Spaces: iPad App for Conceptual Design

As far back as in 2015 in the article, “Why Isn't There a Smarter BIM Tool for Building Design, Yet?,” I had bemoaned the lack of a smart conceptual design tool for architecture, asking:

Is there nothing else we can do to make the process of conceptualizing a building smarter, more intuitive, more fun? Why can’t we simply be able to sketch out a building design — say a floor plan or a façade — and automatically get a fully detailed, structurally sound, constructable BIM without actually having to model every bit of it? Is this too much to ask for?

Well, it’s been 7 years, but we finally have the start of something like this. It is the new Spaces iPad app, developed by a startup company, Cerulean Labs.


As I emphasized in the above referenced article: “Any tool in which you have to model walls, a floor, and a ceiling to create a space is NOT a conceptual building design tool.” This rules out the use of popular BIM applications like Revit, Archicad, Allplan, Vectorworks, etc. by design architects, project architects, practice owners, practice principals, etc. — those who actually come up with the preliminary design concept for a building project. And they, by and large, are still doing this conceptualizing using traditional sketching with pen and paper (Figure 1), with perhaps some number-crunching in spreadsheets to ensure that they are meeting the area requirements of the project.

It is precisely this technology gap that the Spaces app is aiming to address. And a key part of its solution to digitize conceptual design is by working on a device that is closest in spirit to the pen and paper sketchbook that we currently have: Apple’s iPad in conjunction with the Apple Pencil. The device is already being used extensively for digital art — see for example, this article in Digital Arts magazine from where Figure 2 is taken. Now imagine the iPad being used like this by architects as well to sketch out their design ideas.

Unlike the multitude of apps that are available for creating art on the iPad, we don’t really have any apps for creating building designs. I had looked into this shortly after the iPad was released — see the article, “iPad Apps for AEC: Design and Visualization,” published in 2011 — and the only app that is still around from those that I reviewed back then is Graphisoft’s BIMx. This is somewhat ironical, given that we typically see more applications and apps in any field as time goes by rather than less. In AEC, we are, of course, seeing more mobile apps in construction where tablets and phones are being used to take photographs, add notes, capture updates, view models and drawings, etc. In addition, there are also several visualization apps on the market that architects can use to share design presentations with clients. But when it comes to creating design content on the iPad, we have had only a half-hearted attempt from Autodesk so far in the form of its FormIt app, which doesn’t really cut it.

Enter Spaces, which aims to become a “digital notebook” for architects, allowing them to quickly try out different design concepts on the iPad by sketching with the Apple pencil. And because it is specific to building design, it automatically creates a building model from the sketches and calculates the corresponding floor areas so they can be tracked against the project requirements, as shown in the sample project in Figure 3. Since the conceptual designs can be created very quickly without much effort, many more ideas can be tried just as they would if they were being sketched on paper — we all know how hard it is to discard an idea that you have invested a lot of time in.

Let’s see how Spaces works.


The Spaces app can be installed on the iPad from the App Store. It is a lightweight app and does not need the latest and greatest hardware — it can work with any iPad going back to 2017 (as shown above in Figure 3), provided the iPad has been updated with the latest operating system, iOS15. As mentioned, the Apple Pencil is a critical component of the hardware, so in order to use Spaces to create a design, you would need to use an iPad which supports an Apple Pencil. And of course, you need to actually have the Pencil. Without it, you can still use the app to open and explore a design that has been shared with you, but you cannot create one yourself.

The interface of the app is very simple and intuitive, as can be seen in Figure 3. The left panel shows the 3D model which you can explore by zooming, panning, and orbiting, while the right panel has the 2D view where you can draw. The navigation can be done using the traditional iPad finger-based touchscreen gestures such as pinching for zooming, swiping for panning, etc. The drawing is exclusively done with the Pencil — you cannot draw with your fingers. Most of the tools and options of the app are positioned on the left and top of the interface, while the right side has three panels that can be toggled to display the areas, level heights, and saved views of the design.

