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The Art of Reciprocal Roofs
Tiny Insights for building naturally, building beautifully.
No.077 — Read old posts on Tinyfarmlab.com
Reading Time 3 minutes
A reciprocal roof is more than just a structure.
It’s a mesmerizing interlocking system of rafters,
that eliminates the need for a central support.
This technique has been used for centuries,
with roots in traditional Asian wooden temples,
medieval European timber framing,
and in indigenous roundhouses.
Leonardo da Vinci even sketched reciprocal structures.
Today, they are being revived in natural building practices.
Perfect for roundwood construction,
this design blends strength with visual elegance.
They can also be used on amoeba-shaped buildings.
Here’s how you can build one step by step:
Understanding the Reciframe
A self-supporting arrangement of rafters.
Ideal for roundhouse and natural buildings.
Visually striking & structurally efficient.
Preparation & Simulation
Lay rafters flat on the ground in a spiral to visualize.
Mock-up on a 2 ft high low wall to check positioning.
Measure rafter height (RH) from the top of the wall to the center hole.
Marking the Rafters
‘X’ mark: 600mm from the top for safety margin.
Calculate overlap distance (Rummy):
Formula: R = (Diameter × π) ÷ No. of rafters
Example: 1m-wide hole, 12 rafters → R = 262mm.
Mark R distance (600 + 262mm) on each rafter.
Photo credits: A Simple Roundhouse Manual by Tony Wrench
Cutting Grooves
Draw a 200mm angled line (angle = 360° ÷ number of rafters).
Cut a shallow groove with an axe/adze.
Ensure upward tilt for stability.
Building the Tripod & Charlie
Tripod
Use three long poles (rejected rafters).
Tie 1 foot from the thin ends.
Add 500mm-spaced climbing steps.
Align so the top falls over the skylight center.
2. Charlie
Hinged V structure holds the first rafter.
Height = Wall height + RH(measured during mockup) + 300mm.
500mm offset from center. Since we want to have a 1m hole.
Lash Charlie to the tripod for stability.
Erecting the Reciprocal Frame: Step-by-Step Guide
Safety First!
Hard hats mandatory.
10m safety distance for spectators.
Only one person speaks at a time.
Team Roles
Fixer: Works at heights, hammers nails, ties knots.
Rafter Bearers (4-5 people): Lift and hold rafters.
Adjuster: Guides rafters into place.
Tyer: Secures rafters.
Director (You!): Ensures smooth coordination.
Assembly Steps
First rafter placement: Guide it to position & secure to Charlie.
Subsequent rafters: Move clockwise, avoiding danger zones.
Final fixing: Ratchet straps prevent unspiraling.
Remove Charlie:
Wear hard hats.
Cut cords & knock legs outward.
Lash first & last rafters together.
Celebrate!
Extra Rafters for Large Roundhouses
Option 1: Secondary rafters resting on main ones near to the hole.
Option 2: Shorter secondary rafters resting on the middle of primary rafters.
Reciprocal roofs create functional art.
Thinking of building one?
Let’s discuss your project!
Love,
Raghav and Ansh
PS: Check out our latest post on LinkedIn where we share about why India doesn’t need to become sustainable!
What you can watch -
What you can listen to -
What You Can Read - A Simple Roundhouse Manual
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