I'd certainly consider lapping it up behind the skirtings, providing that isn't too difficult a task

 

[Deleted member 174758]

TBH, you aren't going to get a great deal of extra damp proofing by doing that unless the bottoms of your walls a wet through - and if that were the case you'd have evidence of it in your skirting (stains, damp marks, paint peeling, etc))

 

[SaudisLoveAudis]

TBH, you aren't going to get a great deal of extra damp proofing by doing that unless the bottoms of your walls a wet through - and if that were the case you'd have evidence of it in your skirting (stains, damp marks, paint peeling, etc))

on the outside there is old but solid concrete along the walls (no gravel or pebbles), I do not see the dump damage on the inside. There is damage to the ceilings upstairs due to leaking roof but this is another story.
The old wallpaper around the skirting is in tact. The whole walls have been replastered at some point. I don't see the dump damage to the plaster.