Condensation / damp ? under kitchen sink

[trafficman30]

Hi everybody.
For a few weeks now we have a very strong musty smell coming from our kitchen sink unit.
I took the back panel out as it was very old and warped and noticed the plaster on the back wall was sodden and is 'squishy'. The floor below the affected wall was dry. The wall is internal but on a corner next to outside wall and adjoining terrace
The hot & cold pipes and drain pipe were dry.
I honestly cannot explain the reason why the wall was wet.
It still feels cold and damp at this time later (not as soaked) but cannot find where water could be ingressing so am thinking it may have been a previous occurrence
The smell will not go away and was wondering if the only solution is to remove the unit and cut away the plasterwork to the brick and start again.
The walls are solid brick old house.
Any recommendations would be helpful.

 

[jeds]

I don't see any option but remove the unit and get at it properly. Most likely condensation due to lack of air movement behind. If the plaster is that far gone it will have to be hacked off and replaced. Best advice is to insulate the wall before replacing the unit. I'd use a thermal plasterboard mech fixed. If that's not an option re-plaster with a lime based renovating plaster and add some ventilation to the plinths. Also check externally to make sure the path is not built up above ground level and is drained away from the house. And also that there are no obvious defects to the wall.

 

[trafficman30]

Thanks for your reply John

it all makes sense.
Just hope there is no leak I've missed...

I will endeavour to get this sorted before the winter comes.