Required R Value For Attic Insulation

However there is an exception.

Required r value for attic insulation.

It also happens if you place batts rated for one thickness into a thinner cavity such as placing r 19 insulation rated for 6 1 4 inches into a 5 1 2 inch wall cavity. You will need a higher r value of insulation if you live in the northeast than if you live in southern california. Achieving greater r values in exterior walls. Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces.

Recommended insulation levels for retrofitting existing wood framed buildings. If the existing attic floor insulation has an r 11 insulation value then an additional r 27 would be needed to bring the attic floor insulation up to the level recommended for that house. Add insulation to attic. However there is an exception.

Pa302 1 ceilings with attic spaces n1102 2 1 r402 2 1. Lighter in weight than cellulose or mineral wool but it settles more than those materials so you ve got to put in a thicker layer to get the protection you need. Special insulation exceptions related to ceilings with attic spaces ceilings without attic spaces masonry veneer and thermally isolated sunrooms are set forth in iecc. This can happen if you add denser insulation on top of lighter insulation in an attic.

Insulation requirements for slab on grade floors is further specified in iecc section 402 2 8. You can achieve better thermal performance in your attic by adding an additional layer of insulation. Recycled glass or sand that s melted and spun into fibers. R 38 shall be deemed to satisfy the requirement for r 49 wherever the full height of uncompressed r 38 insulation extends over the wall top plate at the eaves.

With an r value of 4 0 to 5 1 per inch depending on the manufacturer pre expanded injection foam provides a higher r value than fiberglass or cellulose and it seals the building from air leakage at the same time. Where you live different climates require different insulation r values. The 2015 irc requires r 49 insulation for ceilings with attic spaces. Most homes in the united states are not well insulated.

R 5 shall be added to the required slab edge r values for heated slabs. Existing 3 4 inches of insulation. There are many ways to retrofit a home with fiberglass and. The homeowner could then check table 1 to find several choices.

Does your home have enough r value. Depending on where you live and the part of your home you re insulating walls crawlspace attic etc you ll need a different r value.