The foam backer actually serves two purposes: Strength & Insulation
Strength & Insulation
A modern formed metal roofing system with foam backer will keep your attic at ambient temperature. The foam backer insulates the roof making it the most energy efficient roof money can buy! The highly reflective coatings of today’s formed metal roofs will reflect about 90% of the sun’s radiant heat. Our foam backer prevents any surface temperature from passing through to the attic, thereby allowing your attic to remain at ambient temperature. Most home owners see a 25-30% reduction in their energy bills.
One of the biggest concerns of a metal roof is walkability. The plumber, the painter, the lawn guy blowing leaves off the roof can all damage a formed metal roof without a foam backer.
The polystyrene foam backer is made mostly of air, which it is a poor conductor of heat, but an excellent convector. It traps the air in small pockets, blocking the flow of heat energy.
It’s not about R-value. It’s about stopping the transfer of conductive heat.
It’s the same concept as a coffee cup. You only need a very thin polystyrene cup to be able to hold a boiling hot coffee in your hand without it being too hot to touch. But if you had the same temp coffee in a same thickness tin cup you wouldn’t be able to hold it.
Not all metal roofs have a foam backer option.
With the foam backer installed the roofing system becomes so strong you can drive a truck over it. This is because the foam backer completely fills the cavity.
The key to a truly permanent roofing system is the quality of the installation. A poorly installed roof will not hold up to the the elements and will require replacement far sooner than a properly installed roof by an experience crew that follows best practices and the manufactures guidelines.