Roof Leak Detection

Roof Leak Detection

Your home will always be one of your most significant investments — both in terms of finances and peace of mind. However, there can be certain issues that arise that lead to you spending more of the former than you intend to. A roof leak can become a costly problem. This is particularly the case if it goes undetected for a period of time before you get a professional in to take care of it. This leads us to the question: How does roof leak detection work?

Not everybody is well-versed in early stage roof leak detection. The good news is that while you need assistance from a professional to repair, you don’t need to be an expert to grasp the tell-tale signs that something is amiss. You won’t require any specialist equipment, either. For the most part, you just have to have a little knowledge and some vigilance.   

So, we’re going to take you through roof leak detection by way of most of the senses. We’ve covered four of the five — because, trust us; you don’t want to use the sense of taste to detect a leaky roof! 


In most cases, you’re likely to discover the first signs of a leaking roof from the visual cues. Some of these will be obvious. However, others can be relatively subtle. 

Some of the visual signs to look out for include: 

  • Water Stains

This is the visual form of roof leak detection that most people will be familiar with. These can be present on the ceilings, in the attic space, and in some cases at the top of your walls where they meet the ceiling. Water stains are generally a sign that your roof has been leaking for a while, as they occur from gathering pools of water that have collected in areas of your attic or crawl space. 

  • Peeling Paint

This can be a sign of a leak at both the internal and external areas of your home. With regard to the inside rooms, this can be most likely to appear on ceiling paint or upper wall paint. Externally, you’re looking for peeling paint beneath the eaves.

  • Presence of Mold

This can start small and get worse over time. Usually it will appear as light spotting in a few areas close to the ceiling. The difficulty with mold is that it can be caused by a number of sources of moisture. If you live in a humid climate or close to a body of water, you could easily mistake this for being common dampness. If you find mold on the ceilings or upper walls, take time to inspect your attic and roof areas.


Your sense of smell can be a vital tool in understanding whether there is potentially a leak in your home. The problem is that the early signs can be quite subtle, and if you’ve lived with the scents of your home for some time, the slight changes that creep in can be easy to miss because you’ve gradually become acclimated to them. This is known as nose blindness. As such, usually your best chance of smelling the lingering signs of a leak is when you’ve just come in from outside, or when they’ve become especially strong.

Some common smells that can suggest a roof leak include:

  • Mildew
  • Mustiness — similar to what you might find in a basement or antique store
  • Earthiness — which is usually present when wood has started to rot, or when gutters have become clogged

When you start to notice any of these smells and the cause isn’t immediately obvious, it’s worth inspecting your roof and attic areas. 


Roof leak detection isn’t always dependent upon the especially invasive signs. You’re not always going to be able to immediately see the creeping damage being caused by a leak, or notice the smells associated with it. However, it is important to also pay attention to any new background noises in your property. Many buildings will have some sort of ambient sound — particularly if you have an HVAC unit. But a leak can add some distinct additions to these. 

You might expect a traditional dripping noise to emanate from a leak. While this can certainly be the case, the sound being made can also depend on the surface it’s hitting and just how much water is entering the roof. As such, you should also be listening out for trickling sounds and knocking. Creaking may also be present if a leak is affecting the integrity of the wooden supports of the building. 


It’s unlikely that you’ll be checking for a leak by touch alone — unless you’re reaching into difficult to see areas. However, that’s not to say that there aren’t some aspects of roof leak detection that can’t help you to either confirm the presence of water damage using your fingers or non-conductive implements (particularly around electrical outlets). 

These can include: 

  • Surface wetness on plaster or paint. 
  • Surface wetness around air vents. In the bathroom this can occur around the extractor fan. While this is most likely to be condensation, prolonged presence of surface water can indicate a roof leak near your vent cap.
  • Distended or bubbling wallpaper or paint on or close to the ceiling. This will be soft to the touch, and may crack when pressure is applied.

Professional Tools

While these elements can help you to gauge the likelihood of a roof leak, you may not be able to confirm it personally. That’s fine, as if you suspect there might be a leak, it’s vital that you get a professional to assist you in any case. You’re unlikely to need a full replacement. But the sooner you can get it taken care of one way or the other, the less chance of more destructive — and more costly — damage to occur.

Alongside their years of experience, your pro may also utilize the following tools designed for roof leak detection. 

  • Electronic Leak Detection (ELD)

An ELD is a relatively simple but very accurate tool in detecting the presence and location of moisture. This tool generates a pulse, which in the presence of even a small amount of surface water can complete a circuit to confirm a potential leak. Probes on the device can then be used to ascertain the direction of the flow, allowing your professional to follow it to the source of the leak. Even when the leak is almost invisible, an ELD can usually find the source. 

  • Infra-Red (IR) Scanning

Some roofing professionals utilize IR scanning technology or thermal imaging to detect the presence of leaks. This can be most successful when performed around dusk. The reason for this is water which has leaked through to the underlayment and saturated areas of it will heat up during the day, just as the rest of the roofing will. However, when the sun goes down, the roof will start to cool off quicker than the heated saturated section of underlayment. This means that thermal imaging can be used to pinpoint areas for further inspection.   

Wrapping Up

Detecting a roof leak can come down to a range of factors. Some of these will be obvious — water stains or strong mildew odors. Others can be more subtle, like light dripping or surface moisture. You may be able to undertake some further inspection yourself if it is safe to do so. However, your first best response is to contact a local professional and discuss the signs you’ve found. They’ll be able to confirm the most appropriate course of action and perform a fix that will mitigate further issues.

Get a Free Roofing Estimate