British Standards Revision

This NAB and the knowledge and understanding required for the exam is based on dimensioning and building symbols used, you also need to know about the different drawings in a drawing set used in building construction.  You need to know how to dimension different shapes using the British Standards rules, and you need to recognise the different symbols.

Dimensioning:

The correct methods for dimensioning shapes are shown below.

General dimensioning rules:

• All measurements are in mm.  There is no need to write mm next to the number.
• All dimensions should be drawn outside of the drawing.
• All dimensions should only be drawn once even if the dimension appears in two views.

Linear Dimensions:

• Leader lines must never touch the drawing and the arrows should reach all the way to the leader lines.
• Smaller dimensions may be shown by pointing the arrows into the leader lines (like the 10 dimensions in the top left corner)
• Numbers should be read from the bottom of the page, or the right of the page (i.e. tilting your head to the left, or turning the page right) And from these views the numbers should appear above the lines.
• Dimensions and their leader lines should not cross each other - i.e. smaller dimensions should be inside larger dimensions.

 Circle Dimensions:

• You should draw on centre lines if they are not already there
• An arrow going through the centre shows that you are giving the diameter (radius should only be used when it is not a whole circle)
• Extended from this arrow the leader line should come out of the drawing, and the number written with the diameter sign in front of it

•  A radius is very similar to the circle, with an arrow from the centre of the arc to the outside
• An "R" precedes the number to show that it is a radius.

Polygon Dimensions:

• Polygons are shown Across Corners (from point to point) or Across Flats (from flat to flat) as shown above.
• AC dimensions will see the circle construction outside the shape
• AF dimensions will see the circle construction inside the shape

Drawing Types:
These are found on page 32/33 of Leckie and Leckie

Location Plan

• Normally drawn to a scale of 1:1250
• Shows the new building with a dark outline and a hatch
• Clearly shows the new buildings and its surroundings
• Shows neighboring buildings, roads, street names
• The symbol in the top right hand corner is the North symbol, the arrow shows the direction of north

Site plan/Block plan

• Normally drawn to the scale 1:200
• There are two drawings shown above, they show different things, depending on what you want to show.  The one on the left is the more traditional site plan.
• The left site plan shows: existing trees, contour lines, drainage features
• The right site plan shows: building outline and roof with dimensions, the position of the house on the site

Floor Plan

•  Floor plans are usually drawn to a scale of 1:50
• The show the arrangements of rooms
• The top floor plan shows the dimensions of the rooms and the positions of windows and doors
• The bottom floor plan shows the materials used to make the walls and the positions of fixtures and appliances needed by builders, plumbers and electricians.

Symbols:

You need to know the following standard symbols.  This is from page 34 of Leckie and Leckie