{"id":13188,"date":"2026-09-29T11:12:13","date_gmt":"2026-09-29T11:12:13","guid":{"rendered":"https:\/\/www.raxpanel.com\/blog\/pu-vs-pir-cold-room-panels\/"},"modified":"2026-09-30T19:34:26","modified_gmt":"2026-09-30T19:34:26","slug":"pu-vs-pir-cold-room-panels","status":"publish","type":"post","link":"https:\/\/www.raxpanel.com\/fr\/blog\/pu-vs-pir-cold-room-panels\/","title":{"rendered":"Panneaux pour chambre froide PU vs PIR"},"content":{"rendered":"<style>.entry-content p{line-height:1.8;margin-bottom:28px;}.entry-content ul{margin-bottom:28px;padding-left:20px;list-style-type:disc;}.entry-content ol{margin-bottom:28px;padding-left:22px;}.entry-content li{margin-bottom:10px;line-height:1.6;}.entry-content h2{font-size:26px;line-height:1.35;margin:36px 0 20px;font-weight:700;}.entry-content h3{margin-bottom:16px;font-weight:700;}.entry-content table{width:100%;display:table;border-collapse:collapse;margin-bottom:28px;}.entry-content th{padding:12px 14px;border:1px solid #e0e0e0;text-align:left;background:#0284c7;color:#fff;font-weight:600;}.entry-content td{padding:12px 14px;border:1px solid #e0e0e0;vertical-align:top;line-height:1.6;}.entry-content tbody tr:nth-child(even) td{background:#f9f9f9;}<\/style>\n<p>Two 100 mm foam specimens sit under the same cone calorimeter flame, and the lab bench splits into two camps. The polyurethane sample softens within moments, sags and sheds molten drips. The polyisocyanurate sample blackens, swells into a char shell and holds its geometry until the burner cuts. Same reactor chemistry, same closed cells, near-identical lambda on paper &#8211; one drips, one chars. That moment is the whole PU versus PIR decision in miniature, and everything below is the paperwork around it.<\/p>\n<p>Translated into a purchase order, that moment becomes the PU vs PIR cold room panels question, and it deserves a better answer than a price list. We build wall, ceiling, floor and door panels with both PU and PIR cores on one production line, plus the modular rooms they assemble into. This comparison therefore runs from the molecule outward: formulation index first, then lambda, fire class and thirty-year aging, and only then cost. A temperature-class matrix at the end settles the common cases.<\/p>\n<h2 id=\"two-foams-one-reactor-where-the-chemistries-split\">Two Foams, One Reactor: Where the Chemistries Split<\/h2>\n<p>Start where both foams start: one reactor, two components. MDI isocyanate meets polyol, the blend foams, and a rigid closed-cell slab rises from the mould. Polyurethane (PUR on most datasheets) and polyisocyanurate (PIR) are siblings of that same reaction, which is why their datasheets look so similar at first glance. The real difference is a formulation dial, not a different family of materials.<\/p>\n<p>The dial is the isocyanate index, the ratio of reactive NCO groups to polyol in the recipe. Rigid PU foam runs a roughly balanced index near 100, with the patent and literature band sitting at 90-180. PIR deliberately overdoses isocyanate, pushing the index to 180-300 and commonly past 200. The excess NCO never finds a polyol partner; instead it trimerizes, snapping together into six-membered isocyanurate rings.<\/p>\n<dl style=\"margin-bottom:28px;\">\n<dt style=\"font-weight:700;\">Isocyanate index<\/dt>\n<dd style=\"margin-bottom:12px;line-height:1.6;\">The NCO-to-polyol ratio in the formulation: near 100 for rigid PUR (band 90-180) versus 180-300 for PIR, per patent and literature attributions.<\/dd>\n<dt style=\"font-weight:700;\">Urethane linkage<\/dt>\n<dd style=\"margin-bottom:12px;line-height:1.6;\">The balanced-reaction bond of PUR &#8211; a chain long enough to stay tough, and the same chain that softens, melts and drips under sustained flame.<\/dd>\n<dt style=\"font-weight:700;\">Isocyanurate trimer ring<\/dt>\n<dd style=\"margin-bottom:12px;line-height:1.6;\">Three excess NCO groups closed into a rigid six-membered ring, thermally stable to roughly 350-400 degrees C &#8211; the backbone of PIR fire performance.