When you open the app, you can start drawing right away, using the Pencil to draw strokes just as you would draw on paper with a pencil (Figure 4). Thanks to one of the default drawing settings, the stroke is automatically converted to a dimensioned line. There is also an option to restrict the drawing to be orthogonal if required. You can continue creating strokes in this manner, and as soon as the shape you are drawing is closed, the closure is detected, and a building is automatically created as a straight-up extrusion of that shape, as shown in Figure 4. The initial number of floors and the level heights of the building come from those specified in a Building Defaults dialog. There is also a Project Settings dialog where you can specify the units for the building and the level of precision.

In addition to the automatic creation of the building from a simple sketched outline, you can also immediately see its area breakdown by toggling open the Area panel on the right as shown. You can create multiple buildings in the same way and select any building to see its areas. The Areas panel has some broad categories such as Commercial, Residential, Retail, etc., that can be assigned to the different levels to flesh out the design concept further, as shown in Figure 5.

While the initial number of levels and level heights come from those specified in Building Defaults dialog, you can modify these by togging open the Levels panel, which also opens on the right side. Here you can adjust the heights of the different levels and add or delete levels. You can also select individual levels and modify their outlines, allowing you to create a design that is a lot more detailed compared to the straight-up extrusion from which you started (Figure 6). The app supports curved lines as well, allowing designs to get even more complex and closer to the kind of conceptual designs architects create when sketching out design ideas.

Additional capabilities of the app include importing a location to situate the design in (Figure 7); drawing out the site outline as well as zones within the site to designate parking, landscaping, etc.; modeling the surrounding buildings in the form of blocks (these were shown in Figure 3) to provide some context to the design; and editing any façade of the building in a dedicated Façade editor mode (Figure 8), which automatically updates the area calculations of the impacted levels. You can also control display settings such as transparency, shading, etc., generate reports of the area calculations, export designs in the PDF format, as well as share models with others by email. (The models themselves are housed in the Spaces cloud, but when you are working on a model, it is downloaded to the iPad.)

A recent addition to the app is a Cladding tool can be used to quickly assign cladding to the building faces to create curtain walls, shading systems, or combinations of both, as shown in Figure 9. Another new feature is the ability to create multiple design options for a project in the same file.

An additional interface feature I found very impressive is that you can use the pencil to write in dialogs and delete entries using scribbles. The handwritten text is automatically converted to digital input using an OCR-like capability. While this is actually part of the Apple Pencil technology, the Spaces app has done a good job of harnessing it. It has also developed similar capabilities as part of its own drawing technology, such as the ability to delete parts of a sketch by scribbling on it, as shown in Figure 10.

Further Development

Given that it has been only a few months since the app was released, there are plenty of features on the horizon for further development, including being able to export the model to the IFC format so that it can be further developed using a BIM application; improving the collaborative design capability beyond sending the link to the model by email; provide the ability to view the model on an iPhone as well in addition to an iPad; and expanding the reach of the application beyond the Apple world by developing a version for the touch-based Microsoft Surface.

More immediately, in keeping with its mission of being a “digital sketchbook” for architects, Spaces is working on developing a separate environment where you can take a snapshot of the model and have the ability to create multiple sketches over it, similar to the sketches architects create on butter paper or tracing paper on top of a design.  This would allow architects to start from a base design and overlay it with different ideas, each on a separate layer.

Another feature that is close to completion is the ability to view the model in a sketch display mode, making it more in tune with the ethos of the app, given that it is for early-stage conceptual design (Figure 11).


Most of the technology devices and applications that we use every day are utilitarian. To me, however, the iPad is different — as I wrote in my 2011 article (see the section, “My Personal Take on the iPad”), I fell in love with my iPad once I started using it and still feel the same way, after all these years. It has been delightful to find a conceptual design tool for architecture that not only runs on the iPad but is completely aligned to it in spirit and harnesses its full potential. Additionally, it also takes the concept of a building model and meshes it with drawing on the iPad, so that you are literally designing actual buildings on the iPad quickly and fluidly.

Spaces is obviously a labor of love, which comes across as you are using the app. I hope it gets a lot of traction and can continue to be developed. We need tools like this in AEC.

About the Author

Lachmi Khemlani is founder and editor of AECbytes. She has a Ph.D. in Architecture from UC Berkeley, specializing in intelligent building modeling, and consults and writes on AEC technology. She can be reached at


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