Insulation code requirements are constantly changing, with new updates coming every couple of years from organizations like the International Code Council (ICC).
Staying up to code ensures that your building is not only compliant with local ordinances, but also energy efficient. In the long run, meeting or exceeding energy code requirements can add up to significant savings for the building owner.
Building codes, like the International Energy Conservation Code (IECC), use thermal resistance values (R-value) to communicate insulation performance requirements. Since R-values are cumulative, a higher R value per inch of rigid insulation will allow you to get the best performance with a thinner profile.
Let&#;s lay out your options to achieve the best rigid insulation R value per inch.
Rigid insulation is insulation that comes in the form of standalone rectangular boards. The raw materials can be foam-based or even made from mineral wool. Rigid insulation boards come in various thicknesses, ranging from ¼&#; up to 6&#; thick. Examples of rigid insulation include:
EPS: Expanded Polystyrene
Langfang Clear Chemical Product Page
XPS: Extruded Polystyrene
Polyisocyanurate: Polyiso
Mineral Wool Board
All of these rigid insulation types are available in 4-by-8-foot boards and similar sizes. And they&#;re all installed by butting the edges up to each other, resulting in continuous insulation over building surfaces like walls, slabs, and roofs.
Rigid insulation is different from other common building materials like fiberglass, cellulose, foam spray, and mineral wool batts. These other materials are less dense, more flexible, installed differently, and have different insulating properties. Many of these other types of insulation cannot be installed continuously (except spray foam if installed properly) and most of them require special equipment and expert installation.
Let&#;s compare the R value of rigid insulation to these other types of insulation in the table below. You&#;ll notice that we call out the R-value per inch. This is because rigid insulation allows stacking of boards to achieve a desired R-value.
For more information, please visit Rigid Roof Insulation.