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A Dummies Guide to Architecture for Ecologists

Don’t know the different between a gambrel and a gablet, a purlin from a rafter, King post from a Queen post, or a truss from a strut? Neither did I! However, an understanding of architectural terms is essential when interpreting architects’ drawings and designing bat mitigation into buildings.

To help others as unknowledgeable as myself grasp the basics of architecture, and so as not to be left feeling as if builders are talking another language, the following article gives examples and explanations of common architectural features, as well as a few less common ones.

Topics covered in this article are:

Types of Residential Building

Usually a residential building can be placed into one of six categories:

Flat

A flat usually describes a self-contained living space which does not take up the entirety of a building. Often a building is a ‘block of flats’ where the entire building is divided into separate living spaces for different individuals.

Bungalow

The term ‘bungalow’ is often used synonymously with ‘cottage’. Yet there are a few distinct features that separate them. A bungalow is based on a design from the Bengali region of India (hence the name). They are single storey, with low roofs and porches and may be raised off the ground several feet with a veranda. Being raised off the ground protected them from flooding, and the shaded verandas offered protection from the scorching sun.

Cottage

Cottages are generally thought of as a building of the English countryside. A true cottage (so named after cotters – peasant farmers) has thick walls, small windows, low ceilings, and were originally thatched and white washed. They are often 1 ½ storey’s high with the attic space being used and characterised by thick timber pillars.

Semi-detached House

A semi-detached house is one which shares a building or a party wall with another house or self-contained living space. Often these houses are mirrors of each other externally and sometimes internally.

Detached house

A detached house is a self-contained, free standing building, unconnected to neighbouring buildings.

Terraced House

There are two types of terraced house – end and mid. A terrace is a line of three or more houses, usually constructed as a single unit, but internally completely separate from each other. An end terrace is only attached on one side to another house, while a mid-terrace house is sandwiched between two neighbouring houses.

Roof Structure

Roofs can come in a wide variety of weird and wonderful forms, some of the more common types you are likely to encounter are described below, as well as some more unusual and introduced foreign designs.

Most houses you see will have a gable end, or even two or more. Gable simply describes the triangular point the roof makes at the end of a building where the wall meets the roof. The most basic roof type is a symmetrical gable but asymmetrical gables may also be encountered.

 

Gable Roofs and Pitches comp

The term pitch will often be used when describing a roof. A roof’s pitch is a numerical measurement of its steepness – a flat roof is not pitched, however all the other examples above are pitched, including a monopitch or pent roof (describes a roof with a single sloping surface). They may have different pitches, however they can all be described as ‘a pitched roof’. A roofs pitch can be calculated and written as a ratio. For every 12 inches along a horizontal plane, how many inches in height does the roof gain. For example, a 12/1 pitch is very shallow as it only gains 1 inch in height for every 12 inches across, where as a 12/18 pitch is greater than a 45° angle.

Beyond this basic structure, numerous variations can be found. For example, – L-shaped buildings retain two gable ends, with a valley in the internal corner and a ridge on the opposite external corner, in addition to the ridge running between the apexes of the two gable ends.

A single piece of terminology can cover a range of different designs and cause confusion. For example, three of the structures in the examples below can be described as cross-gabled. This means that one of the gables runs perpendicular to another of the gables and usually results in the building having three or more gable ends such as the T-shaped building shown to the right. This distinctly separate area attached to the main building is called a wing, and more complicated structures can have many wings on the front and back of the main build. These wings can be of the same height, or lower than the main building they are attached to. Another variation is a double ridged or double pile, whereby a single structure will have two distinct gables which are connected to form a central valley.

 

 

 

A second roof variation is a hipped roof. In this case, no gables are formed, instead, like the other elevations (a particular side of a building), the roof slopes down to meet the end walls. This can be seen by the diagram to the left. Again, additional elevations can form L-shaped, T-shaped and multi-winged cross-hipped structures. Where the sloping roof on each elevation meets to form a point rather than a ridge, this is called a pyramid hip.

While the following structures may be less common, it may be useful to know in the instances that you come across them:

A Frame – an old style, although like a number of designs, re-used by more recent architects. Unlikely to be seen in the UK except as a modern piece, its steep roof was probably to deal with heavy snows which would slide off the roof rather than gather and result in excessive weight.

 

A Frame comp

Butterfly – perhaps initially considered simply a new and modern design, something a bit different, the butterfly design actually has a number of benefits. A key use of its design is the collection of rain water either in water limited areas or in newer, self sufficient eco-homes. It is also more aerodynamically stable with reduced risk of the ‘pulling’ more traditional eaves are subject to in high winds. The design also allows greater penetration of light into the abode.

