Rated R Value For 2x8 Roof Joist

With 1 2 wood structural panels with exterior glue applied at right angles to top of joist or top chord of trusses with 8d nails.

Rated r value for 2x8 roof joist.

Add r3 1 for each inch of new cellulose you blow in 1. Are your rafters rough. When determining how much insulation you need don t guesstimate calculate. Solid panel insulation has amazing r values.

To convert to si r values multiply by 0 176. Insulation rated on its ability to reduce thermal transfer or r value comes in rolls and batts that fit between joists. The thicker the insulation the higher the r value. 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.

I believe 8 1 4 is the thickness on an r 30. These are all us r values. 4 5 rigid will work in rafters as small as 2x6 and will get an r 30 and some change rating. The higher the r value the greater the insulation performance.

2 x 8 f d joists 16 o c 1 layer 3 4 bead board ceiling span 17 18 live load 40 lbs. If you are starting with an un insulated space it is very important to read the section below titled estimating r values for un insulated spaces note. Install it then have mark get out his caulking gun and seal all the corners. For example us r10 si r 1 76.

Thanks 01 03 2008 05 37 pm 8. Most common r value upgrades. Substrate roof floor ceiling time assembly ff file no. This is very important in situations where your code requires an r 21 for the wall but you only have a 2 4 stud because closed cell spray foam is the only way you would achieve the required r value to meet code.

Know exactly how much you need with our project calculators. What r value do i need. If they are you can get cathederal ceiling batts. Sheetrock only has a r value or about 0 5.

Also i believe the overlooked benefit of covering the studs and creating a solid barrier with very few areas for air penetration can be well worth the cost. 2009 ibc from table 720 1 3 minimum protection for floor and roof systems the floor construction of item 21 1 1 is wood joists wood i joists floor trusses and flat or pitched roof trusses spaced a maximum 24 o c. Add blown in cellulose to attic. 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.