We have a damp problem running along two sides of our back bedroom on the ground floor. Externally we have an old concrete slab which is flat rather than at an angle away from the house and when it rains heavily the water tends to stand. As well as this their is down pipe coming from the upstairs neighbours porch roof which has no drain! the drain pipe runs directly over the concrete slab; we are about to get external work done including sorting the drainage and new slabs with a gradient... we need to know what exactly we need to do internally to get rid of the damp.
