This image shows an early design intent drawing of a Junior Tower; that is a 12' by 12' tower suitable for use as a cabin, office space. or spare bedroom.
We decided to start small and progressively build larger towers, so our first project has been to design and build a Junior Tower; that is, a lookout tower with a 12' by 12' cabin supported by an 11' foot open base. Figures 2 and 3 show images snapped from a 3D model of a Junior Tower.
A Junior Tower can be built nearly anywhere: it's foundation requires just four concrete piers, and they can be made by either pouring monolithic large blocks of concrete, or by stacking CMUs (concrete masonry units) and then dumping concrete inside. Because the total height of the tower is less than 25 feet, most residential zoning laws would allow a Junior Tower to be built in a backyard, perhaps to serve as an office or spare bedroom.
If you would like to build your own Junior Tower -- go right ahead and do it. All these design work has been done, and the relevant files are all in the public domain. (Technically, they are covered by a Creative Commons license, and that is explained below.)
This link leads to the .RVT file used to create the images in Figures 2 and 3. An . RVT file is a Revit Project file used by Autodesk's Revit BIM (Building Information Modeling) program. Inside an RVT file is all the architectural details related to the design, such as a 3D model, elevation details, floor plans, and project settings.
Figure 3: The view from below of a Junior Tower.
Figure 4: This window leads to an open source PDF file with detailed specifications for building a Junior Tower. The design was sealed by Ben Brungraber, Ph.D., P.E.. Ben co-founded Fire Tower Engineered Timber (FTET.com) and is a timber frame visionary with more than forty years of experience in the field, including trend-setting research on mortise and tenon joinery.
About Sandbox Towers
Our first project was to define a new class of buildings called Sandbox Towers. This effort was completed in January 2020. This entirely theoretical design process created a set of design goals explaining how we expected Sandbox Towers to be designed and built. The Junior Tower describe above is the first instance of a Sandbox Tower that has been completely designed and engineered.
As the five-page PDF file nearby explains, we expected a Sandbox Tower to use wood columns supporting a rectangular structure with balloon framing. Like shipping containers, we expected Sandbox Towers to be quite flexible, so they could be Apartment Towers, Office Towers, Shopping Towers or multistory homes. We expected Sandbox Towers share these common features to make them easy to design, engineer, and construct:
Sandbox Foundations: a class of support system designed to support Sandbox Towers. Each Sandbox Tower has specific support requirements, and each Sandbox Foundation has engineered support capabilities. This makes it simple to mix-and-match.
Balloon Framing: a style of timber construction that uses long vertical studs or posts to support a multistory building. Each floor is then hung off of the posts.
Sandbox Columns: a class of compound posts designed to support Sandbox Towers. We expected Column to be built by joining two or more rectangular posts in an L or T-shape with many bolts. This will quickly create sturdy corners (and for multi-bay Towers, it would also create sidewall Columns).
Sandbox Anchors: a class of connectors used to tie Columns to the Foundation. We expected each Anchor to have many punched holes: upper holes would bolt onto a Column and lower holes would accept rebar surrounded by concrete. The most common.
Removable Connectors: Sandbox Towers use galvanized bolts and bridge washers, self-taping lag bolts, split-ring connectors, and large screws to lock everything together. These connectors allow the Towers to go up rapidly ... or be disassembled to move or repair the Tower.
Figure 6: Please use this Creative Commons attribution if you reprint or otherwise use the Junior Tower designs shown in Figures 2, 3 or 4.
Creative Commons License
The work shown in Figures 2, 3 and 4 was initially created by Dave Sullivan working closely with Fire Tower Engineered Timber (FTET.com) and is licensed under a Creative Commons Attribution 4.0 International License. We chose this license to promote the open source development of lookout towers while giving credit to people who contribute design and engineering work to LookoutTowers.Org.
If you look up this license on the web, you will find you are free to:
Share — copy and redistribute the material in any medium or format.
Adapt — remix, transform, and build upon the material for any purpose, even commercially.
As long as you agree to the follow these simple terms:
Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.