We, Leslie Cornell Building Restoration Ltd, are passionate about using traditional building methods and techniques for historic building restorations in Cornwall, and endeavour to educate building owners to do the same.

Throughout our Website, we are aware that specialised or uncommon terminology is used when explaining or describing the different methods of restoration works we undertake.  With this in mind, we have put together a Glossary to make our Website more user friendly. 

We hope you find it useful.




Abutment This is a structure built to support the lateral pressure of an arch or span.
Ashlar A method of creating features in the external render.

Fixed to the top of the common rafters above the eaves so that the roof above the eaves has a flatter pitch.  Projecting finish, or bell-cast piece, at the bottom of harling, render, or roughcast finish on a wall, resembling the base of a bell, forming a drip.


The ability of a fabric to allow moisture vapour to be transmitted through the material.

Breathable Paint

This type of paint system has minimal binders, making it breathable. Breathable Paint is almost like a Lime Wash but gives better coverage and fills any cracks.


This is a structure of stone or brick built against, or projecting from, a wall which serves to support or reinforce the wall.

Cem Tie

This is a stainless-steel tie used for a remedial structural repair.


Having the properties of cement.


These are materials that are applied over the substrate to provide a skin or layer.  They are used to provide a degree of thermal insulation and weather resistance.


This is a mixture of clayey sub-soil, straw and water and is used as a building material.


This is usually a hood-shaped covering used to increase the draft of a chimney and prevent backflow. The cowl, usually made of galvanized iron, is fitted to the chimney pot to prevent wind blowing the smoke back down into the room below.

Dropper Course / Weather Ridge

On weather ridges, all the slates on one side overlap the other with the overhang on the lee-ward side.  In Cornish examples a tongue is cut into the lee-side slate and pushed through a slot on the other and pinned in place.  The pin is covered with a dab of mortar.


Material, usually aluminium or galvanized steel, that is used over joints in roof and wall constructions to prevent water seeping in and causing damage.


The sloping fillet of cement or mortar embedding the base of a chimney pot.


A duct for smoke and waste gases produced by a fire, a gas heater, a power station, or other fuel-burning installations.

Half-Hip & Hip Tile

This is a type of tile used on a hip roof or hipped roof. These are a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope (although a tented roof by definition is a hipped roof with steeply pitched slopes rising to a peak). Thus, a hipped roof house has no gables or other vertical sides to the roof.

Helifix Helibar

This is a stainless-steel reinforcing bar that is used for masonry stabilisation and strengthening.


A covering used to protect a newly Lime rendered wall during the drying out period.

Historic Environment

All aspects of the environment resulting from the interaction between people and places through time.

Lateral Restraint Tie

This is a stainless-steel tie that is used for stabilisation purposes.


A thin flat strip of wood, especially one of a series, forming a foundation for the plaster of a wall.

Lead Flashing

Thin pieces of impervious material installed to prevent the passage of water into a structure from a joint or as part of a weather resistant barrier system.


This is a white caustic alkaline substance that is used as a principal binder for mortars, plasters and renders.

Lime Paint

This is a type of breathable paint made from slaked lime and chalk calcium carbonate.


A horizontal support of timber, stone, concrete, or steel across the top of a door or window.

Listed Building

A building that has been placed on one of the four statutory lists maintained by Historic England in England, Historic Environment Scotland in Scotland, Cadw in Wales, and the Northern Ireland Environment Agency in Northern Ireland due to their architectural and historical importance.

Mineral Paint System

Mineral Paint contains a liquid binder (more commonly known as waterglass) and colour powder. The permeability of the water vapour of Mineral Paint is the same as that of the substrate, so maintaining breathability of the structure.


This is a mixture of sand, water and Lime which is used for holding brick/stones together and/or for plastering and rendering applications.


Building openings provide light, ventilation and climate control for rooms.  They are essential functional and design elements of the building, e.g. windows and doors.

Pea Gravel

This is a type of gravel that consists of small rounded stones that is often used for walkways, driveways and drainage trenches.

Perforated Pipework

This is designed to allow water to enter and exit through small holes or slots along the pipe. It is a good pipe to use for external drainage systems as it absorbs any water and drains it out of the way.

Purlin A longitudinal horizontal, structural member in a roof.


An external angle of a wall or building.

Rainwater Goods

A system of guttering and downpipes used to manage rainwater.


A timber surround fitted to the fin of the window or door and used for installing the product into timber framing. The reveal becomes the frame of your window or door covering the stud. The architrave attaches to the reveal to cover the gap between the reveal and the plasterboard (or internal lining).


Metal or plastic flashings that are installed between each course of plain tiles and double lap slates, to weather the junction between a roof slope and an upstand that is parallel with a rafter, such as a wall or roof window

Stone Plinth

A wall constructed to prevent the cob having direct contact with the ground.

Sub Soil

The soil lying immediately under the surface soil.


The materials from which a building is constructed.


This is a permeable fabric used to separate, filter, reinforce, protect or drain.  It enhances the performance and design life of granular layers by providing the filtration and separation functions.  Typical uses for Terram include a weed control for landscaping and around drainage materials. 

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Contact us

Leslie Cornell
Unit 13/14 St Austell Bay Business Park
Par Moor Road
St Austell
PL25 3RF

Tel: 01726 337577

Email: cornellcob@outlook.com