Garage Moisture/Damp?

[Adam Bill]

I have a garage which is attached to the main house, this is being used as a utility room/storage area.
Recently I noticed hard black ball shapes coming from the carpet, I looked into this and formed the opinion this was caused because of damp. I pulled up the thin carpet tiles and noticed that there was chipboard underneath which was damp and rotten, this chip board was placed directly on the main garage floor (I have attached picture of what this looked like). I have removed all the carpet and chipboard and am left with concrete.

I have got a moisture meter and this states there is over 2% moisture in the concrete and there is an indicator on the meter which flashes green, amber and red and it is flashing red when held to the concrete. However don't know if this is due to water getting into the garage over the years or having an inefficient/no damp proof membrane. I have noticed that when it rains the water has been able to get into the garage and so have purchased a Stormguard Garage Threshold to prevent this https://www.screwfix.com/p/stormguard-garage-threshold-seal-black-2-5m/37019

What I am unsure of is whether I can seal and then paint the floor buy purchasing the following:
Sealer - http://www.wilko.com/gloss-paint/wilko-concrete-sealer-clear-25l/invt/0342003
Paint - http://www.wilko.com/invt/0342004

Or whether I have to look at something like a liquid damp proof membrane e.g https://www.amazon.co.uk/dp/B00D1RI...t=&hvlocphy=9045027&hvtargid=pla-435331173511

At this moment in time I am not looking to put any flooring on top of the concrete, however would like the option to do this in the future.

Please help, I am really unsure of what to do on this one.

 

[foxhole]

Your meter is intended for damp in timber, not accurate in any other material, though 2% would be expected as concrete sweats and should not be covered with carpet etc .Keep floor clear of covering and wash any stains away with a bit of bleach.No other action is needed.

 

[Adam Bill]

Thanks for the reply. Once cleaned do you think there would be any harm using the concrete sealer and paint that I mentioned above on the floor?

 

[foxhole]

no harm

 

[scbk]

For sealing, watered down PVA is normally used, then maybe thinned floor paint.

Coo-var garage floor paint is good stuff, look it up, it won't cost any more (per litre) than the wilko paint