Article by Offsite Builder Staff • Video by Mark Wille
In this video, Mark Wille interviews the co-founders of Philadelphia, Pennsylvania-based Holzraum Systems (www.holzraumsystem.com). The company offers what seems to be the next step toward realizing the promise of Building Information Modeling (BIM). It’s called SIMM, or Single Integrated Manufacturing Model, and its first customers have been high-performance builders who frame homes with panels.
Architect Ilka Cassidy and Passive House builder Steve Hessler co-founded the company in 2018 along with software developer David Hessler. So far they have worked on 10 custom-home builds, all of them panelized, including standard dimensional lumber panels and cross-laminated timber (CLT) panels.
The HolzRaum team can use data from Revit, as well as from other software programs, to help them create a detailed digital model—a three-dimensional representation of the building. It’s a parts-based model where users can zoom in on any detail, then click on it to see the specifications related to that part. Specifications might include the strength of an individual fastener, beam or roof panel, or the U-value and solar heat gain coefficient of a window.
The model can be sliced into various layers—the foundation, the wall panels, the roof system, the foundation, the structural steel, the mechanical infrastructure, etc. Each layer can be viewed individually or combined with others. “We can look at all of these perspectives separately, or together, and see how they relate to one another,” says Cassidy.
One important benefit SIMM brings to the table is better project communications. The design and construction team will typically hold regular Zoom calls in which they look at the model together to review details and solve problems.
As an example, imagine a call in which the architect, the structural engineer and the MEP contractor sit down to review duct routing. The engineer might point out a specific detail and say: “You can’t cut through that beam at that point for your duct, so you need to build a soffit below the beam.” The architect might counter that a soffit would not be appropriate at that location. A discussion between all parties might then lead to a redesign of the beam, or a rerouting of the ducts.
The ability to manipulate the model on the screen makes this kind of clash detection and problem-solving faster and more effective, and ensures that everyone’s needs get met. All such discussions and their resolution are saved in an issue-tracker database for future reference.
When the SIMM process is complete, a detailed set of drawings is prepared and reviewed by the structural engineer, architect and builder to ensure the whole team agrees with design intent and fabrication strategies.
In addition to finalizing the architectural and mechanical design, the SIMM system also outputs detailed panel specifications to the manufacturer. Cassidy says that the company has worked with manufacturers at various levels of sophistication. For instance, Baltimore, Maryland-based Blueprint Robotics has a highly-automated panel factory so the deliverable was data files for their machinery. But HolzRaum has also worked with smaller companies that do everything manually. “In that case, our output is shop drawings for the panel shop,” says Cassidy.
So far, the projects HolzRaum has worked on have been complex custom homes with low energy use, many of them achieving Passive House performance standards. While these projects have helped the team perfect their process, the ultimate aim is to serve a wider market. They want to stay focused on high-performance homes but are open to working on simpler projects. “We’re a great fit for custom homes because they’re complicated, but we don’t have to take things to that level,” says Cassidy.
The accompanying video provides a more detailed picture of what HolzRaum offers. In it, Cassidy and Hessler talk, in general, about how the service works, then, as an example, they go into some depth on a large and complex custom home in Montana that the company helped design. The home uses standard panels for the walls and CLT panels for the roof and floor system.
Video Time Stamps
00:00 – HolzRaum and its founders:
05:53 – Streamlining passive house using off-site methods:
07:52 – The SIMM model: a communication solution for off-site construction:
15:16 – Modeling a project for manufacturing:
17:38 – Use of the model as a project communication tool :
18:26 – Summary of the benefits and uses of the model:
21:00 – An in-depth look at how the model was used on a complex custom home:
