19 May 2021

External Render Application & Guttering in Winter

Find out all you need to know on external render application and guttering in the winter months.

External Render Application in Winter

External render applications, that are applied when temperatures are 5 degrees Celcius and below are extremely high-risk applications. The water ratio used to mix the formulated render will expand from the substrate during freezing temperatures impeding the bonding strength of render application. When the temperatures return to normal, usually daylight hours, the expanded render contracts, causing deboning of the render from the substrate surface.

Such scenarios will require a façade evaluation, using a hand-held hammer test, to determine the unbonded areas of loose render, affected by a Freeze-Thaw phenomenon.

The re-application of the render, inclusive of an additional key coat, will now be required as a 2-part render specification.

It is recommended that you seek the advice of the manufacturer’s technical team to determine the correct render specification before starting the re-application of the render.

It is vital to check the weather forecast to avoid render applications if rainfall is predicted. Applying render whilst it is raining may cause the plastering term called Lime Bloom to occur. This is more common if deeper colours are applied and finished, using cementitious renders.


A key stage in ensuring you maintain a dry surface during the rendering process is having effective guttering in the place. You should have your parapets fixed into position, with the gutter outlet, funnelling the rainwater away from the masonry surface which is assisted by temporary downpipes. This is standard preparation practice and always recommended.

Knowing the weather forecast and planning the correct render application days are essential pre-planning requirements when Winter Working.

Should you require further information, check out Our Top 3 Tips for Winter Working.

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