{"id":321,"date":"2026-04-25T21:29:29","date_gmt":"2026-04-25T20:29:29","guid":{"rendered":"http:\/\/sadiqur.xyz\/glazing\/index.php\/condensation-between-double-glazing-causes-fixes\/"},"modified":"2026-04-25T21:29:29","modified_gmt":"2026-04-25T20:29:29","slug":"condensation-between-double-glazing-causes-fixes","status":"publish","type":"post","link":"http:\/\/sadiqur.xyz\/glazing\/index.php\/condensation-between-double-glazing-causes-fixes\/","title":{"rendered":"Condensation Between Double Glazing: Causes &#038; Fixes UK 2026"},"content":{"rendered":"<p><strong>Quick answer:<\/strong> If you can see condensation <strong>between<\/strong> the two panes of glass and you can&#8217;t wipe it off from either side, the perimeter seal in your sealed unit has failed. Repairing that costs <strong>\u00a340\u2013\u00a380 per pane<\/strong>. If the condensation is on the <strong>inside<\/strong> of the glass, your home is too humid \u2014 fixable for free. If it&#8217;s on the <strong>outside<\/strong> early in the morning, that&#8217;s actually a good sign your windows are working properly.<\/p>\n\n<p>Three different types of condensation, three completely different causes, three different fixes. This guide walks through each one, tells you exactly what&#8217;s happening, and what (if anything) to do about it.<\/p>\n\n<h2 class=\"wp-block-heading\">First: figure out which type of condensation you have<\/h2>\n\n<p>Wipe the glass with a dry cloth. The behaviour tells you everything:<\/p>\n\n<figure class=\"wp-block-table\"><table>\n<thead><tr><th>What you see<\/th><th>What it means<\/th><th>How serious<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>Wipes off from <strong>inside<\/strong> the room<\/td><td>Internal condensation \u2014 too much humidity in your home<\/td><td>Easy DIY fix<\/td><\/tr>\n<tr><td>Wipes off from <strong>outside<\/strong> (early morning, autumn\/spring)<\/td><td>External condensation \u2014 your windows are insulating <em>well<\/em><\/td><td>No action needed<\/td><\/tr>\n<tr><td><strong>Between<\/strong> the panes \u2014 you can&#8217;t reach it<\/td><td>Sealed unit has failed<\/td><td>Needs replacing<\/td><\/tr>\n<\/tbody><\/table><\/figure>\n\n<p>Each type below has its own section.<\/p>\n\n<h2 class=\"wp-block-heading\">Type 1: Condensation on the INSIDE \u2014 humidity problem<\/h2>\n\n<p>Cold glass meets warm humid air, and the moisture in that air condenses out as droplets. Your windows are doing their job; your house just has too much moisture in it.<\/p>\n\n<h3 class=\"wp-block-heading\">Where the moisture comes from<\/h3>\n\n<ul class=\"wp-block-list\">\n<li>Showers and baths (a typical 8-minute shower releases ~1 litre of water vapour into the air)<\/li>\n<li>Cooking \u2014 especially boiling pasta, slow cookers, kettles without lids<\/li>\n<li>Drying clothes indoors \u2014 a single full load releases 2\u20133 litres<\/li>\n<li>Breathing \u2014 two adults release ~1 litre overnight<\/li>\n<li>House plants, fish tanks, unvented tumble dryers, gas heaters<\/li>\n<li>Recently completed building work \u2014 wet plaster takes 6+ months to fully dry out<\/li>\n<\/ul>\n\n<h3 class=\"wp-block-heading\">5 fixes that actually work<\/h3>\n\n<ol class=\"wp-block-list\">\n<li><strong>Open windows for 10 minutes twice a day<\/strong> \u2014 even in winter. Quick burst-ventilation costs almost nothing in heating because the warm air leaves but the warm walls and furniture don&#8217;t. Brings humidity down by 20\u201330% in most homes.<\/li>\n<li><strong>Use the extractor fan during AND for 15 minutes after<\/strong> a shower. Most people switch it off when they leave the bathroom \u2014 that&#8217;s exactly when it&#8217;s needed most.<\/li>\n<li><strong>Cover pots when cooking<\/strong> and use the kitchen extractor on a higher setting. Free.<\/li>\n<li><strong>Don&#8217;t dry clothes on radiators<\/strong>. Use a vented tumble dryer, dry outside, or use a dehumidifier in a closed room.<\/li>\n<li><strong>Get a humidity meter<\/strong> (\u00a38\u2013\u00a312 on Amazon). Aim for 40\u201355% relative humidity. Above 65% and condensation is inevitable; below 35% and you&#8217;ll get static and dry skin.