Insulating a Hangar or Shelter

Metal conducts heat readily, so uninsulated metal walls and roofs provide little resistance to heat transfer. Where a hangar or shelter requires controlled indoor conditions, a suitable insulation system helps reduce heat loss in winter and heat gain in summer.

Insulation must be considered together with heating, cooling, ventilation, airtightness, and moisture control to achieve the required indoor conditions.

What Requirements Should Hangar Insulation Meet?

The building’s shape, construction materials, and operating conditions influence the choice of insulation. The main considerations include:

• Compatibility with thermal movement: Metal expands and contracts as temperatures change. The insulation system and its connections must accommodate the expected movement without cracking, separating, or losing performance.
• Reliable adhesion or mechanical support: Spray-applied insulation must bond effectively to the prepared substrate. Other insulation systems require suitable fixings or supporting components. The correct method depends on the insulation material and the building design.
• Thermal performance: Thin metal cladding provides very little thermal resistance. Insulation type, thickness, continuity, and detailing must therefore be selected to achieve the required performance, including at structural members and other thermal bridges.
• Low weight: The additional weight of insulation, internal linings, and supporting components must remain within the structure’s design capacity. This applies to both framed and frameless hangars, including arched structures in which the walls and roof form a continuous shell.

A properly specified spray polyurethane foam insulation system can address these requirements where it is compatible with the substrate, structural movement, and intended use.

Spray Polyurethane Foam Insulation

Spray polyurethane foam, commonly abbreviated as SPF, is applied using specialist equipment that meters and mixes its components at the spray gun.

The components react with each other, causing the material to expand and form an insulating foam layer. Expansion depends on the formulation and application conditions; it should not be described as a universal increase of 80–100 times.

Spray application allows the insulation to follow curved or irregular surfaces and form a continuous layer around suitable details. Larger gaps, joints, and movement connections may require separate preparation or detailing.

Adhesion and Surface Preparation

Spray polyurethane foam can adhere to many substrates, including suitable metal surfaces. However, adhesion is not guaranteed on every material or existing coating.

Before application, the surface must be assessed and prepared according to the foam manufacturer’s instructions. It should be sound, clean, dry, and free from contaminants that could interfere with adhesion.

Preparation may include removing dust, grease, oil, loose rust, and poorly bonded coatings. Some metal surfaces require additional treatment or a compatible primer. Removing dust alone is not always sufficient.

Comparing Insulation Options

The cost of insulating a hangar or warehouse with spray polyurethane foam depends on the surface area, required thickness, substrate condition, access, and complexity of the structure. Surface preparation and any specified protective layers also affect the price.

Alternative materials include mineral wool and rigid foam boards. Bituminous products may form part of a waterproofing system, but they should not be treated as a direct substitute for a properly designed thermal insulation layer.

The choice should be based on the performance of the complete system rather than initial cost alone. Relevant factors include thermal resistance, fire performance, moisture behaviour, durability, installation quality, and maintenance requirements.

Mineral wool and rigid foam insulation remain established options. They should not be dismissed as obsolete merely because spray polyurethane foam is available.

Mineral Wool and Moisture

Moisture can reduce the thermal performance of insulation, but its effect depends on the material, the amount of water present, and the construction arrangement.

Mineral wool should be installed as part of a system that manages rainwater, condensation, and water vapour. The necessary membranes, drainage, ventilation, and internal layers must be selected for the particular building.

A universal claim that wet mineral wool loses up to 90% of its insulating performance should not be used without evidence for the specific product and conditions.