A Guide to Fitting High-Performance Glazing Systems

Performance begins at the connection

The success of glazing lies in how it connects to the building fabric. Depending on the material, there are different connection details to take into account which will help to prevent condensation risks and, ultimately, building deterioration.

• Are you using SIP panels or is this a traditional cavity wall construction? 
• If it is a cavity wall, where is that cavity positioned? 
• Is that cavity closed, ventilated, or insulated?
• How is ventilation or drainage from that cavity being managed?

Depending on the situation, glazing specialists will apply a vapour barrier or membrane. However, there are different types of membrane to consider – a waterproof membrane stops the water and the weather completely, while an internal vapour barrier acts a bit like a Gore-Tex coat, protecting against the weather while still being breathable. This mitigates the chances of condensation within the building envelope, which is essentially what leads to deterioration of a building, whether it’s stone timber or steel. For more on this, take a look at our blog, What causes condensation on windows and how to prevent it.

Managing cold bridges and steelwork

Many buildings will require steelwork, and this raises a number of other questions to contend with as steelwork can be a weak point when it comes to weather proofing.

When you put a steel across a cavity, it creates a ‘cold bridge’. This means there is the risk of heat transferring, which can be damaging for the building and a point for condensation. So it is important to factor in details to mitigate this.

Mitigating this requires:

• Careful thermal break detailing
• Correct insulation around steel penetrations
• Coordinated drainage strategies within cavities

Each scenario presents unique challenges – from cavity ventilation and insulation placement to damp proof course alignment – all of which must connect precisely to the glazing system.

Getting it right at design stage 

To get the fitting considerations right takes a collaborative effort, with architects and structural engineers  as well as home owners. But it is all part of the design process. Once a client has their heart set on ‘I want those doors’, it is up to the glazing experts to work with the architect to do the background tasks to make sure the provisions are there for the frames to fit correctly. Not only that they fit correctly but also that they function correctly.

This means checking that: 

• Structural openings are correctly sized and supported
• Fixings are sufficiently secure to the building 
• Insulation is in the correct voids to prevent condensation
• The correct weatherproofing system is in place
• Frames are able to accommodate movement without failure

Structural considerations to avoid deflection

Large-scale glazing is highly sensitive to even minor deflection. When you’re dealing with ultra-precise, minimal systems, even small changes in the building can have a catastrophic effect if they’re not accounted for.

Structural considerations for fitting include:

• Wind loads – has the environment been taken into consideration? 
• Physical loads – what material is the roof/ building construction? 
• Dynamic loads – what changes might take place that could affect the load – for example, a sedum roof will be heavier in winter than summer; is the weight of snow going to be a factor in the harsher months?

All these factors need to be considered when doing the design work: a steel beam that bows by only a few millimetres under load can compromise the smooth operation of a frameless sliding system – unless that movement has been anticipated and designed for. For more on this take a look at our blog, Weather performance and testing for architectural glazing.