Walling

Walling covers the use of Portland Stone on all walls except cladding (see  external cladding section). Load bearing walling is the traditional building method of Portland Stone and covered most external buildings until the  onset of cladding in the late nineteenth century. 

Types of Walling

Walling is rarely used as the construction method for commercial buildings but is often used for smaller domestic properties, sometimes in combination with bricks. There are many different variations of this walling but we have divided them into three categories based on the product used:


Ashlar Walling

The stones are cut ashlar blocks, which can be cut to the projects requirements.


Split Faced Walling

The stones have a cut top and bottom with a machine split face to give a natural appearance.

The stones are naturally produced from off-cuts from the cladding projects in the factory and this re-use of stone is reflected in the price. There are various different installation methods: coursed, brought to courses, un-coursed etc. The stones vary in length


Hand Dressed Walling

To create a more rustic appearance, the edges of the Split Faced Walling can be hand pitched to create a convex face.

There are various different installation methods: coursed, brought to courses, un-coursed etc. The stones vary on length and height and are 100mm thick.  This stone can be purchased from us via our  Portland Stone Landscaping website.

Construction

All walling stone can be used as a solid construction or cavity wall construction.  

We recommend that a specialist stone masonry designer is consulted at an early stage for solid wall construction as the only guidance document BS 5390 has been withdrawn.

Walling stone for cavity construction should be built similar to a brickwork outer skin. The stone outer wall should be built at the same time as the inner block work leaf, with stainless steel wall ties at appropriate locations. The joints for all walling will vary with walling being typically 10mm to 20mm. The mortar should be: 1 white cement, 2 lime and 8 to 9 Portland Stone Dust. Lime mortars may be considered appropriate.

The design should consider the water management issues with dpcs, cavity trays and weep holes and projecting weathering courses with dip details designed to throw the water off the façade.

Walling can be used in conjunction with quoin blocks, traditional window surrounds and copings manufactured in matching Portland Stone.

Site Practice

All products leaving our works are packed in a manner to ensure safe delivery to site.

This entails protection by CFC free polystyrene strips, shrink-wrapping and delivery on suitably sized pallets, frames or crates. These normally contain a maximum of 1tonne for safe handling on site. It should be noted that it is the customer's responsibility to ensure safe unloading of delivery vehicles.  

A suitable storage area will need to be set aside for the stone, which should be stored on firm, level surfaces and, to avoid contamination, should be sited  away from wet or muddy areas. Storage should be as near as practical to the areas of working in order to minimise handling, damage and waste. Pallets should not be stacked on top of each other. Should it be necessary to store the material on site for any length of time, it should be protected from the elements and the environment.

The designer will need to be aware of the manual handling regulations and ensure appropriate lifting equipment is available to move and fix the heavy stones.

Maintenance

It is important to remember that Portland Stone does not normally require cleaning to safeguard its durability, but we recommend that the stonework is inspected on an annual basis to check if any maintenance is required.

The most common cause of maintenance is defects resulting from water management such as leaking rainwater pipes causing dampness and staining.

It is worth noting that split faced and hand dressed walling, due to the course stone faces, often hold salts and moisture more than ashlar stones and depending on the micro-climate, may be subject to algae growth, particularly in the first couple of years. Some clients may find this an acceptable temporary phenomenon, whilst others may prefer the walling cleaned and the algae controlled.

Cleaning

It is recommended in BS 8298 (albeit for cladding) that stone buildings are cleaned every 5 to 10 years.

Buildings cleaned more regularly will benefit from not requiring more severe treatment by such techniques as grit blasting and chemicals.  Atmospheric pollution, especially particulate emissions from diesel vehicle exhausts, will in time lead to the surface soiling of many building materials, both on new construction and older buildings recently cleaned.