{"id":30,"date":"2026-08-04T10:50:25","date_gmt":"2026-08-04T10:50:25","guid":{"rendered":"https:\/\/dampdeck.com\/?guide=damp-in-a-conservatory-or-flat-roofed-extension"},"modified":"2026-08-04T10:50:25","modified_gmt":"2026-08-04T10:50:25","slug":"damp-in-a-conservatory-or-flat-roofed-extension","status":"publish","type":"guide","link":"https:\/\/dampdeck.com\/?guide=damp-in-a-conservatory-or-flat-roofed-extension","title":{"rendered":"Damp in a Conservatory or Flat-Roofed Extension"},"content":{"rendered":"<p>Conservatories and flat-roofed single-storey extensions are prone to damp for structural reasons distinct from the rest of the house: large areas of glazing lose heat fast (creating cold surfaces for condensation), and flat roofs are more failure-prone than pitched, tiled roofs if not built and maintained correctly.<\/p>\n<h2>Condensation on glazing<\/h2>\n<p>Single-glazed or older double-glazed conservatory panels cool rapidly once the heating&#8217;s off, and a large glazed area means a lot of cold surface for warm, moist household air to condense on. This is especially common where a conservatory is used for drying laundry or houses a lot of plants, both of which add moisture to the air.<\/p>\n<h2>Flat roof leaks<\/h2>\n<p>Flat roofs (felt, fibreglass\/GRP, or rubber membrane) have a shorter typical lifespan than pitched tiled roofs and are more prone to leaks at joints, upstands, and where they meet a wall. A leak here can show as a damp patch on the ceiling or in the corner where the extension roof meets the main house wall &mdash; a detail that&#8217;s a common weak point.<\/p>\n<h2>Cold bridging where the extension meets the house<\/h2>\n<p>The junction between an extension and the main building is a common place for a &#8220;cold bridge&#8221; &mdash; a point where heat escapes faster than the surrounding structure, creating a persistently cold, damp-prone spot regardless of ventilation.<\/p>\n<h2>What to do<\/h2>\n<ul>\n<li>For glazing condensation: ventilate well, avoid using the space to dry laundry, and consider secondary glazing or blinds with an air gap if the room is in regular winter use.<\/li>\n<li>For a suspected flat roof leak, check the roof (or have someone else check it) after heavy rain, looking for standing water, bubbling, or splits in the membrane, particularly around any upstands or the join with the house wall.<\/li>\n<li>For a persistent damp patch at the extension-to-house junction that doesn&#8217;t respond to ventilation changes, this may be a cold-bridging or flashing detail that needs a builder to inspect rather than a DIY fix.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Conservatories and flat-roofed extensions have their own damp patterns, driven by big glazed areas and roofs that are easy to get wrong.<\/p>\n","protected":false},"featured_media":0,"template":"","meta":{"footnotes":""},"dd_pillar":[2],"dd_damp_type":[],"class_list":["post-30","guide","type-guide","status-publish","hentry","dd_pillar-diagnosis"],"_links":{"self":[{"href":"https:\/\/dampdeck.com\/index.php?rest_route=\/wp\/v2\/guide\/30","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dampdeck.com\/index.php?rest_route=\/wp\/v2\/guide"}],"about":[{"href":"https:\/\/dampdeck.com\/index.php?rest_route=\/wp\/v2\/types\/guide"}],"version-history":[{"count":0,"href":"https:\/\/dampdeck.com\/index.php?rest_route=\/wp\/v2\/guide\/30\/revisions"}],"wp:attachment":[{"href":"https:\/\/dampdeck.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=30"}],"wp:term":[{"taxonomy":"dd_pillar","embeddable":true,"href":"https:\/\/dampdeck.com\/index.php?rest_route=%2Fwp%2Fv2%2Fdd_pillar&post=30"},{"taxonomy":"dd_damp_type","embeddable":true,"href":"https:\/\/dampdeck.com\/index.php?rest_route=%2Fwp%2Fv2%2Fdd_damp_type&post=30"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}