What should I do with a small damp patch?

[Gary111]

What should I do with a small damp patch? The paint has been flaky but not black or mouldy
It's at the bottom of a wall where the old wall meets the extension.
It's a concrete floor.

 

[Ivor Windybottom]

Very likely it's coming from that flat roof, gravity is taking it to the bottom where you're seeing the issue

 

[Gary111]

On this picture I can see a brick at the bottom of the wall that appears to bridge the cavity.

 

[JohnD]

might be dripping or spilling from the gutter. The watermark looks quite high on the inside.

Outside, the corner looks like it has persistent damp. Stand back and take wide pictures of the entire wall, all the way up to the roof and showing gutters, downpipes, plumbing and boiler vent. Is there a bathroom above?

what is that bit of wood in the inside wall?

 

[Gary111]

Thanks John, I'll take those when I'm next there.
It seems like the wood is a batten to attach the plasterboard?

 

[Gary111]

might be dripping or spilling from the gutter. The watermark looks quite high on the inside.

Outside, the corner looks like it has persistent damp. Stand back and take wide pictures of the entire wall, all the way up to the roof and showing gutters, downpipes, plumbing and boiler vent. Is there a bathroom above?

what is that bit of wood in the inside wall?

 

[Gary111]

A few feet of the cement seems to slope towards the back of the house, there is a drain there though.

 

[JohnD]

A few feet of the cement seems to slope towards the back of the house, there is a drain there though.

Looking at the first picture, the brickwork seems darker around the soil pipe and downpipe, starting near the top and running all the way down to the ground. Soil pipes do not leak from the top so more likely there is a leaking gutter connection or blocked downpipe.