Rising damp in old stone house with later added concrete floor

[Phouse]

I was hoping @pigletjohn might be able to provide some advice. A relative has bought an old stone house (1870ish) which appears to have rising damp in the internal walls, and also coming up from parts of the more recently added concrete floor. Before we go down the route of injectables and stripping off plaster is there anything else we can do? And if it is rising through the concrete floor what is the best way to deal with that? The roof appears dry, no obvious cause such as leaks ( and issue is on several different walls). There was a historic leak from water tank in roof which brought down ceiling but that was two years ago ( and into one room whereas several rooms appear effected).

Piglet John will tell you that it isn't rising damp.

Sounds like you either have something leaking somewhere or a condensation issue.

Fireplaces and air bricks blocked up? New double glazing?

And injectables are a con

it could still be a leak in the water supply pipe in the ground. It usually comes up through the floor where the kitchen sink used to be.

Or it might be a leaking drain (gutters or bath)

Take some photos of the wet walls, inside and out, all the way from ground to roof, and showing all pipes, drains and manhole covers, and a plan.

Look at the gutters during and after heavy rain and see if they are spilling or dripping.

Do you think the concrete floor was added to replace an old wooden floor that had rotted (due to damp?)

Do not allow anyone who sells silicone injections anywhere near the house.

Thanks all, will do photos in the morning in better light and attach a plan. There is new double glazing but with vents - the house has had an air vent added at the back but there are no original air vents visible- it's sandstone construction not brick.

Also check to see if external drains have been infilled with concrete - we had damp with a stone / lime mortared house and found that the previous owner had concreted in the drains.

Are the walls solid. If they are you will probably have condensation problems particularly if you have modern double glazing fitted. I used to own a house which had solid slate walls, in some places they were 2ft thick. We had lots of damp problems due to modern glazing which effectively sealed the house allowing no airflow. The solid walls were very cold and any moisture in the air condensed on the walls.
What helped was keeping a couple of windows slightly open all the time and leaving all the internal doors open to allow good air circulation. Good oven extractor fan and extra fans in the bathrooms that remains on for 30mins after use.
Ultimately the cure was removing all the plaster off the internal walls back to stone then lining with a waterproof membrane then batoning the wall to creat a small air gap and plaster boarding with insulated plaster board. It made a massive difference and improved insulation as well as stopping condensation.
It’s a bit like tanking that you have done in subterranean rooms.
The builder we used had worked on a lot of solids stone walled buildings and found this technique to be most effective.

In my opinion, it’s probably the concrete floor causing the damp.

Typically a stone built home will have a flag stone or tiled floor with lime mortar which breathes out moisture from the ground and that evaporates evenly and is dispersed by proper indoor ventilation.
But when you seal the floor with concrete, the moisture from the ground under the floor then starts rising up the walls because stone is porous. The internal walls then get especially damp as less ventilated than exterior walls.

www.oldhouserepairs.uk/damp-in-old-houses

I would be looking for the wrong sort of plaster/cement. Someone has stopped your relative's house from being able to breathe. As an old house it is likely built with lime mortar - any cement will stop it breathing and cause damp, often wrongly called rising damp.

Commonly this is due to coats of modern plaster but given you have a great big concrete floor and the damp looks associated with it, I agree with @PlanDeRaccordement that it's the concrete floor that is the issue.

It needs removing and redoing with limecrete if a new base is required.

No injections ever.

If it's stone, I don't think you'd be able to have silicone injections anyway (just as well)

Take a good look at the spab.org (society for the protection of ancient buildings) website, they outline well the main issues that will be at play here, acquaint yourself with the way traditionally built buildings stay healthy and well before you engage anyone to advise you or work on it, that way you will stand less chance of being taken for a ride.

If you are in the northwest I can suggest some good proffesionals.

Do not engage the help of any professional who has any financial interest in the solution which they will inevitably recommend. As PP have explained, modern materials can be very detrimental to old houses.