{"id":3421,"date":"2024-09-02T10:30:54","date_gmt":"2024-09-02T10:30:54","guid":{"rendered":"https:\/\/ikoknowledgecenter.com\/docs\/uncategorized\/what-are-the-key-considerations-when-applying-a-bituminous-cap-sheet\/"},"modified":"2025-06-26T13:36:50","modified_gmt":"2025-06-26T13:36:50","password":"","slug":"what-are-the-key-considerations-when-applying-a-bituminous-cap-sheet","status":"publish","type":"docs","link":"https:\/\/ikoknowledgecenter.com\/en\/docs\/flat-roof-systems\/what-are-the-key-considerations-when-applying-a-bituminous-cap-sheet\/","title":{"rendered":"What are the key considerations when applying a bituminous cap sheet?"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">For a high-quality two-layer waterproofing system, the cap sheet is preferably installed with full-surface torch welding. Only then will the cap sheet and the underlayer form a seamless whole, resulting in excellent waterproofing and wind resistance.<\/p>\n\n<p class=\"wp-block-paragraph\"><strong>General guidelines:<\/strong><\/p>\n\n<ul class=\"wp-block-list\">\n<li>The substrate must be smooth, dry, clean, and free of grease and dust.<\/li>\n\n\n\n<li>To ensure a good welded seam, a bitumen bead of \u2265 5 mm must always flow out at the overlap.<br\/><br\/><\/li>\n\n\n\n<li>Remove the protective wrappers from the rolls before installation.<\/li>\n\n\n\n<li>Always install the cap sheet in the same direction as the underlayer.<\/li>\n\n\n\n<li>T-joints at end overlaps should be avoided by trimming the corner.<\/li>\n<\/ul>\n\n<ul class=\"wp-block-list\">\n<li>The cap sheet is laid in a staggered (half-bond) pattern with a minimum distance of 2 meters between transverse overlaps.<\/li>\n\n\n\n<li>Avoid cross joints at transverse and longitudinal overlaps to reduce water stagnation.<\/li>\n\n\n\n<li>Always position the cap sheet staggered relative to the underlayer, both longitudinally and transversely. The overlap of the cap sheet should preferably be offset by half a roll width from the underlayer overlap. This ensures the best waterproofing result.<\/li>\n<\/ul>\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-7387b849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<figure class=\"wp-block-image size-full\"><img fetchpriority=\"high\" decoding=\"async\" width=\"535\" height=\"340\" src=\"https:\/\/ikoknowledgecenter.com\/wp-content\/uploads\/2024\/09\/aanbrengen-bitumineuze-toplaag-1.png\" alt=\"\" class=\"wp-image-735\" srcset=\"https:\/\/ikoknowledgecenter.com\/wp-content\/uploads\/2024\/09\/aanbrengen-bitumineuze-toplaag-1.png 535w, https:\/\/ikoknowledgecenter.com\/wp-content\/uploads\/2024\/09\/aanbrengen-bitumineuze-toplaag-1-300x191.png 300w, https:\/\/ikoknowledgecenter.com\/wp-content\/uploads\/2024\/09\/aanbrengen-bitumineuze-toplaag-1-360x229.png 360w\" sizes=\"(max-width: 535px) 100vw, 535px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<ol class=\"wp-block-list\">\n<li>Roll width of the waterproofing membrane<\/li>\n\n\n\n<li>Staggered positioning of cap sheet relative to underlayer (half width)<\/li>\n\n\n\n<li>Minimum distance between end overlaps<\/li>\n\n\n\n<li>Chamfered corners to prevent capillarity<\/li>\n\n\n\n<li>Recommended drainage direction for this laying pattern (without cross joints in the overlap)<\/li>\n<\/ol>\n<\/div>\n<\/div>\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n<p class=\"wp-block-paragraph\">For more information, see our guide:<br data-start=\"1669\" data-end=\"1672\"\/><strong data-start=\"1672\" data-end=\"1743\">\u201c<\/strong><a href=\"https:\/\/eu.iko.com\/en\/documentation\/flat-roof-systems\/this-is-how-you-choose-and-install-the-bituminous-cap-sheet\/\" target=\"_blank\" rel=\"noopener\">This is how you choose and install the bituminous cap sheet<\/a><strong data-start=\"1672\" data-end=\"1743\">\u201d<\/strong>, available on the <strong data-start=\"1762\" data-end=\"1777\">IKO website<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>For a high-quality two-layer waterproofing system, the cap sheet is preferably installed with full-surface torch welding. Only then will the cap sheet and the underlayer form a seamless whole, resulting in excellent waterproofing and wind resistance. General guidelines: For more information, see our guide:\u201cThis is how you choose and install the bituminous cap sheet\u201d, available [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","template":"","meta":{"footnotes":"","_members_access_role":[],"_members_access_error":""},"doc_category":[63],"doc_tag":[64,877,65,307,869,848],"glossaries":[],"class_list":["post-3421","docs","type-docs","status-publish","hentry","doc_category-flat-roof-systems","doc_tag-bitumen-en","doc_tag-flame-welding","doc_tag-flat-roof","doc_tag-roofing-en","doc_tag-top-layer","doc_tag-waterproofing"],"year_month":"2026-10","word_count":232,"total_views":"573","reactions":{"happy":"0","normal":"0","sad":"0"},"author_info":{"name":"Luna Degraeve","author_nicename":"luna","author_url":"https:\/\/ikoknowledgecenter.com\/en\/author\/luna\/"},"doc_category_info":[{"term_name":"Flat roof systems","term_url":"https:\/\/ikoknowledgecenter.com\/en\/docs-category\/flat-roof-systems\/"}],"doc_tag_info":[{"term_name":"bitumen","term_url":"https:\/\/ikoknowledgecenter.com\/en\/docs-tag\/bitumen-en\/"},{"term_name":"flame welding","term_url":"https:\/\/ikoknowledgecenter.com\/en\/docs-tag\/flame-welding\/"},{"term_name":"Flat roof","term_url":"https:\/\/ikoknowledgecenter.com\/en\/docs-tag\/flat-roof\/"},{"term_name":"roofing","term_url":"https:\/\/ikoknowledgecenter.com\/en\/docs-tag\/roofing-en\/"},{"term_name":"top layer","term_url":"https:\/\/ikoknowledgecenter.com\/en\/docs-tag\/top-layer\/"},{"term_name":"waterproofing","term_url":"https:\/\/ikoknowledgecenter.com\/en\/docs-tag\/waterproofing\/"}],"knowledge_base_info":[],"knowledge_base_slug":[],"_links":{"self":[{"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/docs\/3421","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/docs"}],"about":[{"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/types\/docs"}],"author":[{"embeddable":true,"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/comments?post=3421"}],"version-history":[{"count":1,"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/docs\/3421\/revisions"}],"predecessor-version":[{"id":3422,"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/docs\/3421\/revisions\/3422"}],"wp:attachment":[{"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/media?parent=3421"}],"wp:term":[{"taxonomy":"doc_category","embeddable":true,"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/doc_category?post=3421"},{"taxonomy":"doc_tag","embeddable":true,"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/doc_tag?post=3421"},{"taxonomy":"glossaries","embeddable":true,"href":"https:\/\/ikoknowledgecenter.com\/en\/wp-json\/wp\/v2\/glossaries?post=3421"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}