Leak Under a Solid Floor in an Orpington Post-War House

A warm patch on a solid floor, a boiler pressure gauge that keeps falling, or a water meter that moves with every tap off usually means a pipe has failed inside the floor screed. In Orpington’s post-war houses and bungalows the copper was often laid straight into the screed, and after sixty years it corrodes from the outside. The leak can be found from above with thermal imaging, acoustic listening and tracer gas, so only one small section of floor needs to come up, and often the best repair is to re-route the pipe above the floor rather than dig in the old channel.

Why Orpington’s post-war homes have this problem

Orpington grew twice: once after the railway, and again after the war. The large post-war estates and bungalows at Ramsden, Goddington and Green Street Green were built quickly, and a common way of running pipes in that era was to lay bare copper on the slab and pour the screed over it.

Copper and cement do not get on. Lime and moisture in the screed slowly attack the outside of the pipe, and the damage is invisible until a pinhole opens. By then the pipe is about sixty years old and has been heating and cooling every day of its life, so the joints and bends are tired too.

The same thing happens in the 1930s semis out towards Crofton, where the heating was added after the house was built and the pipes were chased into the front-room floor.

Is it the heating or the mains?

This matters, because the signs differ.

Heating pipe leak (the more common one)

• The boiler pressure gauge drops, you top it up, and it drops again over days or weeks.
• A warm or hot patch on the floor, often in a line.
• Carpet or laminate that feels damp or lifts, sometimes with a musty smell.
• Radiators going cold at the top because air is getting in as water gets out.

Mains water leak

• The water meter moves when every tap and appliance is off.
• A cold damp patch, or damp at the bottom of a wall or skirting.
• Low pressure at the taps.
• A sound of running water when the house is quiet.

If you have a combination boiler, its pressure gauge is on the front. Topping it up is described in the boiler manual. Anything inside the boiler itself is a job for a Gas Safe registered engineer, not us.

A quick test you can do tonight

For a suspected mains leak:

1. Turn off every tap, and make sure the washing machine, dishwasher and toilets are not filling.
2. Find your water meter (in a pavement box, a box at the boundary, or indoors near the stopcock) and note the reading or take a photo.
3. Do not use any water for an hour.
4. Read the meter again. If it has moved, water is escaping somewhere.

For a suspected heating leak, note the boiler pressure in the morning and again in the evening for a few days. A steady fall with no visible drip from a radiator valve points to a hidden leak.

How we find it without lifting the floor

Lifting a whole kitchen or hall floor to look for a pinhole is the old way, and nobody wants it. Non-invasive tracing usually narrows it to a spot about the size of a tile.

• Thermal imaging. For heating leaks, a camera shows the warm water spreading under the floor. The hottest point is usually close to the leak.
• Acoustic listening. A ground microphone picks up the hiss of water escaping under pressure. It works well on mains leaks.
• Tracer gas. The pipe is drained and filled with a safe hydrogen and nitrogen mix, which rises through the screed and is picked up by a detector on the surface.
• Pressure testing. Isolating sections of pipe and testing each one confirms which run has failed.

We then mark the floor, open one small section, and confirm.

Repair in the floor or re-route?

Once the leak is found, there are two options.

Repair in place. Cut out the damaged section and fit a new piece. Quick, but the rest of the pipe in that screed is the same age and condition, so another pinhole nearby is likely.

Re-route above the floor. Abandon the buried pipe and run a new one along the skirting, in a boxed channel or through the ceiling void. In most sixty-year-old floors, this is the better long-term answer, because it takes the problem out of the screed for good.

We will tell you what we find and give you both options with the price before we start.

Does insurance pay?

Many buildings policies include “trace and access” cover, which pays for finding the leak and making good the floor afterwards. The failed pipe itself is usually not covered. Ring your insurer before major work starts and ask:

• whether you have trace and access cover, and the limit;
• whether they want to send their own contractor;
• what evidence they need.

Our insurance help page explains the paperwork we provide. If you are on a meter and the leak was on the mains, Thames Water expects a leak on your side to be fixed within four weeks once you know about it, and you may be able to claim a leak allowance for the lost water.

When to call

Call us if the boiler keeps losing pressure, there is a warm or damp patch on a solid floor, or your meter moves with everything off. See leak detection in Orpington and heating leaks in Orpington, or read more on our Orpington area page.

If you smell gas at any point, leave the house and call National Gas Emergency on 0800 111 999.

Need a plumber now?

Call 07868 281022 and tell us your postcode, what you have noticed (warm patch, gauge dropping, meter moving), and whether the water is off. We agree the price with you before any work starts.