You’re going on site to document existing conditions, which method should you use?

In this article, we’ll break down the pros and cons of several ways you can document existing building conditions. As architects and engineers, we’ve had the opportunity to capture building data using all of these methods. Some were very efficient, others created lots of followup work after the site visit. Here’s what we found:

1. The Clipboard Method

Before laser scanning or tech such as Matterport, architects documented created existing conditions documentation the “old school” way. This usually entailed walking the site with a tape measure and clipboard with a set of drawings.

While we’ve come a long way since then, there are still architects that prefer to use this method.

PROS

Accessibility: most people have access to pen, paper, and a clipboard. There aren’t many advantages to using the clipboard method unless the project is small. Typically, the time savings gained during the walkthrough are lost when you have to download and transpose everything back at the office.

CONS

Methods for Capturing Existing Conditions

1. The Clipboard Method

Disadvantages:

• Time-consuming: You lose a lot of time after the visit organizing photos and translating notes into a digital format.

• Inaccurate: This method relies on everyone taking notes that are legible and similar in format.

• Disconnected: Data is captured manually, meaning it won't be natively connected to as-built drawings, floor plans, or a Revit model.

When to Use This Method:

Use this method only if you need to, such as for a last-minute walkthrough where you can’t prepare ahead of time.

2. The Laptop on Wheels Method

Pros:

• Accurate Data: Access to a computer during a walkthrough helps find and note deviations between the model, floor plans, or construction documents and pre-existing conditions. However, this requires having accurate data sources from the start. With older buildings, you may be starting from outdated scans or documentation.

Cons:

• Disconnected: Common building data such as notes, photos, and condition ratings are still disconnected from your model or the documents you are referencing. This means you’ll still waste time searching for information in different channels in the future.

• Time-consuming (and awkward): You will still spend time in the future searching for photos and other data that can’t be directly input into Revit. Additionally, you will need to purchase a laptop stand to wheel around while on site.

When to Use This Method:

This method is useful if you already have good digitized documents or a model and don’t mind wheeling around a laptop cart.

3. Laser Scanning or "Scan to BIM"

Pros:

• Connected: The end product of a laser scan is a point cloud or digitized cartesian coordinates (x, y, z). Multiple scans can be combined and cleaned up in software such as Autodesk Recap, then directly exported to Revit to create a model.

• Efficient: Scanning is highly efficient as it doesn’t require as much time on site as other options. However, the turnaround time for a detailed model can be lengthy depending on the size and complexity of your project.

• Accurate: Scan to BIM is highly accurate when performed under the correct conditions. However, too much ambient light can distort results since the scanner may have trouble detecting points on reflective surfaces. This might require scanning at night or during non-operational hours in an industrial setting.

  In addition, 3D scans can be almost too accurate, capturing uneven walls and objects out of plane. Scanning might be overkill for small and mid-sized projects.

Cons:

• Data is still disconnected and potentially time-consuming: As mentioned above, rich building data like notes, photos, and condition ratings will still be disconnected from the Revit model. This can lead to wasted time hunting for this information in different channels in the future.

• Expensive: This option is significantly more costly than others, requiring expensive, large, and hard-to-transport hardware.

• Timing: The scanning crew will need access to the site when they can turn off all ambient light sources. This may not be an issue for commercial buildings where tenants leave in the evening, but it can be a challenge for hotels, manufacturing sites, or other facilities that operate around the clock.

When to Use This Method:

This method is generally used for complex existing buildings with large spaces where clash detection is the desired goal.

4. Photogrammetry

By NELAC - N.ELAC, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=124639071

Similar to the 3D Scanning Method, photogrammetry generates a 3D model by using a comprehensive photo scan to gather data. Unlike lidar scanning which shoots light at a surface, this method uses many photos "stitched together" to capture a space. This makes the equipment for a photogrammetry scan 1/10 or less of the price of a typical laser scanner.

PROS

– Connected: Similar to the 3D Scanning Method, a photogrammetry scan can be used to create a point cloud and data can be imported directly into Revit.

– Accurate, kind of: Depending on the space you’re documenting, photogrammetry can be very accurate. The texture of surfaces makes a difference in the type of data that is captured. Smooth, flat surfaces make it difficult for photogrammetry scans to work, leaving you with inaccurate data.

CONS

– Still disconnected and time-consuming: Photogrammetry does a better job of capturing material types than a 3D Scan, but you will still need to translate that data into the Revit model. Also, note that the initial scan can be time-consuming.

– Expensive: While this option costs less than 3D scans, the software required to capture and stitch the photos together has monthly fees and extra fees for the point cloud output. You will also need to do multiple scans to connect the rooms together. All of this means the price can add up quickly.

WHEN TO USE THIS METHOD

It’s best to use this method when documenting existing conditions with smaller room sizes that don’t have smooth, flat surfaces.

5. The Mobile App Method

There is a wide range of mobile apps on the market that make it easy to create robust forms to input data. While some products provide the ability to upload drawings, most are geared towards construction workflows.

This is the primary reason we created Layer App. We built a tool specifically for architects and designers who need to capture existing building conditions. The added bonus of using Layer is that it is the only mobile app on the market that connects captured data to Revit.

PROS

– Accurate: Layer’s diverse range of form fields lets users input any kind of data accurately and consistently.

– Connected: Layer connects directly to Revit or Floor plans at any time in a project, regardless of whether there is a model at the time of your site visit.

– Efficient: Capture data only once and find it later in one intuitive dashboard that makes it easy to view your data right in Revit.

– Affordable: Layer’s new Drawing View gives you unlimited everything, including the number of sheets, for one low monthly fee that you can include in client contracts.

– Easy to Use: Layer was recognized by Architect Magazine for our intuitive mobile-friendly interface that makes it easy to capture data on the go, even when you’re not connected to WiFi.

WHEN TO USE THIS METHOD

Layer can be used for any type or size of project. Built to be flexible, the app comes with a suite of robust team communication tools that make it easy to coordinate teams on site. And while Layer was built to connect project data to Revit, it can also be used at any time without Revit, making it an easy-to-use solution for team members who don’t know Revit.

What’s the right solution for you?

The right solution will depend on the size of project you’re documenting, the type of information you’re capturing, and the budget you’re working with. If you’re looking for a flexible documentation tool that connects to Revit, we recommend that you try Layer.

Get started by scheduling a quick demo