Your facade only leaks when it rains. We at Ultrices Leak Detection analyze building physics such as wind pressure, driving rain, and capillary action around masonry, window frames, sealant joints, and expansion joints.
We check the cavity wall for thermal bridges and leaky cavities, lead flashing, roof edge, and gutter with downpipe, plus cracks in the brickwork. Using thermography, smoke test, dye test, endoscopy, and moisture measurement, we locate the source of the leakage and infiltration.
Afterwards, we arrange repairs, repointing, caulking, impregnation, and hydrophobing for water repellency, plus maintenance and facade cleaning. Read our Google reviews 5 out of 5 in experiences regarding Facade leaks only when it rains.
Table of contents
Facade leaks only when it rains: meaning and causes
"Facade leaks only during rain" means that water penetrates only during precipitation and usually during wind. This is typical of rain penetration and facade penetration and differs from condensation or pipe leakage. According to NEN 2778, this falls under moisture penetration due to rain in combination with wind pressure. At Ultrices leak detection, we frequently see this in masonry with aged pointing, cracks, porous brick, contaminated cavity walls, open weep holes, faulty details around window frames, and barriers such as lead flashing or EPDM that no longer seal. Westerly winds with showers, as measured by the KNMI, lead to high pressure on the facade, causing water to migrate inwards through cracks and capillary action. TU Delft and ISSO describe this as a building physics interplay of wind pressure, suction, capillaries, and water film formation on the facade surface. The result is wet interior walls, mold, peeling paint, and short circuits at electrical outlets, especially immediately after rain.
How driving rain and wind pressure push water through the facade
With facade leaks occurring only during rain, where wind-driven rain plays the leading role. High wind speeds increase pressure on the exterior and cause a pressure difference between the outside and the inside. Water seeks the path of least resistance through mortar joints, cracks, expansion joints, window frame connections, leaking drip edges, or through contamination in the cavity, creating water bridges. Capillary action in fine pores draws water further inward. Materials with insufficient water repellency or decreasing hydrophobia show increased absorption. A vapor-permeable yet water-repellent system, such as with correct ETICS or a well-impregnated brick, limits this effect. Using thermography from FLIR cameras, we combine thermal imaging with moisture measurements from Tramex and Protimeter to identify cold, wet zones.
Typical sources for a facade that only leaks when it rains
- Weathered mortar: Washed-out or cracked joints create open capillaries, allowing rainwater to reach the cavity directly and drain indoors through cavity contamination.
- Window frame connectionsMissing or outdated sealant joints and incorrect mounting frames allow water to run behind the frame, especially during driving rain with side winds.
- Lead flashing and water hammer: a slab that is too short or a flat water hammer without a slope causes backflow and water ingress into the connection
- Open butt joints and expansion joints: necessary openings for ventilation or operation can lead to penetration through the facade without proper waterproofing
- Cavity contamination: mortar joints and bridges create a direct connection between the outer and inner leaf, allowing water to reach the inner wall
For situations involving heavy rainfall, we recommend specialist investigation and, if necessary, a targeted water test and infrared analysis. Read more about our approach to rainfall with a clear explanation via Practical advice on rainwater hitting the facade.
Our leak detection approach without demolition or breaking
We combine science, practice, and recordable measurements. Available nationwide, on-site within 1 hour in emergencies, 15 years of experience, VCA VOL and NEN 3140 certified, professional equipment, and a comprehensive expert report within 3 days. No solution, no payment, and a 99 percent success rate. This is how we systematically address facade leaks only during rain.
- Anamnesis and context: we link your report to KNMI rain and wind data and analyze material, year of construction, and details on drawings and on site
- Non-destructive measurements: thermography with FLIR, moisture mapping with Tramex and Protimeter, endoscopy in the cavity and inspection of sealant and jointing
- Targeted water test: phased spraying per detail in accordance with guidelines from NEN 2778 and ISSO so that we see exactly where runoff occurs
- Trace tests: use of dye, smoke, and a blower door test under slight negative pressure to make leak paths visible without demolition
- Diagnosis and advice: clear cause, photographic evidence, repair advice with materials such as Illbruck compriband, Sika or Remmers impregnating agent and EPDM details
Leak detection process request
If you want us to carry out the work without breaking anything and document everything immediately for the insurer, view our method via Leak detection without demolition or breakingFor direct localization of facade routes, you can also read on about professional facade leak detection.
