InSite | [eBook] Guide to Using Sealants

Guide to Using Sealants

By Clive Everett, Facades Technical Standards Director In Technical Advice

Whether undertaking a new build or refurbishment project, sealant joints are rarely given the attention and budget they require. This is surprising considering the array of tasks that sealants are used for.


Traditional constructions use mass walls and drainage channels to absorb and shed water before it reaches their inner surfaces. Modern constructions, however, utilise lightweight masonry wall, rainscreen, render, and curtain wall systems, which rely heavily on sealant joints, to provide air and weather seals whilst accommodating building movements such as thermal expansion, settlement, creep, sway, differential slab edge deflections, etc.


It is common for these joints to frequently suffer from poor design and/or installation. To preserve their effectiveness, sealant joints have to be maintained and periodically replaced.


If a failure occurs in a sealant joint, it can affect the performance of the building envelope, the structure and internal finishes and furnishings. Special attention must be given to the design and specification of concealed joints, as these will be far more difficult to access for repair or replacement.


Taking the time to ensure that good quality products are selected and installed correctly is repaid many times during the life of the building by the reduction in costs associated with the damage caused by failed sealants and of frequent remediation works.


The majority of modern sealants are composed of an elastomeric compound, for flexibility, together with a filler product. Sealants are usually polymers - these pliable compounds allow gaps to be bridged and the sealant to resist a degree of movement, if required.


There are many different sealant products available, each designed for a different application, including structural applications e.g. for structural glazing, or bonding façade elements together.

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