Mysterious damp on kitchen floor and understairs

[Nasa89]

Hi,
I recently bought a house. Surveyor found some damp by the front door, he recommended a damp survey and the EA recommended a company who assessed the damp in all downstairs wall and treated the wall by the door. When we moved in we noticed dampness on the wall in the space under the stairs (salts on wall and tide mark) the floor is damp). One of the walls is external, the other wall goes to the kitchen (in that same corner in the kitchen is the stopcock). We were losing pressure in the gas heater so we got the plumber to try and find the leak, he opened the floor on that corner of the kitchen and it was all wet rubble and the old wet tiles (1930s semi). Finally the leak was upstairs, Completely unrelated problem.
What can I do to find out the source of the dampness? Could it be a small leak in the pipe coming from outside? We did not see any damp course when we excavated about 40cm deep in that corner.

Second, will the insurance cover finding the source of the damp? Do we have any case seekimg compensation from the damp surveyor (they came to the house and recognised they should have seen it and offered to repair it by... injecting the walls and putting new plaster. Guy was clueless about the cause of the damp 😞

btw, if the ground dips near your yard gully, that is typical of local settlement where a leak has washed away the ground beneath.

We replaced our service pipe up to and into our house ourselves. We hired a mini digger to excavate across the drive and garden (it needs to be at least 2ft 6in deep); lined the bottom of the trench with sand and laid the blue water pipe we had got from a plumbers merchant. We just got a plumber in to connect to the internal stop tap and the water company to connect to the external stop tap. The water company also replaced the company service pipe (the bit that joins the external stop tap to the main in the road) as that was also lead.
It did help that I knew in theory what to do as I worked for a water company for 10 years.

Another way to check for external leaks on the service pipe is to look for areas of the garden that are lush and verdant compared with other areas.

😊 thank you PigletJohn was always your reply make me chuckle! Being from the internet generation I always go for the good reviews and fancy website, so I must change my mindset. We have to break through tarmac and there are gas pipes and the electric under threat driveway too so me ir my husband don’t feel confident to do it. I will take your approach and check for recommendations. The water co will change their end of the pipe and connect us for free.

What do you mean with your last post? By the extend of the dampness in the walls (about 4 m in length) and how careless the previous owners were we think that the leak might have been there for a while. I hope there is not much damage to the foundations!

you will find out when you dig it up.

IME, on an older house, the mortar gets washed away between the bricks by a long term leak. As long as the brickwork has not actually collapsed, I like to hose the mud out of the joints and repack with mortar. A builder would probably use a pointing gun, which pushes mortar into the joint, but you can do it by hand, pressing very hard. You will see if there is a cavity or pool of mud underlying the foundation, if so you had better contact your insurance company as there is a chance of subsidence. Older houses often have footings of stepped brickwork, getting wider as they go down, but you might find a concrete raft or a concrete strip. It depends on local practice and soil conditions. Concrete has more chance of bridging over a weak patch.