# Saddle roof picnic shelter: Waterproof membrane design concept [View illustrated instructions](https://diyplans.org/plans/saddle-roof-picnic-shelter/variants/waterproof-membrane) [Plan and other configurations](https://diyplans.org/plans/saddle-roof-picnic-shelter.md) 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. ## License [CC BY-NC-SA 4.0 International](https://creativecommons.org/licenses/by-nc-sa/4.0/). You may share and adapt this free design for noncommercial purposes with appropriate credit, a link to the license, an indication of changes, and the same license on adaptations. See [the FAQ](https://diyplans.org/faq#license) for details and exceptions. Revision: 3 Status: published Difficulty: advanced ## Before you start - This is a design concept for viewing and further development, not a construction plan. Do not use these files to order, cut, erect or tension the shelter. - The roof geometry and reference timber frame are modeled, but their load capacity, connections and foundations have not been established. Areas without heavy snow can still require wind, rain and snow design. - An accepted membrane/fabricator specification, biaxial properties, installed tension, compensated cutting patterns, qualified seams, clamps and weather seals are required before fabrication. - Supporting beams extend below the 7 ft 6 in low membrane reference, reducing clear headroom. The CAD envelope is 1 mm thick for display; the reference product sheet states 0.78 mm. - The roof area and component inventory are geometric quantities. Actual shopping and cutting lists are unavailable. ## Dimensions - Outer beam triangle, each side: 40 ft. The roof ends at this equilateral triangle; no eave extension is included. - Post spacing: 20 ft. Three post centers form an equilateral triangle. - Lowest roof height: 7 ft 6 in. Above grade. Beams extend below this level, reducing headroom. - Roof height at outer corners: 11 ft 6 in. Above grade. - Roof height at center: 17 ft 6 in. Above grade. - Curved roof area: 72.606 m². Excludes seams, hems, reinforcement, overlaps, fitting allowances and waste. Do not use this as an order quantity. ## Shopping list Real shopping and cutting quantities depend on the engineered membrane, connection system, frame and foundations. The provided inventories contain modeled geometry only. ## Materials in the model 96 stored CAD solids for geometric review. Includes 12 footing regions representing three foundations, and connector/spacer solids. No component capacity or procurement schedule is established. - Architectural fabric assembly envelopes: 3 installed pieces - Schematic backing zones for 12 membrane edges: 12 installed pieces - Schematic upper clamp zones for 12 membrane edges: 12 installed pieces - Weather closure envelopes: six crown-joint wings and three central sectors: 9 installed pieces - Reference round timber posts: 3 installed pieces - Reference crown beam members, forming three paired runs: 6 installed pieces - Reference single perimeter beam members: 6 installed pieces - Reference connectors and spacers: 33 installed pieces - Reference footing regions, four at each of three posts: 12 installed pieces Not quantified: - Final procurement specification and quantity, compensated cloth area and factory seam layout. - Edge reinforcement, hems, abrasion protection, designed clamp rails, backing interfaces and fasteners. - Crown weather seals, central junction details and controlled water discharge. - Engineered support members, connectors and foundations after membrane reactions are established. - Temporary works, lifting access, tensioning equipment and installation consumables. ## Tools and equipment - FreeCAD or a compatible STEP viewer for geometry inspection - Blender for scene editing and rendering ## Instructions ### 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. These are nominal model dimensions. Check: Identify the three low attachment nodes and distinguish the outer triangle from post spacing. ![Dimensioned envelope plan and elevation with seven labeled control points, post locations and roof heights.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-dimensions/dimensions.png?brand=1) Envelope plan and elevation with node labels, 40 ft outer triangle, 20 ft post spacing and reference roof heights. These are development dimensions. ![Top view of a triangular membrane roof divided into three panels around a central crown.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-roof-plan/roof-plan.webp?brand=1) Top view of the three roof sections. Use the dimensioned drawing for measurements. ### 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. ![Three-post timber picnic shelter with three smooth white saddle-shaped roof sections meeting at a raised central crown.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-overall/overall.webp?brand=1) Three posts support the roof, leaving the center open. ![Reverse view of a white three-panel membrane canopy on three timber posts.