Technical Advice | Useful Information about Architectural Glazing

What is driving rain?

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Rebecca Clayton

Written by Rebecca Clayton

Edited by Dan Finnegan

Fact-checked by Michal Piekarewicz

Aug 19, 2026

Last verified: Aug 19, 2026

Next review: Aug 19, 2026

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Driving rain on oversized structural glazing

Driving rain on structural glazing 

Driving rain refers to rain that is accompanied by strong wind, causing the raindrops to be carried at an angle rather than falling vertically. Driving rain can be especially problematic because it can penetrate buildings and structures more easily than rain that falls straight down leaving the building susceptible to mould and structural degradation due to the lack of water tightness 

What are the key considerations relating to driving rain with glazing? 

Key considerations concerning driving rain on structural glazing (including all glass windows, glass doors , roof glazing systems and oversized glazing), combine the quality of products, the design, testing, location & orientation, and climate. 

Water tightness in glazing is an essential component of a building envelope. Glazing systems need to be designed and installed to prevent driving rain from entering the building's interior through the structural glazing.  

Effective sealants and gaskets contribute to maintaining the weather tightness of glazing systems. These components are responsible for sealing the gaps between the glazing and the building structure. 

The design and installation of glazing systems should consider the potential for driving rain. Adequate flashing and drainage details are essential to direct water away from the interior of the building.

Dynargh Cornwall 

Water tightness testing for wind-driven rain, may be conducted on glazing systems to assess their performance under simulated driving rain conditions. This testing helps identify any vulnerabilities that need to be addressed. 

 An obvious key consideration is Building Regulations Compliance related to water resistance and driving rain for glazing systems to ensure the safety and integrity of the building (particularly if the building is exposed to strong wind loads such as hurricanes).  

Regular maintenance of glazing systems are important to detect and address any issues that may compromise their water resistance over time. This includes checking and resealing joints and ensuring that drainage pathways are clear. 

Building design and glazing selection should take into account the local climate, including the potential for driving rain due to wind patterns and the frequency of heavy rainfall events. 

Quality installation by trained professionals, such as IQ Glass, is critical to achieving the intended water resistance of glazing systems. Improper installation can lead to gaps and vulnerabilities that allow driving rain to penetrate. 

Addressing the challenges of driving rain in structural glazing requires a combination of careful design, quality materials, precise installation, and ongoing maintenance. Ensuring the water resistance of glazing systems not only protects the interior of the building from water damage but also contributes to energy efficiency, including glass windows, doors and roof glazing performance

At IQ Glass, our unwavering commitment to designing and supplying sustainable high performance glazing systems that exceed our clients' desired aesthetics is one of our key motivations.  

Our dedicated team worked on precision performance glazing to a new build on a challenging site in the exposed coastal location of Mawgan Porth where driving rain and high winds exceeded 90mph. Follow the link to read about our wind load on windows case study 

 

Are you working on a project requiring high performance glass or hurricane resistant glazing systems?

Contact our expert team today! 01494 722 880