When choosing a roof, we think about a durable covering, good materials and careful workmanship. It is equally important to consider how we will check the finished work and what we will know about the roof's condition after several seasons. This is especially relevant to flat roofs, where the layers that keep out water and retain heat remain out of sight.
When a water stain appears indoors, the cause needs to be diagnosed. While a roof is still being built, a way to monitor its condition can be planned from the outset. Watertightness testing and moisture monitoring answer different questions, so they are best treated as complementary tools.
What smoke testing can reveal about a roof
In this method, a specialist generator introduces diagnostic fog beneath the waterproofing. In a roof build-up assessed as suitable for the test, the fog spreads beneath the covering and may emerge through a leak. The visible outlet helps the contractor locate an area that needs repair, such as a membrane joint or a roof detail.
The test uses diagnostic equipment with flow and pressure control. The specialist must select the fluid, the injection point and the operating conditions in accordance with the instructions for the equipment and the waterproofing system. An ordinary smoke machine used at parties does not, by itself, provide a suitable way to test a roof.
Assess the construction first
Before testing, the contractor should review a cross-section of the roof. Knowing only that the building has bituminous felt, PVC or EPDM is not enough to choose a method. The way the waterproofing is fixed, access to its surface and whether the fog can move freely through the space being tested all matter.
A fully bonded membrane may restrict the spread of the fog. Gravel, terrace surfacing or green roof layers can make it difficult to see where the fog emerges. In these cases, the specialist assesses whether the waterproofing needs to be exposed locally or selects a different test. No single method works equally well on every roof.
Preparing for the test may require a carefully made opening or a suitable connection fitting. Once the test is complete, that point must be professionally sealed to restore watertightness. Correct test procedure is equally important: uncontrolled positive pressure can damage or detach the waterproofing. It is therefore worth agreeing the scope of work with the roofing contractor in advance.
What a well-prepared test involves
- Assess the roof and the purpose of the test. The contractor checks the build-up, the way the covering is fixed, access and information about the symptoms observed.
- Select the method and prepare the area. They establish whether smoke testing will be useful, how to introduce the fog and how to seal the test point afterwards.
- Carry out a controlled test and observe. They conduct the test, observe the surface and details, and mark areas requiring further investigation.
- Repair and recheck. Confirmed defects are repaired using a method appropriate to the system. The scope of testing after the repair must be agreed with the contractor.
- Document the result. It is worth obtaining a record of the area tested, the points identified, the repairs carried out and the limitations of the test.
No visible smoke still requires interpretation
If fog does not appear on the surface, this does not automatically mean that every roof layer is dry and there is no leak, however small. The result depends on access to the area being tested, the ability of the fog to flow and the observation conditions. Waterproofing system instructions also indicate that smoke testing may need to be supplemented by other tests.
Assessing moisture within the layers is a separate issue. Locating a hole in the covering does not establish how far the problem has spread or what needs repair. Further measurements or inspections may therefore be needed during diagnosis. Testing beneath the waterproofing should also not be confused with a building airtightness test, known as a blower door test: its purpose and procedure are different.
Plan VILPE Sense for a new building
If you are still building, it is worth going a step beyond a one-off test at handover. At AMBIT, we recommend considering VILPE Sense at the roof design stage. It is then easier to select sensor locations, plan the required components and coordinate them with the installation of the waterproofing.
VILPE Sense is a family of solutions that use temperature and humidity measurements. It helps track changes inside the structure that may remain invisible during a routine roof walkover. It can be used for leak detection and, in a separate configuration, for humidity control with ventilation.
Leak detection
RHT-2 detectors installed in the insulation layer measure temperature and relative humidity. The data are sent to a cloud service via a base station. A map prepared on a roof plan helps compare readings from different zones and identify an area to inspect. Properly configured notifications make it easier to arrange an inspection when concerning changes occur.
This is periodic monitoring, rather than an instant alarm for every hole. RHT-2 sends new measurements twice a day, and notification timing also depends on the alarm settings. The map identifies a zone with elevated humidity; the precise cause and location of the damage must be confirmed through diagnostic investigation.
Humidity control and assisted drying
In the second configuration, RHT-1 sensors work with a controller and an EC roof fan. The system compares conditions inside the structure with those outdoors, then regulates ventilation to help remove excess moisture.
This function requires an airflow path and a supply of make-up air. Not every roof build-up provides these conditions. Rigid insulation and bonded waterproofing without suitable channels may prevent the necessary airflow. Monitoring and drying are therefore selected separately, based on the design rather than the building's area alone.
What to establish before ordering monitoring
Before discussing your project, prepare a roof cross-section, its area and details of planned installations, such as solar PV or building services equipment. Information about the insulation type, how the waterproofing is fixed and how the structure is divided into zones will also be needed. Only then can the configuration, detector layout and any ventilation be selected.
It is also necessary to decide who will receive notifications and what they will do after an alarm. A sensor provides information, but does not repair damage. The value of monitoring comes from combining a well-chosen system, correct installation and a response to the readings.
VILPE Sense can also be used in existing buildings once the installation method has been assessed. On green roofs, the position of the waterproofing matters: the manufacturer permits suitable build-ups with waterproofing above the thermal insulation and excludes inverted green roofs.
Let's talk about your roof
Are you planning a new building or looking for better insight into the condition of an existing roof? Contact AMBIT. We will review your project's needs and discuss the selection of VILPE Sense and the components that should work alongside it.
If you already have signs of a leak, describe them and gather the available information about the construction. This will help us discuss the next steps. Watertightness testing, repair and monitoring each have different roles; when properly planned, they can work together to help keep the roof in good condition.
Frequently asked questions
Can every flat roof be tested with a smoke machine?
Not every roof build-up is suitable for this method. The way the waterproofing is fixed, access to the covering and the ability of the fog to spread beneath it must all be assessed. An ordinary party smoke machine is no substitute for specialist diagnostic equipment and a qualified contractor.
Does smoke testing require an opening in the waterproofing?
It may require a carefully made opening or a connection fitting. The scope depends on the roof and the test system used. The point where the fog is introduced must be professionally sealed afterwards, so non-invasive testing should not be promised for every building.
Does VILPE Sense replace watertightness testing at handover?
No. Testing checks the roof at a particular point in time, while Sense tracks subsequent changes in temperature and humidity. Monitoring helps identify an area requiring inspection, but does not repair the waterproofing or confirm that every point is watertight.
Does every VILPE Sense kit dry the roof?
No. Detection with RHT-2 is for monitoring. Drying by ventilation requires a separate configuration with RHT-1, a controller and an EC fan, along with a clear, designed airflow path. Selection depends on the construction.
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