Assessing mechanical performance, reducing installation risk at height and thermal expansion joint techniques applied on modern high-rise towers.
Category: Technical insights
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Analysis of Pressure-Equalized Solutions & Rainwater Penetration Prevention on Unitized Façades
Pressure Equalization Chamber – PEC
In the envelopes of skyscrapers, rainwater leakage does not simply come from open cracks; it is the inevitable result of fluid dynamics when three conditions are present together: (1) Surface water, (2) Gaps in the material, and (3) A driving force (the pressure difference between outside and inside the building).
Traditional face-sealed silicone systems (Barrier Wall Systems) often deteriorate quickly after 3 – 5 years due to UV, wind vibration and thermal expansion. That is why the CPM Unitized façade fully applies the principle of Rainscreen & Pressure-Equalized.
Formula for eliminating the penetration force:
ΔP = Poutside (dynamic wind) – Pbuffer cavity (PEC) → 0 (Pa)When the air pressure inside the cavity (PEC) instantly equals the gusting wind pressure outside the glass, the driving pressure difference ΔP becomes 0. Rainwater on the aluminium ledges loses the energy to travel further inside and falls freely into the drainage channel.
3 Core Water-Stopping Factors on a Unitized Panel
REAL-WORLD MALE – FEMALE UNITIZED MULLION ASSEMBLYFigure 2: Corner section of the interlocking split mullion with vulcanised EPDM gasket grooves at the CPM factory. ACCURACY: ±0.5 MMAt the junction between the male and female mullions, CPM uses a self-interlocking press connection with no exposed screws. This completely eliminates the risk of tearing the waterproof membrane when the building undergoes story drift under level-7 seismic loads.
Mock-up Test Values
The results below are taken from independent test report no. KĐ-CPM/2025/HN certified by the International Testing Centre:
Test item Reference standard Pressure / Load Actual result Status Air infiltration ASTM E283 / TCVN 9259 300 Pa (50 Pa test base) 0.05 m³/h·m² EXCEEDS STANDARD Static water penetration ASTM E331 720 Pa (15 minutes continuous) 0.00 ml (no water leakage) 100% PASS Dynamic water penetration AAMA 501.1 (jet propeller) 1,000 Pa (simulated gusts) 0.00 ml (no water in inner cavity) EXCELLENT Structural frame load ASTM E330 +3,600 Pa / -3,600 Pa Deflection L/210 (< L/175 max) SAFE Seismic drift AAMA 501.4 Horizontal displacement ±35 mm No glass breakage, returns to position COMPLIANT * Tested in a 120m³ pressure chamber with 9 interconnected panels.Download the full lab report (PDF)open_in_new -
Simulating pressure equalisation & rainwater penetration prevention in level-15 storms
Applying the pressure-equalised rainscreen principle for absolute leak-proofing.
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Controlling heat radiation & the urban heat island effect with Double Low-E insulated glass
Analysis of a 0.9 W/m²K U-value that reduces HVAC energy consumption by 28%.
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Mock-up testing in an ASTM E330 & E331 dynamic wind chamber at an international lab
Assessing structural deformation under static wind pressure and testing dynamic water pressure.
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Comparing the life-cycle maintenance economics of Unitized and Semi-Unitized façade systems
Analysing initial CapEx against maintenance OpEx over a 25-year cycle for a Grade-A commercial building.