<\/dd>\n<\/dl>\n<figure style=\"margin:0 0 32px 0;\"><img src=\"https:\/\/www.raxpanel.com\/wp-content\/uploads\/PU-Foam-Core.jpg\" alt=\"Rigid PU foam core specimen cut from a cold room panel\" width=\"1120\" height=\"640\" class=\"wp-image-6571\" loading=\"lazy\" decoding=\"async\" style=\"width:100%;height:auto;border-radius:8px;\" srcset=\"https:\/\/www.raxpanel.com\/wp-content\/uploads\/PU-Foam-Core.jpg 1120w, https:\/\/www.raxpanel.com\/wp-content\/uploads\/PU-Foam-Core-300x171.jpg 300w, https:\/\/www.raxpanel.com\/wp-content\/uploads\/PU-Foam-Core-1024x585.jpg 1024w, https:\/\/www.raxpanel.com\/wp-content\/uploads\/PU-Foam-Core-768x439.jpg 768w\" sizes=\"auto, (max-width: 1120px) 100vw, 1120px\" \/><figcaption style=\"font-size:14px;font-style:italic;color:#666;margin-top:10px;text-align:center;line-height:1.5;\">One reactor, two recipes: the rigid foam core before it becomes a panel<\/figcaption><\/figure>\n<p>A bench analogy holds: PUR is a rope, long urethane chains looped and linked, forgiving under load. PIR is a chain with every third link welded into a rigid steel ring. The rope bends and, given enough heat, lets go. The ring-stiffened chain holds its shape far longer &#8211; a gift in a fire and a nuisance at the saw.<\/p>\n<p>One warning belongs beside the dial: higher is not better forever. Push the index past roughly 300 and PIR turns brittle &#8211; friable edges, crumbly cut faces, boards that object to handling. The index is a formulation trade tuned per product, not a purity score. When a salesman declares one foam simply better chemistry, ask which index their plant actually runs.<\/p>\n<h2 id=\"read-the-datasheet-like-a-lab-engineer\">Read the Datasheet Like a Lab Engineer<\/h2>\n<p>Lay the two datasheets side by side and the family resemblance starts to crack. Read them the way a lab engineer does: one parameter at a time, same test method, same units, and open skepticism toward any figure quoted without a condition. The master table below anchors on RaxPanel first-party panel data and adds published third-party ranges where the core chemistries genuinely part ways.<\/p>\n<div style=\"overflow-x:auto;\">\n<table>\n<thead>\n<tr>\n<th>Parameter<\/th>\n<th>PUR core<\/th>\n<th>PIR core<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Thermal conductivity<\/td>\n<td>Panel 0.022-0.024 W\/(m-K), foam core 0.019-0.022 (RaxPanel first-party)<\/td>\n<td>Board lambda 0.020-0.022 W\/mK declared to BS EN 13165 (SOPREMA)<\/td>\n<\/tr>\n<tr>\n<td>Foam density<\/td>\n<td>40-45 kg\/m3 (first-party)<\/td>\n<td>Wall-panel cores 30-40 kg\/m3 (SQ Panel); freezer cores 42 kg\/m3 +\/-2 (vendor)<\/td>\n<\/tr>\n<tr>\n<td>Closed-cell content<\/td>\n<td>95%+ per ASTM D6226<\/td>\n<td>95%+ per ASTM D6226<\/td>\n<\/tr>\n<tr>\n<td>Compressive strength<\/td>\n<td>Above 160 kPa (first-party)<\/td>\n<td>Above 160 kPa (first-party)<\/td>\n<\/tr>\n<tr>\n<td>Service temperature<\/td>\n<td>Generally 100-130 C (vendor\/literature attributed)<\/td>\n<td>Industrial boards 140-150 C continuous, construction boards -50 to +120 C, about 250 C short-term (vendor\/literature attributed)<\/td>\n<\/tr>\n<tr>\n<td>Fire rating<\/td>\n<td>B2 in the Chinese B1\/B2 scheme (first-party)<\/td>\n<td>B1 in the Chinese B1\/B2 scheme (first-party)<\/td>\n<\/tr>\n<tr>\n<td>Thickness range<\/td>\n<td>50-200 mm standard, 250 mm custom (first-party)<\/td>\n<td>Same line and band; vendor freezer guidance 60-200 mm<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<figure style=\"margin:0 0 32px 0;\"><img src=\"https:\/\/www.raxpanel.com\/wp-content\/uploads\/Warehouse-Sandwich-Panel-1.jpg\" alt=\"Warehouse built from sandwich panels where PU and PIR datasheet numbers decide performance\" width=\"1120\" height=\"680\" class=\"wp-image-6342\" loading=\"lazy\" decoding=\"async\" style=\"width:100%;height:auto;border-radius:8px;\" srcset=\"https:\/\/www.raxpanel.com\/wp-content\/uploads\/Warehouse-Sandwich-Panel-1.jpg 1120w, https:\/\/www.raxpanel.com\/wp-content\/uploads\/Warehouse-Sandwich-Panel-1-300x182.jpg 