Recommended R Rating For Wall Insulation

An r value is a rating which measures how well insulation can resist heat flow.

Recommended r rating for wall insulation.

R value is a measure of insulation s ability to resist heat traveling through it. 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. Insulation is rated in two ways r value and u 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. Recommended home insulation r values. R stands for thermal resistance. 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.

The higher the r value the better the thermal performance of the insulation. The r value is a calculation which measures the flow of heat through an insulation product or its. Fiberglass is usually installed between studs joists and rafters in unfinished walls floors and ceilings. R value level depends on a number of things such as the type of material its density and thickness.

See the department of energy s doe ranges for recommended levels of insulation below. Note from this. Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system. 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.

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. 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. Insulation level are specified by r value. The r value per inch for different types of insulation varies depending on the.

In most wall applications you will use r 13 or r 15 kraft faced fiberglass insulation rolls for these two by four stud walls. However it offers relatively low r values spanning r 3 1 to r 4 3 per inch. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.