Unit 103 - Lesson 1

Unit 3 - The Built Environment Life Cycle

Open Ended

What do you think the built environment life cycle is?

​INTRODUCTION

Careful thought and skilful planning are required to create and maintain the built environment. In this chapter, we will discuss how planning decisions and systems of work are defined and applied to create safe and efficient buildings and structures.
They must be designed to minimise damage to the natural environment, from the planning stage right through to the end of their useful life. Buildings and other structures require significant physical resources throughout their life cycle, and planners must consider the potential effects on the environment of maintenance and conservation activities.
We will consider how reusing existing buildings and recycling materials from demolished buildings are important aspects of supporting a sustainable built environment.

Building safe and durable structures that work efficiently is a complex process that requires the application of a range of skills and construction principles.

​

​Design of buildings and structures

​Surveying

Surveyors are trained to take exact measurements and determine property

boundaries.

Their role includes calculating heights, depths, relative positions, property lines and other characteristics of terrain.

During the construction process a surveyor will set out roads, drains, foundation heights and positions of buildings or structures. Surveyors ensures: 

 

• everything is in the correct position 

• drains fall at the correct angle​

• buildings are positioned at the right level and heights 

• roads and pavements are in the right position with camber  

Multiple Choice

What is the area of a building measuring 6m x 3m?

• 18m²
• 12m²
• 20m²
• 15m²

Multiple Choice

What is the volume of a room measuring 12m x 6m x 3m?

• 192m³
• 240m³
• 216m³
• 180m³

This is referred to as a temporary bench mark (TBM). The TBM often takes the form of a peg, which is secured in concrete and protected from potential disturbance by machinery movements or other construction activities.
It is important that he TBM is not disturbed, since all levels for buildings and structures on a site are transferred from it.

​Surveying Principles

​A surveyor uses established methods and principles to make exact calculations and set out measured positions accurately. To establish heights and depths on site, a reference point called a datum is set up.

​The TBM is taken from a permanent reference point, known as an ordnance bench mark (OBM). In the United Kingdom, OBMs are survey reference points made by a regulated organisation called Ordnance Survey. Most commonly, they are found on old buildings or other long-standing features.

​Although the physical network of OBMs is no longer being updated, this feature is still in existence in many places, and the markers will remain until they are eventually destroyed by redevelopment or erosion. The location of OBMs around the country can now be conveniently referenced through a licensed database.

​Temporary benchmark:

a fixed point on site that is referenced from the ordnance benchmark.

All other heights and positions are referenced from this across site to calculate heights of foundations, floors, openings in buildings.

Multiple Choice

What is a datum?

• A datum is a measurement of time.
• A datum is a type of software application.
• A datum is a fixed point or height from which reference levels can be taken

• A datum is a collection of data points.

Multiple Choice

What is the definition of a fall in construction terms?

• A fall is a type of construction material used for insulation.
• A fall is the process of demolishing a building.
• A fall is the slope or gradient of a surface in construction.
• A fall refers to a sudden drop in construction costs.

Open Ended

Identify as many area's of a domestic property that would require a fall.

​Task:

Working in groups, research the below methods of surveying a building site.
Chain Surveying
Compass Surveying
Theodolite
Automatic Levels
Laser Levels
Laser Scanners

Chain surveying is a simple traditional method used to survey measurements when the area is fairly level and is small and free from obstacles. It uses a network of triangles to plot positions using a chain. ​  

A metric chain has links every 200mm with tallies positioned at every 10 links (2m); a brass ring is fitted in between each tally at five links, denoting every 1m.​ 
Example:  Ring 1m, tally 2m, ring 3m, tally 4, two links = 4.4m 

 

​​Chain surveying 

To transfer levels and datums for a range of tasks using various methods and points.  

​Compass surveying 

 

When an area is too large for chain surveying, compass surveying is used. However, it can not be used if the area contains iron ore or power lines as these can affect the compass readings.​ 

 

While a chain uses triangulation to measure, a compass uses traversing. This is where directions of survey lines are determined with a compass and the length of the lines are measured with a chain or tape. 

 

​Modern surveying equipment  

​Theodolites
​

Theodolites have been used since the mid-1700s.

They are used for measuring angles both vertically and horizontally.

Modern theodolites are often electronic (digital) and measure very precisely

​An automatic level uses a swinging prism that hangs.

This will self level if its positioned close to level on a tripod.

They have an inbuilt telescope that enables accurate readings to be taken from a staff when transferring levels or measuring datum points.

​Automatic levels

​Laser levels

​Rotary laser levels are available for precise setting out on site. By using a staff and detector they can be used as a traditional automatic level.

Smaller non-rotating levels are often used by a range of trades persons on site to set out partitions, transfer datum points for suspended ceilings, check for plum when fitting door and window frames, check for level when fitting kitchen, hanging wall papers, and so on

​Laser scanners

​Laser scanners are available in both 2 and 3D, with 3D scanners most often used in construction.

Laser scanners work by combining two sets of information from different cameras trained on an object.

Readings taken from a laser are then collated on a computer and a three-dimensional model can be generated which allows for virtual walk throughs.

​Digital measuring equipment

​Digital measuring tools can accurately measure lengths, widths and heights, they can calculate square and cubic meterage at a push of a button. ​

Some devices can also calculate the hypotenuse by using the run (length) and rise (height) measurements

Multiple Choice

Identify what is in the image here?

• Theodolites

• Automatic Level

• Laser Level

• Metric Chain

Multiple Choice

Ordinances survey benchmarks can be referenced back to:

• The high tide level in Newlyn in Devon

• The high tide level in Newquay in Devon

• The mean sea level in Newlyn in Cornwall

• The mean sea level in Newquay in Cornwall

Multiple Choice

At what intervals will tallies be found on a metric chain?

• 100mm

• 2000mm

• 500mm

• 1000mm

Multiple Choice

What method is used when compass surveying?

• Traversing

• Estimating

• Gastrulation

• Triangulation

Multiple Choice

What is fitted to an automatic level enabling it to set itself accurately?

• A gyroscope

• A oscilloscope

• A swinging prism

• A counterbalance

Multiple Choice

To calculate the hypotenuse a digital measuring tool requires what two measurements?

• Length and width

• Length and height

• Diameter and width

• Diameter and height

Multiple Choice

Laser scanners use two cameras and a projector to capture 3-dimensional images.

• True

• False