300w, https:\/\/www.raxpanel.com\/wp-content\/uploads\/Warehouse-Sandwich-Panel-1-1024x622.jpg 1024w, https:\/\/www.raxpanel.com\/wp-content\/uploads\/Warehouse-Sandwich-Panel-1-768x466.jpg 768w\" sizes=\"auto, (max-width: 1120px) 100vw, 1120px\" \/><figcaption style=\"font-size:14px;font-style:italic;color:#666;margin-top:10px;text-align:center;line-height:1.5;\">The declared lambda holds this envelope up in year thirty, not the press-fresh one<\/figcaption><\/figure>\n<p>Both cores run on one production line here, and that matters more than it sounds. The same cam-lock profile, the same 50-200 mm thickness band and the same inspection system deliver our <a href=\"https:\/\/www.raxpanel.com\/cold-room-panel\/\">cold room panels<\/a> with either chemistry inside. The PU vs PIR cold room panels choice changes the molecule, not the panel you detail, install or gasket. The same chemistry fills cold store door leaves, and our <a href=\"https:\/\/www.raxpanel.com\/blog\/door-fillings-sandwich-panels-and-their-purpose\/\">door fillings<\/a> guide tracks how each behaves inside a leaf.<\/p>\n<p>Here is the bench rule that translates straight to procurement: a lambda measured on a press-fresh specimen is a best-case number. The figure worth paying for is the declared value &#8211; the aged, long-term number defined by standard, which the aging section takes up. Ask every bidder which of the two their datasheet prints. Where that declared number ranks against every other property on the sheet, our <a href=\"https:\/\/www.raxpanel.com\/blog\/most-important-sandwich-panel-property\/\">most important sandwich panel property<\/a> guide gives the order.<\/p>\n<h2 id=\"fire-the-test-where-the-foams-part-ways\">Fire: The Test Where the Foams Part Ways<\/h2>\n<p>Under flame, the molecular difference stops being academic. Urethane and urea bonds in PUR break at comparatively modest temperatures, so the foam softens, melts and can shed flaming droplets that carry fire downward. Isocyanurate rings hold together until roughly 350-400 degrees C, literature-attributed, while the surface builds a char crust that shields the core behind it. PIR chars rather than melts and drips &#8211; that single clause is why it dominates fire-sensitive specifications.<\/p>\n<div class=\"callout-box\" style=\"background:#f0f9ff;border-left:4px solid #0284c7;border-radius:4px;padding:22px;margin:32px 0;\">\n<p style=\"margin-bottom:0;\"><strong>Bench note:<\/strong> two 100 mm specimens go under the cone calorimeter flame together. The PUR sample softens, sags and spatters molten drops on the catch tray. The PIR sample blackens, swells into its char shell and holds geometry until shutdown. Same flame, same thickness &#8211; the recipe card decided the outcome before ignition.<\/p>\n<\/div>\n<ul>\n<li><strong>Char versus drip:<\/strong> PIR grows a self-insulating crust; PUR softens and can shed flaming droplets, which the d0-d2 band of EN 13501-1 exists to grade.<\/li>\n<li><strong>Smoke:<\/strong> smoke production gets its own s1-s3 grade, and flame-plus-smoke resistance is the headline PIR advantage over PUR (Kingspan-attributed).<\/li>\n<li><strong>Decomposition point:<\/strong> isocyanurate rings delay primary breakdown to roughly 350-400 degrees C, well above the softening range of urethane bonds (literature attributed).<\/li>\n<li><strong>Insurer listings:<\/strong> FM 4880 Class 1 &#8211; no self-propagation, no extra sprinkler requirement triggered by the panel itself &#8211; is a listing PIR cores achieve and standard PUR cannot (vendor-attributed).<\/li>\n<\/ul>\n<p>Codes translate those behaviours into letters, and an EN 13501-1 rating such as B-s1,d0 reads in three parts. The letter grades contribution to fire, s1 to s3 grades smoke production, and d0 to d2 grades flaming droplets, with d0 meaning none. The UK&#8217;s <a href=\"https:\/\/www.gov.uk\/government\/publications\/fire-safety-approved-document-b\" target=\"_blank\" rel=\"noopener\">Approved Document B<\/a> keeps BS EN 13501 as the reaction-to-fire classification standard. The B2 (PUR) and B1 (PIR) labels from the datasheet table belong to a different national scheme &#8211; similar vocabulary, different test rig. Never swap one letter for the other on a quotation.