<\/li>\n<\/ol>\n\n<h3 class=\"wp-block-heading\">When the fixes aren&#8217;t enough<\/h3>\n\n<p>If you&#8217;ve tried the above for 4 weeks and condensation persists in winter:<\/p>\n\n<ul class=\"wp-block-list\">\n<li>You may have <strong>blocked or missing trickle vents<\/strong>. UK building regs (Approved Document F, 2022) require trickle vents on most replacement windows now \u2014 older windows often don&#8217;t have them. Check the top of each frame; if there&#8217;s a small slider, open it.<\/li>\n<li>You may need a <strong>positive input ventilation (PIV) unit<\/strong> \u2014 a \u00a3350\u2013\u00a3600 loft-mounted device that gently pushes filtered fresh air into the home. Often cheaper than chasing single-room dehumidifiers.<\/li>\n<li>If you have <strong>black mould<\/strong> appearing alongside the condensation, that&#8217;s a separate issue \u2014 mould requires both moisture and the right surface, so cleaning alone won&#8217;t fix it. Tackle the humidity first.<\/li>\n<\/ul>\n\n<h2 class=\"wp-block-heading\">Type 2: Condensation on the OUTSIDE \u2014 actually good news<\/h2>\n\n<p>Counter-intuitive but true: external condensation is a sign your windows are <strong>insulating very effectively<\/strong>. The outer pane stays cold (because no heat from inside is escaping through to warm it), and any moisture in the early-morning air condenses on it.<\/p>\n\n<ul class=\"wp-block-list\">\n<li>Most common in <strong>autumn and spring<\/strong>, when overnight temperatures drop sharply but daytime humidity is high<\/li>\n<li>Usually clears within 30\u201360 minutes once the sun warms the glass<\/li>\n<li>Modern A-rated and triple-glazed windows show this <em>more often<\/em> than older inefficient windows \u2014 a counter-intuitive but well-documented effect<\/li>\n<\/ul>\n\n<p><strong>Action needed: none.<\/strong> If it&#8217;s bothering you cosmetically, anti-condensation glass coatings exist but cost \u00a380\u2013\u00a3150 per pane to retrofit and rarely justify the spend. Most people just live with it.<\/p>\n\n<h2 class=\"wp-block-heading\">Type 3: Condensation BETWEEN the panes \u2014 failed seal<\/h2>\n\n<p>This is the only type that means your window itself has a problem. The perimeter seal in the sealed glass unit (IGU) has failed \u2014 moisture is now getting into the gap between the panes, and the gas that used to insulate has escaped.<\/p>\n\n<h3 class=\"wp-block-heading\">Why it happens<\/h3>\n\n<ul class=\"wp-block-list\">\n<li><strong>Age<\/strong> \u2014 typical IGU seal lifespan is 10\u201325 years. Over that range it&#8217;s a probability game.<\/li>\n<li><strong>UV exposure<\/strong> \u2014 south-facing windows fail sooner than north-facing ones<\/li>\n<li><strong>Cheap manufacture<\/strong> \u2014 single-seal units fail in 5\u201310 years; dual-seal lasts 15\u201325<\/li>\n<li><strong>Bad install<\/strong> \u2014 units must seat on packers without bridging the drainage holes; a sloppy install accelerates failure<\/li>\n<li><strong>Pressure-washing<\/strong> \u2014 high-pressure water forces past the gaskets and into the seal<\/li>\n<\/ul>\n\n<h3 class=\"wp-block-heading\">What it costs to fix<\/h3>\n\n<p>You don&#8217;t need a whole new window. You replace just the sealed glass unit \u2014 frame stays put, hardware untouched. Typical UK pricing in 2026:<\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Small standard pane:<\/strong> \u00a340\u2013\u00a360 fitted<\/li>\n<li><strong>Medium pane:<\/strong> \u00a355\u2013\u00a385<\/li>\n<li><strong>Large pane or door panel:<\/strong> \u00a380\u2013\u00a3140<\/li>\n<li><strong>4-window package booked together:<\/strong> \u00a3200\u2013\u00a3300<\/li>\n<\/ul>\n\n<p>Full breakdown of when to repair vs replace the whole window: see our <a href=\"\/glazing\/index.php\/misted-window-repair-cost-uk-or-replace\/\">misted window repair cost guide<\/a>.<\/p>\n\n<h2 class=\"wp-block-heading\">What NOT to do (mistakes we see all the time)<\/h2>\n\n<ul class=\"wp-block-list\">\n<li><strong>Don&#8217;t try to drill a &#8220;drain hole&#8221; in a misted unit<\/strong>. People do this; it never works long-term and ruins the warranty on any future repair.<\/li>\n<li><strong>Don&#8217;t seal up trickle vents<\/strong> to &#8220;stop draughts&#8221;. You&#8217;ll trade a cold corner for a black-mould problem within 18 months.<\/li>\n<li><strong>Don&#8217;t blame the installer for external condensation<\/strong> \u2014 it&#8217;s a sign of good performance, not a fault.<\/li>\n<li><strong>Don&#8217;t ignore inside-glass condensation<\/strong> over winter. Unaddressed it leads to mould, peeling paint, and water damage to window cills.