How to choose the right Glazing Sealant for your job!
A glazing sealant is a sealant used in the process of glazing. Glazing which derives from the Middle English for ‘glass’ is a part of a wall or window, made of glass. There are a wide variety of products that can be used to suit the wide variety of applications. There is the traditional applications including the glazing of single glass, these have developed through the years to double and triple glazed units used in homes and even in structural aluminium systems that dominate city skylines. Choosing the right product for the right application is imperative to the success of each different window system.
In traditional single glass systems, the panes are bedded and beaded with putty systems. This traditional glazing method is certainly waning with advances in window technology and the drive for greater thermal efficiency in housing. However, there are certain properties where modern glazing is not aesthetically possible. For these applications the best option is often a ‘bedded system’ this is where the base of the window unit or edge sealant is completely immersed in silicone. This is to stop water gathering and damaging the unit or causing it to leak. As the glazing sealant is coming into contact with a different technology in the edge sealant, you can only use a high quality silicone, If you were to use an extended product this would lead to unit failure, our recommended product for this application is the market leading Silfix U9. The other products used include the butyl tape system where the edge of the glass is bonded between the frame and the edge of the glass creating a seal to allow no water ingress. This all designed to prevent water passing into the dwelling and help increase the units thermal performance. The Hodgson glazing systems for these applications can be found here: https://hodgsonsealants.com/technical/glazing-systems.
For the majority of household installations whether the substrate is aluminium or PVC-U the window systems and the glazing products used are largely similar. The system typically comprises of a combination of three products, which provide a long lasting weather tight seal between windows and doors and the building envelope. These products when used in a system have improved performance in terms of thermal and acoustic properties and are fully airtight.
Once the unit is in place in the rebate the best glazing sealant to use around the window frame perimeter would be a good quality low modulus silicone or hybrid (elastic in nature classified as 20 or 25LM). These should have adequate movement accommodation and adhesion to withstand the expansion and contraction of units. Not all silicone sealants are the same, if you were to use the wrong product for this application, say a caulk or general-purpose silicone product, you may see the caulk cracking or the silicone shrinking and losing adhesion to the brickwork. This would lead to ‘whistling’ when conditions are windier, water ingress leading to damp and occasionally it can even effect the edge sealant of the unit causing the unit to break down and need replacing. We would recommend either the Silfix LM or Silfix U8 for this application. When fitting the window there may be a need for filling voids around the rebate to increase thermal efficiency, in this scenario we would recommend an expanding PU foam such as Foamfix. Internally there will be gaps between the window frame and the house interior, this would need sealing and we would recommend the use of an LM hybrid such as our HYSPEC 25 or a caulk such as Aquacaulk for this application. The LM hybrid has greater movement accommodation and will be resistant to unit expansion and contraction; both of these products are paintable.
Structural systems that are commonplace in large new projects giving a seamless glass look even require glazing products. Often the structural systems leave small gaps that require a non-structural weather seal as a glazing sealant. The weather seal helps with the expansion and contraction of units and naturally require a high quality silicone product. We would not recommend any product that is extended (added oils) for this application, due to the technical nature and scale of replacement. Our new Silfix U8 is the ideal product to help any contractor feel secure in the products they are using.
If there are any further questions on the process of glazing or which products are needed for your job please get in touch with our Technical Support team at: firstname.lastname@example.org or call 01482 868321.
There is also a wealth of information to be found on the Glass and Glazing Federation (GGF) website, of which we are founder members: https://www.ggf.org.uk/publications/glazing-manual/glazing-manual-section-4-products-glazing-techniques-maintenance/
See our company profile at: https://www.county.construction/company-news/hodgson-sealants/
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