R-values help homeowners decide which type of insulation material to use, and in what thickness. An R-value is a measure of a given material’s thermal resistance, or its ability to inhibit warm
R Value Cost / sq. ft. Cost / sq. ft. per R value; Fiberglass batt: 13-30: $0.20-$1.00: $0.02-0.03: Loose fill such as fiberglass, cellulose & mineral wool (8-23 inches thick) 30-50: $0.45-$2.25: $0.03: Open cell polyurethane spray foam (3.5 inches thick) 12.6: $1.70-$2.50: $0.17: Closed cell polystyrene spray foam (1 inch thick) 6.5: $1.30-2 The R-value for wood ranges between 1.41 per inch (2.54 cm) for most softwoods and 0.71 for most hardwoods. Ignoring the benefits of the thermal mass, a 6-inch (15.24 cm) softwood log wall has a clear-wall (a wall without windows or doors) R-value of just over 8. Input depth of existing blown-in insulation (in inches). Click the button to calculate the approximate R-value for this job. This calculator is to be used as an estimating tool ONLY. R-values are additive. 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. R-value Units. As we said before, the R-value measures the thermal resistance of a material. May 01, 2009 · Although the nominal R-value of polyiso is the highest of the three major types of rigid foam, its cold weather performance is lower: As the temperature drops, so does the R-value. Some builders working in cold climates give it an R-value of 4.5 or 5 per inch. Polyiso is not rated for ground contact. Mar 20, 2019 · This is an even more dense and more expensive foam board insulation. It provides an R-value of 6 per inch of thickness and often comes foil-faced to help reflect radiant heat. Polyiso comes in several thicknesses and is used over house sheathing underneath siding or in attic spaces where its reflective properties are very effective. Per-inch, R-value of softwood is 1.41. In hardwood, it is 0.71. Logs of around 6 inches would then have an R-value that is about 8. This value, when compared to other insulating materials, is actually pretty low; it is so low that it is below many industry standards.
[30] Divide this per inch numberby 2 to obtain the R-value for 1/2" medium density fiberboard = R 1.22. Fiberboard insulating sheathing, regular density, per inch: 2.64 30 : Questionable; [30] Divide this per inch number by 2 to obtain the R-value for 1/2" regular density fiberboard = R 1.32
Just a note on some of the information on this thread. Celotex manufactuers all the product mentioned above fiberboard sheathings and polyiso sheating Thermax and Tuff R. The poly iso board are R 7.2 per inch stabilized R value. I believe NAHB web site has info on the testing. •Falls in the middle of the three types of rigid-foam insulation in both cost and R-value •Used most in walls or below grade applications •Recyclable, and at about R-5 per inch, costs around 42¢ per sq. ft. for a 1-in.-thick 4×8 panel •Comes unfaced or with a number of different plastic facings In November 1992, NRCA issued another bulletin in which it reaffirmed recommending an in-service R-value of 5.6 per inch of foam thickness for HCFC-blown polyisocyanurate board products. In the manufacturing process for polyisocyanurate, blowing agents defuse from the cellular structure of the foam for many years after manufacture.
An R-value is the resistance value of particular components in construction and includes materials such as plasterboard, brick or insulation. info@celotex.co.uk 01473 820850
Feb 06, 2013 · R-value is a measurement of thermal resistance and measures the ability of heat to transfer from one side of an object to another. As a benchmark, one inch of solid wood has an R-value of 1. In comparison, an inch of blown fiberglass insulation has an R-value of 3.1 - 3.4 and an inch of blown cellulose in an attic has an R-value of 3.2 - 3.7 Polyiso has a high R-value per inch compared to other insulation products. Polyiso is unique in that the R-value increases with the thickness of the foam, so three inches of polyiso has a higher R-value per inch than two inches. The R-value for FOAMULAR® XPS insulation is provided from testing at two mean temperatures, 40ºF and 75ºF, and from two aging (conditioning) techniques, 180 day realtime aged (as mandated by ASTM C578) and a method of accelerated aging sometimes called “Long Term Thermal Resistance” (LTTR) per CAN/ULC S770-03. The R-value at 180 day real Just a note on some of the information on this thread. Celotex manufactuers all the product mentioned above fiberboard sheathings and polyiso sheating Thermax and Tuff R. The poly iso board are R 7.2 per inch stabilized R value. I believe NAHB web site has info on the testing.