Advice on repairing a damp wall please!

A 200 year old house, in a terrace, each back garden plot is seperated by an old stone/mortar wall which butts up to the house.

Recently the interior wall (ground floor) has become really damp. The plaster is at this stage wet to touch and is coming off the wall. I believe it is linked to the external wall as it only comes up to the height of the wall and extends inwards about .5m.

We can't demolish the external wall as it basically links to another wall which supports our neighbours garden - basically an avalanche would ensue!!

So what should I do - is it a case that the external wall needs to be repaired - does it need to be sealed? Would a builder know how to deal with this or do I need to ring one of these damp proof companies (we really do not have a huge budget).

Any advice whould be greatly appreciated as I am completely in the dark at the moment!

Hi Roo,

Firstly, you do not need to knock the wall.

How long since you noticed the problem?
Any chance that the gutter is broken and water is coming down the wall to cause the problem?
What sort of condition is the gar n wall? Solid/Crumbling etc.
What is condition of rear wall of house?
What materials were used in garden wall and rear wall?

It would be unusual for the garden wall to be tied into the back wall. They rarely did in the old days!
It should be possible to rake out the pointing between the wall and the house and fill with a waterproof or tanking cement which should stop your problem.
It may also be sufficient(temporarily) to just repoint with silicone the top and side of the wall where it butts the house.

If raking out the joint between wall and house, it may be a good idea to cover with plastic and leave for a while to dry.

In my experience, the materials are expensive but the labour from a specialist contractor is extraordinarily expensive.

There are a number of companies out there. I have no affiliation to any but I can happily provide a recommendation, if you wish.

Best of luck.