Required R Value For Attic Insulation

Recycled glass or sand that s melted and spun into fibers.

Required r value for attic insulation.

However there is an exception. 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. You will need a higher r value of insulation if you live in the northeast than if you live in southern california. Insulation requirements for slab on grade floors is further specified in iecc section 402 2 8.

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. Does your home have enough r value. 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. Pa302 1 ceilings with attic spaces n1102 2 1 r402 2 1.

R 5 shall be added to the required slab edge r values for heated slabs. Special insulation exceptions related to ceilings with attic spaces ceilings without attic spaces masonry veneer and thermally isolated sunrooms are set forth in iecc. Existing 3 4 inches of insulation. This can happen if you add denser insulation on top of lighter insulation in an attic.

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. However there is an exception. Add insulation to attic. You can achieve better thermal performance in your attic by adding an additional layer of insulation.

Most homes in the united states are not well insulated. Achieving greater r values in exterior walls. 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. The homeowner could then check table 1 to find several choices.

Where you live different climates require different insulation r values. The 2015 irc requires r 49 insulation for ceilings with attic spaces. There are many ways to retrofit a home with fiberglass and. Recommended insulation levels for retrofitting existing wood framed buildings.

Your home s age if your home is more than 10 year old you likely need more insulation. 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.