- Puddles to the ground below.
- Property is wet, stained or slimy external walls.
- Rising damp or damp patches in rooms.
- White tide marks on internal plasterwork.
- Blown plaster and mould on walls, not to mention damp smells.
- There are a number of reasons why downpipes leak.
- They sometimes become blocked and start overflowing at a joint.
- They may have split, cracked, or become dislodged.
- uPVC downpipes can be vulnerable to impact damage.
- Cast iron pipes may have rusted through, discharging water straight on to the wall.
- If water in a blocked cast iron downpipe freezes, it is likely to expand and split the pipe, saturating the wall to which it is fixed.
Blocked downpipes can be cleared using a long pole or stiff wire pushed down the pipe to dislodge the blockage. The property gully (the ground-level drain) below the downpipe should first be covered to stop any debris entering the drainage system. Where downpipes are connected at their base directly to underground drains – rather than discharging over gully gratings – access for clearing blockages can be restricted (unless it’s connected via a lead gully with an integral rod eye). You may need to temporarily disconnect and remove the pipe (or the lower section) in this event. Cracked and broken pipes should be replaced. This tends to be a fairly straightforward job with uPVC pipes, simply requiring the brackets to be unscrewed so that the pipe can be taken out and replaced. (Brackets are required at every joint, and should be no more than 1.8m apart.) Old cast iron pipes, however, are held by metal brackets (or integral metal earlobes) attached to the wall with big metal spikes driven into the brickwork, sometimes into fixing holes with metal or wooden plugs. They can be hard to remove without damaging the brickwork. Although, sometimes brackets are fitted with spacers to prevent the pipe contacting the wall — leaving sufficient space for periodic painting to inhibit corrosion.
- Signs may include:
- Damp walls
- Blown plaster
- Damp musty smells
- Rotten timbers
In most cases this will be down to leaks and overflowing gutters or downpipes splashing. But damp problems at ground level can also develop where down pipes discharge directly on to the ground next to the house, or where a gully has become blocked. Over time this can cause the ground to become marshy and unstable, even affecting the support to walls from foundations — at worst, causing localised subsidence. Damp in walls at low level is commonly misdiagnosed as rising damp, with expensive and unnecessary injection damp treatments carried out at the behest of mortgage lenders, rather than solving the true cause of the problem.
Where down pipes discharge on to the ground, they should be diverted away from the house and connected to an underground surface water drainage system or to a soakaway to prevent flooding from causing damp to the main walls. If the water from a downpipe is overshooting the gully and subsequently splashing the wall, the pipe can be extended at its base by fitting a shoe, which will enable it to discharge accurately. Ponding of water around a gully indicates that the water is not running away properly, often due to a build-up of grease and/or solid matter in the trap, or a blockage caused by debris. A simple blockage may be solved by removing leaves from the gully grating. Alternatively, the blockage can be cleared with a solution of caustic soda or by flushing through with a high-pressure hose. Modern gullies have a fitted back inlet to allow for rod access. Fitting a protective cover over a gully is always a good idea to restrict ingress of leaves.