Protecting Your Mortar

One of mortars most important functions is to provide wind and watertight protection to walls, joints and rendered surfaces. Proper mixing and application will ensure that the function is completed to the highest proper standard. It is therefore imperative to establish that new work is properly specified and allowed to fully cure from its wet state into a fully functioning mortar. Sufficient protection must be given to mortars during and after their application, until it is adequately cured to perform its given task.

It is essential that before work takes place, the structure be assessed; drainage, roof membranes, gutters etc. should all be in working order to avoid water ingress and over saturation of fresh mortars.

Throughout the application and after, protection should be in place for the mortar to cure properly and then dry sufficiently. Moisture content should be measured before protection is removed and should ideally be approximately 8%.

Moisture should be allowed to dry out properly before the commencement of work, as it is present in saturated walls. When this is not possible, the mortar should have the best void structure available to improve the maximum evaporation occurring through the mortar. Treat this as a design consideration as the aggregates / binders ratio may change.

Sharp sands with a good coarse content will allow the mortar and wall to dry quicker, due to moisture being able to pass more readily through.

Exposure to weather conditions is a major consideration when starting a project. The main factors to be aware of are:

• Rapid drying caused by direct sun, heat & wind
• Insufficient drying caused by heavy rainfall, low temperatures and humid or damp conditions
• Freeze thaw action (Weathering through the thawing of ice and frost)

To combat these issues we recommend you should always ensure that you have the best possible protection, for every stage of the project.

Rapid Drying
The best option when avoiding rapid drying is to screen against sunlight and the erection of physical barriers to reduce wind action.
A cheap method is screening work with small sized mesh, heavy-duty plastic sheeting or a robust tarpaulin on the outside of any scaffold in place.

Insufficient Drying
When mortar dries too slowly, water held inside will slow or diminish the rate of set. Protection of wall heads and any functioning drainage should be in place at all times.

Freeze Thaw Action
Close covering with hessian or tarpaulin should be provided if you are at risk of freeze thaw action, with additional heating as necessary.