Repair and prevention for a facade that only leaks when it rains
- Targeted repair of jointing: grinding out and replacing joints with appropriate mortars, followed by hydrophobic impregnation based on silane or siloxane
- Detail corrections: renewing sealant joints around window frames with proper vapor permeability and installing Illbruck tape at the adjustment joint
- Optimizing reversibles: new EPDM or lead flashing with upstand and clamp fixation and correct water barriers above lintels and at galleries
- Cavity renovation: removal of mortar bridges, installation of cavity lead and water-repellent membrane where details require it
- Testing after recovery: inspection with thermography and repeat water test so that the facade leaking only during rain is permanently resolved
Scientific substantiation and evidence for insurer
We substantiate the claim that the facade leaks only during rain with measured values, photos, and a reproducible test setup. We refer to recognized knowledge of NEN 2778, ISSO publications, and building physics from TU Delft to ensure your case is strong. Our expert report is clear, quantifies the risk of consequential damage, and links every recommendation to a measurement finding. Thanks to our collaboration with insurers and a guarantee of coverage in the event of policy conditions, you are in a stronger position during claims handling.
Regional factors and material behavior
KNMI data shows higher rainfall on the coast and in open polder fields than in sheltered urban areas. With brick and calcium silicate, a weathered facade reacts differently than a plastered facade or an ETICS system. Orientation is also crucial. West and southwest receive the most rainfall. Using WUFI simulations and field measurements, we determine whether impregnation, joint repair, or detail correction is most effective. This ensures that facade leaks that only occur during rain do not return, not even during heavy showers with wind gusts.
You can reach us day and night at 085 2505 217 or via WhatsApp. You can also email us at info@Ultriceslekdetectie.nl. We operate nationwide for both private and business clients, active 24 hours a day, 7 days a week, without any demolition or breaking work, and entirely on a no-cure-no-pay basis, with 5 out of 5 Google review stars. If you prefer immediate clarity regarding planning and costs, request a clear quote with a quick response via Free facade leak quote within 24 hours.
Frequently asked questions
Why does my facade only leak when it rains and the wind comes from a specific direction?
Rain penetration forces water into weak spots of the building envelope. Think of porous or cracked mortar joints, open butt joints without a functioning damp-proof course, cracks around window frames, outdated sealant joints, damaged lead flashing under the windowsill, leaking rainwater drains, or a poorly finished fascia board. Facade penetrations, expansion joints, and seams in cladding are also often culprits. Capillary action and negative pressure caused by wind amplify this effect.
Because the problem coincides with showers, it is rarely a pipe leak. You see damp streaks appearing after rain, mold on the interior wall, a musty cavity, and sometimes peeling paint. We link the pattern to the rain pressure and orientation and pinpoint the leak path specifically, so that you can make targeted repair choices without unnecessary interventions.
How do you trace a facade leak that only occurs during rain without hacking and breaking?
We start with a structural inspection, moisture measurements in a logical grid, and infrared thermography to visualize thermal bridges and leakage traces. Next, we use endoscopy to examine the cavity for damp-proof courses, contamination, and protruding mortar bridges. Where applicable, we use the NEN 2778 assessment frameworks for moisture in buildings to ensure that findings are reproducible.
Next, we perform a phased spray test per detail, a smoke test through the cavity, and, if necessary, a dye test to trace the exact leak path. Everything is documented with photos and video. At Ultrices Leak Detection, VCA VOL and NEN 3140 certified specialists work nationwide, without any demolition or breaking, with a 99 percent success rate. If you want to see how we simulate this, take a look. Simulate rain impact on your facade.
How much does it cost to detect a facade leak and how soon can you start?
The investment depends on the property type, the number of facade details, and which tests are required, such as a spray test, smoke test, endoscopy, and a full report. You will receive a free quote within 24 hours, and we work on a no-solution, no-payment basis, so it is 100 percent risk-free. Our customers rate us 5 out of 5 stars. For an indication, see View our current rates for facade leak detection.
With our emergency service, we are often on-site within 1 hour, 24 hours a day, 7 days a week. You will receive a comprehensive expert report within 3 days, including the cause, evidence, and repair recommendations. We coordinate with your insurer where relevant and ensure your file is complete and clear for quick decision-making.
Is damage caused by a facade leak that only occurs during rain covered, and do you provide a report?
Consequential damage from facade leakage is often covered by buildings insurance, while the cause and overdue maintenance vary by policy. We provide a complete and clear report including findings, measurement data, photos and video, a traceable leak path, and repair advice. This allows your insurer to assess coverage based on the facts.
We conduct evidence-based tests and establish the temporal relationship with rain, so that causality is demonstrable. You will receive the report within 3 days, and we will assist you with the claim processing. Request your documentation directly here via Request your insurance report for facade leakageAt Ultrices Leak Detection, you work without demolition or breaking, with 15 years of experience and a very high success rate.