Damp showing on internal walls but not in floor

[morchoxplz]

1935 ex council house. Concrete floor. Damp clearly visible to 1.5ft up some-(though not all) internal walls. We had a chap from a flooring company out today (v reputable) as we feared we needed a liquid DPC over the whole floor area to rectify this. He tested the floor under the carpet in several areas- with a damp meter. In some places there were Marley tiles and in others just bare concrete. At all points the readings were low and he said that a liquid DPC to the floor would not solve our problems. He then tested the walls which were much higher in terms of damp. We have a vinal cushion floor in the kitchen (fitted 5 years ago) so he could not lift that to test the floor area there but he stated that the floor would have not have lasted this long if there was damp underneath.

curious that the floor is not wet. It could have a DPM or bitumen but strange if the floor was laid in 1930s. Could it be newer?

Walls so wet makes me think that there is a leaking water pipe. Have you got a water meter? It could also be your neighbour's pipe.

Are the wet walls near the kitchen, or between the kitchen and wherever the outside stopcock is?

Have you got cavity walls? Do the outside walls of the house look wet?