Building Components

This page describes the various components that go to make up an historic building. The success of any conservation project is largely dependent on getting the details right. This means that every aspect and component of a protected structure should be carefully considered before any work is carried out. A clear methodology for doing the work should be established, based on best current practice.

The following list some of the basic components that go to make up an historic building and gives a brief outline regarding best practice for repair and conservation of the component.


  • Stone walls
  • Brick walls
  • Roofs
  • Floors
  • Windows
  • Doors
  • Plasterwork

Stone walls

Stone walls have existed for thousands of years. They were first constructed by farmers and primitive people by piling loose field stones in what is called a dry stone wall. Later, the use of mortar and plaster came into being, especially in the construction of city walls, castles, and other fortifications prior to and during the Middle Ages. Stone walls are usually made of local stone, varying from limestone, flint, granite and sandstone. However, the quality of building stone varies greatly, both in terms of its endurance to weathering, resistance to water penetration and ability to be worked into regular shapes before construction. Worked stone is usually known as ashlar, and these stones are often used for corners. Granite is very resistant to weathering, while some limestones are very weak. Some limestones, however, such as Portland stone, have a deserved reputation for resistance to the weather.

Pointing of both stone and brickwork is very important and joints should always be pointed using a lime mortar. The use of a hard cement mortar will damage an old stone or brick solid wall, as the hard cement mortar does not allow water to evaporate out through the joints in the way that lime does. This means water tries to find an escape path through the stone and gets trapped and in frosty conditions can freeze, expand and cause damage to the stone.

The following table illustrates some common lime mortar mixes for both stone and brickwork and also for plastering applications:


Application NHL: Typical Mix: Approx. Coverage per 25kg bag:
InternalPlastering Backing Coats (10mm) NHL2 2.5 Sand:1 lime 8m2
Finishing coat (3mm) NHL2 2 Fine Silica Sand: 1 lime 26.5m2
External rendering Coat (10mm) NHL2 2.5 Sand:1 Lime 8m2
  NHL3.5 2.5 Sand:1 Lime 8m2
Pointing Rubble Stone   NHL2 2.5 Sand:1 Lime 10m2
  NHL3.5 2.5 Sand:1 Lime 10m2
Pointing brickwork   NHL2 2.5 Sand:1 Lime 16m2
  NHL3.5 2.5 Sand:1 Lime 16m2
Harling/Wet dash/ Roughcast   NHL3.5 2.5 Sand/Aggregate:1 Lime 7.5m2
Slurry Coats   NHL2 2.5 Sand:1 Lime Refer to supplier
  NHL3.5 2.5 Sand:1 Lime Refer to supplier
Lime Concrete   NHL5 1.5 Mixed Aggregate:1 Lime Refer to supplier


Brick walls

Bricks are typically produced in common or standard sizes in bulk quantities. They have been regarded as one of the longest lasting and strongest building materials used throughout history. In the general sense, a 'brick' is a standard-sized weight-bearing building unit. Bricks are laid in horizontal courses, sometimes dry and sometimes with mortar. When the term is used in this sense, the brick might be made from clay, lime-and-sand, concrete, or shaped stone. In a less clinical and more colloquial sense, bricks are made from dried earth, usually from clay-bearing subsoil. In some cases, such as adobe, the brick is merely dried. More commonly it is fired in a kiln of some sort to form a true ceramic. Solid brick walls, as commonly found in Geoargian buildings, should be pointed in lime mortar in order to allow the wall to 'breathe' and allow water to evaporate from the joints. In addition, lime mortar allows for movement in the entire wall, whereas the use of a hard cement mortar prevents this movement and and often cause cracking in the brick wall. Some useful lime mortar mixes are given in the table above.


A roof protects the building and its contents from the effects of weather. In most countries a roof protects primarily against rain. In Persia the citizens used their roofs for milling wheat, farming, gardens and extra space. Depending upon the nature of the building, the roof may also protect against heat, sunlight, cold, snow and wind. Other types of structure, for example, a garden conservatory, might use roofing that protects against cold, wind and rain but admits light. A verandah may be roofed with material that protects against sunlight but admits the other elements. The characteristics of a roof are dependent upon the purpose of the building that it covers, the available roofing materials and the local traditions of construction and wider concepts of architectural design and practice and may also be governed by local or national legislation.It is important when repairing a roof that appropriate replacement materials are used. For example, in the repair of a typical Georgian or Victorian slate roof it is important to use natural slates for replacement slates, which match the original slates and are sourced locally.


Floors vary from simple dirt in a cave to many-layered surfaces using modern technology. Floors may be stone, wood, bamboo, metal, or any other material that can hold a person's weight. The levels of a building are often referred to as floors although a more proper term is storey. Floors typically consist of a subfloor for support and a floor covering used to give a good walking surface. In modern buildings the subfloor often contains services such as; electrical wiring, plumbing, and other services. Because floors meet many needs, some essential to safety, floors are built to strict building codes. The conservation of an existing floor will almost always involve the repair of the existing floor. Where the flooor needs to be strengthened, for example a suspended timber floor in a period house, the original timber joints can normally be left in place and new joists can be bolted to the side of the existing.


The typical window found in both Georgian and Victorian buildings is the sliding sash type. This window type is made of hard wood and composed of an upper and a lower sash that slide vertically in relation to each other. The number of panes in each sash tell us what the 'pattern' of the window is. For example a sliding sash window with four panes in each sash is commonly termed a 'four over four' pattern. Unfortunately, a common misconception that grew up during the latter part of the twentieth century was that these windows cannot be repaired and the best thing to do with them when they appear old and rattling is to remove them and install modern windows. This has led to the destruction of many period facades in our towns, cities and countryside. The character of the facade having been lost entirely with the removal of these sash windows and often modern uPVC installed in their place, which will never match the original character of the timber sliding sash window. Thankfully, the message that these sash windows can be successfully repaired has started to be recognised in more recent years. Most of the time the bottom rail or the cill of the window has perished and it is relativelty easy to replace these sections with new hard wood and thereby prolonging the life of the window and preserving the character of the building elevation.

Another common complaint with these windows is that they rattle and allow draughts into a building. Again, this is something which can easily be remedied through repair of the parting beads at the sides of the sash window.


Doors form an intrinsic element in the design of an historic building. One thinks of the Georgian doors of Dublin, giving such a variety of pattern and colour to the city streetscape. Doors are typically made of hardwood and are composed of different elements, with styles forming the vertical parts of the door framing and rails forming the horzontal parts of the door framing and between we have the panels. Replacemnt of original doors with modern doors will always destroy the design of the interior because the doors are normally designed with the proportions of the interior rooms in mind, therefore they form an essential part of the design. The first repsonse from a conservation point of view is to repair rather than replace. Where a door has clearly gone past its useful life and is impossible to repair then the next best option is to find a similar door in the building and use this as a template to make the new door, matching the proportions, size and thickness of the door so as not to affect the door frame and architrave.


Plasterwork refers to construction or ornamentation completed with plaster, such as a layer of plaster on an interior wall or plaster decorative moldings on ceilings or walls. The process of creating plasterwork has been used in building construction for centuries. In a protected structure the plasterwork is normally lime plaster and some useful mixes are contained in the table above.