Rapid-Build 4-post Structure


This module includes the parts list, design specification, and build description for a rapid build Hello Hub structure, using (readily available) 4-post server racks(link is external) as the primary structural component.

Many of these racks have high strength specifications, offer modular mounting options, and can be shipped flat-packed (will be great for multiple-hub builds). They are generally a slightly smaller footprint than our current spec (3' x 2' instead of 3' x 3'), but this should be ok as we have been working hard to reduce the power consumption of the system and the result is that we have a reduced number of PV panels to hold up.

Additional specs on this 4-post rack: http://goo.gl/bXlzmR(link is external)

Parts list:


Name Quantity Item
Rack 1 Heavy Duty 4-post standard server rack
Beam 2 1.5” x 4” x 9' Steel Square tube, with 1/8” wall thickness
Purlin 5 1.5 x 3” x 6' Steel Square tube, with 1/8” wall thickness
Panel 3 6' x 3' Metal Roof panels (ribbed or corrugated, high gauge preferred)
Bracket 10 Angle bracket
Fastener 5lb Self-tapping metal screw 3/4” #12
Fastener 5lb Self-tapping metal screw 1 1/2” #12
Rock 100LB Clean 1” Gravel
Concrete 1.5 QY 1.5 QY of Concrete Mix
Rebar 100LF 3/8th rebar, 24" grid reinforcement.
Bolt 4 Concrete 1/2" bolt or similar, to secure rack to slab.
Water as needed Water for concrete mixing
Paint 1 gallon Exterior waterproofing paint for rack and bare metal.
Braces 4 10' wood 2x4, or bambo or similar. For temporary bracing while concrete sets.
Screws 1 1lb wood screws
Strapping 1 roll of metal strapping, to secure braces to metal posts

Tools Required:

  • Cordless drill or impact driver 18v+ with drill and driver bits
  • Hand Level
  • Wheelbarrow
  • Drill bits
  • Shovels & Tamper
  • Buckets
  • Paintbrushes
  • Concrete floating tool (diy ok)
  • Forming material (scrap wood 4" wide) and stakes.

Build Instructions:

  • Slab Foundation. Prepare Foundation by exavating 4 inches of soil. Fill with gravel to grade and tamp down with tampers. Add forms, rebar grid, and position j-bolts in proper positions to secure rack. Mix and pour concrete into formed area. Float as needed. Let concrete cure, make sure to keep damp if very hot.
  • Install rack via securing to set j-bolts.
  • Roof pieces is attached to set frame with brackets and self-tapping screws.
  • Roof panels are attached to roof pieces with self-tapping screws.
  • Equipment panels will be attached to frame as needed with self-tapping screws.

Here's a render of the completed Hello Hub, using the 4-post rapid build structure.