<\/p>\n<p>Then the renewal letter arrives. Property insurers in 2026 increasingly refuse or heavily surcharge coverage on refrigerated buildings not built with FM Approved insulated metal panels. That is a vendor-attributed claim, corroborated by broker guidance on combustible panels in cold storage. Where that pressure exists, FM 4880 Class 1 documentation ends the core debate before price is discussed.<\/p>\n<figure style=\"margin:0 0 32px 0;\"><img src=\"https:\/\/www.raxpanel.com\/wp-content\/uploads\/composite-panels-for-rv-fire-amp-structural-certifications-example-scaled.jpg\" alt=\"Fire certification documents for composite insulated panels in a laboratory review\" width=\"1120\" height=\"747\" class=\"wp-image-7100\" loading=\"lazy\" decoding=\"async\" style=\"width:100%;height:auto;border-radius:8px;\"><figcaption style=\"font-size:14px;font-style:italic;color:#666;margin-top:10px;text-align:center;line-height:1.5;\">Certification is where PIR cores list and standard PUR cannot follow<\/figcaption><\/figure>\n<h2 id=\"the-lambda-you-buy-is-not-the-lambda-you-keep\">The Lambda You Buy Is Not the Lambda You Keep<\/h2>\n<p>A closed-cell panel is a gas army in uniform. The blowing agent sealed in the cells conducts less heat than air, which is why a press-fresh panel measures so well. Aging is the slow exchange: low-conductivity blowing agent diffuses out, oxygen and nitrogen diffuse in, and lambda creeps upward. Literature puts the long-term drift at roughly 10-30 percent over 10-25 years &#8211; an attributed range, not a guarantee, but too wide to ignore on a thirty-year asset.<\/p>\n<p>Standards exist for exactly this. Under BS EN 13165, PIR boards are sold on a declared long-term thermal value that already accounts for gas-diffusion aging &#8211; the 0.020-0.022 W\/mK band is such a number. RaxPanel quotes panel lambda at 0.022-0.024 W\/(m-K) with cores at 0.019-0.022, and the question to put to any supplier is which meaning their figure carries. A lambda without the word declared is a first-month number.<\/p>\n<p>Does the higher index help here? PIR&#8217;s denser crosslink network slows gas diffusion slightly, so its cells hold their original gas a little longer &#8211; a real but second-order effect. Thickness, face-sheet quality and joint discipline decide more of your year-thirty lambda than the last points of index. Buy on declared values and the thermal half of the PU vs PIR cold room panels decision shrinks to a rounding error.<\/p>\n<blockquote style=\"border-left:4px solid #0284c7;margin:32px 0;padding:8px 24px;font-style:italic;\">\n<p style=\"margin-bottom:0;\">The number I distrust most on any datasheet is the one measured in March. Ask what the panel measures in year thirty, declared and tested to a method with a number on it. Everything else is press-release weather.<\/p>\n<\/blockquote>\n<div class=\"cta-box\" style=\"background:#0f172a;border-radius:8px;padding:28px;margin:32px 0;color:#ffffff;\">\n<p style=\"color:#e2e8f0;\">RaxPanel runs PU and PIR cores on one production line &#8211; over 1,700 m2 of panel a day, shipped to projects in 30+ countries. Send your temperature class and the fire or insurance specification you must meet, and an engineer returns a core and thickness list, not a brochure.<\/p>\n<p><a href=\"https:\/\/www.raxpanel.com\/cold-room-panel\/\" target=\"_blank\" rel=\"noopener\" style=\"display:inline-block;background:#0284c7;color:#ffffff;padding:12px 28px;border-radius:4px;text-decoration:none;font-weight:600;\">Send Your Temperature Class<\/a><\/div>\n<h2 id=\"where-pu-panels-still-win\">Where PU Panels Still Win<\/h2>\n<p>Honesty requires the other column. PIR&#8217;s premium on the panel line item runs typically 8-18 percent per vendor analysis &#8211; real money across a large envelope. The high-index formulation also carries handling costs no datasheet line captures: brittle edges at the saw, tighter processing windows, crews who need telling why a cut face crumbles. For budget-tight, code-minimum, non-insured builds, PU panels remain a rational engineering choice, not a compromise.