Lime mortars allow traditional stonework to breathe, unlike cement mortars which can be impermeable to moisture, trapping it within the structure leading to dampness and internal decay.
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. Depending on the time of year, an NHL 3.5 lime mixed with sharp sand usually works great for most stone work. 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 setting while also protecting the new mortar from unfavourable weather conditions. When partially set, (time dependent on the time of year) the new mortar is ready to be brushed back. This will reveal the aggregate within the mortar and leave a watertight and breathable structure.
Stone 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 dried, which usually takes around 24 hours, we rub back and shape the lithomex to recreate the desired structure. This also reveals a stone like finish that is now watertight and breathable. Here we can also dress on any surface finish to match the surrounding stonework.
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 the joints that will be pointed 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 should be carried out when there is significant damage to the stone or structure. In some cases this can pose as a potential risk to the public. Large cracks and heavy decay are a sure sign of a stone in need of replacement.