Knee Wall Insulation R Value

These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.

Knee wall insulation r value.

At an r6 per inch it provides an air barrier and outstanding thermal break. As part of my sealing and insulation project for my attic i ve been trying to determine what would be considered the proper r value for insulating the knee walls. Installation instructions this section provides info on how to install insulation it contains specific information and details on wall and knee wall insulation that will assist with proper installation to meet resnet grade 1 criteria for fiberglass and mineral wool batt insulation. I m assuming it s somewhere between what would normally be recommended for an area s walls and for an area s attic but that s a lot of territory.

We treated the knee wall as an outside wall stapling up house wrap tyvek visible in the picture above. Although kneewalls can help turn attics into living space they often present insulation challenges most builders install fiberglass batts between the studs and some type of blown insulation between the floor joists. Verify that top bottom plates and a fire rated rigid backing have been installed. Insulating this space inside the knee wall improves the energy efficiency of the home and prevents heat transfer from the attic.

This knee wall has been encapsulated with 2 part closed cell spray foam. It covers details for proper installation of fiberglass and mineral wool batt insulation. The advantage here is that your knee wall is probably already insulated this way so it s just a matter of buying some foam so cheap. 2 4 insulation has an r value of 13 5.

The disadvantage is that it would be very very hard to reach the desired r value from r 49 to r 60 depending on climate for attic insulation. By adding an r19 to the existing r13 cavity insulation the knee wall assembly total r value is near r30 and is air tight. This would be for a vented roof and for my area of the country summer attic heat is. With 2 layers between the joists and another layer running perpendicular over top the r value of the insulation in the side attic is in the range of r 40.

A well insulated side attic. Verify insulation material is the correct width and r value. Cavity insulation as indicated in approved construction documents completely fills the knee wall cavity with no compression or gaps the manufacturer s r value mark is readily available and meets the approved r value per construction documents. Kneewalls short walls under sloped ceilings are common in story and a half homes and in bonus rooms above garages.

Find your zone on the map and then use the above insulation r value chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. One downs side to spray foam down side is cost. 1 use an r value map to determine the amount of insulation you need.