Clapham

Before anything else, stop the water

Turn off the stop valve in the flat the water is coming from if you can get to it, or the main valve for the building if you cannot. If the ceiling below is bulging and holding water, do not stand under it. Turn off the electrics to the affected rooms at the consumer unit. Photograph everything now, with timestamps, before anyone moves furniture. That last one matters more than people expect, and it costs nothing.

Three questions that get confused with each other

Almost every argument about a leak between converted flats is actually three arguments happening at once, and separating them does most of the work.

1. Who has to repair the pipe? Answered by the lease and, where the flat is let, by statute.
2. Who is liable for the damage the water did? Answered by the law of negligence and nuisance, not by geography.
3. Whose insurance pays, and who bears the excess? Answered by the block buildings policy and the lease.

They have different answers. It is entirely normal for the upstairs flat to be responsible for repairing the pipe, for nobody to be liable in negligence, and for the block policy to pay for the ceiling below with the excess shared through the service charge. That combination surprises people, but it is the ordinary outcome.

The repair obligation

Read the lease first. In a typical Clapham conversion the demise runs to the internal surfaces, the leaseholder maintains everything serving only their flat, and the freeholder maintains structure and anything serving more than one flat. Where a flat is let to a tenant, section 11 of the Landlord and Tenant Act 1985 implies an obligation on the landlord to keep in repair the structure and exterior, including drains, gutters and external pipes, and to keep in repair and proper working order the installations for the supply of water and for sanitation, extending to parts of the wider building the landlord owns or controls that serve the dwelling.

So on a let flat there are frequently two people with obligations: the leaseholder under the lease and the landlord under statute, and they can be the same person or not.

Liability is about conduct, not about which floor you live on

This is the part that is most often stated wrongly. A leaseholder is not automatically liable for damage simply because the water started in their flat. To recover, the flat below generally has to show that the flat above failed to take reasonable care, and that the failure caused or worsened the damage.

Which is why the timeline matters so much more than the plumbing. A concealed pinhole in a pipe inside a floor void, with no prior sign and no way of knowing, is close to the definition of something nobody was careless about. A washing machine hose that was visibly weeping for three weeks, or a shower tray that was reported and ignored, is a different matter, because once someone knows about a problem and does nothing, the position changes.

That is the whole reason we date the damage in a report where the evidence allows it. Staining that has dried and re-wetted in rings, corrosion at a joint, swelling in a floorboard, rot in a joist: these say something about duration, and duration is what the negligence argument turns on.

Insurance, and the excess nobody expects

A converted house is normally insured under one buildings policy taken out by the freeholder or the residents' management company, paid for through the service charge. That policy typically covers escape of water damage to the building including the flats. Contents remain each occupier's own business.

Two things reliably cause friction. The first is the excess, which on escape of water is often set high and which the lease may allocate to the flat where the leak originated, to the claiming flat, or to all leaseholders through the service charge. Check the lease before you assume. The second is trace and access: most policies will pay for the work of finding and exposing the leak and making good afterwards, but the insurer will want a documented trace, not an invoice that says "found leak". Our insurance claims pages set out what a loss adjuster actually asks for.

What a useful report contains

We get asked to write reports that say whose fault it is. We do not write those, because no insurer or tribunal will give weight to a plumber's view on liability, and offering one makes the rest of the document look partisan. What a report should contain is narrower and far more useful:

• The failure itself, identified and photographed: which pipe, which fitting, which material, which failure mode.
• The method used to find it, and what was ruled out on the way.
• Evidence of duration where the physical condition supports it.
• The path the water took, which in a converted house is rarely straight down.
• The extent of the damage, including what is still wet behind finishes.
• What making good requires, priced separately from the detection and the repair.

That is the document that lets two insurers and two sets of solicitors reach an answer without a third visit.

Where the water actually comes from in these houses

Clapham conversions share a pattern: a Victorian terrace or semi split into two or three flats, usually in the 1980s or 1990s, with a bathroom installed where there was never a bathroom. That bathroom often sits over a front or rear reception room, on suspended timber joists never designed to carry a tiled wet room, with waste pipes threaded through notched joists at whatever fall was achievable.

So the common failures are not dramatic burst pipes. They are shower tray perimeter seals, waste connections behind the bath, concealed shower valves in stud walls, and the joint where a new plastic waste meets the original stack. Almost all of them are intermittent, which is exactly why they run for months before anyone downstairs sees anything. Start with a shower leaking through a ceiling if that matches what you are seeing.

Our part of it

We find the failure, repair it, and put the ceiling, the plaster and the decoration back, which is the half most firms leave for somebody else to arrange. Reinstatement is quoted separately from detection so that the insurer can see the two as distinct lines. Detection is £150 an hour, fixed before we attend, and if we do not find it you do not pay for the time we spent looking.