Rendering in winter: don’t get caught out in the cold!
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.
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 synthetic top-coat renders rely on evaporation to set to form a durable, wearing finish. If drying conditions are slow due to low temperatures, coatings are vulnerable to being washed off before they have a chance to set.
Top 10 tips for winter working
Work can’t stop just because it’s getting colder, so how can you avoid these potential pitfalls when you are working in unfavourable conditions? We’ve got some tips to help.
Regularly monitor the forecast and plan accordingly
You should not apply any render materials in temperatures below 5°C, so be aware of the previous day and night temperatures. Even if the air temperature is 5°C it could have been sub-zero a few hours previous and so the substrate is likely to still be freezing.
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 that 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.
Consider an accelerator
If using weberpral M, weberpral D or webertherm M1, consider using weber monocouche accelerator, 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.
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.
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.
Extend the scrape time
weber monocouche retarder is a retarder solution that may be used to provide scrape time flexibility and extend scrape time, especially for winter working, allowing a next-day scrape in colder months.
Check where the water feed is coming from
If it is coming straight from the mains it may be too cold. Consider using a water butt stored inside for water additions or feeding machines.
Clean your tools
Make sure you clean your tools at the end of the day. Anything left wet or with water in it may freeze overnight.
Store materials correctly
Store all materials in a lock-up off the floor or move them to a location that is heated or warmer prior to mixing and application.
Look after yourself!
Keep warm! Wear two pairs of socks and insulated boots. Standing on concrete or outdoor surfaces for long periods of time can make it difficult to stay warm. Also, remember to take care of your hands, wear gloves and carry barrier cream and moisturiser in your van to help prevent dry or chapped hands.