Recommended R Rating For Wall Insulation

For example insulation that is compressed will not provide its full rated r value.

Recommended r rating for wall insulation.

Recommended home insulation r values. How to achieve r 21 in a 2x4 wall. Note from this. For example a wall with 3 fiberglass batting r value of 10 8 11 9 may have an overall r value of nearly 14 because of siding sheathing and drywall.

Fiberglass is usually installed between studs joists and rafters in unfinished walls floors and ceilings. However it offers relatively low r values spanning r 3 1 to r 4 3 per inch. A 12 inch thick fiberglass blanket rated at r 4 is enough to reach the recommended insulation level of r 48 for attics located in zone 4. The r value is a calculation which measures the flow of heat through an insulation product or its.

While there are additional considerations such as venting and moisture problems to take into account when you insulate under floors the united states department of energy recommends an r 25 rating in cold climates and an r 11 in warmer parts of the country. 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. While rated differently these two types of insulation are close enough in thickness that they can both fit into modern two by four wall systems. The higher the r value the better the thermal performance of the insulation.

Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system. R value is a measure of insulation s ability to resist heat traveling through it. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. The overall r value of a wall or ceiling will be somewhat different from the r value of the insulation itself because heat flows more readily through studs joists and other building materials in a phenomenon known as thermal bridging.

The table below shows what levels of insulation are cost effective for different climates and. In most wall applications you will use r 13 or r 15 kraft faced fiberglass insulation rolls for these two by four stud walls. Insulation is rated in two ways r value and u value. See the department of energy s doe ranges for recommended levels of insulation below.

For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3. Insulation level are specified by r value. The r value per inch for different types of insulation varies depending on the.