What is a section drawing?

Written by LetsBuild

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A section drawing is a drawing that shows the vertical cut transecting a building.  This vertical cut is normally along the primary axis, but it can be done anywhere.  The drawing will show the interior and exterior profiles, as well as the interior spaces, the walls that separate the inside from the outside, and more.  Basically, it is all the information that you need to see and that you otherwise would not see in other drawings.

Perspectival projection is what happens when you look at the interior elevations of the primary architectural surfaces.  This allows you to see the depth of the interior as a space instead of a basic one-dimensional drawing.

While that is an excellent option, a section drawing is best since it allows you to see the interior elevations of both walls and surfaces.  This is much better than seeing everything from the top down, because from the top down doesn’t show much of anything.

You can also cut through drawings horizontally, but that way will have you cutting through walls and not floors.  When you do that, you are basically seeing inside walls and not the information that you truly need.

You may think that creating section drawings are easy, but you cannot simply just cut a sheet of paper in half and have the information that you need.  Instead, you must draw each section drawing that you need.  While simple cross sections are enough for some buildings, any complex construction will require multiple cross section drawings.

There is not a specific number of section drawings that you need, but you should at least have a few specific items included in them.  Those section drawings should include the following:

  • The exterior wall layers
  • The structural walls, as well as beams and posts
  • The stair framing details
  • The heights and variances for the floors and ceilings
  • The molding and trim work – If all the doors and windows and baseboards are done the same way, this is only needed for one. If not, you will need them for all the different ones
  • The details of the cabinetry and custom furniture – The construction workers may not be responsible for these, but it is still good for them to have the information.
  • Any additional details that can help a construction worker understand the design for the home or building

You will never complete the section drawings until all the floor plans and elevations are finished.

Steps for a Section Drawing

  1. Choose your line

You first need to choose the line where you will cut through for the section details.  It is important that you have this line and know where it is, so you do not confuse one section for another.

  1. Draw the outside of the building

Once you know where your section line is, you will need to draw the outside of your building.  This is just the shell, so you do not need to add doors or windows yet.

  1. Add in the floors and ceilings

This is the point where you will add the floors and ceilings to your building.  This is where you will need to know the thickness of the flooring and ceiling joists, as well as the attached flooring.  You must draw these to scale, or your entire section drawing will be wrong.

  1. Add in all side windows, doors, and frames

The dimensions of all the windows, doors, and frames must be accurate as well and you will draw them in after you finalize the ceilings and floors.

  1. The interior walls and other structural elements

All posts and beams need to be added to your section drawing at this point, as well as all the interior walls.

  1. Add in all facing windows and doors

Now that you have your interior walls in place, you can finally add the facing windows and doors.  This will make the drawing look like a real house or building, and it will start to come to life.

  1. Add in those dropped ceilings and raised floors

Since every ceiling and floor is not always at the same level, you will need to add those dropped ceilings and raised floors at this point.

  1. Label everything

Now that you have all this information in place, you must begin to label it all.  This will ensure that you know what everything is, as well as the measurements for it all.  This is also the time to make sure everything is to scale, because if something is not, you must start over again or the entire project will be at risk.

  1. Section drawings must have a title block

Title blocks are necessary for section drawings, because it allows you to know who did them, when they were done, and what version it is.  This ensures that you are always looking at the most recent section drawing.  Basically, the section drawing should include the following:

  • Name of the project
  • The date
  • The person’s name who did the section drawing
  • The view name
  • The drawing scale

Wall layers can be a little trickier to draw, but they are easy if you simply draw from one side to the other.  The scale for wall layers is much larger than it is for other section drawings.

As you can see, section drawings are truly needed when it comes to building anything in the construction industry.  These drawings will allow you to see exactly how everything should look when it is done, and they can also help you notice problems before you get too far into the project.

In fact, you should study any section drawings carefully before you start a project, so you can catch those minor, or major, issues immediately.  After all, it is much better to fix them before too much work has been completed than it is to try to fix things afterwards when you need to start tearing things down and starting again.

Basically, follow your section drawings as you are working on the building process and you will not have any problems along the way.