Guidance for protecting Lime work all year round

Tŷ-Mawr ‌‌ posted this on 25 Aug 2016

Guidance for Protecting Lime work all year round

As with all good building practice using any mortars, plasters/renders and paints, protection should be provided against frosts, the wind, rain and direct sunlight.

Please note, it is not recommended to use lime products (lime mortars, renders and limewashes) when temperatures are liable to fall below 5°C (41°F) for several weeks/months after the product has been used, this is especially true for Non Hydraulic/Fat Limes/Air Limes and the weaker Natural Hydraulic limes (NHL's). Protection is also required in hot summer months from drying in the sun.

In winter months unless adequate weather protection is provided Non-Hydraulic/Fat Limes/Air Limes and the weaker Natural Hydraulic Limes (NHL's) should not be used externally until spring.

If work must continue, then please note:

• Damp walls must be allowed to dry out prior to the application or mortars, renders or plasters.

Protection is vital – see product specific application guides – but note tarpaulins and/or bubble wrap (available from Ty-Mawr) are often better at vulnerable times of the year than hessian as they can prevent excess moisture from entering the render/plaster/mortar/limewash (excess moisture will make the products more vulnerable to frost damage) but air must still be able to circulate between the protection and the render/mortar/limewash. If there is a good drying, sunny day, the protection should be taken down during the day to help the carbonation. Please note - protection may need to be left up throughout the vulnerable time until the danger of frost is over. We also sell mortar fleece for protecting work to the tops of unroofed walls. Summer protection is vital to stop lime mortars/plaster/paints from drying out too quickly from winds and direct sun – (hessian is ideal as it can be wetted down). Lime should be kept damp for at least 7 days from application otherwise it will just dry and crumble.

• Be aware that too much moisture can retard carbonation/setting so if your substrate is already wet (e.g. if a cement render has just been removed or if it is very exposed or if it has just rained), you will not need to dampen down the background, you will need to allow the background to dry out;

• Different elevations and applications need to be treated differently as they will get different weather – know your site, know which way the weather comes from, know which parts do not get any sun/remain in shade and give them as much help as possible – extra protection, extra damping down – don’t expect that the same product will behave the same throughout different elevations and applications on the site. Even internally, different substrates may need to be treated differently e.g. one wall may be particularly wet for some reason, this will slow carbonation down and may impede it all together;

• Record the temperature (using a min/max thermometer) – prolonged periods of less than below 5°C (41°F) may cause problems in the future – it is advisable to keep records;

• With external renders, it may be necessary to introduce heat into the space between the covers and the render if the temperature is around or below 5°C (41°F) for prolonged periods.

In winter work can carry on indoors if minimal heat is provided to keep the building above 5°C (41°F) – however direct heat can also cause failures. Always ensure adequate ventilation is maintained at all times.

  • Do not add cement, anti-freeze, additives, etc under any circumstances
  • Products should be stored in a frost-free dry environment, off the ground but please see specific product storage instructions in the application guides.
  • Please read this in conjunction with the application guide for your specific product.

Lack of appropriate tending at any time of year can effect carbonation and lead to failures. Please be aware that we cannot be held responsible for the way in which goods are stored or used after delivery.

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Disclaimer - no responsibility can be accepted for any errors or omissions or any loss or damage as a result of using the information provided in these guidelines.