MAGU ADS diffusion vents are evenly distributed across the roof at intervals of 100–200 m². In the areas where the vents are installed, the old waterproofing and insulation are removed down to the vapor barrier.

The diffusion vent allows water and water vapor to escape to the outside. Due to the vapor pressure gradient inside the roof, several hundred grams of water per hour are often released through the vent at the start of the drying process. Icicles in winter are therefore not uncommon.

Once most of the drying process has taken place—usually after the first year—the diffusion vents are sealed with special MAGU ADS cylinders. These are both vapor-permeable and thermally insulating. They can be easily removed at any time for inspection.

Another major advantage of the MAGU ADS diffusion vents is the ability to look inside the roof. The hood and foam cylinder can be removed in a single step. You can see what’s going on inside the roof at any time. You can measure the relative humidity in the roof yourself using a hygrometer, allowing you to monitor building physics processes firsthand. The flat roof is no longer a mystery—it now has „transparent viewing ports.“.

In the case of a damaged roof where the vapor barrier is still intact, the entire roof assembly is often saturated with water. The insulation boards then have a water content of 50 percent by volume or even more.
Completely saturated thermal insulation gradually loses its insulating effect. However, as moisture levels rise, the roof’s structural framework is put at particular risk. Often, the vapor barrier holds the water back, so one might think the flat roof is fine. The increase in heating costs is a gradual process that the building owner cannot pinpoint. Over the years, water has seeped into the roof unnoticed and been absorbed into the insulation boards in the form of water vapor. In an industrial building with, for example, 1,000 m² and an insulation thickness of 10 cm, the weight of the dry insulation is approximately 1.5–3 kg/m². However, the weight of completely water-saturated insulation can be as high as 100 kg/m². Thus, the weight of the wet insulation is 33 times that of the dry insulation—a total of 100,000 kg—an additional weight on the roof equivalent to 65 VW Golfs!

If snow or driving rain are added to the mix, the structural integrity of the building is in serious danger! Further calculations by our MAGU ADS engineers will ultimately determine how much water will diffuse through the SecuTherm system and over what period of time—and when your old insulation will be dry again.
Even insulation that is completely soaked—to the point where it can be wrung out—dries out reliably within 1–2 years thanks to the MAGU ADS system. The MAGU ADS roof analysis and our building physics calculations form the basis for our drying guarantee. You also won’t have to pay for expensive disposal of the old, heavy insulation.

Insulation materials such as EPS, XPS, and PUR absorb very little water, even when stored underwater. EPS absorbs between 4 and 7 percent by volume, while XPS absorbs only about 4 percent by volume. That is why the floats in our toilet tanks are also made of EPS—polystyrene. Nevertheless, we often install insulation boards on flat roofs that contain more than 50 percent by volume of water per square meter. As a result, a single EPS, XPS, or PUR board—for example, one that is 10 cm thick—can suddenly weigh more than 50 kg per m².
This water enters the panel as water vapor: Over time, water seeps into the roof assembly through a leak in the waterproofing or the vapor barrier. This water initially accumulates on the vapor barrier. Since the vapor barrier is located below the insulation layer and the building is heated, the water is usually around 20 °C. As a result, a vapor partial pressure of, for example, 2300 pascals builds up directly above the water film, seeking to equalize the pressure. The upper sections of the insulation are still dry and ‚unsaturated‘—that is, the partial vapor pressure is significantly lower in the outer region, so that the water diffuses into the insulation in gaseous form and, once the saturation pressure is reached, condenses again and is stored as water within the panel.

According to statistics published so far, damage to flat roofs is caused by:
– 45%: Defective workmanship
– 34%: Planning error (no planning)
– 14% Material failure or improperly installed sheets
– 7% Improper Use During the Construction Period
Source: ddD e.V.; W. Ernst

A water test is an excellent way to check the roof’s watertightness. This is done by raising the inlet level of the drains, for example, with a 5-cm-high ring. The MAGU ADS vents serve as excellent inspection openings here, allowing a view of the old vapor barrier. If no moisture appears in the vents after 2–3 days, the test is usually considered passed. A leak test should be a standard part of flat roof acceptance procedures today.
Every plumber must perform a pressure test on all water lines prior to final inspection. When it comes to flat roofs, those involved are often reluctant to perform a leak test—fearing that a potential leak could mean having to start the work all over again—a risk that neither the contractor, the designer, nor, in many cases, the building owner themselves want to take.
With the MAGU ADS system, even a failure of the leak test is not a problem thanks to the diffusion-open design, and it does not in any way limit the roof’s usability—once the issue has been successfully corrected and the roof has passed a new inspection. All parties involved benefit from the highest level of safety. Trust is good—but verification is often better!

A vapor barrier is a layer installed on the warm side of a building component that prevents the diffusion of water vapor. Its purpose is to prevent the insulation layer from becoming excessively saturated with moisture due to the diffusion of water vapor.
Since the MAGU ADS system is a diffusion-open construction, a functional vapor barrier is not necessary. Details are specified in DIN 4108-3. A diffusion-open construction is described in more detail here, for example, in Table 4.

In the experiment shown here, the vapor-tight metal lid of a jam jar was replaced with a ‚diffusion-permeable‘ film. Even after several years and with additional heat applied beneath the jar, there is no significant evaporation of the water inside.
If you also consider that a wine bottle cork is many times more permeable to water vapor than any plastic film—and yet it takes years for even a single millimeter of the bottle to evaporate—which, extrapolated to one square meter, would amount to one liter —it becomes clear that this cannot be a suitable remediation method.

If a flat roof is renovated using our MAGU ADS system in accordance with our building physics analyses and calculations, as well as our specifications, we, MAGU Bausysteme GmbH, Hüfingen, guarantee that the old insulation will dry out within the specified time period. In almost all cases, we can guarantee that the old insulation will dry out completely within the first two years. The rate of drying ultimately depends on the type of building, the roof structure, and the building’s use. This guarantee is reinsured and backed by our product liability insurance.

In principle, this building physics system works for all flat roofs on heated buildings. The system relies on a building physics-based vapor pressure gradient from the interior of the building—the concrete slab or water-saturated insulation—outward toward the relatively cooler and drier outside air. In the tropics or in very warm regions of the world, this principle works less effectively or not at all, since the partial vapor pressure of the outside air there is usually higher than inside the building. For every MAGU ADS renovation, MAGU prepares an individual drying calculation. The amount of moisture to be removed is calculated, and the timeframe for successful remediation is defined. In principle, any type of thermal insulation can be dried—whether EPS/XPS polystyrene, PUR foam, mineral wool, or even cork.