Inspiration behind Sandbox Lookout Towers
The inspiration for Sandbox Lookout Towers comes from the classic U.S. Forest Service Lookout Towers built on hilltops across the United States. The lookout tower building boom reached its climax in the 1930s and continued through the 1950s. By 1953, a survey showed over 5,000 lookout towers across the country. Each tower would house a solitary firewatcher who kept watch for distant smoke plumes. This system effectively caught fires when they were still small and easily extinguished.
After other methods of observing fires became available, most lookouts were neglected and eventually disappeared through rot, vandalism or deliberate governmental removal. But the Pacific Northwest still has over 400 lookout towers, and a few of these have paid firewatchers each summer. The remaining towers have become popular tourist destinations and many are rented consistently to folks who want a rustic getaway. For more general information about lookout towers and how they can be rented, we recommend looking at the Forest Fire Lookout Association website.
Lookout towers have a magical charm that comes from their simple, functional design: they use wood trusses to put a cabin high enough to get awesome views. Their iconic design is unlike any other building, and they are just plain awesome.
Fortunately, the Forest Service has collected and published the original blueprint drawings for their lookout towers from 1936 to 1965. We decided to model Sandbox Lookout Towers after the popular and iconic CT-2 fire lookout towers that had their widest success in the 1930s. But we couldn't use the CT-2 designs directly: They had steep stairs and drafty cabins. We wanted Sandbox Lookout Towers to use modern materials while retaining the historic character of forest service lookouts.
Figure 1: Two fire towers from the same class of designs.: a 12'-by-12' Junior Tower on the left, and a 20'-by-20' Papa Tower on the right. The same basic design can be stretched dramatically while retaining lots of standardized parts. For example, both designs would use exactly the same stairway flights, column posts, anchors, and connectors. Many other parts would be almost identical, such as catwalks, railings, and roof and floor structures.
Sandbox Lookout Tower Family
This page describes a family of Sandbox Lookout Towers: small towers with a 12' by 12' foot base, medium towers with a 16' by 16' base, and large towers with a 20' by 20' base. Each Sandbox Lookout Tower is a specific instance of the generic class of Sandbox Tower.
A key goal behind the designs on this page has been to use standardization to drive down cost. Standardization in the software world drives the marginal cost down to zero. That will never happen in the architectural world, but standardization should chop the cost at least in half for Sandbox Lookouts. Volume production always results in huge efficiencies and often in unexpected ways.
As an example, consider the Sandbox Design for a Junior Tower with a 12'-by-12' cabin shown nearby. This Junior Tower looks a lot like the 20'-by-20' Papa Tower next to it for good reason: they both the same stairs, anchors, connectors, and other parts.
We hope thousands of the Junior Towers to be built around the world. They are likely to sprout up in backyards as playhouses, in parks as motel units, on timber parcels as hunting lodges, and in lagoons on South Pacific atolls as fishing cabins. As production ramps up, factories will produce inexpensive tower kits, sell them online, transport them on flatbed trucks or shipping containers, and the buyers will assemble them quickly with just a few battery-powered tools. These towers also avoid most site prep because they only need four simple concrete pads for their foundation.
Figure 3: This 3D model of a 20' by 20' Tower was also created by Fire Tower Engineered Timber (FTET.com). With its flat roof and larger cabin size, it would be much cheaper to build per square foot than the Junior Tower shown in Figure 2. If you have access to AutoCad, you may want to open this .RVT file that contains the full 3D model.
Early Sandbox Lookout Design Principals
The four-page PDF file embedded nearby was created in January 2020 and contains early design intent drawings for small, medium, and large Sandbox Lookout Towers.
Most United States Forest Service lookout towers were constructed between 1920 and 1960, and they were tall, dramatic structures designed to put a small cabin high in the sky so a firewatcher could spot distant smoke plumes. While their visual profile looked great, by today's standards they were terrible buildings to live in. They had lots of very steep and narrow stairs, tended to rot out (even when they used smelly creosote as a preservative), were drafty and had no insulation.
Sandbox Lookout Towers will retain the iconic profile of Forest Service Lookouts, but they will be safe and comfortable. So Sandbox Lookout Towers will share these common design features:
Twelve-foot base sections. Modern building codes require stairs to have a landing every 12-feet to give people a place to rest. So all Sandbox Lookout Towers will have cross-braced base sections that are 12-feet tall--the maximum allowed between landings. By arranging things carefully, this will make it possible to use one stair design for all tower sizes.
