Sectional views show the internal structure of an object by imagining a cut through it. Lines are drawn at 45 degrees called cross-hatching to represent solid metallic portions cut through. The correct method is to draw thin, uniformly spaced lines at 45 degrees to the horizontal unless another angle provides an advantage. Various symbols are used in sectional views to represent different building materials like brick, concrete, steel, etc. and indicate the materials of construction.

2. SECTIONAL VIEWS
Section may be defined as an imaginary cut
made through an object to expose the interior
shape.
A view in which all or a portion of the view is
sectioned is known as a sectional view.
In case of a section, some outer portion of the
object, which is obstructing the lines of sight to
see the inner details, is considered to be
removed, an orthographic view is then drawn for
the remaining portion.
With the help of sectional views inner shape is
clearly shown without any ambiguity.
For more hidden features at different positions
inside the object, a number of cutting planes may
be assumed and corresponding sectional views
may be drawn separately.

5. Solid metallic portions in sectional
view are shown by section-
lining, sometimes called cross-
hatching.
Very fine lines are drawn at 45 deg
with the principal lines in the
view at a uniform spacing
varying from 1/16-in to 1/8-in.
For bigger portions to be cross-
hatched, spacing close to 1/8-in
is used, whereas for smaller
portions, spacing close to 1/16-in
is preferable.
CROSS-HATCHING

6. SECTION-LINING RULES
 The correct method of drawing section lines is shown in part
(a). Draw section lines with a sharp medium-grade pencil (H
or 2H).
 Always draw lines at 45º with the horizontal unless there is an
advantage of using a different angles.
 Space the section lines as uniformly spaced as possible by eye.
Section lines should be uniformly thin, and not varying in
thickness.
 Avoid running the section lines beyond the visible outline, or
stopping the line too short.

7. SYMBOLS FOR BUILDING MATERIALS
In building drawing, there are a
number of different symbols to
represent various materials like
brickwork, plain cement
concrete, reinforced cement
concrete, earth filling, sand
filling, and various steel shapes,
etc.
Using these symbols in the
sectional views, we can have an
idea of the materials of
construction even if these are
not mentioned in writing.

9. Cutting plain line:
 The cutting plane line is a thick dark line which uses one
of the special patterns shown.
 The cutting plane line can be left out when it is obvious
where it must lie from the appearance of the section itself.