<\/li>\n<li><strong>Don&#8217;t assume one misted window means all of them are about to go.<\/strong> Each unit is sealed independently; one failing doesn&#8217;t trigger the others.<\/li>\n<\/ul>\n\n<h2 class=\"wp-block-heading\">Frequently asked questions<\/h2>\n\n<h3 class=\"wp-block-heading\">Why do my new windows have more condensation than my old ones?<\/h3>\n<p>Two reasons. First, modern windows seal the home much better \u2014 the moisture you generate inside has fewer places to escape. Second, A-rated glass keeps the outer pane colder, which makes external condensation more visible. Both are signs of better windows, not worse. The fix is ventilation, not blaming the install.<\/p>\n\n<h3 class=\"wp-block-heading\">Will a dehumidifier solve internal condensation?<\/h3>\n<p>Yes, but ventilation is usually cheaper and addresses the root cause. A dehumidifier is the right call when ventilation alone isn&#8217;t enough \u2014 typically in flats with limited airflow or homes with new wet plaster still drying out. Budget \u00a3150\u2013\u00a3300 for a quality unit; \u00a380\u2013\u00a3150 of electricity per year to run.<\/p>\n\n<h3 class=\"wp-block-heading\">Can a misted window cause damp in the wall around it?<\/h3>\n<p>Not directly \u2014 the moisture is sealed inside the unit. But the failed seal usually means worse insulation, which makes the wall around the frame colder, which means more internal condensation forms there. Replace the unit and the surrounding damp usually clears within a few weeks of normal heating.<\/p>\n\n<h3 class=\"wp-block-heading\">Should I worry if condensation only appears in one room?<\/h3>\n<p>Not necessarily. Bathrooms, kitchens and unheated rooms naturally show more condensation. Single-room condensation usually means a single-room cause: bath without extractor, washing dried in there, no heating in winter.<\/p>\n\n<h3 class=\"wp-block-heading\">How long do new windows last before condensation between the panes appears?<\/h3>\n<p>10\u201325 years for the sealed unit, depending on quality. Frames last longer. Full breakdown: <a href=\"\/glazing\/index.php\/how-long-do-double-glazed-windows-last\/\">how long do double glazed windows last?<\/a><\/p>\n\n<h2 class=\"wp-block-heading\">Get quotes for sealed-unit replacement or new windows<\/h2>\n<p>If your sealed units have failed and you&#8217;d like quotes from local glass-only specialists or full FENSA-registered installers, we&#8217;ll match you with up to 4 vetted UK installers in 24 hours. Free, no obligation, no pressure.<\/p>\n<p style=\"text-align:center;font-size:1.15em;\"><a href=\"\/glazing\/index.php\/quote\/\" style=\"display:inline-block;background:#2d6a4f;color:#fff;padding:14px 28px;border-radius:10px;text-decoration:none;font-weight:700;\">Get my 4 free quotes \u2192<\/a><\/p>\n\n<p style=\"font-size:13px;color:#64748b;\"><em>Sources used: Eco Experts condensation guide (2026), Homebuilding &#038; Renovating condensation analysis, MyJobQuote condensation removal cost data, Anglian Home Improvements draughty\/condensation clinic, FENSA Building Regs Part F guidance (2022 updates), Glass and Glazing Federation IGU lifespan data. Last reviewed: April 2026.<\/em><\/p>","protected":false},"excerpt":{"rendered":"<p>Three types of window condensation \u2014 inside, outside, and between the panes \u2014 each with totally different causes and fixes. Here&#8217;s how to spot which is which and what to do about it.<\/p>\n","protected":false},"author":1,"featured_media":312,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[20,21,16,22],"class_list":["post-321","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-condensation","tag-humidity","tag-misted-windows","tag-ventilation"],"_links":{"self":[{"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/posts\/321","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/comments?post=321"}],"version-history":[{"count":0,"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/posts\/321\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/media\/312"}],"wp:attachment":[{"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/media?parent=321"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/categories?post=321"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/sadiqur.xyz\/glazing\/index.php\/wp-json\/wp\/v2\/tags?post=321"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}