The walls of a property are, quite evidently, the barrier which keeps the elements, and particularly water, from reaching your comfortable internal environment.
In order to fulfil that function effectively, however, they need to be clear of soil and ground level build up.
Already prone to rising damp, solid and cob wall structures will deteriorate significantly more rapidly if soil or other material is allowed to build up in contact with the structure.
Damp conditions will speed the deterioration of the protective render layer and, once this is compromised, the masonry or cob underneath can become damp. The result can be decorative issues inside, rotting of timbers embedded in the walls (like joists) and an unpleasant, musty internal environment.
In extreme situations, damp affected cob or solid walls could lose their structural rigidity and fail.
A modern home is protected from rising damp by a damp-proof course (DPC), usually installed at around 150mm above ground level. However, this is only effective so long as it is not breached by a ground-level or soil build-up above the DPC.
If the ground-level is allowed to build up to above this level, moisture will be able to enter the external leaf. If this is able to track across the cavity, perhaps via a wall-tie or mortar drippings, then it can impact the internal environment in the same ways as above – creating unpleasant damp stains, deteriorating decorative finishes and providing for a musty, unpleasant living space.
Whilst potentially serious, this problem is not going to be an issue for most homeowners – particularly those on flat, landscaped plots.
That said, the seriousness of the consequences indicate that routine inspection is sensible. A simple walk around the external envelope (exterior facing walls) of the property every year is sensible. Check for soil, leaf or other vegetation build up and clear away anything that may present an issue.
If a piece of sloping ground near your house slips and comes into contact with the walls of the property, don’t delay in removing the debris and clearing the walls.
In a modern house, also check that the DPC has been fitted properly – with several millimetres of clearance beyond the face of the brickwork. If this clearance isn’t maintained – due to poor workmanship or deterioration – rising damp could progress up the wall via the gaps in the barrier.