Rendering in cold weather: potential pitfalls and how to avoid them

Weber render winter working advice

If you’re a contractor or applicator, you might dread working outdoors over the long winter months. Aside from the cold being unpleasant, winter weather can cause lots of issues for construction workers, particularly if you’re working with render.


3 reasons you shouldn't render in bad weather

Rendering in poor weather conditions can lead to a number of issues that will impact on the final finish of the job. Here are 3 reasons you shouldn’t render in bad weather:

1. Lime bloom

When renders are subjected to damp conditions and/or low temperatures during early curing, they can be affected by lime bloom. This happens as a result of the cement’s intolerance to the slower drying conditions during its early stage of hydration. While lime bloom does not affect the integrity or strength of the render, it causes a thin film of white to form on the surface.

2. Colour and texture inconsistency 

Working while it’s raining, as well as rain falling on newly applied render can cause problems with the colour and texture consistency of the finish. As well as this aesthetic issue, excessive amounts of water can affect the bond/adhesion between coats, and could lead to more serious issues.

3. Top coats can be compromised

Our top coat renders rely on evaporation to set, forming a durable finish. If drying conditions are slow, such as in low temperatures, coatings are vulnerable to being washed off before they have a chance to set.

Our top tips for rendering in winter

Work can’t stop just because it’s cold out, so how can you avoid these potential pitfalls when you are working in unfavourable conditions? We’ve got some tips to help.

1. Protect the substrate

If the elevation is exposed to rain and allowed to become saturated, it will be at risk of a greater amount of movement due to drying shrinkage than an elevation which has been adequately protected. This movement means there’s a greater risk of cracking within the substrate, which could lead to cracking in the render. Protecting the elevation from the weather by tenting the scaffolding will protect the substrate. 

2. Consider an accelerator

If using weberpral M or webertherm M1, consider using weber accelerateur monocouche, which is a liquid additive used in place of a portion of the gauging water at the mixing stage. While it’s not an anti-freeze, this product will speed up the initial set time. If dosed correctly, a 20°C degree scrape time can be achieved at 5°C. This leaves the render less susceptible to lime bloom.

3. Beware of frost

Frost and render don’t mix. Never work with frosted materials, on frosted substrates or apply below the recommended temperature listed on a product’s datasheet. Take note of expected weather, and don’t apply if low temperatures are expected during the drying or curing period. In frosty conditions, work should only proceed where suitable protection is provided by enclosing the scaffolding and the temperature is raised with the use of heaters.

4. Protect the finish

Newly applied renders must be protected from damage. Artificial enclosures around scaffolding may be formed using tarpaulins, close mesh netting, polythene or other suitable material to overcome adverse weather conditions.

5. Try weberend retardateur monocouche

weber retardateur monocouche is a retarder solution which may be used to provide scrape time flexibility and extend scrape time, especially for winter working, allowing a next-day scrape in colder months.

Unfortunately, work stoppages due to weather are inevitable over the winter months. If the temperature gets too low, or there’s no suitable way to continue with rendering, it’s best to push the job back until the weather has picked up.

What tips do you have for working in cold weather? Let us know on twitter @SGWeberUK!

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