 

 

 

Catslide & Outshot – catslides can be found on any type of building, but were historically found on thatched buildings where a new area (extension/ outshot) was added to a cottage, and a thatched section was attached to the original roof. They can be of the same or different pitch to the main roof, but typically extend close to the ground. It is assumed that a cat was either seen or simply imagined at some point as slipping from the top of a thatched roof, down the extension to the ground – hence the name.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Clerestory – is used to describe a section of wall that supports windows above eye level to let in light and fresh air rather than to look out of. These can be found in old churches, factories and more modern buildings including residential houses. The following are two types of clerestory roof:

1. A monitor (or double clerestory) roof is one on which another section of wall projects from the ridge of a building, with a second roof parallel to the lower roof. The wall often supports windows or louvers for light and ventilation.

Clerestory - Monitor conp

2. Another variation that might be seen in modern residential designs is the half monitor in which the two pitches of the roof are of different height with a section of wall connecting the ridges, often with windows set within it.

Clerestory - Half monitor comp

Gablet – also known as a Dutch gable is a combination of a gable and hip roof – the lower section being in the hip style, with a small section at the apex forming a miniature gable. This creates a smaller attic space, but the benefits include deeper eaves to provide shade, even extending over verandas – tailored to warmer climes which don’t get high levels of snow.

Gablet comp

Gambrel – is a structure often found in America in old barns, brought across by Dutch settlers. It is thought to be related to the European mansard design (see below) and is occasionally found in the UK. Forming gable ends but with each side of the roof structure having two distinct pitches, shallower at the top and steeper at the side. In contrast to the gablet roof, this creates a larger internal roof space.

Gambrel comp

Half Hip – also known as Barn Hip, Clipped Gable, Dutch Hip or Jerkin Head, this is another combination of a gable and hip design but with the lower section being gabled and a small upper section of the roof forming a hip. This smoothing of the gables peak reduces its susceptibility to wind stress.

Half Hip comp

Hip and Pent-hip – may be known by other names and not commonly recognised, however, it does describe the structure illustrated below. Similar in appearance to the clerestory designs; however the windows present on the upper walls are not merely to allow light penetration and ventilation, but make up an additional, smaller floor used for living space. While a pent roof refers to one with a single slope, it could be considered that this structure consists of a typical hip roof on the upper level, with four pent roofs forming a pent-hip around the lower elevations.

Hip & Pent-hip comp

Lean-to – could also be called a monopitch or a pent roof but specifically one that is attached to the side of a building forming a completely separate roof from the main build.

Lean-to comp

Mansard – like a hipped version of a gambrel. Each elevation of roof having two distinct pitches (often dormers are present in the steeper, lower pitch). This creates a larger, habitable roof void as well as increased wind resistance. They became more common in the UK in the 1800’s.

Mansard comp

 

M-shaped – similar to the double gable or double pile roof, it has two separate gables and apexes. However, the central valley is not at the same level as the eaves, but noticeably higher, creating a rough ‘M’ shape. When clay tiles were more commonly used (in the 1750’s and earlier), it required steep pitches to make them weather resistant, resulting in large and heavy roofs. To overcome this, dividing the roof into two parts reduced the height of the roofs without reducing the pitch.

M-shape comp

 

Sawtooth – not something you’re likely to find used for residential housing, but quite distinct and useful to know. Named after the similarity of its shape to the teeth of a saw, it’s a design you’ll most likely see used in factories. The vertical sections of the roof often have clerestory windows which are typically northward facing. This is to protect works and machinery from direct sunlight (so long as you are in the northern hemisphere), but to still allow natural lighting of the interior.

Sawtooth comp

 

Dormers

Dormer windows are structures that project vertically from a sloping roof with their own walls and roof. Windows that are present within the slope of the main roof that do not have their own walls or roof are known as skylights. Dormers are popular for increasing the space within and the lighting of roof voids without projecting above or beyond the side of the main building. There are a number of different dormer designs based on its roof type and shape:

Canted Dormer – ‘Cant’ in this instance refers to an oblique angle (not a right angle). A canted dormer (or bay window) is made up of three or more faces which can be the same or different sizes, and form oblique corners.

Canted Dormer comp

Flat-roof Dormer – probably the cheapest form of dormer to construct, it’s often used to increase the area of the lot space that can be used. They can be significantly larger than depicted, extending from one end of the roof to the other.

Flat Roof Dormer comp

Gable Fronted Dormer – probably the most common form of dormer, it can be built out from the existing ridgeline, or set below.

