R Value Of Attic Air Space

The r value calculator is best used as follows.

R value of attic air space.

Typically we suggest you have an air gap between 1 2 and 3 4 for the radiant barrier to work. Achieving greater r values in exterior walls. Doesn t insulation count as an air space. The total insulation r value for the assembly will be an r 39 r 20 r 19 which complies with the prescriptive requirements of the 2009 iecc.

Work out all the different materials and surfaces that make up the wall ceiling or surface you want to work out the r values and u values for. Fibers from recycled post consumer paper that are treated for insect and fire resistance. I m in georgia iecc climate zone 3 where our current state code requires r 13 in exterior walls r 18 in attic kneewalls r 19 in floors and r 30 in ceilings. 1 and 6 the r value of a non reflective air space and vinyl siding provides an r value of about r 0 64.

Fiberglass batt 3 14 fiberglass blown attic 2 20 1 fiberglass blown wall 3 20 rock wool batt 3 14 rock wool blown attic 3 10 rock wool blown wall 3 03 cellulose blown attic 3 13 cellulose blown wall 3 70 vermiculite 2 13 air entrained concrete 3 90 urea terpolymer foam 4 48 rigid fiberglass 4 lb ft3 4 00 expanded polystyrene bead board 4 00 extruded polystyrene 5 00 polyurethane. Insulation is technically a solid with a lot of air in it therefore. Existing 3 4 inches of insulation. You can achieve better thermal performance in your attic by adding an additional layer of insulation.

What i m talking about is a house with ducts in unconditioned space especially an unconditioned attic. Fibers from rock or recycled slag from blast furnaces. If we put ducts in unconditioned space they have to be insulated to either r 8 if they re in an unconditioned attic or r 6 in any other type of unconditioned space. Our r value cognitive dissonance.

Material r inch r thick ness insulation materials. R value of building materials. Remember the horizontal or vertical orientation of the material is important to get its insulation value correct. Cathedral ceiling above mass insulation r 6 summer r 2 winter 2200 series double sided reflective insulation.

Recommended insulation levels for retrofitting existing wood framed buildings. It appears that a reflective surface in a very leaky air space provides little to no thermal benefit in comparison to an air space formed with non reflective surfaces astm c1363 testing example 1. Applications air space requirements. Air gaps larger than this work well too they promote ventilation on the foil and help keep the air dry and the air temps lower.

The most common blown in material used but it can rot and grow moldy if exposed to moisture. Add insulation to attic.