Protecting Insulating Glass Units Before Installation
Why correct storage and handling matters
Insulating Glass Units (IGUs) are designed to deliver long-term performance in energy efficiency, durability and comfort. However, like many high performance building materials, their performance depends not only on manufacturing quality but also on correct handling, storage and installation practices between production and final installation.
At Viridian, we occasionally receive enquiries about the potential effects of UV exposure, heat and moisture on IGUs prior to installation. Understanding how these factors interact with insulating glass can help prevent premature seal failures and ensure the product performs as designed over its service life.
The importance of proper storage
IGUs are manufactured and processed in controlled factory environments. Production processes include limiting external exposure of sensitive coatings, as well as the proper storage and routine testing of the moisture-absorbing materials used within the insulating glass construction.
Once completed, units are stored in covered factory or warehouse areas prior to transportation to customer factories and project sites. However, if delays occur before the glass is installed into window systems or building façades, it is important that the units continue to be protected from direct weather exposure and excessive heat build-up. These conditions can affect the materials used within the insulating glass edge seal.
Our global sealant suppliers have recently reconfirmed that unfavourable storage conditions should be avoided between production and final installation. Exposure to direct solar radiation combined with high humidity may influence the long-term performance of the edge seal system that bonds the glass panes together.
European testing standards such as EN 1279-4 – Glass in Building: Insulating Glass Units – Methods of Test for Physical Attributes of Edge Seals demonstrate that prolonged exposure to these conditions can affect seal integrity over time.
For this reason, Viridian’s technical guidance is to ensure IGUs are stored under cover wherever possible. Where this cannot be achieved, exposure should be minimised — particularly during rain events, overnight dew formation, or periods of high solar heat — unless suitable protection is provided.
Why edge seals matter
The edge seal system in an IGU performs several critical functions:
- Maintaining the airtight and hermetically sealed cavity between panes
- Preventing moisture ingress
- Supporting the long-term durability of the insulating unit
- Ensuring thermal performance remains consistent
When IGUs are left exposed to direct sunlight and humidity for extended periods prior to installation, the temperature within the unit and at the edge seal can rise significantly. This can place unnecessary stress on the components and the seal system before the glass is even installed in the building.
Best practice for on-site handling
To ensure the longevity and performance of insulating glass units, installers and site teams should follow a few simple best-practice guidelines:
- Protect from weather
Store IGUs in a covered area and shield them from rain, condensation and high humidity. - Avoid direct sunlight exposure
Do not leave units exposed to direct solar radiation for extended periods. - Maintain dry storage conditions
Glass should be stored in a well-ventilated location where moisture cannot accumulate. - Limit storage duration on site
Where possible, schedule delivery and installation to minimise the time glass remains on site before installation. - Follow manufacturer guidance
Always refer to manufacturer storage and installation instructions.
Warranty considerations
Viridian product warranties include conditions relating to correct handling, storage and installation. Failure to follow recommended practices — such as allowing glass to remain exposed to weather or sunlight for extended periods prior to installation — may impact warranty coverage.
These conditions exist to protect the long-term performance of the product and ensure the glass performs as designed once installed in the building envelope.
For more information about Viridian’s warranties, refer to our Warranties page via link here.
The bottom line
Insulating glass units are designed to perform for many years, but the period between manufacturing and installation is an important part of that lifecycle.
By protecting glass from excessive sunlight, moisture and weather exposure during storage, builders and installers can help ensure that IGUs maintain their performance and durability long after installation.
Following best practice on site ultimately protects the quality of the installation, the performance of the building envelope, and the longevity of the glazing system.