HOW TO UNDERSTAND ARCHITECTURAL DRAWINGS
A house design is more than just a floor plan.
There are a suite of drawings that need to be read together in order to get a complete picture of the design. You will need to look at elevations, sections and maybe even 3D perspective drawings, before you completely understand what you are going to build.
Most people struggle with this.
A lot of people focus too heavily on the floor plan and then simply extrude this up into a house. This is a mistake. A building is a three dimensional, sensory, spatial experience and the design needs to be considered from every angle to get it right.
Whether you are designing the house yourself or looking at drawings produced by others, it is vital to completely understand the design while it is still just lines on paper. You might be in for a nasty surprise if you wait until your builder starts on site!
So what do you need to know?
The main three types of drawings you will need to understand are as follows:
This is the type of architectural drawing you are probably most familiar with. It is the one published in magazines, online and in builders’ promotional materials.
A plan is the view you would get of your house if you took a slice right the way through it, about 1m above the floor, then took the top off and looked in.
Floor plans usually only set out the horizontal elements of a design. They are dimensioned to show the width and depth of each room, the wall thicknesses and the location of fixed features like windows and doors, plumbing, staircases and joinery.
Walls are usually denoted with thick dark lines with windows three, thinner, parallel lines. Doors are also always shown open with an arc to illustrate the extent of its swing.
Plans usually include:
- The layout of the house with each room labelled
- Horizontal dimensions of each room
- Wall thicknesses
- All doors with direction of swing and size
- All windows with dimensions
- All fixed plumbing fixtures and locations of appliances
- Location of fixed joinery items – such as wardrobes, cupboards, kitchen benches etc
- Floor finishes and levels
- The line of eaves, roof or ceiling features above
- Directional arrow to show the building’s relationship to north
- Labels and notes to indicate section planes and detail references (see below)
This is like a plan, in that it represents a slice through the building, but this time you are cutting the building vertically. It is used to show the vertical aspects of the design, internal heights and finishes, and the wall and floor build ups (once your drawings get more detailed, these are usually drawn at a larger scale – more on ‘scale’ later)
The line along which this slice has been taken, the section line, should do shown on the plan drawings so that you know what you are looking it. There are often a number of sections taken through different parts of a building and each section might be given a reference letter or number.
Sections are also the best drawings to describe construction methods and materials, especially if things are hidden within walls or floors.
Sections usually include:
- Concrete slab or foundations
- Floor thickness and/or construction
- Wall thickness and/or construction
- Roof thickness and/or construction
- Wall finishes and materials
- Floor finishes and materials
- Ceiling heights, form and materials
- Staircase details
- Window heights and frame types
This is probably the most abstract type of architectural drawing.
An elevation is a straight-on, perpendicular view of something, usually an external view of one side of the house. There is no distortion as you might see in a ‘perspective’ drawing. It is completely flat.
In reality, unless you are able to view the house from a great distance, you will never actually see the house in this way. However, they are very useful drawings when it comes to choosing finishes, estimating materials and actually building the house.
You will almost always have at least four elevation drawings (one for each side of the house), unless your house is semi-detached or part of a terrace, and often they will include ‘context’ such as adjacent buildings or landscaping.
Elevations usually include:
- Roof and ridge heights
- Ground and floor heights
- Exterior materials and finishes
- Roof pitches
- Windows sizes and locations
- External door sizes and locations
- External features and decorative elements
Understanding Drawing Scales and Using a Scale Ruler
Im sure you’ve heard the term ‘scaled drawing’ before, but what does it actually mean?
It’s quite simple really.
Scaled drawings are essentially drawings that are an exact number of times smaller than the real thing. For example, 1:100 (‘one to one hundred’) is a metric drawing scale. This means that every 1mm drawn at this scale represents 100mm in the real building.
Other scales you will likely come across are 1:50 and 1:20.
To draw and check scaled drawings it is usually necessary to have scale ruler. Think of this as a really long ruler than has been compressed, so that it becomes an exact number of times smaller than the original. A 1:50 ruler would be 50 times smaller than the original ruler, for example
Scale rulers usually come with a number of scales marked on them.
The markings on the scale ruler represent dimensions at that particular scale. They are divided into mm and m, as with standard rulers, but each of these markings represents a different amount depending on the scale. So 1mm at 1:20 represents 20mm, while at 1:100 it represents 100mm.
What Do Line Weights Mean?
The final aspect of architectural drawings that I want you to understand is the importance of ‘line weights’. Different thicknesses of lines are used to represent different qualities in the various features of the building.
The intention is to approximate how we see things in the real world, how our eyes perceive distance and depth, so that we might better understand the drawings.
Let me explain.
Heavier lines always represent something that has been cut though. So for example in a floor plan, if the walls run full height but you are making your ‘cut’ at 1m above floor level, then these walls will be shown with a thick line. Similarly with section drawings, when the ‘slice’ goes through a wall or other solid element, this is usually shown in a thicker or bolder line.
Items with thinner or lighter lines are usually behind the cut plane, and the varied thickness of these lines is intended to indicate depth. The thinner the line, the further away from the ‘slice’ it is.
The same principles apply to elevational drawings.
Imagine you are stood outside looking at the building. The parts of the design that are closer to you will be shown in bolder lines and in more detail (because they are closer to you, you can see them more clearly). Likewise, items which are further away are much fainter, sometimes in outline only.
Train Your Mind’s Eye
Even armed with this knowledge, it will take some time before you can fully visualise a room or space by simply looking at the drawings.
This stuff takes practice.
I recommend standing in an existing building with a set of drawings that describe it. As you walk around follow your path on the floor plan, and as you look up and around you refer back to the section. Look at the external elevations and identify features and materials on the finished building.
Train your mind’s eye to connect lines on paper with three dimensional space.
I hope you have found this article helpful and that you will be more confident looking at and working with architectural drawings in the future.
Do you have more tips you would like to share, or perhaps you have struggled to read drawings in the past with disastrous consequences?! Please share your story in the comments box below – Id love to hear from you!