Fiber Cement Siding R Value

Most siding including fiber cement have an r value of less than 1 when installed alone with out additional layers or types of insulation.

Fiber cement siding r value.

Fiber cement siding doesn t add much insulation to your wall system measuring in at a mere r 0 50. That s a little less than you ll get from vinyl siding which is rated as r 0 61 but the. Asbestos cement shingle siding. Asbestos cement board r value.

Because vinyl siding is thinner than fiber cement siding it can better accommodate insulation beneath its surface. Asbestos loose packed fibers powder. This is an increase of 13 of effective thermal resistance. For instance if you have a material with an r value of 12 attached to another material with an r value of 3 then both materials combined have an r value of 15.

Foam thicker than a half inch will yield even higher r values. This means as a stand alone product fiber cement isn t going to add much insulation to your home. This beats fiber cement which has an r value of 5 at most. Esr 1844 noncombustibility see page 1 section 3 1 flame spread and smoke developed see page 1 section 3 1 1 hour fire walls see page 2 section 4 3 design wind loads see page 4 5 table 4 r values see page 3 table 2.

Adding foam back vinyl siding leaves fiber cement in the dust as that has at minimum 1 8 r value. Asbestos lagging and paste will have a lower value. R value see table 2. According to table 5 1 of the ashrae fundamentals handbook fiber cement has an r value of 15 better than brick and stone but lower than vinyl at r 60 wood at r 81 and insulated vinyl siding at r 2 0 3 5.

Underlayment material even a foam board doesn t offer much extra and would be applicable to both materials. While fiber cement siding is energy efficient vinyl siding has the potential for this too. Adding inch of rigid foam insulation r 2 in this example will increase a 2x6 stud wall from an effective r 15 to an effective r 17. Thermal conductivity k 0 15.

Half inch thick rigid foam insulation has an r value of r 2 to r 3 5. When vinyl siding is optionally insulated it can achieve r 2 values and even greater. That means you ll need to use a superior grade of insulation inside of your walls attic and crawl space to ensure that your home is up to code in this regard. As we said before the r value measures the thermal resistance of a material.