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-reverse/reverse.webp?brand=1) The three fabric roof sections meet at the raised center. ![Front elevation of the membrane shelter, with a tall center crown, two raised corners, three timber posts, and exposed footings.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-front-elevation/front-elevation.webp?brand=1) Front view with the central peak, raised outer corners and buried footings exposed. ![Side elevation of the shelter showing curved membrane panels above the timber frame and exposed footings.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-side-elevation/side-elevation.webp?brand=1) Side view of the roof and timber supports. Footings are shown below ground level. ### 3. Inspect the exposed frame - Use the underside and frame views to see the beams below the fabric and the three foundations. The drawing exposes buried footing regions for explanation. These inherited supports require structural design for membrane loads. Check: Distinguish the reference frame and footing geometry from an engineered support specification. ![Low view beneath the white canopy showing the three timber posts, sloping crown beams, and perimeter beams.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-underside/underside.webp?brand=1) Timber beams extend below the fabric, reducing clear headroom. ![Three timber posts with sloping beams, roof attachment strips and exposed concrete footings.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-frame/frame.webp?brand=1) Fabric and ground hidden to show the frame and footings. These supports still require structural design. ### 4. Understand the proposed attachment - The connection view shows the intended location of continuous edge clamps and post/beam connections. The bands are schematic zones, not dimensioned rails or tested joints. Crown closures, reinforcement, fasteners and watertight details remain undeveloped. Check: Recognize which illustrated attachments are placeholders for further design. ![Close-up of a timber post cap and sloping beam connection beneath the membrane edge.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-connection-detail/connection-detail.webp?brand=1) Proposed post, beam and roof-edge connection. Fasteners, load capacity and weather seals must be designed before fabrication. ### 5. Use the matching design files - Open the native CAD for direct geometry inspection, STEP for exchange and Blender for rendering. Stored control points and display thickness do not parametrically 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. ![Dimensioned envelope plan and elevation with seven labeled control points, post locations and roof heights.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-dimensions/dimensions.png?brand=1) Envelope plan and elevation with node labels, 40 ft outer triangle, 20 ft post spacing and reference roof heights. These are development dimensions. ### 6. Plan the engineering needed to build - Before construction, obtain accepted fabric data and a numeric site/load envelope, then coordinate membrane form-finding, frame and foundation design, fabric patterns, drainage and installation details. Only the completed coordinated design can supply actual shopping and cutting schedules. Check: Do not begin fabrication or construction from this concept package; identify the required membrane fabricator and structural design work. ![Three timber posts with sloping beams, roof attachment strips and exposed concrete footings.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-frame/frame.webp?brand=1) Fabric and ground hidden to show the frame and footings. These supports still require structural design. ![Close-up of a timber post cap and sloping beam connection beneath the membrane edge.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-connection-detail/connection-detail.webp?brand=1) Proposed post, beam and roof-edge connection. Fasteners, load capacity and weather seals must be designed before fabrication. ## Drawings and views ![Three-post timber picnic shelter with three smooth white saddle-shaped roof sections meeting at a raised central crown.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-overall/overall.webp?brand=1) Three posts support the roof, leaving the center open. ![The saddle-roof picnic shelter in a grassy outdoor gathering space.](https://diyplans.org/media/packages/e7b483021e26b088e4bbbae3a1f436eb88cfdcdd4dca231250c6c9f2ede68678/cad-lifestyle/lifestyle.png?brand=1) The saddle-roof picnic shelter in a grassy outdoor gathering space. AI Generated from CAD files for inspiration ![Reverse view of a white three-panel membrane canopy on three timber posts.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-reverse/reverse.webp?brand=1) The three fabric roof sections meet at the raised center. ![Front elevation of the membrane shelter, with a tall center crown, two raised corners, three timber posts, and exposed footings.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-front-elevation/front-elevation.webp?brand=1) Front view with the central peak, raised outer corners and buried footings exposed. ![Side elevation of the shelter showing curved membrane panels above the timber frame and exposed footings.