Fabric canopy of inverted cones on white columns over a city plaza

Custom Tensile Structures

Engineered membranes for sail, peak, inverted peak, and saddle forms: form finding, patterning, and fabricated panels, ready for your certified installer to tension in place.

Engineering Expertise for Custom Tensile Structures

A custom tensile structure is a building whose roof or enclosure is an architecturally engineered membrane, stretched and tensioned over a custom-designed frame or a system of masts, cables, and anchors. The fabric is an active structural element rather than a cladding, carrying load in tension the way a cable does. That is what separates a tensile structure from a canopy with fabric laid over it.

What Is a Custom Tensile Structure?

What Does Lightweight Structures Provide?

Lightweight Structures manufactures the fabric panel systems used in custom tensile structures. We take a design intent and produce the engineering and the finished membrane: form finding, patterning, panel layout, seam and edge details, keder or cable edges, and the fabricated panels themselves, ready for a certified installer to tension in place.

We manufacture fabric panels and serve as an engineering partner. We do not bid on the whole building against the people who build it.

Bring us in early. The most useful thing an architect or engineer can do is talk to a membrane manufacturer during schematic design, when the form, spans, and anchor locations can still move. That’s where a tensile structure gets cheaper, cleaner, and easier to build.

Proven Tensile Forms for Every Application

Most custom tensile work resolves into a small family of forms, and nearly every large project is an array or combination of them. The typical project sizes below are the ranges we see most often for each form.

Form	Geometry	Typical project size
Sail	A doubly curved panel tensioned between corner anchor points, usually three or four. The most economical way to put shade over an open area.	500–10,000 sq ft
Peak	A conic form pulled up at a high point over a mast or tension ring, shedding water outward to low points at the perimeter.	1,500–50,000 sq ft
Inverted peak	The conic form reversed: the membrane is drawn down to a low point, which collects and directs water at a controlled location.	1,500–50,000 sq ft
Saddle	An anticlastic surface with two high corners and two low corners. Stiff in wind because the two curvatures oppose one another.	1,000–50,000 sq ft

Sizes are a starting point for conversation, not a limit. Larger enclosures are built as arrays of these forms, and we also fabricate tensile shade panels, entry canopies, walkway covers, grandstand and stage covers, and tensioned facade panel systems for new construction and remodels.

Advantages of Tensile Architecture

Shorter Build Times

Much of the structural work is manufactured off site, so there is less interruption on site. Tensile structures go up faster than conventional buildings of the same footprint.

Less Material

A tensioned membrane covers large spans with a fraction of the material a rigid roof needs, which keeps both cost and embodied material down.

Natural Light

Translucent options across the architectural fabrics we fabricate with bring daylight into the space, reducing the lighting load underneath.

Column-Free Space

Load travels through the membrane, cables, and a few masts or anchor points, so the space underneath stays open. The double curvature also gives designers a form no conventional roof offers.

How Custom Tensile Structures Compare

Custom tensile is the fully custom, architecturally driven option: the form is designed for the site, the membrane and cables do the structural work, and nothing has to stay plugged in for the building to stand up. An air dome trades that freedom for clear span, and needs a blower running continuously. A pre-engineered frame structure sits between the two, modular and semi-custom on a rigid frame.

For a side-by-side breakdown of design, support system, power and typical use, see Comparing Structure Types.

Plan-view fill stress plot of two four-point fabric membranes under a wind load case

Engineering That Carries Into the Field

A tensile membrane performs best when the shape, fabric, and connection details are engineered as a complete system. Lightweight Structures provides in-house engineering and design support to ensure each component works together from design through installation.

Our services include:

Form finding and stress analysis
Fabric patterning and compensation for material behavior under load
Structural load and stability analysis for applicable codes and jurisdictions
Shop drawings for fabricators, steel suppliers, and installers
Professional engineer certification where required

Because we engineer and manufacture the membrane panels, the design documents and finished fabric system remain aligned throughout the project. See design and engineering services for the full scope, including the certification and disclaimer language that governs our stamped work.

Replaceable Membranes Extend Structure Life

Yes, and it is normal practice. A tensile membrane is a replaceable component of a permanent structure: when a skin reaches the end of its service life, or is damaged, the frame, masts, and foundations stay in place and only the fabric changes. We fabricate replacement membranes for structures we did not originally build, working from field measurements and the existing connection details. See structure reskins, and Renew Keder for restoring a worn keder edge instead of replacing a whole panel.

Certified Installation Partners Complete Every Project

Lightweight Structures does not install. Your project is completed by our network of certified installation partners. Tensioning a membrane is specialist work: sequence, pretension, and hardware all matter, so the structure is erected by installers who do it for a living. A specifier does not have to go looking for one. We work with installers who are already familiar with our panels, our keder details, and our engineering.

Scope is defined from the ground up. Foundations and attachment structures are specified but excluded from our scope; our engineers provide the reactions at every anchor point so your local engineer can design those elements for the same loads under the governing building code.

Fabric Sourcing

On a custom tensile structure, the membrane is the architecture, so we decide the material before the panel layout. We engineer and fabricate every membrane we quote, choosing it for the loads, span, light transmission, and finish the design calls for.

Materials We Fabricate Tensile Panels From

Product

Keder

Keder is the rope edge that connects a fabric panel to its frame. It slides into a channel in an aluminum rail, and the rails fit almost any existing frame.

Product

Fabrics

Compare PVC-coated polyester, PTFE-glass, ePTFE, fluoropolymer film, polyethylene, solution-dyed woven, and PVC mesh. Selection guidance and free samples.

Bring Us In at Schematic Design

Send us a sketch, a site plan, or a rough idea of the space you want covered. We will tell you what is buildable, what it takes to engineer it, and what the membrane options do to the result.

Schedule a Consultation