Roofs In Irlam And Sale

Key takeaways

• A roof is only half the system. Where the water goes after the downpipe matters just as much.
• On flat low ground, gullies and drains struggle when the water table is high, which backs water up.
• Water pooling at the base of a wall is a drainage symptom that gets blamed on the roof.
• Discharging a downpipe onto the ground rather than into a gully causes disproportionate harm here.
• Checking the gully is the cheapest and most overlooked maintenance on the whole system.

The half of the system nobody looks at

People think about roofs in terms of what is above the gutter. In practice the system continues: gutter to outlet, outlet to downpipe, downpipe to a gully at ground level, gully into an underground drain, and from there into a sewer or a soakaway. Any restriction along that chain backs water up towards its source, and the further down the chain the restriction is, the less obvious it is that it is the cause. On ground where drainage is already working hard, the lower half of the system is where problems concentrate, and it is the half that gets inspected least.

Why low flat ground is different

Water leaves a site by soaking into the ground or by running away through drains, and both work less well when the ground is flat and the water table is high. Saturated ground cannot absorb more, so surface water lingers. Drains with little fall move water slowly and are more easily overwhelmed during prolonged rain. During an extended wet spell, an entire local system can be running at capacity, at which point a gully that normally clears in seconds simply will not take what is arriving. None of that is a fault in the property, and all of it affects how water behaves around it.

Symptoms that look like a roof problem and are not

Water pooling at the base of a wall after rain. A gully that backs up and overflows across a path. A damp patch low on an internal wall on the same side as a downpipe. Persistent damp in a ground floor room where the wall outside is repeatedly soaked. These all originate below the gutter rather than above it, and they are routinely attributed to the roof because water and buildings are involved. The distinguishing feature is height: roof related damp typically appears high on a wall or on a ceiling, whereas drainage related damp appears low and near a downpipe or a gully.

The downpipe that does not reach the drain

A surprising number of downpipes discharge onto the ground, into a border, or onto a path rather than into a gully, either by original design or because a shoe or a connection has broken and never been replaced. In most places that is untidy. On low lying saturated ground it is genuinely harmful, because the water has nowhere to go and simply sits against the base of the wall. Over time that saturates the masonry, keeps the ground beside the foundations wet, and produces damp inside at low level. It is also one of the cheapest things to put right, which makes it worth checking on every elevation.

Gullies, and what to look for

A gully is the small chamber at the base of a downpipe, usually with a grating over it and a trap below. They silt up with leaves, moss and grit washed off the roof, and once the trap fills, water backs up. Checking one takes moments: lift or look through the grating, see whether water drains away freely after rain, and look for standing water or debris. Clearing a silted gully is a reasonable ground level job for a homeowner. Where clearing the trap changes nothing, whatever is stopping the water sits beyond it underground, and that is a job for a drainage contractor.

Where responsibility sits

Drainage responsibility is not always the property owner's. In England and Wales, many shared drains and sewers transferred to water companies some years ago, which means a blockage in a shared run may not be your responsibility to clear. The pipework serving only your property generally is. Establishing which is which before commissioning work can save both money and argument, and the local water company can advise on where responsibility divides. It is worth asking that question when a problem appears to be below ground rather than assuming the whole thing falls to you.

What the roof can do to help

If the drainage below is working hard, reducing the load on it helps. That means gutters clear so water reaches the downpipes rather than overflowing at random points, downpipes clear so they deliver to the gully rather than to the wall, and enough outlets that the system is not relying on a single pipe. On some properties, directing rainwater to a soakaway or a water butt rather than into a drain that is already at capacity is a genuine improvement, though where a soakaway is proposed the ground conditions have to suit it and there may be rules about connection that apply locally.

The seasonal pattern to watch for

The tell for drainage rather than roofing is timing. Roof problems follow individual rainfall events: it rains hard, water comes in, it stops. Drainage problems on saturated ground follow prolonged wet periods: nothing happens through the first day of rain and then things start backing up after a week of it, and they persist while the ground stays wet. If your problem appears in the middle of a wet spell rather than during the heaviest downpour, and takes days rather than hours to subside, look below the gutter rather than above it.

Water butts, soakaways and reducing the load

Where the drainage system is working hard, taking some of the roof water out of it is a genuine improvement rather than a gesture. A water butt on a downpipe holds a useful volume during the early part of a storm, which is exactly when the system is most stressed, provided it has an overflow that discharges somewhere sensible rather than against the wall. A soakaway takes the water out of the drain entirely, though it requires ground that can absorb it, which is precisely what low lying saturated sites lack, so it needs assessing rather than assuming. There may also be local rules about how rainwater can be discharged or connected. Both options are worth considering on a property where the gully struggles, and both should be looked at before spending money on the drain itself. Reducing what arrives at a struggling gully is usually cheaper and less disruptive than trying to increase what that gully can take away.

Ground levels and the wall above them

One further detail matters disproportionately on low lying ground. Where paths, patios or raised borders have been built up over the years against the wall of a house, the ground level can end up above the damp proof course, which lets moisture bypass it entirely. That produces damp at low level inside that looks like a drainage failure and is in fact a levels problem. It is worth checking where the external ground sits relative to the internal floor and to any visible damp proof course, since this is a common and easily missed cause, and lowering a path is generally cheaper than any of the alternatives people try first.

Frequently Asked Questions

Why does water pool at the bottom of my downpipe?

Usually because the gully is silted up or the ground is already saturated and cannot take more. Sometimes because the downpipe discharges onto the ground rather than into a gully at all. All three keep water against the base of the wall, which causes damp at low level inside.

How do I tell drainage damp from roof damp?

Height and timing. Roof related damp usually appears high on a wall or on a ceiling and follows individual rainfall events. Drainage related damp appears low, near a downpipe or gully, and follows prolonged wet periods, persisting while the ground stays saturated rather than clearing within hours.

Can I clear a blocked gully myself?

Usually yes, since it is at ground level and often just silt, leaves and moss in the trap. Lift or look through the grating and check whether water drains freely after rain. Where it changes nothing, the restriction lies beyond the trap and underground, which is a drainage contractor's territory.

Whose responsibility is a blocked drain?

It depends where the blockage is. Pipework serving only your property is generally yours. Many shared drains and sewers transferred to water companies some years ago, so a blockage in a shared run may not be. The local water company can advise where responsibility divides, which is worth establishing before commissioning work.

Would a soakaway help?

It can, by diverting rainwater away from a drainage system that is already at capacity. The ground conditions have to suit it, which is exactly the problem where the water table is high, and there may be rules about how rainwater may be connected or discharged locally. It is worth checking before building one.

The problem only appears after days of rain. What does that mean?

That it is probably drainage rather than the roof. Roof faults respond to individual downpours and stop when the rain stops. Saturated ground and overloaded drains respond to cumulative wet weather, so problems appear part way through a wet spell and persist for days after it ends.