{"product_id":"breathable-roof-membrane-underlay-120gsm-1m-x-50m","title":"Breathable Roof Membrane Underlay 120GSM | 1m x 50m Roll","description":"\u003cp\u003eBreathable roof membrane underlay at 120GSM is a vapour-permeable felt designed for use beneath tiled or slated pitched roofs. This 1m x 50m roll allows moisture vapour to escape while blocking water ingress, making separate eaves ventilation unnecessary in most applications.\u003c\/p\u003e\n\n\u003ch2\u003eSpecifications\u003c\/h2\u003e\n\u003ctable\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003ePolypropylene non-woven fabric\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eGrade\u003c\/th\u003e\n\u003ctd\u003e120GSM\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eNominal Size\u003c\/th\u003e\n\u003ctd\u003e1m x 50m per roll\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eCoverage\u003c\/th\u003e\n\u003ctd\u003e50 square metres per roll\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eUse Class\u003c\/th\u003e\n\u003ctd\u003ePitched roofs, tiled or slated, warm or cold roof construction\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eWhat it's used for\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eUnderlaying concrete, clay or natural slate roof tiles on pitched domestic and commercial roofs\u003c\/li\u003e\n  \u003cli\u003eWarm roof and cold roof construction where vapour permeability removes the need for a separate ventilation gap\u003c\/li\u003e\n  \u003cli\u003eFull supported or unsupported installation over rafters or sarking boards\u003c\/li\u003e\n  \u003cli\u003eRefurbishment and re-roofing projects where the existing sarking felt is being replaced\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eFitting and handling\u003c\/h2\u003e\n\u003cp\u003eLay the membrane horizontally across the rafters with a minimum 150mm overlap at horizontal laps and 100mm at vertical joints, working from eaves to ridge. Fix using clout nails or a staple gun at each rafter, ensuring the membrane is taut but not over-tensioned, as some drape between rafters aids drainage. Store rolls upright in a dry location away from prolonged UV exposure before installation.\u003c\/p\u003e\n\n\u003ch2\u003eFAQ\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eDoes a 120GSM breathable membrane remove the need for roof ventilation?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIn most cases, yes. A vapour-permeable underlay at 120GSM allows moisture vapour to pass through the membrane and dissipate, so a separate ventilation gap between the underlay and insulation is not required. Always check current building regulations and the tile manufacturer's guidance for your specific roof build-up.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eHow many rolls do I need for my roof?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eEach roll covers 50 square metres at 1 metre wide. Measure the total rafter slope area of your roof, then add approximately 15% to allow for overlaps at horizontal and vertical laps. For a straightforward calculation on site, divide the total slope area by 50 and round up to the nearest whole roll.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan this membrane be used on a cold roof as well as a warm roof?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes. The BreatheShield 120GSM membrane is suitable for both warm roof and cold roof construction, ventilated or non-ventilated, whether laid fully supported over sarking boards or unsupported directly over open rafters.\u003c\/p\u003e\n\n\u003cp\u003eNottage Timber Merchants supply breathable roof membrane alongside a wide range of sheet materials including \u003ca href=\"\/collections\/osb\"\u003eOSB boards\u003c\/a\u003e, available to trade and retail customers across Bridgend and South Wales, with next-day delivery options to the local area. Call or order online to confirm stock and quantities.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Does a 120GSM breathable membrane remove the need for roof ventilation?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"In most cases, yes. A vapour-permeable underlay at 120GSM allows moisture vapour to pass through the membrane and dissipate, so a separate ventilation gap between the underlay and insulation is not required. Always check current building regulations and the tile manufacturer's guidance for your specific roof build-up.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How many rolls do I need for my roof?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Each roll covers 50 square metres at 1 metre wide. Measure the total rafter slope area of your roof, then add approximately 15% to allow for overlaps at horizontal and vertical laps. Divide the total slope area by 50 and round up to the nearest whole roll.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can this membrane be used on a cold roof as well as a warm roof?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. The BreatheShield 120GSM membrane is suitable for both warm roof and cold roof construction, ventilated or non-ventilated, whether laid fully supported over sarking boards or unsupported directly over open rafters.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"Nottage Timber Merchants","offers":[{"title":"Default Title","offer_id":52953484493137,"sku":null,"price":49.9,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0994\/1467\/1697\/files\/breath.webp?v=1770040846","url":"https:\/\/www.timberonline.co.uk\/products\/breathable-roof-membrane-underlay-120gsm-1m-x-50m","provider":"Nottage Timber Merchants","version":"1.0","type":"link"}