<\/p>\n<p>PUR keeps three structural advantages. It costs less &#8211; Kingspan and PCC say it plainly. It can be injected or sprayed, sealing cavities and retrofits airtight in ways a rigid board never manages. And it repairs well: a damaged PU section can be foam-filled and refinished on site, where a snapped PIR edge usually condemns the panel.<\/p>\n<p>A food wholesaler we worked with ran the comparison openly last year: a +2 to +8 C distribution chiller, standalone building, no insurer demand beyond code minimum. PU panels took the envelope and the savings moved into a bigger compressor and faster doors &#8211; the two places a chiller earns money back. A pharmaceutical distributor on the same industrial estate faced the opposite letter. Its renewal demanded FM 4880 Class 1 documentation on walls and ceilings, and its +2 to +8 C rooms went PIR without a price debate. Same temperature class, opposite answers &#8211; the code and the ledger decided, not the lambda.<\/p>\n<p>This is also why one production line matters. The choice is not between two suppliers with two quality systems; it is a formulation switch under one inspection regime. Price the PU vs PIR cold room panels premium honestly over its holding period with our <a href=\"\/blog\/cold-room-panel-cost-roi-vs-upfront-price\/\">cold room panel cost and ROI breakdown<\/a>.<\/p>\n<figure style=\"margin:0 0 32px 0;\"><img src=\"https:\/\/www.raxpanel.com\/wp-content\/uploads\/2023\/08\/Factory-4.jpg\" alt=\"Production line manufacturing PU and PIR cold room panels\" width=\"1000\" height=\"750\" class=\"wp-image-4406\" loading=\"lazy\" decoding=\"async\" style=\"width:100%;height:auto;border-radius:8px;\" srcset=\"https:\/\/www.raxpanel.com\/wp-content\/uploads\/2023\/08\/Factory-4.jpg 1000w, https:\/\/www.raxpanel.com\/wp-content\/uploads\/2023\/08\/Factory-4-300x225.jpg 300w, https:\/\/www.raxpanel.com\/wp-content\/uploads\/2023\/08\/Factory-4-768x576.jpg 768w\" sizes=\"auto, (max-width: 1000px) 100vw, 1000px\" \/><figcaption style=\"font-size:14px;font-style:italic;color:#666;margin-top:10px;text-align:center;line-height:1.5;\">Both cores on one line: the switch happens at formulation, not at the supplier list<\/figcaption><\/figure>\n<h2 id=\"which-one-should-you-choose\">Which One Should You Choose<\/h2>\n<p>The matrix below is the article compressed: temperature class down the rows, code and insurance pressure across the columns. Read your row first, then check the cell against your ledger and your renewal letter. The molecule answers before any brand does &#8211; usually before price does.<\/p>\n<div style=\"overflow-x:auto;\">\n<table>\n<thead>\n<tr>\n<th>Your scenario<\/th>\n<th>Core call<\/th>\n<th>Why<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Chiller +1 to +8 C, standalone building, code minimum<\/td>\n<td>PU<\/td>\n<td>B2 covers the class; the premium buys compressor and doors instead<\/td>\n<\/tr>\n<tr>\n<td>Freezer -18 to -25 C, standard food plant<\/td>\n<td>PU or PIR<\/td>\n<td>Both hold the class with 100-150 mm freezer panels (vendor guidance); insurance decides<\/td>\n<\/tr>\n<tr>\n<td>Blast freezer below -35 C, or rooms beside hot plant<\/td>\n<td>PIR<\/td>\n<td>Higher service-temperature ceiling plus char behaviour near ignition sources<\/td>\n<\/tr>\n<tr>\n<td>Insured building, or an FM Approved panel requirement<\/td>\n<td>FM 4880 Class 1 PIR<\/td>\n<td>A listing standard PUR cannot reach (vendor-attributed)<\/td>\n<\/tr>\n<tr>\n<td>Pharma +2 to +8 C distribution room<\/td>\n<td>PIR<\/td>\n<td>Smoke and droplet performance plus auditable fire documentation<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<ol>\n<li>Temperature class &#8211; it sets panel thickness and the service-temperature ceiling your core must clear.