How Is a Membrane Structure Building Insulated? Multi-Layer Construction, Materials and Verification for Overseas Buyers

A single layer of membrane fabric has almost no thermal resistance or heat storage capacity. Without dedicated insulation, an air-supported membrane building loses heat quickly in winter and overheats in summer. To make such a building genuinely usable year-round, insulation must be designed as an integrated assembly: the outer membrane, an inner liner, and a continuous insulation layer between them.

How the Insulated Multi-Layer Construction Works

Insulation in a tensile membrane structure does not come from making the membrane thicker. It comes from a multi-layer construction that intercepts air and heat transfer in stages:

• Outer membrane: the structural layer that resists wind and snow loads and maintains the building's shape under internal air pressure.
• Insulation layer: a continuous blanket suspended or fixed between the two membranes. It can be attached at steel cable nodes or prefabricated as finished multi-layer membrane units and assembled on site.
• Inner liner: separates the occupied space from the insulation, protects it from contact damage and moisture from inside.

Together, the roof and walls form a continuous insulated shell. Thermal bridges are reduced to a limited number of locations — foundation connections, door openings, air inlet points — and are handled with detailing at those interfaces. In short: the outer membrane keeps out weather, the insulation layer resists the temperature difference, and the inner liner protects against contact and interior moisture. All three are needed.

Common Insulation Material Options

The choice of insulation material depends on the project. No single option suits every case:

• Glass fibre wool with aluminium-foil-faced glass-fibre cloth on both sides: strong fire performance (non-combustible or flame-retardant ratings are readily achievable), often preferred for sports halls, schools and large public membrane buildings. The foil face reflects radiant heat and provides some vapour resistance. The wool itself loses insulating value when wet, so moisture protection during fabrication, transport and operation is essential.
• XPE (cross-linked polyethylene foam) with foil on both sides: lightweight, non-absorbent, closed-cell structure with good moisture performance. Suited to smaller membrane buildings or weight-sensitive structures. Mid-range thermal performance and relatively moderate cost.
• EPDM/rubber-plastic insulation foam with foil on both sides: flexible, easy to wrap and overlap at irregular nodes, with good resistance to moisture and condensation. Flame-retardant grade can be selected per project requirements.
• Aerogel blanket: thin and highly efficient, used where insulation thickness is constrained but high thermal resistance is required — for example, some laboratory or retrofit projects. Considerably more expensive; only cost-effective when low thickness and high performance are genuinely required.

Material selection should reflect the building's climate zone, interior use (continuous occupancy, temperature and humidity requirements), applicable fire approval conditions and budget. These should be calculated and agreed per project, not assumed from a generic list.

Insulation Must Be Designed Together with Condensation Control

Insulation and condensation control cannot be discussed separately, especially in high-humidity applications such as swimming halls, water parks or heated winter training facilities. The principle is simple: warm humid indoor air condenses on any surface below the dew point. If the insulation layer has gaps, loose laps, or exposed metal fasteners on the indoor side, those spots will collect condensate first — eventually wetting the insulation, causing liner mould and cable corrosion.

Three measures are normally addressed together:

1. Insulation continuity: at membrane panel seams and at interfaces with cables and foundations, reliable laps and sealing must prevent indoor humid air from reaching cold surfaces.
2. Vapour control placement: a foil face or other vapour barrier is positioned on the warm (indoor) side of the insulation to block vapour ingress, while the outer side must still allow outward vapour diffusion — the assembly should not be sealed on both sides.
3. Condensate drainage paths: if small amounts of condensate do form, they should run along the membrane slope or gutters to low points and be piped away, not accumulate at membrane surfaces or nodes.

In high-humidity projects these are not optional extras. They should be specified at the design stage; retrofitting later is difficult and costly.

How Climate Zone Shapes the Insulation Scheme

The same building design may need completely different insulation depending on location and interior use:

• Severe cold and cold regions: large indoor–outdoor temperature differences in winter require high thermal resistance. Materials balancing fire and moisture performance — such as foil-faced glass fibre wool — are common, with thermal bridging at doors, windows and air inlets treated as priorities.
• Hot-summer/cold-winter and hot-summer/warm-winter regions: heat flow is often outward-to-inward or reversed. Beyond insulation, solar heat gain and condensation matter; moisture-resistant materials such as XPE or rubber-plastic foam are frequently used, combined with ventilation and dehumidification strategies.
• High-humidity regions: condensation control and condensate drainage can be a higher priority than insulation thickness. Dew point position should be checked so any condensate forms where it can be drained away, not trapped inside the insulation.

Building use also matters: a warehouse and a sports training hall have different temperature and humidity requirements, and a swimming hall is a special case. For procurement purposes, this means your enquiry should state the project location, intended use, approximate dimensions and any drawings you have, so the insulation build-up can be proposed against actual conditions rather than a generic template.

How Insulation Performance Is Verified

Insulation performance of a finished multi-layer membrane unit can be measured rather than estimated. Common laboratory methods include the heat flow meter method and the hot box method: a sample unit is placed in the test apparatus, the heat passing through it is measured, and a thermal transmittance (U-value) is obtained. This figure appears in the material test report.

For an actual project, if you have concerns about insulation performance, you can require testing in the contract, or verify test reports before materials are delivered. One point to check carefully: whether the test conditions correspond to your project's actual temperature and humidity conditions — the same material performs differently in different environments, so report values should be aligned with the design conditions.

When finalising a scope, we recommend that the insulation construction, material specifications, testing standard and acceptance criteria are all written down together, so that expectations are clear on all sides.

What Overseas Buyers Should Clarify When Requesting a Quote

Before sending an RFQ (Request for Quotation) for design coordination, custom fabrication or component supply, it helps to define the supply scope explicitly. As a checklist, confirm with your project engineer and with the supplier:

• Project location, climate conditions and intended use
• Approximate dimensions, span, height and any available drawings
• Required insulation material, thickness and target thermal performance
• Fire, moisture and vapour-control requirements applicable to your project
• Which services you are commissioning: membrane fabrication only, or including steel components — and whether installation is handled by your local team
• Drawing inputs, revision approval process and interfaces with your foundation, doors and mechanical systems
• Material documentation, packing lists and handover information your local installer will need
• Any testing or acceptance criteria you want written into the contract

Note that responsibility for structural design sign-off and compliance with local building regulations should be agreed between you and your project engineer, and the supplier's design and supply boundaries should be confirmed in the contract.

If you are considering an air-supported or tensile membrane structure project, send us the intended use, approximate dimensions and any site photos or drawings, together with a clear statement of which services you wish to commission — membrane fabrication only, or fabrication with steel components. We will analyse the project against those conditions rather than applying a generic checklist.

Contact us to discuss your project's insulation construction, custom fabrication and supply scope.