There is a brown ring on the hallway ceiling. It grows a little after every storm, and when you go outside and look up, the roof looks fine. No missing tiles, nothing hanging loose. This is the most common call we get about leaks, and it is why roof leak detection is a job in its own right. Finding where the water gets in usually takes longer than fixing it.
Here is how we track a leak down on Mornington Peninsula homes, what you can safely check yourself, and what to have ready before a roofer turns up.
The stain is rarely under the hole
Water almost never drops straight down. It gets in at one point, then runs along the underside of a tile, down a batten, along a rafter or across the top of the sarking (the foil or membrane layer under the tiles or roof sheets) until it finds a low spot. Only then does it fall onto the ceiling.
On a pitched tile roof that path can be a metre or two. On a long, low pitch metal roof it can be a lot further. So when someone patches the roof directly above the stain and the leak comes back, the patch was usually fine. It was just in the wrong place.
That is also why one leak can leave stains in two rooms, and why two different leaks can make one stain.
What you can check from inside, without going on the roof
Please stay off the roof. Wet tiles and metal are slippery, old tiles crack underfoot, and a fall from a single storey can do serious harm. The useful checking for a homeowner happens indoors.
If you have safe access to the ceiling space, go up with a good torch during or soon after rain. Walk only on the ceiling joists, never on the plasterboard between them. Look for:
- dark or wet timber on rafters and battens
- drips or tide marks on the sarking
- daylight where there should not be any
- wet insulation, which often sits flatter and darker than the rest
Follow the wet trail uphill from the stain as far as you can and take photos. Even if you cannot see the entry point, the direction of the trail saves a lot of time later.
Keep a few notes too. Did it leak in light rain or only in a downpour? Was the wind strong, and from which direction? Did it start straight away or hours into the storm? A leak that only shows up in wind driven rain points somewhere quite different to one that drips every time it showers.
How we narrow it down on the roof
Every job we do starts with an inspection on the roof, not a guess from the street. For a leak, that inspection follows a fairly set order.
First, the usual suspects
Most leaks come from a short list of places, and we check the ones uphill of the stain first:
- flashings around chimneys, walls, vents and skylights
- valleys, where two roof slopes meet and channel a lot of water
- ridge capping, plus its bedding and pointing on tile roofs
- cracked, slipped or broken tiles
- screws, rivets and sheet laps on metal roofs
- box gutters and their outlets
On tile roofs we lift tiles where needed to see what is happening underneath. On metal roofs we look closely at fixings, because a loose or rusted screw can let water in without looking like much from a ladder.
Then, a controlled water test
If nothing obvious turns up, we test with a hose. The trick is to start low and work uphill, one small section at a time, with someone inside watching the ceiling space. Soak the whole roof at once and you learn nothing. Going section by section tells you exactly where the water gets in, because the drip starts when you reach it.
It is slow work. It is also the most reliable way we know to confirm a source on a dry day.
Where moisture meters and thermal cameras fit
Some leak detection companies offer thermal imaging and electronic moisture testing. These tools can show where a ceiling or wall is holding water, which is handy for mapping damage inside the house. They are less useful for pinpointing the exact gap on the roof itself, so on most homes a careful look and a proper water test still do the heavy lifting.
Why Peninsula leaks can be harder to find
A few local conditions make leaks here behave differently to a sheltered suburb.
Wind is the big one. Storms coming off Port Phillip or Bass Strait push rain sideways and even uphill, under sheet laps, tile edges and the tops of flashings. Those same spots stay dry in normal rain, which is why a roof can be fine for months and then leak in one particular storm. We go into this pattern in more detail in our piece on why some roofs only leak in heavy rain.
Salt air is next. Closer to the water, around Rosebud and Rye for example, fixings, flashings and older metal sheets corrode faster. A pin hole in a rusted flashing is easy to miss until you are right on top of it.
Then there are trees. In leafy streets in Mount Eliza and Mount Martha, leaves and needles pack into valleys and box gutters. Water backs up, rises over the edge of the flashing and runs inside. The roof itself may be sound. The blockage is doing the damage.
If your roof is Colorbond or Zincalume, our metal roof leak repair service covers both finding the leak and fixing it, so you are not paying one person to find it and another to repair it.
Sometimes it is not the roof at all
Part of good leak detection is ruling things out. Not every wet ceiling is a roof leak. We regularly find:
- condensation under metal roofs with no sarking, dripping on cold mornings when it has not rained
- a leaking pipe, hot water service or bathroom above the ceiling
- blocked gutters overflowing back into the eaves
- a failed membrane on a balcony or deck that sits over a room
If the stain appears on dry days, or only after someone showers upstairs, tell us. It changes where we look first, and it may mean you need a plumber rather than a roofer.
What to do while you wait
Put a bucket under the drip with a towel in it to stop splashing. Move furniture, rugs and anything electrical out of the way. If the ceiling is sagging or bulging, keep people out of that room. If water is near a light fitting or power point, switch that circuit off at the board.
Photograph the stain each time it rains, with the date. Those photos help us, and they help if you end up talking to your insurer.
Common questions about roof leak detection
How do you locate a leak in a roof?
Start inside and follow the water trail uphill from the stain, then inspect the flashings, valleys, ridges and fixings above that point. If the source still is not obvious, a hose test working from the bottom of the roof upward, one section at a time, will usually confirm it. That part means working on the roof, so leave it to a roofer.
How much does it cost to get a roof leak detected?
It depends on how easy the roof is to access and how long the source takes to find. A leak with an obvious cause can often be found and fixed in one visit, while an intermittent wind driven leak may need water testing. Our guide to what drives the price of fixing a roof leak explains the factors, and we always give a written quote that sets out exactly what is included.
What are the three types of leak detection?
Broadly, visual inspection, water testing and electronic testing such as moisture meters or thermal cameras. On roofs, the first two find most leaks. Electronic tools are more useful for mapping where water has spread through ceilings and walls.
Can you find a roof leak when it is not raining?
Often, yes. A controlled hose test recreates rain on one section of the roof at a time, which is how we confirm a source on a dry day. Wind driven leaks are the hardest to recreate, so your notes about wind direction during the storm are worth keeping.
How can I stop water leaking from my roof in the meantime?
Inside, catch the water, protect your belongings and switch off any affected circuit. Do not climb onto a wet roof to tarp it yourself. The roof needs a proper repair once the source is found, and a temporary fix in the wrong spot can hide where the water is really coming from.
Is it normal for a roof to leak in heavy rain?
No. A sound roof should handle heavy rain without letting water in. A leak that only appears in big storms usually means a flashing, lap or valley is near its limit, and it tends to get worse, so it is worth finding while the damage is still small.
Get the source found, not guessed
If you have a stain that keeps coming back, or a leak nobody has managed to pin down, we can come out and work through it properly, anywhere from Hastings and Somerville to Rosebud and Rye. We are available 7am to 7pm, Monday to Sunday. Book an inspection through our roof leak detection and repairs page and we will show you what we found before any work starts.