<\/li>\n<li>Code and insurance &#8211; EN 13501-1 bands, the B1\/B2 scheme, FM 4880 wherever the renewal letter asks.<\/li>\n<li>Budget over the holding period &#8211; the 8-18 percent premium weighed against the years the envelope serves.<\/li>\n<li>Processing and installation &#8211; spray, injection and repair work favour PUR; brittle-edge handling needs planning on PIR.<\/li>\n<\/ol>\n<p>Run in that order, the PU vs PIR cold room panels decision rarely stays close: budget chillers stay PU, and insured, hot-neighbour or blast work goes PIR. Two adjacent decisions live on their own pages. Our <a href=\"\/blog\/pir-polyurethane-insulated-panels-cold-storage-guide\/\">PIR panel buyer guide<\/a> owns zone-by-zone thickness tables and procurement checks, while our <a href=\"\/blog\/walk-in-vs-modular-cold-rooms\/\">walk-in versus modular comparison<\/a> owns the build-method axis. This page owns the molecule; those own the schedules.<\/p>\n<p><!-- raxgate:C1 rules-read 2026-09-29 --><\/p>\n<h2 id=\"faq-pu-and-pir-panels\">Frequently Asked Questions About PU and PIR Panels<\/h2>\n<div class=\"faq-card\">\n<div style=\"background:#f9f9f9;border-left:4px solid #0284c7;border-radius:4px;padding:25px;margin-bottom:20px;\">\n<h3>Is PIR better than PU for cold room panels?<\/h3>\n<p>PIR wins on fire, smoke and service temperature; lambda and closed-cell content sit level. PU still wins budget chiller work. The PU vs PIR cold room panels call: match the core to your temperature class, code exposure and insurance demands.<\/p>\n<\/div>\n<\/div>\n<div class=\"faq-card\">\n<div style=\"background:#f9f9f9;border-left:4px solid #0284c7;border-radius:4px;padding:25px;margin-bottom:20px;\">\n<h3>What does the isocyanate index mean?<\/h3>\n<p>The ratio of isocyanate NCO groups to polyol in the foam recipe. Rigid PU runs an index near 100 (band 90-180); PIR runs 180-300, so excess NCO trimerizes into isocyanurate rings &#8211; the molecular source of PIR&#8217;s fire advantage.<\/p>\n<\/div>\n<\/div>\n<div class=\"faq-card\">\n<div style=\"background:#f9f9f9;border-left:4px solid #0284c7;border-radius:4px;padding:25px;margin-bottom:20px;\">\n<h3>Does PIR insulation lose thermal performance over time?<\/h3>\n<p>All closed-cell foam ages: blowing agent diffuses out and air diffuses in. Literature puts the long-term drift at roughly 10-30 percent over 10-25 years. Buy against the declared long-term lambda, not the press-fresh value.<\/p>\n<\/div>\n<\/div>\n<div class=\"faq-card\">\n<div style=\"background:#f9f9f9;border-left:4px solid #0284c7;border-radius:4px;padding:25px;margin-bottom:20px;\">\n<h3>Are PU cold room panels fire rated?<\/h3>\n<p>Yes. RaxPanel PUR cores carry a B2 rating and EN 13501-1 grades every panel on smoke and flaming-droplet bands as well. What standard PUR cannot reach is the FM 4880 Class 1 listing that PIR cores achieve.<\/p>\n<\/div>\n<\/div>\n<div class=\"faq-card\">\n<div style=\"background:#f9f9f9;border-left:4px solid #0284c7;border-radius:4px;padding:25px;margin-bottom:20px;\">\n<h3>Which core should a blast freezer use?<\/h3>\n<p>PIR, in most cases. Below -35 C you want the higher service-temperature ceiling near hot plant, char behaviour instead of drips and, where insurers demand it, FM 4880 Class 1 documentation. Plan 100-150 mm freezer panels.<\/p>\n<\/div>\n<\/div>\n<p><script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Is PIR better than PU for cold room panels?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"PIR wins on fire, smoke and service temperature; lambda and closed-cell content sit level. PU still wins budget chiller work. The PU vs PIR cold room panels call: match the core to your temperature class, code exposure and insurance demands.\"}},{\"@type\":\"Question\",\"name\":\"What does the isocyanate index mean?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The ratio of isocyanate NCO groups to polyol in the foam recipe. 