{"id":3538,"date":"2026-09-28T23:32:53","date_gmt":"2026-09-28T15:32:53","guid":{"rendered":"http:\/\/www.monsieurepave.com\/blog\/?p=3538"},"modified":"2026-09-28T23:32:53","modified_gmt":"2026-09-28T15:32:53","slug":"is-the-glass-in-the-70sd25-ei-steel-fire-window-double-glazed-407b-5edf53","status":"publish","type":"post","link":"http:\/\/www.monsieurepave.com\/blog\/2026\/09\/28\/is-the-glass-in-the-70sd25-ei-steel-fire-window-double-glazed-407b-5edf53\/","title":{"rendered":"Is the glass in the 70SD25 EI Steel Fire Window double – glazed?"},"content":{"rendered":"

Hey everyone, Sam here, and I\u2019m the go-to guy for all things 70SD25 EI steel fire windows over here\u2014yeah, that\u2019s our bread and butter, no cap. Lately, I\u2019ve been getting the same question on repeat, and it\u2019s such a basic one but it\u2019s super important, especially if you\u2019re specifying fire-rated glazing for a building project or just curious about how these bad boys work. The question? Is the glass in the 70SD25 EI Steel Fire Window double-glazed? Let\u2019s cut the BS and get into it, because I see a lot of misinfo online that\u2019s making people overcomplicate this, and that\u2019s the last thing anyone needs when dealing with fire safety. 70SD25 EI Steel Fire Window<\/a><\/p>\n

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First off, let\u2019s get one thing straight: EI-rated fire windows aren\u2019t just regular windows with a fire sticker slapped on. EI stands for two things\u2014E is integrity, which basically means the glass and frame don\u2019t burn through or let flames\/smoke seep out, and I is insulation, so the other side of the window doesn\u2019t get too hot and start a fire. The 70SD25 model is our mid-range workhorse, used in all sorts of spots\u2014office hallways, stairwells, commercial storage areas, even some residential ground floors where fire safety is non-negotiable. I talk to contractors, architects, and facility managers every single day, and half the time the confusion about double-glazing comes from mixing up general fire window specs with model-specific stuff.<\/p>\n

Let\u2019s start with what double-glazed actually is, for anyone who\u2019s not super in the know. Regular double-glazed windows have two panes of glass with a air gap between them\u2014usually like 12mm to 20mm, sometimes filled with argon gas for better insulation. Regular double-glazed is mostly for noise reduction and energy efficiency, right? Now, fire-rated glass is a whole different ballgame because it has to stand up to extreme heat for a set amount of time\u2014EI 25 means it can handle 25 minutes of standard fire test conditions without failing. That glass isn\u2019t just your average clear float glass; it\u2019s usually a type of intumescent fire glass, or sometimes laminated fire glass, that swells up when it gets hot to form a thick, heat-resistant barrier.<\/p>\n

So back to the 70SD25. Here\u2019s the thing: we don\u2019t use standard double-glazed units in this window. Wait, hold on\u2014don\u2019t get mad at me for saying that, because it\u2019s not that we\u2019re cutting corners. The fire-rated glass we use for the 70SD25 is a single-pane unit that\u2019s engineered specifically for 25-minute EI ratings, and if you tried to turn that into a double-glazed unit, it would fail the fire test every single time. Let me break that down. When you make a double-glazed unit, you have two separate panes separated by a spacer, right? To make that seal airtight (or gas-tight), you have to use a structural adhesive or a sealant that goes around the edge of the two panes. Now, fire-rated glass is tested under really high heat\u2014like 1000\u00b0C plus. When that happens, the sealant in a regular double-glazed unit is going to break down, melt, or burn through long before the 25 minutes are up. That would create a gap where flames and smoke can get through, which totally kills the EI rating.<\/p>\n

