{"id":15,"date":"2026-08-04T10:50:25","date_gmt":"2026-08-04T10:50:25","guid":{"rendered":"https:\/\/dampdeck.com\/?guide=damp-and-mould-in-the-bathroom-causes-and-what-to-do"},"modified":"2026-08-04T10:50:25","modified_gmt":"2026-08-04T10:50:25","slug":"damp-and-mould-in-the-bathroom-causes-and-what-to-do","status":"publish","type":"guide","link":"https:\/\/dampdeck.com\/?guide=damp-and-mould-in-the-bathroom-causes-and-what-to-do","title":{"rendered":"Damp and Mould in the Bathroom: Causes and What to Do"},"content":{"rendered":"<p>A hot shower can release a large amount of water vapour into the air in minutes. In a small room with poor extraction, that moisture has nowhere to go except onto the coldest surfaces &mdash; tiles, grout, the ceiling above the shower, and window frames.<\/p>\n<h2>Why it keeps coming back<\/h2>\n<p>Mould in bathroom grout and silicone sealant is extremely common and, on its own, isn&#8217;t usually a sign of a structural damp problem &mdash; it&#8217;s a sign the room isn&#8217;t drying out between uses. The most common causes are an extractor fan that&#8217;s underpowered, not switched on, or not run for long enough after showering, and a lack of any window ventilation as a backup.<\/p>\n<h2>What to check<\/h2>\n<ul>\n<li>Does the extractor fan actually pull air, or is it just noise? Hold a piece of tissue near it &mdash; it should be pulled toward the fan.<\/li>\n<li>Is the fan wired to run for a set time after the light switches off (a &#8220;run-on timer&#8221;), or does it stop the instant you leave?<\/li>\n<li>Is there mould specifically around a window frame or an external wall, rather than just grout? That can point to condensation from a colder surface rather than just poor extraction.<\/li>\n<li>Any staining or bubbling paint that follows a pipe run (behind a bath panel, under a sink) rather than a general spread &mdash; that&#8217;s more likely a leak than condensation.<\/li>\n<\/ul>\n<h2>What to do<\/h2>\n<ul>\n<li>Run the extractor fan during the shower and for at least 15&ndash;20 minutes afterwards.<\/li>\n<li>Wipe down tiles and the shower screen after use &mdash; this alone significantly cuts the moisture left to evaporate into the room.<\/li>\n<li>Leave the bathroom door open (or a window cracked) after bathing to let moisture escape rather than migrate into the hallway or bedroom.<\/li>\n<li>Re-seal grout and silicone if it&#8217;s already black &mdash; mould in old sealant is very difficult to fully clean out and usually needs replacing.<\/li>\n<li>If the fan is weak or has no run-on timer, a qualified electrician can usually upgrade it relatively cheaply &mdash; get more than one quote before committing.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Bathrooms generate more moisture than any other room in the house. Here&#8217;s why mould keeps coming back and what actually stops it.<\/p>\n","protected":false},"featured_media":0,"template":"","meta":{"footnotes":""},"dd_pillar":[2],"dd_damp_type":[],"class_list":["post-15","guide","type-guide","status-publish","hentry","dd_pillar-diagnosis"],"_links":{"self":[{"href":"https:\/\/dampdeck.com\/index.php?rest_route=\/wp\/v2\/guide\/15","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\/15\/revisions"}],"wp:attachment":[{"href":"https:\/\/dampdeck.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=15"}],"wp:term":[{"taxonomy":"dd_pillar","embeddable":true,"href":"https:\/\/dampdeck.com\/index.php?rest_route=%2Fwp%2Fv2%2Fdd_pillar&post=15"},{"taxonomy":"dd_damp_type","embeddable":true,"href":"https:\/\/dampdeck.com\/index.php?rest_route=%2Fwp%2Fv2%2Fdd_damp_type&post=15"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}