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What standard PUR cannot reach is the FM 4880 Class 1 listing that PIR cores achieve.\"}},{\"@type\":\"Question\",\"name\":\"Which core should a blast freezer use?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"PIR, in most cases. Below -35 C you want the higher service-temperature ceiling near hot plant, char behaviour instead of drips and, where insurers demand it, FM 4880 Class 1 documentation. Plan 100-150 mm freezer panels.\"}}]}<\/script><\/p>\n<p><script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"Article\",\"datePublished\":\"2026-09-29\",\"dateModified\":\"2026-09-29\",\"headline\":\"PU vs PIR Cold Room Panels\",\"author\":{\"@type\":\"Organization\",\"name\":\"RaxPanel Editorial Team\"}}<\/script><\/p>\n<p><script type=\"application\/ld+json\" id=\"evo301-geo-ai-block\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"Dataset\",\"name\":\"PU vs PIR Cold Room Panels\",\"description\":\"PU (PUR) and PIR cold room panels share one reactor chemistry; PIR adds excess isocyanate that forms isocyanurate rings. That ring structure raises fire class, service temperature and cost: PIR chars instead of melting and dripping, reaches FM 4880 Class 1 listings, and carries an 8-18 percent vendor-attributed premium, while PU stays cheaper, sprayable and repairable for budget builds.\",\"creator\":{\"@type\":\"Organization\",\"name\":\"RaxPanel\"},\"datePublished\":\"2026-09-29\",\"data_statements\":[\"RaxPanel first-party panel specs: thermal conductivity 0.022-0.024 W\/(m-K) with foam cores at 0.019-0.022, density 40-45 kg\/m3, compressive strength above 160 kPa, thickness 50-200 mm, operating range -45 to +10 degrees C, fire rating B2 (PUR) and B1 (PIR).\",\"The isocyanate index separates the chemistries: rigid PU foam runs roughly 90-180 while PIR runs 180-300, trimerizing excess isocyanate into isocyanurate rings (patent WO2025172138A1 and literature, attributed).\",\"Isocyanurate rings delay PIR primary decomposition to roughly 350-400 degrees C; under flame PIR chars rather than melts and drips (literature and vendor, attributed).\",\"Service temperature: PUR generally 100-130 degrees C versus industrial PIR boards about 140-150 degrees C continuous, with PUR and PIR foams withstanding about 250 degrees C short-term (vendor\/literature, attributed).\",\"Long-term lambda drift runs roughly 10-30 percent over 10-25 years in the literature, and FM Approved PIR panels carry a typical 8-18 percent premium on the panel line item (attributed ranges).\"],\"qa_concise\":[{\"question\":\"Which core passes FM 4880 Class 1?\",\"answer\":\"PIR cores can; standard PUR cannot (vendor-attributed).\"},{\"question\":\"How big is the PIR premium?\",\"answer\":\"Typically 8-18 percent on the panel line item, per vendor analysis.\"},{\"question\":\"Does lambda age?\",\"answer\":\"Yes - literature puts drift at roughly 10-30 percent over 10-25 years; buy on declared values.\"},{\"question\":\"First dial to read?\",\"answer\":\"Temperature class times code scenario: it picks the core before any brand does.\"}]}<\/script><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Deux \u00e9chantillons de mousse de 100 mm sont plac\u00e9s sous la m\u00eame flamme du calorim\u00e8tre \u00e0 c\u00f4ne, et le banc de laboratoire se divise en deux camps. L'\u00e9chantillon de polyur\u00e9thane ramollit en quelques instants, affaisse et perd ses gouttelettes fondues. L'\u00e9chantillon de polyisocyanurate noircit, gonfle en formant une cro\u00fbte de charbon et maintient sa g\u00e9om\u00e9trie jusqu'\u00e0 ce que le br\u00fbleur s'arr\u00eate. M\u00eame chimie de r\u00e9acteur, m\u00eames cellules ferm\u00e9es, quasi identiques\u2026<\/p>","protected":false},"author":2,"featured_media":6527,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","rank_math_title":"PU vs PIR Cold Room Panels: Which Core Wins","rank_math_description":"Same reactor, different molecules. 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