What to Do When Your Roof Is Leaking

Step 1: Contain the Water

Before anything else, deal with the water that’s already in the building. Place buckets or containers under any active drip points. Lay towels on the floor around the buckets. Move furniture, rugs, electronics and valuables clear of the affected area.

If water is pooling on a ceiling and the plaster is bulging, there is a risk of ceiling collapse. In this situation, carefully pierce the lowest point of the bulge with a screwdriver — this sounds counterintuitive, but it drains the accumulated water in a controlled way through one small hole rather than causing the ceiling to fail across a wider area.

Step 2: Don’t Go on the Roof

The instinct to get up and look is understandable, but roof surfaces in wet weather are extremely dangerous. The smooth surfaces of wet clay tiles and Welsh slate — common across Oxford’s older properties — provide virtually no grip. Falls from roofs cause serious injury. Leave access to the roof to people with the right equipment and training.

Lead flashing failure at chimney stacks is the single most common cause of active roof leaks on Oxford's period housing, based on our own field data 2025. — Source: own field data 2025

Step 3: Try to Locate the Source

Water frequently travels along rafters and timbers before dripping through a ceiling, which means the drip point is often not directly below the source. From inside, check the loft space if safe to access. Look for:

• Daylight through the roof deck (a tile that has slipped or broken)
• Wet timber or water running along a rafter from a higher point
• Staining on the felt underlay indicating where water is pooling
• Wet or dripping at a specific point such as a chimney breast, valley or dormer

This information is useful to tell the roofer when they arrive. Even if you can’t pinpoint it, the location of the interior drip point helps narrow down the roof area to inspect.

Most Common Causes of Oxford Roof Leaks

Lead Flashing Failure (Most Common on Victorian & Edwardian Properties)

The single most common cause of roof leaks on Oxford’s older housing stock. Original lead flashings at chimney stacks in Jericho, North Oxford, Headington and Marston are now 80–130 years old. When the lead upstand pulls away from the mortar joint — a process accelerated by thermal cycling — water tracks behind the stack and into the ceiling below.

The repair is re-dressing the lead into the raked mortar joint correctly. Silicone is not a durable fix — it bonds to the lead-to-brick interface but splits within one or two seasons as the lead expands and contracts. See our lead work page for full detail.

Valley Blockage and Overflow (Most Common in Autumn)

Oxford’s extensive tree canopy drops enormous volumes of leaves, seeds and small debris through October and November. Lead valleys and mortar valleys on all sides of the roof collect and channel this debris. When a valley blocks, rainwater backs up behind the obstruction and overflows under the adjacent tile course rather than running to the gutter.

The result is a leak that appears during or after rain, typically tracking down a wall or at a ceiling junction near a valley. This is often misdiagnosed as a flashing failure. Clearing and inspecting the valley is the first step. If the valley lining itself is damaged, relining is required.

Slipped or Missing Tiles

Nail sickness (covered in detail in our nail sickness guide) causes tiles to slip progressively. A slipped tile creates a gap that exposes the underlay or the tile below to direct water entry during driven rain. On 1960s–1970s estates in Barton, Blackbird Leys and Risinghurst, this is the most common emergency call we receive.

Ridge Mortar Failure

The mortar bedding that holds ridge tiles in place degrades over 30–50 years. When it fails, the ridge tiles can shift or lift in wind, creating gaps at the ridge line that allow water entry. This is particularly common on the 1930s semi-detached stock across Summertown, Cowley and Kidlington where original mortar is now 85–90 years old.

Flat Roof Failure

Felt flat roofs on rear extensions and garages across Oxford’s 1970s and 1980s stock fail through UV degradation and moisture fatigue over 15–25 years. A leak through a flat roof often appears directly below the roof rather than tracking, making it easier to locate. Temporary patches buy limited time — GRP fibreglass replacement resolves the problem permanently. See our flat roofing page.

Step 4: Call a Roofer

A roof leak is not something to leave for several days. Water entering a building causes damage that compounds rapidly. Oxford’s older lath-and-plaster ceilings spread water laterally — a small ingress over a weekend can require significant plaster and decoration repair that costs more than the roofing repair itself.

We offer same-day and 24/7 emergency call-outs across Oxford and Oxfordshire. We will make the roof watertight, diagnose the cause, and give you a written quote for the permanent repair. Call 0186 580 3181 at any time.

Related: How to Find a Roof Leak · Leaking Flat Roof Repair · Emergency Roofer Oxford · Lead Work Oxford · Roof Repairs Oxford