Why is the wall wet at the bottom of my downpipe?
Water leaving a downpipe at ground level either goes into a drain or onto the ground. When it hits a hard surface it splashes back onto the wall, repeatedly, in exactly one place.
- Difficulty
- beginner
- Time
- 25 min
- Read
- 2 min
Short answer
Look at what the downpipe discharges onto. A shoe discharging onto paving throws water back against the wall every time it rains. Connecting into a gully or drain, or leading it away from the house, removes the splashing and the wet band on the wall that comes with it.
This is a small fault with a disproportionate effect. A band of persistently wet wall low down, often with green growth and sometimes with damp showing inside at skirting level, traces back to water bouncing off a hard surface. It is easy to see, easy to fix and easy to overlook because it happens at ankle height.
Step by step
- Look at the bottom of the downpipe in rain.Water landing on paving or concrete splashes outwards and back. You will see a spray pattern against the wall and often a horizontal tide line of algae or staining.
- Check whether the gully is blocked or has been paved over.Many downpipes originally discharged into a gully that has since silted up or been covered by a patio. Water then sheets across the surface instead of going down.
- Look for a hard surface sloping towards the house.Paving that falls towards the wall sends the discharged water straight back to the building, which is worse than splashing.
- Connect the downpipe into a gully or drain where you can.GuideHQ has a guide on connecting a downpipe into a drain. It is the tidiest answer and it removes the water rather than relocating it.
- Use a shoe and lead the water away where you cannot.A shoe directing water onto a soakaway, a gravel strip or a channel that carries it clear of the wall is a legitimate answer, provided the destination can take the volume.
- Consider a water butt.It intercepts most of the discharge, which reduces splashing and is useful in the garden. Note that a butt overflow still needs somewhere sensible to go.
- Check the ground level against the damp course.Repeated saturation matters far more where paving has been built up close to or above the damp proof course. That combination is a common cause of internal damp at skirting level.
Questions people ask
Is a gravel strip enough?
Often, yes. It breaks the splash and lets water soak away instead of bouncing. It works less well where the ground is already saturated or falls towards the house.
Could this be causing damp inside?
It is one of the more common external causes of a low-level damp patch, particularly with high ground levels. It is worth ruling out before assuming rising damp.