While construction work is in progress, understanding a complex drawing is sometimes a challenging task. Normally construction work is progressing on the fast track and construction experts at the site have a lot of actions on their to-do list. They have to make many decisions, making progress reports, handling labor, etc. they might have been left with limited time to read the drawings before execution of the construction works. Minor mistakes in reading the drawings can cause a major issue. For example, if coordinates marked on a foundation drawing are read incorrectly, the foundation will be cast at the wrong location. The casting of the foundation at wrong coordinates will cause a mismatch in other interconnecting items or structural elements. The error in reading the coordinates seems to be very minor, but may be very difficult to handle later on.
These tips will help you to quickly read important information from foundation drawing.
When you receive a foundation drawing, quickly go through the following sections of the drawing to get familiar with the drawing.
Notes provided on a foundation drawing are as important as the layout, sections, and details of the foundation. The notes generally contain important information, like specifications for materials, units of measurements, construction methodology/sequence, any special instructions, etc. Sometimes these notes are ignored by construction engineers and supervisors considering these of least importance. But, it is very important to read all notes and follow them during construction, because designers prefer writing notes for all those elements which are difficult to be shown in detail.
TOG Top of Grout
TOC Top of Concrete
FGL Finished Grade Level or Finished Ground level
NSL Natural Surface Level
NGL Natural Grade Level or Natural Ground level
THK. Thick or Thickness
RCC Reinforced Cement Concrete
CC Cement Concrete
PCC Plain Cement Concrete
C/C Center to Center
T&B Top and Bottom
B/W Both ways
Reference drawings and documents such as general notes, relevant specifications, or any other relevant document are listed in this section. Related drawings from other engineering disciplines, e.g. equipment GA (general arrangement), piping layouts, and other electrical or mechanical drawings are also referred to. These reference documents contain a lot of necessary information, which can not be put on each drawing due to space limitations and ease of understanding. before starting the execution of the construction works, you must be familiar with the reference drawings. In our later posts, we will discuss use of specifications and general notes in detail.
When required details are ‘more in number’ or complex in nature, all details are not provided in a single sheet. All additional details are provided on continuation sheets. Cross-referencing is provided between details and layouts of different sheets. One must understand cross-referencing systems for the drawings so that no detail is overlooked at the site. Cross-referencing procedures are not universal, these are project-specific in nature. These procedures are normally defined in a project documenting procedure or drafting practices.
Design Information for Foundation Drawing
These details are the main area of the foundation drawing and are normally not overlooked by the site engineer. following are the main elements provided in a foundation drawing and must be studied in detail before proceeding to the construction activities.
- Foundation Layout
- Reinforcement details
- Coordinates (Northing & Easting)
- Key plan
- Anchoring details (where applicable)
Although these elements seem to be of less importance, in fact, have a very important role to make a foundation drawing presentable. The main features related to appearance are the following.
In addition to the above, a drawing prepared with defined drafting practices is always easy to read and understand. Further, a foundation drawing must have a controlled drawing number, revision and signatures of engineers and draft-persons etc.