Why Errors and Omissions on Construction Documents

Construction Documents are not new to anyone in the construction industry and the problems associated with these documents are not aliens to Designers, Engineers and Contractors on the construction site. Many a time during construction, the Contractor is the least person the Architect wants to receive a call from, not because he does not want to have any dealings with him but because he knows there is a possibility to receive a call for an RFI due to missing drawing or a section thereof, errors and/or omissions.

It is not uncommon to witness drawings produced by reputable firms just like any other produced by emerging firms to contain inconsistencies, inaccurate information and sometimes un-related information to the project for which construction information have been produced.

A lot of Professionals have wondered why architectural drawings for construction are usually clustered with errors and omissions and poorly coordinated. I want to comment at this point that with transition from the traditional tools of production to CAD tools, Architects, Engineers and others in the construction industry have automatically inherited some or all the drawbacks of CAD. This has brought CAD related liability to this sector and consequently, this type of liability will be under the Errors and Omissions Insurance. As a result of this potential for liability all drawings leaving the Architects’ Office and other Consultants’ Office should be coordinated and reviewed.

There are many factors, reasons and causes of common drawing errors and omission, I will discuss some of them as follows:

Traditional Principles of Production
Back in the days when all drawings are predominantly hand generated, certain design and graphic standards were followed but with the advent of CAD many of these standards have become non-relevant either intentionally or by oversight. These principles and/or standards were inherent to the quality and completeness of architectural drawings. One of such standards is the grid or dimensional module, a module in metric system is 100mm and a group of this module is referred to as multi-module for instance 200mm, 300mm, 400mm and so on. With this kind of standard it is possible for most construction materials to fit in the project because most of these materials are module based. Secondly drawing annotation can become too excessive to the detriment of the drawings if not coordinated as required.

Referencing of Drawings
Anyone familiar with AutoCAD will understand the advantages and benefits of using External Reference. On the other side the embarrassment that can be received from the job site regarding a blank sheet of drawing is not something anyone intends to experience. The question is: Has the Drafter, Designer or Architect deliberately omitted this information? The truth is that with due diligence all the information might be on the CAD drawing file. With a view to some of the problems associated external drawing reference they can be associated with one or more of the following:

• Non-uniformity in CAD skills and knowledge among the project team. Often team members are aware of the concept of External Reference (XRef) but may not be exposed to the difference between overlay and attachment options. For example, With drawing “A” referenced into drawing “B” as overlay and drawing “B” is now referenced to drawing “C” for one reason or the other, then drawing “A” will not be visible in “C” whereas with attachment option all drawings will be visible in drawing “C”. Depending on the intended purpose, overlay can be as useful as the attachment option. In most cases, missing drawings in XRef based drawings can be as a result of overlay option.

• It is understood that some Architect’s office are in the habit of not inserting base drawings on dedicated XRef layer(s) or layer “O” as the situation might be depending on how the objects were created. The Drafter or Designer can insert their drawings on defpoint layer without paying proper attention to the current layer. Remember that nothing prints on defpoint layer while your drawing objects will be physically visible on your file. If this is the case, you are likely to receive a call for missing drawing information.

Wipeout is seldom used by many people but it still remains a useful command in masking part of a drawing. The use of wipeout is another source of missing information on drawings especially when there is no adequate communication between the team members regarding wipeouts. If used correctly it can be a great tool but when wipeout is deleted or erased by another team member who is either not conversant with wipeout or do not understand why that wipeout has been applied can either speculate that masked objects have been erased or expose masked objects. As a result wipeout deletion, this revised drawing can now contain irrelevant information which can give reasons for the Contractor to send Request For Information (RFI). Therefore, watch out for these wipeouts or establish at the onset whether wipeout will be used in your project or not.

Also, it is important to keep new team member informed about the level and degree of CAD complexity being implored for the particular project, for example, intermediate or advanced CAD skill level. In a situation where this new member do not meet required level, a remedial course or an upgrade can be organized.

Notes on Drawings
Most drawings if not all drawings carry along with them “notes” describing the objects in each drawing. Excessive notes can result to confusion therefore, notes need to be concise and precise. It cannot be overemphasised that terminologies used in the notes should be the same as those terms in the specification.

It is true that you can encounter a situation where you need to repeat the same note on a previous drawing, it is recommended that you create typical notes to be applied on the first applicable situation and in subsequent cases refer to that note or notes on other drawings in order to avoid duplication. The advantage to you is that you only have one or two places maximum to revise your note and it will reduce the possibility of leaving such notes without revision in all instances.

In every drawing that has been set-up with time efficiency in mind the use of blocks cannot be avoided. This can be a block for: doors, windows and annotations just to mention a few. The creation method with respect to insertion point is vital and a standard should be followed by the project team or the firm as a whole.

Sometimes you encounter simple block or complex blocks otherwise known as nested blocks. Either of these block types can be created with good intention and purpose but when not properly used or due to lack of knowledge in working with blocks. Architectural drawings can experience unexpected mess or chaotic state.

For a nested block that has been inserted by a team member on a drawing in multiple locations and because of different conditions at placement, this so called nested block can be scaled, rotated or mirrored. When you do not understand how to edit such blocks in-place and due to your frustration and pride to ask for advice or help you can be tempted to explode one of the blocks. By doing this you can see the drawing objects scattered all over the place or notice that the block is out of place. It is not uncommon thing for you to blame the person who has previously worked on the drawing. Therefore, understand the standards applicable to your team with how you create, insert and use the blocks before you explode any block in a drawing you know little about.

Blocks, XRef vs. Copied Objects
Despite the fact that blocks improve productivity they also help to manage time and reduce inconsistencies in drawing information. Few employees are used to copying objects to the clip board with the purpose of pasting it on another drawing without changes to the copied objects in the forward drawing. If you fall into this category, it is advisable to use XRef for objects or section of drawings that will repeat in more than one drawing file and use block when you need a multiple of these objects in different locations in a particular drawing.

Details from other Projects
In an attempt to use applicable details from previous projects it is sometimes noticed that a well-drawn detail might not be relevant to the current project because the required revisions and customization have been overlooked. This is another scenario where RFI is needed by the Contractor.

What about BIM Project?
BIM inevitably resolved some or most of the problems already highlighted. Though the model is the same in all views but there is need for coordination of views containing annotations (2-d based objects) just as you coordinate CAD drawings. Also, any detail developed as 2d- based object are view specific and because it might have been drawn on top of the model, this detail view requires revision if changes to the model affect this part in such a way that will change the detail component.

Can you Reduce Problems of Production Drawings?
The answer to this question is definitely Yes. To achieve this purpose the project team members will need high level communication skills to enable everyone share project information more adequately. This helps other team members to be aware of changes, reason for the changes and any customized CAD standards involved in that change.

Also, along with an established office policy it is a good practice to revise and issue all drawings affected by the change rather than effecting change in one drawing while ignoring other related drawings. This practice can reduce the number of RFI’s or litigation.

What do you think about reducing common errors and omissions on Construction Documents?


Olajide Ageh