Stone walls

Stone walls are a type of masonry construction, which have been used for thousands of years. 

The first walls were constructed by piling loose field stones into a dry stone wall. This was modified later on, by the addition of mortar and plaster. 

Stone walls are usually made using local materials, varying from limestone and sandstone to flint and granite

Common Problems

The deterioration of stonework is often water-related but the cause of deterioration and similarly any remedial works is highly dependant on the type of stone.

Some common problems include: 

Serious decay of mortar joints and stones, because of, salt crystallisation, attack by acidic rainfall or frost action.

Cracking or distortion of stonework for reasons such as rotten timber lintels over windows and doors, tree root activity, or, in smooth-faced and square ‘ashlar’, the corrosion and expansion (‘rust-jacking’) of embedded iron cramps.

Staining arising from, for instance, the effects of tarry pollutants, run-off from limestone onto another limestone or sandstone, or rusting of cast iron rainwater fittings or metal window bars.

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Flint walls

Most common in the South of England, flint walling was thought to have been first done by the Romans. 

It has been used for thick, rubble cored walls and, from the 19th century, facing skins on backings of bricks or other stone. 
Walls can be approximately dated by using their coursing, mortar composition and whether flints are used whole, fracture or knapped. 

Common Problems

The impervious nature of flint, the irregularity shape and differing sizes can lead to poor bonding. Over time, this may be weakened further by rain penetration and a lack of maintenance.

Inappropriate repair methods and materials can also contribute to deterioration.

Problems range from the localised displacement of flints to loosely-bonded dressings and the detachment of facing flint work from rubble cores or backings of stone or brick.