{"id":1020,"date":"2026-08-10T10:00:00","date_gmt":"2026-08-10T10:00:00","guid":{"rendered":"https:\/\/pressure.mobi\/blog\/?p=1020"},"modified":"2026-08-10T10:00:00","modified_gmt":"2026-08-10T10:00:00","slug":"cleaning-composite-decking-trex","status":"publish","type":"post","link":"https:\/\/pressure.mobi\/blog\/cleaning-composite-decking-trex\/","title":{"rendered":"Cleaning composite decking without voiding the warranty"},"content":{"rendered":"

Composite decking is sold as maintenance-free, grows mould anyway, and can absolutely be damaged by a pressure washer \u2014 a combination that surprises nearly everyone who owns it. Safe deck cleaning<\/a> on Trex and its cousins is a matter of following the manufacturer’s numbers.<\/p>\n

Why ‘maintenance-free’ grows mould<\/h2>\n

Composite boards are wood fibre in a polymer matrix, usually with a harder cap layer. The embossed grain texture that makes them look like timber also gives organic material somewhere to sit: pollen, leaf tannin and airborne spores settle into the pattern, and in shade the surface grows mould exactly like wood does.<\/p>\n

It cleans off readily \u2014 the material is genuinely easier to clean than timber \u2014 but it does need cleaning, which is the part the marketing skips.<\/p>\n

The warranty numbers<\/h2>\n

Most composite manufacturers publish care guidance with a maximum pressure and a minimum nozzle distance, and several warranties are conditional on following it. Exceed the numbers and the cap layer can be permanently marked \u2014 often as a lighter, roughened patch that no product will restore.<\/p>\n

The safe approach is the one we use anyway: an appropriate cleaner, soft brush agitation in the grain direction, and a low-pressure, wide-fan rinse from a respectful distance. The chemistry does the work; the water rinses.<\/p>\n

The two composite-specific problems<\/h2>\n

Early-generation uncapped boards stain deeper and may retain some tannin shadowing after cleaning \u2014 honest expectations apply. And spot-cleaning one bad area often leaves a visibly cleaner patch, which is why the right unit of work is the whole deck, not the stain.<\/p>\n

Know your board brand if you can. It changes the chemistry we choose and what we promise about the result.<\/p>\n

Tell us what the deck is made of when you send photos \u2014 composite and timber are quoted as different jobs because they are.<\/em> Read more about deck cleaning →<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Composite decking is sold as maintenance-free, grows mould anyway, and can absolutely be damaged by a pressure washer \u2014 a combination that surprises nearly everyone who owns it. Safe deck cleaning on Trex and its cousins is a matter of following the manufacturer’s numbers.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"pagelayer_contact_templates":[],"_pagelayer_content":"","footnotes":""},"categories":[6],"tags":[],"class_list":["post-1020","post","type-post","status-publish","format-standard","hentry","category-deck-fence"],"_links":{"self":[{"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/posts\/1020","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/comments?post=1020"}],"version-history":[{"count":1,"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/posts\/1020\/revisions"}],"predecessor-version":[{"id":1091,"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/posts\/1020\/revisions\/1091"}],"wp:attachment":[{"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/media?parent=1020"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/categories?post=1020"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pressure.mobi\/blog\/wp-json\/wp\/v2\/tags?post=1020"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}