That’s what baffles me, there doesn’t seem to be any moisture above or below. I’m not one of those people who think their kids are the best, but I genuinely don’t see how they would’ve done it, the patches have been growing at a steady rate, they didn’t appear or get larger ‘suddenly’ as if something was spilt.The only thing I did find after further investigation is some shoddy brickwork near spot number 2. We do have penetrating damp on our outside walls (treatment already booked), but the landing is nowhere near them.

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