L-shaped corner posts. Nearly all Forest Service lookouts used corner posts made from 8"-by-8" lumber, and these narrow posts provided almost no lateral resistance. To keep from swaying in the wind, virtually all Forest Service towers used guy wires anchored at 45-degree angles from the four corners. Sandbox Towers will use large L-shaped corner posts to help resist bending forces. Each corner post will be built by joining two 4-by-12-inch beams of Douglas Fir at right angles. Of course, tall Sandbox Lookout Towers will also rely on guy wires to keep them rigid.
Heavy post anchors. Corner posts will be anchored to concrete by making custom anchors from a 1/4-inch (12mm) steel plate bent into an L-shape. First, the plate will have lots of holes punched in it; then the plate will be bent to form a right angle. The lower holes will receive rebar to lock into concrete; upper holes will receive 3/4-inch bolts to secure corner posts. Together the corner posts and anchors will resist bending forces effectively.
Wide eaves and waterproof catwalks. The best way to keep wood from rotting is to keep water from getting on it in the first place. By using wide eaves and waterproof catwalks, it will take a strong wind to blow water onto the wood base.
Well preserved lumber. The posts, cross-braces and beams in a Sandbox Tower base will be made from Douglas Fir lumber. First, all pieces will be cut to size and all holes and notches will be made. Then, all pieces will be pressure treated so the preservative can soak into every penetration.
Industrial connectors. Sandbox Lookouts use 3/4-inch galvanized bolts, 3-inch bridge washers, 4-inch split-rings, TimberLok connectors and screws to fasten everything together. Not only will these connectors look impressive, they will let the Lookout to go up rapidly. Since bolts and screws can be removed, a Sandbox Lookout can easily be moved or taken apart for repairs.
Prefabricated metal stairs and railings. Unlike Forest Service lookout towers, Sandbox Lookouts will meet international building codes to create safe stairs and railings.
Top view of a L-shaped corner post in a Sandbox Lookout Tower. Each corner post is built by joining two Doug Fir beams together. Then the post is anchored to the ground with 3/4" bolts that go through steel plates (shown in red).
Corner Posts and Anchors
Our early design intent drawing expected the Sandbox corner post system to be the secret sauce that would make Sandbox Lookouts work well. We expected each corner of a Sandbox Lookout to be made by joining two 4" by 12" Douglas Fir beams in an L-shape. This works like a piece of angle iron to make the corner stiff in all directions.
Then corner posts would be attached to the ground with anchors made from 1/4" steel plates (shown in red).
Side view of a Sandbox Anchor as it's being manufactured. First the steel plate gets lots of holes punched in it, as shown here. Then the plate is bent into an L-shape.
Side view of an anchor that has been embedded in concrete but hasn't yet been attached to its corner post.
Barbara Sullivan installs 3/4" bolts with 3" bridge washers on a timber-framed entrance arch to her timberland property. The steel anchor plate is hidden in a slot in the posts. We expect this general method of attaching posts to the ground will be used by most Sandbox Lookout Towers.
Sandbox Anchors are made from 1/4-inch (12mm) steel plate that has lots of holes punched in it; then the plate is bent to form a right angle. The lower holes receive rebar to lock into concrete; upper holes receive 3/4-inch bolts to secure corner posts. Together the corner posts and anchors resist bending forces effectively.
Sandbox Anchors allow a Lookout to be built safely by holding corner posts rigid during construction. If necessary, because the bolts can be removed, they allow a Lookout to be repaired or moved.
For monolithic concrete foundations, it will be possible to thread rebar through the bottom holes in each Anchor. This will tie the building’s Anchors together in a really serious manner. Pier-based foundations will make it harder to bend and thread rebar through the holes, so it may be easier to insert bolts instead. Both methods are shown in the nearby image.
The top part of each Anchor has holes to bolt onto the Lookout Tower's corner posts. By using a lot of bolts, corner posts will be supported entirely by the anchors rather than allowing them to rest on concrete. That way a gap can be maintained between concrete and corner posts making rot less likely.