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Saddle roof picnic shelter

A three-post shelter concept with a curved waterproof membrane roof and eight Blender views.

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Download AllZIP · All individual files for this configurationFreeCAD geometryFCSTD · Directly editable solid geometry with stored reference dimensions. Reference dimensions do not automatically rebuild the model.STEP geometrySTEP · The same 96 modeled solids in millimeters, for compatible CAD applications.Roof envelopesSTEP · Three modeled roof envelopes. No fabrication patterns or compensated fabric dimensions are included.Blender sceneBLEND · Editable meshes and simple materials for viewing and rendering the proposed shelter.Modeled componentsCSV · Inventory of 96 modeled solids. These are not purchasing or fabrication quantities.Envelope coordinatesCSV · Seven nominal control points in millimeters and reference heights in feet. For further design only.Envelope edge lengthsCSV · Twelve assembly edges along nine unique runs. Chord lengths exclude seams, reinforcement, hardware and compensation.Design filesZIP · CAD files, drawings and schedules. Read the instructions on the website.
View Instructions
  • Revision: 3
  • Last updated:
  • Steps: 6
  • Difficulty: advanced
  • License: Owner-confirmed permission to publish; no attribution required
Before you start
  • This is a design concept. Do not order, cut, erect or tension the shelter from these files.
  • Have the membrane, frame, connections and foundations designed for the site's wind, rain and snow loads. Their capacities have not been established.
  • Obtain an accepted fabric specification, biaxial properties, installed tension, compensated cutting patterns, qualified seams, clamps and weather seals before fabrication.
  • Check headroom below the beams, which extend below the 7 ft 6 in low membrane reference. The reference fabric is 0.78 mm thick; the 1 mm CAD envelope is for display.
  • Use the roof area and inventory for geometry review only. Purchasing and cutting schedules require the completed design.
Plan details

Waterproof membrane design concept

A proposed permanent membrane roof using Tenseo Advanced 1002 S2 as the fabric reference. Intended for U.S. areas without heavy snow. No wind, snow or foundation rating has been established.

Explore a triangular shelter with three saddle-shaped fabric assemblies meeting at a raised crown. The gallery, dimensioned envelope drawing, CAD and illustrated guide explain the proposed form and support arrangement. This is a design concept; structural design, fabrication and construction instructions are not complete.

FreeCAD contains stored solid geometry that can be edited directly. Its control points and display dimensions are reference metadata, not a parametric sizing system.

Rebuild and coordinate adjoining geometry, drawings and schedules after a dimensional change. STEP preserves geometry for exchange; the Blender file provides meshes for rendering.

Dimensions and opening sizes
Outer beam triangle, each sideThe roof ends at this equilateral triangle; no eave extension is included.
40 ft
Post spacingThree post centers form an equilateral triangle.
20 ft
Lowest roof heightAbove grade. Beams extend below this level, reducing headroom.
7 ft 6 in
Roof height at outer cornersAbove grade.
11 ft 6 in
Roof height at centerAbove grade.
17 ft 6 in
Curved roof areaExcludes seams, hems, reinforcement, overlaps, fitting allowances and waste. Do not use this as an order quantity.
72.606 m²
Shopping list

Real shopping and cutting quantities depend on the engineered membrane, connection system, frame and foundations. The provided inventories contain modeled geometry only.

Tools & equipment
  • FreeCAD or a compatible STEP viewer for geometry inspection
  • Blender for scene editing and rendering

BEFORE YOU BUILD

Use this work at your own risk

These files have not been checked for accuracy, safety, structural adequacy, or building-code compliance. They may contain serious errors and are not construction-ready. Obtain independent qualified design and review before building.

No person or organization makes any guarantee or warranty, express or implied, regarding this design, its documentation, digital files, or website views. They are not professional services and do not create an architect-client or other professional-client relationship. No promise is made about accuracy, completeness, reliability, code compliance, or fitness for your project.

Buildings and building projects are complex, and many things can go wrong. You are responsible for checking dimensions and site conditions, choosing suitable materials and methods, obtaining permits, following codes and manufacturer instructions, and getting qualified professional help when needed. To the fullest extent permitted by law, DIYPlans.org disclaims liability for damages resulting from use of this work. Read the FAQ about your responsibilities.

Instructions

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Step 1 Read the triangular layout

  • Use the dimensioned plan to locate the three posts and seven envelope nodes. The outer triangle has 40 ft sides and the post triangle has 20 ft sides. Use them to review the concept layout.

Check: Identify the three low attachment nodes and distinguish the outer triangle from post spacing.

Step 2 Compare the roof views

  • Compare the overall, reverse and elevation views. Three saddle-shaped membrane assemblies meet at the central crown. The low roof reference is 7 ft 6 in, outer corners are 11 ft 6 in and the crown is 17 ft 6 in above level grade.

Check: Locate the crown, three raised outer corners and three low attachment points in the views.

Step 3 Inspect the exposed frame

  • Locate the beams below the fabric and the three foundations in the underside views. Have these supports designed for the membrane loads.

Check: Distinguish the reference frame and footing geometry from an engineered support specification.

Step 4 Review the proposed attachments

  • Locate the proposed continuous edge clamps and post-to-beam connections in the connection view.
  • Treat the bands as attachment zones. Rail dimensions, crown closures, reinforcement, fasteners and watertight joints still need design.

Check: The attachment zones and missing connection details are identified.

Step 5 Use the matching design files

  • Open the native CAD for direct geometry inspection, STEP for exchange and Blender for rendering. Do not rely on changing stored control points or display thickness to regenerate the solids. Read the seven-page guide and geometric inventories together.

Check: Confirm the files are for this three-assembly membrane concept and that inventory rows are not purchase or cutting instructions.

Step 6 Arrange the remaining design work

  • Obtain accepted fabric data and numerical site loads.
  • Coordinate membrane form-finding, frame and foundation design, fabric patterns, drainage and installation details with the fabricator and structural designer.
  • Prepare purchasing and cutting schedules only after that coordinated design is complete.

Check: The membrane fabricator and structural design work needed before construction are identified.

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