{"id":14310,"date":"2024-09-01T15:14:30","date_gmt":"2024-09-01T15:14:30","guid":{"rendered":"https:\/\/insulation.org\/io\/?post_type=articles&#038;p=14310"},"modified":"2024-10-18T20:16:26","modified_gmt":"2024-10-18T20:16:26","slug":"back-to-basics-r-value-and-u-value","status":"publish","type":"articles","link":"https:\/\/insulation.org\/io\/articles\/back-to-basics-r-value-and-u-value\/","title":{"rendered":"Back to Basics: R-Value and U-Value"},"content":{"rendered":"<p><a href=\"https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_01.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-14287\" src=\"https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_01-300x191.jpg\" alt=\"\" width=\"300\" height=\"191\" srcset=\"https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_01-300x191.jpg 300w, https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_01-1024x653.jpg 1024w, https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_01-768x490.jpg 768w, https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_01-1536x980.jpg 1536w, https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_01.jpg 1788w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>The R-value of an insulation product is a thermal resistance rating that tells us how well a material resists heat flow. The higher the R-value, the better the insulation restricts heat transfer. Most insulation manufacturers use the ASTM C518 test to measure a material\u2019s resistance to heat flow. Established by the American Society for Testing and Materials (ASTM), the ASTM C518 test is a standardized method that assesses the steady-state thermal transmission properties of a material using a heat flow meter apparatus. In addition to serving as an essential tool for many industries, ASTM C518 is a building code requirement for insulation.<\/p>\n<p>R-values for metal building insulation range from R-8 to R-30. The most common fiberglass metal building insulation R-values include:<\/p>\n<ul>\n<li>2\u201d (R-8, before lamination)<\/li>\n<li>3.4\u201d (R-10)<\/li>\n<li>3.7\u201d (R-11)<\/li>\n<li>4.3\u201d (R-13)<\/li>\n<li>5.3\u201d (R-13)<\/li>\n<li>6.3\u201d (R-19)<\/li>\n<li>8.0\u201d (R-25)<\/li>\n<li>9.25\u201d (R-30)<\/li>\n<\/ul>\n<p>It should be noted that thicknesses are nominal, as manufacturers produce different thicknesses to meet R-values. Commercial energy code requirements dictate the minimum R-value necessary for all new construction, additions, and alterations performed in the United States.<\/p>\n<p>Once the R-value is determined, designers can use this data to better understand how a material will perform in an assembly. Heat flow through a material is driven by the temperature difference on each side of the material or assembly. Most construction types and code tables leverage the R-value table as a guide to code compliance. However, it is important to remember that the R-value table should not be mistaken as a reference for the total performance of an assembly. Metal-framed walls, wood-framed walls, and metal building walls and roofs undergo testing that determines the U-value of the entire assembly. The result of that testing can be found in the U-value table.<\/p>\n<p>A U-value, also called a U-factor, measures heat transfer, or loss, through the assembly over time. While the R-value measures a single product\u2019s ability to resist heat, the U-value measures the entire assembly\u2019s resistance to heat transfer. The lower the U-factor, the better the insulation. Mathematically, R-values and U-values are reciprocals of one another: U-value = 1\/R-value, R-value = 1\/U-value. ASTM C1363 is the standard test method of U-values and includes a hot box apparatus. See <em>Figure 1<\/em> and <em>Figure 2<\/em>.<\/p>\n<p><a href=\"https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_03-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-14289\" src=\"https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_03-142x300.jpg\" alt=\"\" width=\"142\" height=\"300\" srcset=\"https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_03-142x300.jpg 142w, https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_03-486x1024.jpg 486w, https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_03-768x1617.jpg 768w, https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_03-729x1536.jpg 729w, https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_03-972x2048.jpg 972w, https:\/\/insulation.org\/io\/wp-content\/uploads\/sites\/3\/2024\/10\/IO240902_03-scaled.jpg 1216w\" sizes=\"auto, (max-width: 142px) 100vw, 142px\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The R-value of an insulation product is a thermal resistance rating that tells us how well a material resists heat flow. The higher the R-value, the better the insulation restricts heat transfer. Most insulation manufacturers use the ASTM C518 test to measure a material\u2019s resistance to heat flow. Established by the American Society for Testing<\/p>\n","protected":false},"author":[677],"featured_media":0,"template":"","categories":[665,676],"class_list":["post-14310","articles","type-articles","status-publish","hentry","category-metal-building","category-september-2024","author-nias-metal-building-laminator-committee"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v24.0 (Yoast SEO v24.6) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Back to Basics: R-Value and U-Value - Insulation Outlook Magazine<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/insulation.org\/io\/articles\/back-to-basics-r-value-and-u-value\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Back to Basics: R-Value and U-Value\" \/>\n<meta property=\"og:description\" content=\"The R-value of an insulation product is a thermal resistance rating that tells us how well a material resists heat flow. 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