Lime mortar is a traditional type of mortar that is made using lime and sand. It is more flexible and breathable than cement-based mortars. When used in stonework, it can help to preserve the integrity and longevity of the stones, as well as providing a more sustainable and environmentally friendly option.
When replacing lime mortar it’s crucial to ensure the new joints have been raked out properly. This is to allow the new mortar enough space to bond and set. Once cleared, the open joints should then be soaked with water. Again this gives the new mortar the best conditions to set.
Once the lime mortar has been applied, we would then cover the stonework with a material called hessian. This natural material creates the ideal environment for curing while also protecting the new mortar from adverse weather conditions. When partially set, the new mortar is ready to be brushed back. This will reveal the aggregate within the mortar and create a watertight and breathable structure.
Lithomex Surface Repairs
Depending on the extent of damage or decay to the stone, a repair can be the perfect alternative to carrying out a stone replacement. Using the lime based material lithomex, we can apply this over the affected stone giving it the appearance and structure of a brand new stone.
Before applying lithomex it’s important to chisel away all the loose and decaying stonework back to a solid surface. This creates the perfect base for the lithomex to bond to. Once applied and partially set, (which usually takes around 24 hours ) we rub back and shape the lithomex to recreate the original surface.
At this stage we can also dress on any surface finish to match the surrounding stonework.
If a solid surface is not found within the ideal depth due to internal decay, a repair won’t be suitable and we will advise replacing the stone.
We may also recommend a replacement or descaling of the stone due to it’s location on the building.
For example, repairing areas directly above doorways and paths should be avoided. Although a well executed repair can last upwards of 10 plus years, they are temporary and will eventually fail and detach from the original stone.
In this example, the original stone would of been dressed on a comfortable waist high table. Here I’m dressing the repair in situ creating a “stugged” surface finish to match the surrounding stonework.
At this stage we can also cut false joints that will be pointed in lime mortar to create the illusion of a built in stone.
Stone Structure Restoration
Garden walls, pillars, steps, windows, doorways and chimneys. We're highly experienced in bringing these structures back to life, from using a combination of restoration techniques to deconstructing and rebuilding.
This work should be carried out when there is significant cracks or decay within the stone. Sometimes this is difficult to diagnose when looking at stones at height, so when viewing from a scaffold the original scope of works may change.
Any discoveries of this nature will be documented and discussed with the client before starting any extra work.
Decaying stones at height can pose a real risk to the public. Large cracks and heavy spalling are a sure sign of a stone in need of attention.