Gable Fronted Dormer comp

Hipped Dormer – the same idea as a gable fronted dormer, simply with a hipped design instead, perhaps to match it the main structure is also hipped or for its wind resistant properties.

Hipped Dormer comp

Round-topped Dormer – can be used to describe a number of slightly varying designs as depicted below. Not depicted but similar would be Eyebrow Dormer and Round Dormer.

Round-topped Dormer comp

Shed Dormer – has a pent, or monopitch roof with a shallower pitch than that of the main roof. Likely used for the same reason as the Flat-roof Dormer (increasing space without increasing the building’s footprint), but where a sloping roof is more desirable, such as for shedding snow and rain.

Shed Dormer comp

Swpet Dormer – originally used in thatched roofs, but may also be seen in more modern designs. The windows and sections of wall reach higher than the eaves, and the roof line sweeps up and over the windows so as not to block light into the typically few, small windows.

Swept Dormer comp

Wall Dormer – similar to swept dormers in that the windows breach the roof line. The walls of the dormer are continuous with the main walls of the building but have their own distinct roof.

Walled Dormer comp

Roofing Materials

There are many types of materials that can be used to build roofs, including:

  • Asbestos
  • Bitumen
  • Ceramic
  • Wood
  • Concrete
  • Felt
  • Metal
  • Plastic
  • Slate
  • Thatch

These materials can come in many forms – e.g. tiles, corrugated sheets, rolls or liquid. Tiles can come in all shapes and sizes; some are just for aesthetics, others are used on different parts of the roof and have different functions.
Tile Types

Field Tiles – are those which make up the bulk of the roof.

Ridge Tiles – are either ‘v’ shaped or semi-circular, acting as a cap aling the entire length of the main ridge, or ridges formed by hipped roofs.

Gable Tiles – are those that are present at the ends of the ridge above a gable wall.

Hip Tiles – are those that cap the corners between the main ridge and the sloping ridges of the hipped roof.

Ornamental Tiles – are tiles that have an altered shape, or additions to make them aesthetically pleasing. For example, field tiles can come in a range of shapes such as bullnose, club, arrow, fishtail or shouldered variations.

Tile Shapes comp

Aside from the typical flat field tiles, there are many other variations of interlocking tiles. One example is the pan tile. This is an ‘S’ shaped tile which overlaps end to end.

Pan Tiles comp

External Supporting Roof Structures

A number of internal structural components are exposed at some points, such as the ends of the rafters. To protect these features from the weather, as well as supporting the weaker parts of the roof and to support other components (such as gutters), fascias, bargeboards and soffits are common features on buildings.

Fascias, Barge Boards, Soffits comp

Eaves – are the sections of roof that project over the edges of a wall.

Fascias – are flat sections of wood, plastic, or possibly some other material, that covers the rafters. They are often attached directly to the ends of rafters and so are found under the eaves of buildings. It is to these structures that gutters are attached.

Soffits – forms an external ceiling between the top of a building’s wall and the edge of the roof, or when fascias and bargeboards are present, they connect the wall to the ends of these features forming a soffit box.

Bargeboards – are unlike fascias in function, but are found along the verges of gable ends. They are attached to the ends or purlins or other horizontal supporting structures.

Verges – are the equivalent of eaves, but are present at the gable ends.

Walls

Last but not least – a little bit about building walls.

Single Leaf – a wall without a continuous vertical joint or cavity.

Double Leaf – has two parallel sections that form a vertical, mortared joint.

Cavity Wall – has two single-leaf walls parallel to each other creating a cavity between them

Wall Structure comp

The way bricks are used to construct walls can vary simply for design, or for different purposes. However, first you need to know that the different parts of a brick have different names. In fact, some have multiple names which change based on the way that the brick is being used.

Bricks and Wall Designs comp

The normal orientation of a brick would be laid has the long thin (stretcher) surface as the external face, with the smallest (header) surface facing that of the next brick, creating a header joint. The largest surface is called the bed and forms bed joints. Some bricks, typically red clay bricks, have indentations on the larger faces. This indentation is called a frog and creates a margin around the edge of the brick. The edges of the brick are called arrises (singular: arris) – a sharp edge formed by the meeting of flat (or curved surfaces).

Walls where the header or rowlock surface of a brick can be seen indicate that the wall is solid as the rest of the brick will be projecting through the wall (like the single leaf shown above).

Walls that are formed with stretcher, shiner, soldier, or sailor bonds are more variable. Often stretcher bond walls can indicate a cavity wall, but may also be single leaf or double leaf.

 

More information about bat surveys can be found in our articles – I Need a Bat Survey and Bat Surveys Made Simple.

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