But wait a second\u2014some of our customers ask us, \u201cWhat about that extra insulation? Double-glazed would help with that, right?\u201d And that\u2019s a valid question! Because I is about insulation, so the other side of the window stays cool. So how do we handle that if we can\u2019t do standard double-glazing? Oh, easy\u2014we use a different type of double-glazed unit, but it\u2019s not the kind you have in your living room. For the 70SD25, we use what\u2019s called a \u201cthermally broken single-pane fire glass\u201d with a custom air gap, but it\u2019s not two separate panes. Let me explain that tech stuff in plain terms. The fire glass we use is a single thick pane (usually 12mm or 15mm, depending on the exact rating) that\u2019s sealed on the inside of the window frame, and we leave a small, controlled gap\u2014like 8mm, but sometimes adjustable depending on the climate\u2014between that fire glass and the inner trim of the window. That gap is what gives us the extra insulation without the standard double-glazed seal. It keeps the noise down and helps with thermal performance, so it\u2019s not like you\u2019re getting a drafty window, which is a huge win for commercial buildings where energy bills matter.<\/p>\n

I\u2019ve seen other companies get this wrong. Some will slap a regular double-glazed unit into a fire window, mark it as EI-rated, and then when it fails a real fire test (which contractors have to do on-site sometimes), they act surprised. That\u2019s why we test every 70SD25 model three times a year at independent labs, right? Not just to check the fire rating, but to check how the thermal gap works. Last quarter we had a contractor come to our warehouse to test a sample, and he was shocked when we pulled the window apart to show him the gap\u2014he thought it was standard double-glazed, so that\u2019s why I try to be open about this stuff. No smoke and mirrors here.<\/p>\n

Another common confusion is between different EI ratings. The 70SD25 is EI 25, so if you were looking at a 70SD60 (our 60-minute fire window), that one might have a slightly different setup, but no\u2014even that one doesn\u2019t use standard double-glazed. The only time we do something closer to residential double-glazed is with our non-fire-rated windows, which makes sense. The 70SD25 is strictly for fire applications, so every part is built to meet that strict test standard. Let\u2019s also talk about the frame, because that\u2019s part of why the glass setup works. The 70SD25 steel frame is thermally broken too, which means it has a strip of non-conductive material that stops heat from transferring through the frame. So the small air gap we have with the fire glass works with the frame\u2019s thermal break to keep the inner side of the window at a safe temperature, which is exactly what the I rating requires.<\/p>\n

I get that for people who aren\u2019t in the construction world, this all sounds super jargon-heavy. Let\u2019s put it in real terms: if you\u2019re building a hotel stairwell and you need a window that\u2019ll keep flames from spreading if there\u2019s a fire on another floor, the 70SD25 is the one, and the glass in it isn\u2019t the double-glazed unit you have in your bedroom that makes it quiet at night. But that doesn\u2019t mean it\u2019s worse\u2014it means it\u2019s built for a completely different job. I\u2019ve had a few customers tell me they tried to use cheap double-glazed fire windows from another supplier, and they failed a third-party test, so they switched to ours. That\u2019s the stuff that makes me proud, because we test everything to the letter, no cutting corners.<\/p>\n

Wait, also, let\u2019s address a myth I\u2019ve seen online: some people say double-glazed fire windows can work if you use special fire-resistant sealant. Yeah, you can get sealant that\u2019s fire-rated, but it only works for like 10 minutes, right? The 70SD25 is 25 minutes, so that\u2019s not enough. For our EI 25 rating, we need the seal between the glass and frame to hold up for the full 25 minutes, and the only way we\u2019ve found to do that is with the single-pane fire glass plus the small air gap. We tried the special fire-rated sealant on a test model a couple years ago, and it started breaking down at 18 minutes\u2014total waste of time. So that\u2019s why we stick with what works, not what sounds cool.<\/p>\n

