Redline & As-Built Drawings Explained for Construction Companies and Architects

What do Redling & as-built drawings services for construction entail? Redlines refer to the original blueprints where red ink marks the changes made. Every time builders remodel or build a structure, they follow a set of drawings that an engineer or architect has prepared. As they work, they often make changes and adjustments to the project. The changes are then drawn in red ink on top of the original plan to document all the changes made. Since red ink is not generally used in blueprints, the changes are more visible and stand out.

Redlining is a term that means drawing in red on top of the blueprint to show changes. Redline drawing experts draft blueprints that were drawn by hand. As-builts are new plans showing how a structure is built, and an as-built includes every change outlined on redlines. When comparing redline and as-built drawings, it is essential to understand that builders make redlines while architects or engineers draw as-builts. Once changes are made to the project and everything is outlined on redlines, the drawings will be given to the engineer or architect.

They will then prepare a set of as-builts according to redlines and often based on a site inspection. As-builts are typically forwarded to the building department to get an updated permit. The building departments only accept as-builts approved and stamped by an architect or engineer and don’t accept redlines. Remember that redlines are not considered an official set of plans. Instead, these drawings contain details drawn over official plans.

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As-built drawing services draft official plans, and architects or engineers prepare and stamp them to show how to build a structure. As-builts also show the entirety of the structure with all updates included. As-builts are essentially an updated set of blueprints reflecting the changes indicated in the redlines. 

Table of Contents 

What are redline drawings?

In the most basic explanation, redline drawings are the original blueprints where red ink is used to draw changes to the project. Blueprints show how a structure is built and detail dimensions, sizes, heights, setbacks, foundations, steel, lumber, framing, doors, windows, finishes, etc. Builders use red ink to outline every change they make to the blueprints. When builders make changes, everything should be documented so that they can show these to the engineer or architect for approval. They will then prepare the as-built plan based on the changes and a site inspection.

All changes made must be drawn on the blueprints so that everyone involved in the project can see them. Aside from new layouts, redlines also include specifications. Any changes made should be detailed, no matter how small, for the design engineering company or architect to review them. Any specification or change made on the job must also be outlined on redline drawings. 

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There are instances when the changes made might not be to code. In cases like this, the engineer or architect will tell the builder what must be done to bring the structure back to compliance. This is why recommended changes are limited only to minor things that will not breach a building code. For instance, moving a window or door a few inches must be shown in a redline drawing to the architect. This kind of change won’t often result in violating a building code. 

What are as-built drawings?

As-builts are specifications and drawings from architectural detailing services that present how the building is built. As-built drawings are updated sets of blueprints that an engineer or architect draws. These drawings combine the original blueprint and the changes made and outlined in redline drawings. An as-built plan includes the final specifications and drawings that are then provided to the building department and the owner. 

Redline drawings can become as-built drawings in a few ways:

• Some builders require their subcontractors to issue redlines rather than as-builts. They will take all the redline drawings and develop a new plan that shows every mechanical work on a single plan. It is handy for large-scale projects involving several subcontractors because everyone will work from a single master set of blueprints. Subcontractors with these types of jobs often don’t prepare their plans, making redlines work better.
• The builder might also require all subcontractors to develop as-builts with specifications for their part of the project. Some mechanical subcontractors make their plans so they can do some updates themselves instead of the architect. 

Every change made to the project is ultimately indicated on as-built drawings, and it is recommended to undergo the redline process before moving to as-builts. 

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Are redline and as-built drawings the same?

Based on the explanations above, redline and as-built drawings are different. 3D Modeling & drawing professionals create Redline drawings which are blueprints with changes drawn in red ink on top, while as-built drawings are official updated plans showing every single change made throughout the construction process. Redline drawings are not official plans, meaning they cannot be used to obtain updated permits. As-builts, however, are official sets of plans. If your change is substantial enough to necessitate an updated building permit, you will need a set of as-built drawings prepared and approved by the engineer or architect. 

Another key difference is that every subcontractor that usually has its own set of plans can make redlines. It is a common practice among mechanical contractors. However, it can result in some issues since other contractors only work based on the official blueprints and might not see the redline drawings of the subcontractors. If the subcontractors don’t work off the same plans, it can lead to problems. It is why more significant projects often require as-builts. 

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What are the differences between redline and as-built drawings?

Redline drawings are blueprints with red ink to draw the changes on top. The builder or a subcontractor can make redlines, and all the changes made from the original blueprint must be detailed and indicated in redline drawings. As-builts are officially updated blueprints showing the original design and every change made. Redlines are not official blueprints, unlike as-builts. For instance, if a change is made and it requires the building department’s approval, you will need an as-built instead of a redline drawing.

Redline drawings show the changes made to the engineer or architectural drawing firm so the plans can be updated in the form of as-builts. Redlines always come first in documenting the changes made on a blueprint. As-builts follow these to outline the changes in the redline drawing as the blueprint’s official part. 

Importance of redline drawings 

Redlines are a critical aspect of the construction process. Architects, engineers, designers, builders, and subcontractors use them to document the changes made to the designs and blueprints of the project. All deviations must be drawn in red so the project team can see the change. It helps ensure that all the designers and workers are always on the same page about what is being constructed and when. All redline drawings are ultimately given to the other designer or architect so they can proceed to prepare an as-built. Preparing accurate as-builts would be more expensive and difficult without redline drawings. 

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Below are some helpful tips for preparing redline drawings:

• The scale of the redline must always be matched with that of the original drawing.
• Indicate clearly if the contractors installed any equipment not presented on the blueprints. 
• Date when every redline is added to the plan. 
• Document every change as precisely as possible. 
• Include shop designs and drawings.
• Keep the redlines on site to allow contractors to review them. 
• Use identical legends to those of the original. 
• List all applicable setbacks, measurements, and dimensions. 
• Redline the new designs for the finishes. 
• Underground utility drawings must show ground cover, elevation, flow direction, depth, and diameter. 

Importance of as-built drawings 

As-built drawings are a crucial aspect of construction, outlining every change to the original blueprints. All subcontractors on the project and the structural engineer, architect, builder, and inspectors must work based on an accurate plan reflecting not just how the structure will be built but also how it will be built. Dealing with project changes is a part of being a contractor, and every change should be documented. Redline drawing is the first step, with an as-built drawing following it. 

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• As-built drawings help eliminate mistakes since everyone has the same accurate and updated plan. 
• They serve as an official record for consultants, inspectors, future builders, and clients. 
• They assist future workers in understanding mechanical systems and how they are in the structure. 
• An as-built drawing helps with future maintenance and operation work. 
• Accurate and updated plans offer a basis for future repairs or upgrades. 

Every project must have an accurate and updated plan for everyone involved to work off of that, including once the job is finished. It helps with future upgrades, additions, renovations, and repairs to the structure and its mechanical systems.

How Cad Crowd can assist

At Cad Crowd, we have the privilege of working with some of the world’s best freelance as-built drawing designers. If you’re looking for help with your project, get in touch with us for a free quote.