Required R Value For Attic Insulation

There are many ways to retrofit a home with fiberglass and.

Required r value for attic insulation.

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. R value is a measure of insulation s ability to resist heat traveling through it. The higher the r value the better the thermal performance of the insulation. Insulation level are specified by r value.

In general to optimally isolate an attic on average an r value of the insulation is required ranging from r 50 to r 60. The further north northeast you go the colder it is and the more necessary r value will grow. The table below shows what levels of insulation are cost effective for different climates and. Where you live different climates require different insulation r values.

If structural sheathing covers 40 or less of the exterior continuous insulation r value shall be permitted to be reduced by no more than r 3 in the locations where structural sheathing is used to maintain a consistent total sheathing thickness. Climate zone 1 consists of the following south florida counties. You can achieve better thermal performance in your attic by adding an additional layer of insulation. The florida building code identifies two distinct climate zones.

However this value varies not only on the basis of the type of insulating material but also on the area. You will need a higher r value of insulation if you live in the northeast than if you live in southern california. Insulation which is compressed will not give you its full rated r value. Recommended home insulation r values.

The higher the r value the better the thermal performance of the insulation. Recycled glass or sand that s melted and spun into fibers. This can happen if you add denser insulation on top of lighter insulation in an attic. 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.

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. The homeowner could then check table 1 to find several choices. Typically current best home building practices indicate an r 30 to r 38 for attic insulation. 2015 code requires walls to be insulated with a minimum of r 20 or r 13 5 13 5 means r 13 cavity insulation plus r 5 insulated sheathing.

Broward collier hendry lee miami dade monroe and palm beach and require a minimum r 30 attic insulation. Your home s age if your home is more than 10 year old you likely need more insulation. Achieving greater r values in exterior walls. 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.