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-side-elevation/side-elevation.webp?brand=1) Side view of the roof and timber supports. Footings are shown below ground level. ![Top view of a triangular membrane roof divided into three panels around a central crown.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-roof-plan/roof-plan.webp?brand=1) Top view of the three roof sections. Use the dimensioned drawing for measurements. ![Low view beneath the white canopy showing the three timber posts, sloping crown beams, and perimeter beams.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-underside/underside.webp?brand=1) Timber beams extend below the fabric, reducing clear headroom. ![Three timber posts with sloping beams, roof attachment strips and exposed concrete footings.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-frame/frame.webp?brand=1) Fabric and ground hidden to show the frame and footings. These supports still require structural design. ![Close-up of a timber post cap and sloping beam connection beneath the membrane edge.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-connection-detail/connection-detail.webp?brand=1) Proposed post, beam and roof-edge connection. Fasteners, load capacity and weather seals must be designed before fabrication. ![Dimensioned envelope plan and elevation with seven labeled control points, post locations and roof heights.](https://diyplans.org/media/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/image-dimensions/dimensions.png?brand=1) Envelope plan and elevation with node labels, 40 ft outer triangle, 20 ft post spacing and reference roof heights. These are development dimensions. ## Downloads - [FreeCAD geometry](https://diyplans.org/downloads/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/download-native-cad/saddle-roof-picnic-shelter-waterproof-membrane-r3-model.FCStd): FCStd, 130102 bytes, file revision 3. Directly editable solid geometry with stored reference dimensions. Reference dimensions do not automatically rebuild the model. SHA-256: 2eb5a1860babdd5490c26873b42a5b68d4da5c6f3438dd227801f378c5537981 - [STEP geometry](https://diyplans.org/downloads/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/download-step-cad/saddle-roof-picnic-shelter-waterproof-membrane-r3-model.step): STEP, 667825 bytes, file revision 3. The same 96 modeled solids in millimeters, for compatible CAD applications. SHA-256: f2052a775a83485ceb39398f5f2cfb2c67319f66840fe5e74a908d372ecbe7ef - [Roof envelopes](https://diyplans.org/downloads/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/download-membrane-cad/saddle-roof-picnic-shelter-waterproof-membrane-r3-model-2.step): STEP, 24486 bytes, file revision 3. Three modeled roof envelopes. No fabrication patterns or compensated fabric dimensions are included. SHA-256: 5d2a4f290487a9b1065fb269ccb226ee3b335af503335697b8fd0082aa40a3ae - [Blender scene](https://diyplans.org/downloads/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/download-blender-scene/saddle-roof-picnic-shelter-waterproof-membrane-r3-scene.blend): BLEND, 4013492 bytes, file revision 3. Editable meshes and simple materials for viewing and rendering the proposed shelter. SHA-256: fd7a6fb9cb9f82d63ed9c1d6bb637ab9aee14fbb0f15d758dca3832595956556 - [Modeled components](https://diyplans.org/downloads/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/download-model-components/saddle-roof-picnic-shelter-waterproof-membrane-r3-schedule.csv): CSV, 8045 bytes, file revision 3. Inventory of 96 modeled solids. These are not purchasing or fabrication quantities. SHA-256: f4f258e64f10688dfdb69505ed20bc2917396c1bf0c718a542f9a3e01752245e - [Envelope coordinates](https://diyplans.org/downloads/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/download-envelope-coordinates/saddle-roof-picnic-shelter-waterproof-membrane-r3-schedule-2.csv): CSV, 898 bytes, file revision 3. Seven nominal control points in millimeters and reference heights in feet. For further design only. SHA-256: 4a28f8191d41fb9a7302205f69243542f7a59cfb4d499a47555a93eeee324cff - [Envelope edge lengths](https://diyplans.org/downloads/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/download-envelope-edges/saddle-roof-picnic-shelter-waterproof-membrane-r3-schedule-3.csv): CSV, 1532 bytes, file revision 3. Twelve assembly edges along nine unique runs. Chord lengths exclude seams, reinforcement, hardware and compensation. SHA-256: acbd4bb37ed9c6ae9c51058f150ff609cf7c9c0ae59b1196107658046cf7958d - [Design files](https://diyplans.org/downloads/packages/54bc1bd8b9eedd13dfa4aeb279fc97e6869e7289f36ec25d5f8936efe786c796/migrated-pdf-free-archive/saddle-roof-picnic-shelter-waterproof-membrane-r4-package.zip): ZIP, 1698611 bytes, file revision 4. CAD files, drawings and schedules. Read the instructions on the website. SHA-256: 2cb8891d5996e93cb425b87393364215ef6bf1942b87a5683ecd943979194800 ## Using the CAD files - 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.