8th topic

Construction drawings features

Construction drawings are drawn up according to general requirements of graphic documentation standards but have their specifics and are different from mechanical drawings. Some requirements for construction drawings are given in ISO standards ISO 11091, 1516, 128-23.

The main features of construction drawing are as follows:

• Scales 1:50, 1:100, and 1:200 are usually used in construction drawings. Individual structures or details are drawn on a smaller scale of 1:5, 1:10, 1:15, 1:20, and 1:25 drawings. Enlargement scales are not used at all or very occasionally.

• In construction drawings of buildings, projections have their own names. They are written above the drawing picture. The front view of a building is called a facade, top view or horizontal section - plan.

1. Often, individual projections of the building - plans, sections, facades - are drawn on separate sheets due to their large dimensions.

2. The width of the main line in construction drawings also depends on the scale of the drawing and format, but it is smaller than in machine drawings. In the plans and sections of the building, the main one, a wide line (1.0...0.8 mm) draws only those contours in the cut plane. Visible contours outside the cut plane are drawn with a narrow solid line. Building facades are drawn in narrow lines, except for the wide line of the base (horizon) of the building.

3. Dimensional lines are completed in construction drawings (except for metal structures) not by arrows but by intercepts forming an angle of 45 with the dimension line.

4. In the drawings, the dimensions are given in millimetres and usually in whole chains of dimensions. The exact dimension can be repeated in other projections.

5. In the drawings of metal constructions, the images are not arranged according to the so-called applied Europe first angle design method (we used it in the projective drawing) and according to the third angle method used in America and some other countries. In this case, the top view is drawn above the main image, the left view is the image on the left side of the main image from right to the right and the bottom view to the bottom of the main view. Above each image (except for the most important one) is written with markings A, B, etc. t., The most important image is indicated A, B, etc., i.e. directions.

6. Rolled metal profiles are drawn without rounding and are not crossed in the section. Small in-scale drawings, profiles can be drawn with a line of equal width.

A building plan is a horizontal section of the building. The intersecting plane is conditionally drawn slightly above the window sills or at a certain height. Can be drawn a separate layout of foundations (Pic. 8.2), floors, roof, overlaps, and other plans. The premises are decided from the building plan layout and size, windows and doors, plumbing fixtures, etc. arrangement.

Floor plans show a view taken from a horizontal section of a building at some point above floor level. You are supposed to push back the top of the building and look down at the floor plan of the rest of the bottom. This plan view not only illustrates the arrangement of rooms, spaces and their shapes but also shows the thickness of all exterior and interior walls.

A section of a building is an image obtained by mentally cutting through the building in a vertical plane and transferring it to the plane of projections parallel to the intersecting one. Sections are drawn through staircases and windows and the doorway. Sections can be staggered, showing the heights of the building's constructions, windows and doors, etc.

A facade of the building is the view of the building from one side or end. Above the building facade drawing, "Facade 1 5" is written, "Facade 5 1", etc. These notations indicate between which axes the plot is drawn facade. Facades are drawn with narrow lines, except for the baseline, different shadows may be cast in watercolour.

The building facade, plan, and section can be drawn on one sheet (necessary projection connection) or separate sheets.

Images on the garage drawing (Pic. 8.3) are not connected, but all the images have indications and scale sizes. 

Assembly drawings provide information to contractors which enables them to construct buildings on-site. They include the assembly of both structural and nonstructural elements, components and materials.

Landscape plan - a yard plan for a particular house with utility rooms (garages, sheds for firewood or garden tools), natural elements (flowers, trees and grass), and artificial elements (garden furniture, gazebos, and pools, as well paths, stairs, and lighting).

Model use for drawing sheet

3D modelling programs provide for the use of models to obtain different images for the drawing - views, sections, sections, and of course the possibility of putting the necessary information - dimensions and additional annotations.

In this video, the garage model used to get an image on the sheet and then convert the sheet to a PDF file is demonstrated.

Do not miss to answer the question in the video!

Model images and annotations for drawings

Also, the program allows you to view a section of the whole model, a section of a part of the model, or a view of the model—see the video.

In this video, the garage model used to get an image on the sheet and then convert the sheet to a PDF file is demonstrated.

Do not miss to answer the question in the video!

Grids and axes

„CAD modelling systems assemble the model information needed to generate production drawings based on Cartesian coordinates of all relevant points needed to define the project. In the following sections, we have shown a stylized 3D building to convey the requirements of a fully coordinated system, which applies to either  a 2D or 3D design project.“

„The use of grids to which sizes and locations of building components may be related is helpful in the preparation of all types of drawings, particularly so when modular coordination is applied to design and construction. Grid rotations should be used as appropriate for each form of a grid. The most common grid rotation is using letters to define the lines on the axis and numerals to define the lines on the other axis“.

Dimensional coordination (DC) is essential to ensure the system's success and consists of a range of dimensions relating to the sizing of building components and assemblies and to the buildings incorporating them. DC enables the coordination of the many parts that go to make up the total construction supplied from widely separated sources. At an international level, 100 mm is accepted as the basic module (often referred to by the letter ‘M’).

Dimensional coordination relies on the establishing rectangular three-dimensional grids of basic modules into which components can be introduced in an interrelated pattern of sizes, Pic. 8.4.

The axes of the building are drawn with a narrow line and finished with circles of 8...12 mm, arranged usually on the left side and bottom of the building plan. When the building plan is complex or separate building supporting elements (columns, walls) are only on one side or back of the building, axes can be displayed from all sides of the plan. Usually, the axes of the building are not drawn for the entire walls, but only the alignment of the walls is shown on the axis.

The longitudinal axes of the building are designated by letters in alphabetical order from bottom to top, and the transverse axes by numbers from left to right. Letters and numbers in circles are written in a larger font than dimensions.

Features of construction drawings dimensions :

1. Dimensions, except for altitudes, are written in millimetres (without specifying the units).

Sometimes, the dimensions can be expressed in centimetres, indicating this in the technical drawings in the conditions.

2. Dimensions can be arranged in closed circuits, and individual dimensions can be contained within it repeated in the drawing. As shown in Pic. 8.5, a, the intersection of dimensions and raised lines are completed with a short main with a narrow dashed line, as shown in Pic. 8.5, a.

3. Height dimensions (altitudes) are indicated in meters with three decimal places (Pic. 8.5, b).

The floor level of the first floor is taken as the conditional zero altitudes (Pic. 8.5, c), and below it, dimensions are written with a minus sign. In sections and elevations, altitudes are written on the callouts or outline lines with a conventional label (Pic. 8.5, b). Heights are reported on plans with a minus or plus sign and are defined by a rectangle, e.g., + 4.500.