Redlines vs. As Builts-What’s the difference?

Last Updated on November 14, 2021 by Jose Villegas Jr.

What are Redlines?

Redlines are original drawings that have been redlined to reflect modifications that have been made. These are usually manually incorporated into the design drawings and mark changes by hand.

When a new project is implemented, the construction team uses specifications and various plans to guide them in building the project.

Due to variations, errors, and revisions, changes happen during the process of having the project being constructed. To capture these changes, the project drawings are redlined to reflect the carried-out changes.

Redlining drawings occur when you draw over the drawing (usually using a red pen) to show what’s installed actually.

There is a misconception that redlines are only limited to project drawings. It’s not the case!

Redlines should not be limited to drawings. It is crucial and even more vital, to ensure that specifications are updated in line with the way in which control sequences are really implemented.

What are As Builts?

As-builts are drawings and specifications that describe the way a building is constructed. The documents are part of the “final set” of specifications and drawings that will be given to the owner or client.

Two ways the redlines can be transformed to as builts

The first way – The main contractor requires the subcontractors to produce as-builts for their respective portions of the drawings and specifications. This method may be useful on certain projects but the problem arises when multiple subcontractors create as-builts of the same documents.

Second way – The general contractor submits redlines for documents with multiple subcontractors (like mechanical blueprints) which will then be integrated into all the redlines into one document set.

The issue with this option is that in the event that redlines from several contractors conflict, the main contractor could choose to use one red line instead of contacting both the subcontractors. It all depends on the speed of the project and how inexperienced the general contractor is working on the project.

How are as builts prepared?

Preparations of as built drawings shall be based on the approved redline markup drawings.

In the event that redline markups can be accepted as to be accurate, then the only effort required in as-built documents will be to review and confirm that all redline markups have been represented and reflected in the cad file drawings.

Moreover, careful transcription of all revisions made to the specifications that occurred during the construction process should be updated in the as-builts as well.

Why are as built drawings important in construction projects?

A Guide to redline markup drawings and as built drawings

To better manage as built drawings, here are some recommendations:

1. Do not use words like similar or equivalent, and instead provide relevant details about the equipment installed in the project.
2. For detailing purposes, it is recommended that the scale of the as-built drawing matches the scale of the original design drawing.
3. Do not delete or alter original measurements and dimensions. The as-built drawings must include the revised dimensions by crossing out or writing an “X” over the original dimensions. To demonstrate the change, write down the new value and incorporate it with a cloud.
4. Include fabrication, erection, installation, and shop drawings if permitted by the contract.
5. Various details have to be included with all new equipment and materials, including location, size, and type of material.
6. You must clearly indicate if other contractors installed specialty equipment in the asbuilt drawings.
7. Underground utilities should have elevation, ground cover, depth, diameter, and flow direction.
8. Location (stationing, elevation, levels, coordinate offsets, etc.) information shall be included in the field redline.
9. Notes and documents must be stamped with a time and date that indicates when they were incorporated into the drawing.
10. Ensure that all drawings are dated once the redlines are completed. Ensure everyone is aware of the revision date by being consistent with the date location.
11. The individual who created the external design has to stamp and seal some drawings and details.
12. Include all notes on a specific sheet in one drawing. By doing so, the as-built will be completed more efficiently and mistakes will be minimized.
13. During the construction process, as-built drawings should always be kept on site.
14. Drawings as-built must be controlled by one person who manages access.
15. Color-code the following: Red indicates deleted items; green indicates additions to the project or new equipment; and blue indicates details or specific information.
16. Clearly explain changes if necessary. Make notes and corrections if necessary.
17. Make all legends identical to the originals.
18. Shop drawings can be appended to the drawing as appendices and notes can be added in the appropriate section.
19. Mark a drawing as “as built” when no changes need to be made.
20. The final as-built package should include an index sheet.
21. Clearly identify drawings as “red line drawings for as built preparation only” by adding the contractor’s name and date.
22. Scan and upload the drawings to the cloud for future reference.
23. Make sure to document the submission date and completion of the construction project.
24. Markups are typically included in CAD drawings, such as those created in popular CAD software. A redline markup allows users to update existing cad files from Autocad, Microstation, BIM and Revit.
25. Once a markup drawing has been successfully completed, the drawing can also be converted to a pdf file.