Potential Damp in Subfloor - Should I Be Concerned?

[Mr Sparkle]

I lifted the laminate in my kitchen today as the floor was bouncy in certain areas, due to poor levelled of the subfloor..

However as i took up the underlay (which also doubles as a vapour barrier), it stuck to the floor in the area i have taped..

I then noticed that the subfloor (which is of concrete construction with what i assume to be chip board finish) in the taped area was darker, slightly moist to the touch and had a slight dampish smell..

However, it must be noted that after removing the laminate & underlay, the moisture appears to have dried off

If I'm not mistaken this cant be rising damp as i live in a fourth floor flat.. i do have a balcony though

Does anyone have any idea what the issue may be or whether it is an actual cause for concern in the first place?

To be prudent, i have taped some plastic to the floor to see if moisture gets trapped..

The kitchen can get quite cold and i rarely use the heating in there also

https://imgur.com/a/c2GSfNy

Unfortunately, I'm on mobile, so i was only able to post a link to the pic

 

[KenGMac]

Mr Sparkle, good evening.

Is the balcony near the kitchen?

Have you considered a slow small leak from either a waste pipe, or water feed pipe either above or below the floor?

Ken

 

[Mr Sparkle]

@KenGMac thank you for the response

Yes, the balcony is right next to the kitchen

I will investigate the waste pipe and water feed pipe that is above floor

However, do you have any suggestions on how to investigate below the floor?

Also if it was a leak, would the area dry out once the laminate / Underlay was removed?

 

[KenGMac]

Mr Sparkle, good evening again.

To determine if the balcony is leaking rain water into the house is difficult. is the floor surface of the balcony covered with Asphalt? and is there any indication of water leaks down to the ceiling area of the balcony below? OK not easy to ask your neighbour about that?? have a look for any indications of cracking in the waterproof surface of the balcony.

As for the water feed pipework, there is a sort of quick try on if you place your ear on to the tap you may hear a "hissing" sound that indicates a localised leak, problem is that any tap in use in the block can and will induce the tell tale "hissing" noise that can mask a local leak inside your home.

Have you tried to investigate if there is any moisture / water on the concrete floor under the chipboard, I suspect that the chipboard will have been fixed to timber battens, the battens rest on the concrete with the chipboard fixed to the battens.

Hope the above assists?

 

[Mr Sparkle]

@KenGMac i am not sure i have fully grasped the method you mentioned

Shall i turn on the kitchen tap and listen for a hissing sound by the suspected leak? If i have got it wrong, please could you clarify?

I am confident that the balcony is not leaking, but i will ask the neighbour

I will lift up the chipboard tomorrow and investigate

Thanks for the help

 

[KenGMac]

Shall i turn on the kitchen tap

No keep the taps off, both hot and cold, if you are lucky you may??? hear hissing that is an indication of a leak.

Ken.

 

[HERTS P&D]

What is in the cupboard on the left?

Most leaks that I find in kitchens are from the water supply to the washing machine, a slow drip where it runs down the hose or the back of the machine.

Andy

 

[KenGMac]

Another prime suspect is the cold water stop cock??

Ken

 

[Mr Sparkle]

Took up the chipboard and there were no pipes and it was bone dry

The floor comprises of concrete base, with polystyrene insulation between the wood block (joists)

Observations:

The chipboard was structurally strong with black stuff (not really sure it's mould, but it smell like damp) under the chipboard

There are gaps (approx 10-20mm) between the insulation and the joist in the places that showed signs of damp, so i get the feeling that this could be a case of condensation where there is a cold bridge.. What do you guys think

Image below..

https://imgur.com/a/L8aWbA8

If it is an condensation issue, what would be an appropriate/easily manipulated inulation to use

T&G Chipboard is nightmare... i had to break/cut the board awkwardly... Is there another material i could use instead?

Plywood perhaps?

 

[HERTS P&D]

Check all of your pipe work with a tissue, you have a leaking pipe.

Andy

 

[Mr Sparkle]

Another prime suspect is the cold water stop cock??

Ken

Just checked and there are no leaks around the Stop cock...

Thanks

What is in the cupboard on the left?

Most leaks that I find in kitchens are from the water supply to the washing machine, a slow drip where it runs down the hose or the back of the machine.

Andy

The cupboard on the left has all the pipes to the kitchen sink, waste etc..

All checked and there were no leaks there, fortunately..

 

[Mr Sparkle]

Check all of your pipe work with a tissue, you have a leaking pipe.

Andy

Andy, are you saying that you strongly believe that my issue is due to a leak?

 

[HERTS P&D]

Have a look under the plinth. Run the tap and then check the waste pipes.

Andy

 

[HERTS P&D]

Check your kitchen tap does not leak when in use, they sometimes leak around the base and go through the sink to the unit below. Post pictures of your tap and all of the pies/wastes in the kitchen unit.

Andy

 

[Mr Sparkle]

Pic of sink waste, traps connections etc

https://m.imgur.com/JEsjwVl
https://m.imgur.com/jqsJILK?r

Have a look under the plinth. Run the tap and then check the waste pipes.

Andy

Perfect excuse to make a cup tea.. Cheers Andy

I ran the tap for a couple minutes and happy to say there are no leaks anywhere.. Also checked under the plinth and it was bone dry..

How about condensation theory?