Even the most minor building renovation project must begin somewhere. In order to understand the building’s limitations and opportunities, a renovation project typically begins by creating drawings of the building as it currently exists. These drawings become the foundation for everything that follows. This article aims to explain how valuable this initial investment in time and budget is to our clients and describe our process at Childress & Cunningham Architects.
Our goal is to create digital drawing files that we can easily edit and modify using drafting (CAD) software. We have three main ways to gather the information we need; 1) reading the building’s original construction drawing sets, 2) taking manual measurements on-site, and 3) capturing the building with 3D scanning technology.
A floor plan is the most common type of drawing, with side views, cross-sections, axonometric or even perspective drawings often used to gain a thorough three-dimensional understanding. While your renovation project might focus on just one area of the building, it may still be important to show the entire building for context – and may be required to provide the building department with information like occupancy counts, emergency egress paths, and plumbing fixture counts as they are affected by the proposed project.
ORIGINAL DRAWING SETS
Original blueprints that clients provide are certainly valuable. The original drawings often show conditions that are not readily observable in the current building or structure. Sometimes, if these drawings are available as CAD files they can be imported directly into our drafting software, which is ideal. If we receive them as printed copies or scanned images, we cannot directly modify them. The information must be redrawn in our software to become truly usable, with the degree of accuracy necessary for final construction documents.
We can import scanned plans as background images and draw over them; this approach is used for quick, informal studies. It is inadequate for the detailed construction documents required to get a building permit. Scanned drawings create problems because the underlying image cannot be modified, making it difficult to clearly communicate some types of changes, like wall demolition or new openings.
When we have the original blueprints, we can draft digital plans based on the dimensions shown on those drawings. However, not every building component will have its measurements noted on the original drawings. When these unmeasured elements are relevant to the renovation design, we’ll need to physically measure them in the building or capture them with 3D scanning equipment.
MANUAL FIELD MEASUREMENT
We use various measuring tools, from basic tape measures to electronic devices, to gather dimensions on-site as the project requires. Buildings often differ from their original blueprints, in both small and sometimes large ways. We walk through the building to sketch, photograph, and measure these undocumented conditions, then integrate them with known dimensions to create a better overall understanding of the building.
The advantage of direct field measurement is that it uses the same processes that the contractor will use later to construct the new design. We avoid assumptions about concealed conditions, like unusually thick walls or hidden structural elements. Original blueprints can lead to false assumptions because they show what was intended to be built, not necessarily what actually got built. Some clients need precise measurements for lease agreements based on actual square footage, so we verify the space to meet their accuracy requirements. When our measurements suggest something is hidden or unclear, the building owner may be asked to open up walls or ceilings to investigate further.
3D SCAN / CAPTURE
A thorough method at our disposal uses a tripod-mounted scanning camera that we position throughout the building, capturing panoramic imagery and measurement data approximately every fifteen feet. Computer software weaves these scans together into a virtual model that allows us to explore the building digitally and extract floor plans with digital methods. This technology has some limitations, so we typically combine it with traditional measuring in areas where more accurate dimensions are important (such as where minimum clearance dimensions will be applicable).
Because this scanning is essentially advanced photography, we try to schedule it when the building is least occupied to avoid having people included in the imagery. Depending on the building size, scanning can take a couple of hours for a small office renovation or an entire day for something larger. We use a service called ‘Matterport’ that’s popular with real estate companies because it lets anyone explore the building online through a web browser. The camera works by referencing surrounding walls, so it excels indoors. For exterior features like building faces and walkways, other more traditional measuring methods will be used.
After scanning is complete, the data must be uploaded for processing and floor plan generation. The resulting plans from ‘Matterport’ require further processing to integrate into CAD software, and the drafting time needed can offset the initial time advantage over traditional methods. The key benefit is that the project gains a permanent virtual record, allowing the team to revisit the building digitally whenever questions arise during the design and construction document process.
COMBINING THE METHODS
As can be seen from the methods above, we often combine multiple information sources about existing buildings, using each one to fill gaps left by the others. Additional details sometimes turn up on county auditor websites or regional GIS (Geographic Information Systems) mapping sites. Even Google Street View can show how a building looked years ago, helping us figure out when specific changes were made.
Proper documentation of existing conditions helps avoid unwelcome surprises later in the process, when detailed construction drawings need to show how building upgrades will be built. Investing in accurate and detailed existing drawings upfront pays off by supporting well-informed design decisions with reliable reference information. This helps keep construction change order costs under control.
EXISTING CONDITIONS MIGHT BE ALL YOU NEED
We’ve provided services to clients who need building documentation solely to qualify for a new Certificate of Occupancy. While no physical changes are proposed, the building department requires current architectural plans that show safety systems are adequate for the intended use. Should we discover major safety deficiencies, we’ll notify the client and recommend necessary design solutions. However, if the building is likely to be accepted by the building department as safe for the new use, our services may be limited to preparing existing condition drawings and documenting installed safety features such as fire alarms, exit signs, and emergency lighting systems.
This was the case for a recent client, who provides supervised housing for adults with developmental disabilities. They had purchased a structure and needed a Certificate of Occupancy to use it for their program of services. We visited the property, scanned the building, and confirmed that required safety devices like smoke detectors and carbon monoxide detectors were installed in appropriate locations. The floor plans showed the entire building, including the basement, giving the building department a complete picture of how the space would be used so they could issue the Certificate of Occupancy.
Not all projects enjoy such a direct path to building department approval. Developing reliable drawings of existing conditions helps owners anticipate building code issues that might surface during a building code review. Accurate documentation may lead to creative solutions that minimize necessary modifications while providing cost-effective ways to satisfy client requirements. Clear existing documentation helps the client, the property owner, the architect, and other consultants to understand the building, allowing them to understand what it will take to achieve the client’s desired outcomes.
