Insulation for shops, garages, and steel buildings, where temperature swings and condensation are common concerns. The right approach depends on the structure and how you use it.
Steel-framed buildings behave differently from wood-framed construction. Metal is an excellent conductor, so a steel purlin or girt that is exposed on one side and conditioned on the other acts as a thermal bridge — heat moves along the steel rather than stopping at the insulation. The result is often uneven temperatures and condensation on interior surfaces, especially where the metal is coldest.
Condensation is usually the concern people ask about first. Warm, moist air meeting a cold metal surface can result in water forming on the underside of roof panels and on framing. Left unmanaged, that moisture can drip onto stored equipment and contents. Spray foam helps because it expands to conform to the building, covering the framing itself rather than sitting between members — but no insulation product eliminates moisture. Condensation is managed through the combination of insulation, air sealing, and how the building is ventilated.
Air sealing is the other half of the job. In a typical metal building, air moves around purlins, girts, fasteners, seams, and the base of the walls. Spray foam is often chosen for this reason: it expands into those junctions and reduces the pathways where air — and the moisture it carries — can move through the envelope.
There is no single correct answer for every metal building. The most common starting point is closed-cell spray foam, because its density and lower vapor permeance suit steel assemblies and condensation-prone surfaces. In other cases, open-cell foam or a combination of materials is appropriate. Factors that shape the recommendation include:
Tell us about the structure and how you use it, and we will walk through the options for the roof, walls, and air sealing.
Insulating a living space in a steel building? See barndominium insulation or check our service area.