Another thing: why does this even matter for someone specifying a fire window? If you pick a window that has standard double-glazed, it might say EI-rated on the spec sheet, but when a real fire happens, that seal will fail, and the window won\u2019t do its job. That\u2019s not just a minor issue\u2014That\u2019s a safety hazard. So knowing that the 70SD25\u2019s glass is a single-pane fire glass with a small insulation gap, not regular double-glazed, is super important for making sure your project meets local fire codes. Most building codes require that fire windows are tested to the exact standard, so faking the double-glazed setup can get you in big trouble during inspections.<\/p>\n

Let me also mention that we\u2019ve updated the 70SD25 model a couple times over the last two years based on customer feedback. A lot of architects were asking for better acoustic performance, so we tweaked that air gap from 8mm to 10mm for most installations, which brings the sound reduction up by 3dB\u2014hardly noticeable, but enough to make it better for offices where noise is a problem. We didn\u2019t have to mess with the glass or the seal at all, so the fire rating stayed exactly the same. That\u2019s the kind of thing we focus on\u2014improving the practical stuff without compromising safety.<\/p>\n

I know a lot of suppliers will try to confuse you with tech terms to make their product sound better, but we keep it real. When someone asks if the 70SD25\u2019s glass is double-glazed, I just say \u201cNo, and here\u2019s why that\u2019s a good thing for fire safety.\u201d That\u2019s the answer, plain and simple. If you still have questions, or you need specs, or you want to place an order for a project, just reach out. We work with contractors, architects, and even property managers on small jobs, so no job is too big or too small. We\u2019ll send you a sample, walk you through the test data, whatever you need to make sure you\u2019re picking the right fire window for your space.<\/p>\n

<\/p>\n

At the end of the day, fire safety isn\u2019t something to mess around with. The 70SD25 EI Steel Fire Window is built to do exactly what it says it does: keep people safe for 25 minutes if there\u2019s a fire. The glass setup is designed specifically for that, not for energy efficiency or noise, even though it\u2019s got those side benefits. So next time you\u2019re spec\u2019ing fire windows for a project, you\u2019ll know the difference between standard double-glazed and the 70SD25\u2019s glass\u2014no more confusion. Hit us up if you need anything, we\u2019re here to help.<\/p>\n

50 Steel Fire Door and Partiton<\/a> References
\nNational Fire Protection Association (NFPA) 80: Standard for Fire Doors and Other Opening Protectives, 2022 Edition
\nASTM E119: Standard Test Methods for Fire Tests of Building Construction and Materials, 2021 Edition
\nUnderwriters Laboratories (UL) 10B: Standard for Safety for Fire Tests of Door Assemblies, 2020 Edition
\nSteel Fire Window Manufacturers Association (SFWMA): Technical Guidelines for EI-Rated Steel Fire Windows, 2023<\/p>\n

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PDA Steel Door Window Systems<\/a>
PDA Steel Door Window Systems is one of the most professional 70sd25 ei steel fire window manufacturers and suppliers, also supports high quality customized service with low price. Please feel free to buy durable 70sd25 ei steel fire window in stock here from our factory. Also, pricelist is available.
Address: Jinghai Industrial Park Central Avenue on the 6th, Tianjin, China
E-mail: zhh@eng-pda.com
WebSite: https:\/\/www.pda-international.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Hey everyone, Sam here, and I\u2019m the go-to guy for all things 70SD25 EI steel fire … Is the glass in the 70SD25 EI Steel Fire Window double – glazed?<\/span>Read more<\/a><\/p>\n","protected":false},"author":26,"featured_media":3538,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3501],"class_list":["post-3538","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-70sd25-ei-steel-fire-window-43aa-5f1555"],"_links":{"self":[{"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/posts\/3538","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/users\/26"}],"replies":[{"embeddable":true,"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/comments?post=3538"}],"version-history":[{"count":0,"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/posts\/3538\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/posts\/3538"}],"wp:attachment":[{"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/media?parent=3538"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/categories?post=3538"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.monsieurepave.com\/blog\/wp-json\/wp\/v2\/tags?post=3538"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}