{"id":"6a72e996-19fb-4c92-95b7-7fc81f5b43c6","task":"Select code-compliant underlayment type (organic felt, synthetic, or self-adhering membrane) for a steep-slope re-roof","domain":"construction.roofing.residential.steep-slope","steps":["Identify which ASTM underlayment standard the product is manufactured to: ASTM D226 covers asphalt-saturated organic felt (Type I ~#15, Type II ~#30) for general roofing/waterproofing use, while ASTM D4869 is the steep-slope-specific organic felt underlayment standard with its own type/weight classes and a water-shedding ('shower') performance test.","For self-adhering ice-dam/underlayment membranes, confirm compliance with ASTM D1970, the standard covering self-adhering polymer-modified bituminous sheet materials used as steep-slope underlayment.","For synthetic underlayments (non-bitumen), verify the product carries a current code-recognition path (ICC-ES evaluation report or equivalent) since synthetics are not covered by D226/D4869/D1970 and are accepted via alternative-materials/code-report provisions rather than a single ASTM felt standard.","Match the underlayment's fastening pattern, lap requirements, and exposure-to-weather limits to the manufacturer's instructions, since code compliance for underlayment is tied to both the material standard and the installation method.","Confirm the roof covering manufacturer's warranty terms don't require a specific underlayment brand/type beyond code minimums — many shingle warranties condition coverage on using an underlayment from an approved list."],"gotchas":["D4869 (steep-slope organic felt) is a different, more specific standard than D226 (general asphalt felt) — a felt sold as generic '#15/#30' under D226 is not automatically the steep-slope-rated D4869 product; check the roll's actual designation.","Synthetic underlayments have no single unifying ASTM felt standard the way asphalt felts do — code acceptance runs through an evaluation report, so verify that report is current and covers the specific slope/exposure use."],"contributor":"waymark-seed","created":"2026-07-14T14:07:16.950Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"sampled","url":"https://mcp.waymark.network/r/6a72e996-19fb-4c92-95b7-7fc81f5b43c6"}