{"product_id":"f-ball-stopgap-f77-epoxy-damp-proof-membrane","title":"F. Ball Stopgap F77 Epoxy Damp Proof Membrane","description":"\u003cdiv class=\"wwfs-product-description\"\u003e\n\n  \u003cdiv class=\"wwfs-product-intro\"\u003e\n    \u003cp\u003eF. Ball Stopgap F77 is a professional, solvent-free, two-part epoxy damp proof membrane designed to control residual construction moisture and rising damp in concrete and sand\/cement screeds before installing smoothing compounds, adhesives and floor coverings.\u003c\/p\u003e\n\n    \u003cp\u003eApplied as a single coat, F77 can provide moisture protection at subfloor relative humidity readings of up to 98% RH. It cures from approximately three hours at 20°C, making it ideal for fast-track domestic and commercial flooring installations where waiting for the subfloor to dry naturally would cause unnecessary delays.\u003c\/p\u003e\n\n    \u003cp\u003eStopgap F77 is supplied as a pre-measured resin and hardener kit and is available from WWFS in practical 7kg and 14kg sizes.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eWhy Choose F. Ball Stopgap F77?\u003c\/h2\u003e\n\n  \u003cdiv class=\"wwfs-benefit-list\"\u003e\n    \u003cul\u003e\n      \u003cli\u003eProfessional two-part epoxy waterproof surface membrane.\u003c\/li\u003e\n      \u003cli\u003eControls residual construction moisture and rising damp.\u003c\/li\u003e\n      \u003cli\u003eSingle-coat application at readings up to 98% RH.\u003c\/li\u003e\n      \u003cli\u003eSuitable over commissioned cementitious underfloor heating screeds up to 90% RH.\u003c\/li\u003e\n      \u003cli\u003eRapid curing from approximately three hours at 20°C.\u003c\/li\u003e\n      \u003cli\u003eBlack pigmentation helps installers visually check coverage.\u003c\/li\u003e\n      \u003cli\u003eSuitable beneath compatible Stopgap smoothing compounds and flooring adhesives.\u003c\/li\u003e\n      \u003cli\u003eCan allow earlier installation of wood flooring and other floor coverings.\u003c\/li\u003e\n      \u003cli\u003eSolvent-free formulation.\u003c\/li\u003e\n      \u003cli\u003eAvailable in 7kg and 14kg kits.\u003c\/li\u003e\n    \u003c\/ul\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eIdeal For\u003c\/h2\u003e\n\n  \u003cul\u003e\n    \u003cli\u003ePrepared concrete subfloors.\u003c\/li\u003e\n    \u003cli\u003ePrepared sand and cement screeds.\u003c\/li\u003e\n    \u003cli\u003eNew-build concrete containing residual construction moisture.\u003c\/li\u003e\n    \u003cli\u003eGround-floor installations affected by rising damp.\u003c\/li\u003e\n    \u003cli\u003eDomestic renovation projects.\u003c\/li\u003e\n    \u003cli\u003eCommercial and fast-track flooring installations.\u003c\/li\u003e\n    \u003cli\u003eCementitious underfloor heating screeds that have been correctly commissioned.\u003c\/li\u003e\n    \u003cli\u003eProjects receiving wood flooring, LVT, vinyl, carpet or other suitable floor coverings.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003cdiv class=\"wwfs-advice-box\"\u003e\n    \u003ch3\u003eProfessional Advice\u003c\/h3\u003e\n\n    \u003cp\u003eAlways test and record the subfloor moisture level before choosing the application rate. Stopgap F77 must be applied to a clean, absorbent and mechanically prepared cementitious surface. Concrete or sand\/cement screeds should be free from laitance, surface hardeners, adhesive contamination, oil, grease and other materials that could prevent adhesion.\u003c\/p\u003e\n\n    \u003cp\u003eThe finished membrane must form a continuous, glossy black coating without pinholes, weak areas or missed sections. The specified coverage rate must not be exceeded, as spreading the product too thinly may prevent it from providing the required moisture protection.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eCoverage and Application Guide\u003c\/h2\u003e\n\n  \u003ctable\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003cth\u003eSubfloor Moisture Level\u003c\/th\u003e\n        \u003cth\u003eApplication Rate\u003c\/th\u003e\n        \u003cth\u003eApplication Trowel\u003c\/th\u003e\n        \u003cth\u003e7kg Coverage\u003c\/th\u003e\n        \u003cth\u003e14kg Coverage\u003c\/th\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003ctd\u003eUp to 85% RH\u003c\/td\u003e\n        \u003ctd\u003eApproximately 2.5m² per kg\u003c\/td\u003e\n        \u003ctd\u003eSTYCCOBOND A2 trowel\u003c\/td\u003e\n        \u003ctd\u003eApproximately 17.5m²\u003c\/td\u003e\n        \u003ctd\u003eApproximately 35m²\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003ctd\u003eUp to 98% RH\u003c\/td\u003e\n        \u003ctd\u003eApproximately 1.8m² per kg\u003c\/td\u003e\n        \u003ctd\u003e1.5mm × 5mm trowel supplied with the kit\u003c\/td\u003e\n        \u003ctd\u003eApproximately 12.5m²\u003c\/td\u003e\n        \u003ctd\u003eApproximately 25m²\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003ctd\u003eUnderfloor heating screeds up to 90% RH\u003c\/td\u003e\n        \u003ctd\u003eApproximately 1.8m² per kg\u003c\/td\u003e\n        \u003ctd\u003e1.5mm × 5mm trowel supplied with the kit\u003c\/td\u003e\n        \u003ctd\u003eApproximately 12.5m²\u003c\/td\u003e\n        \u003ctd\u003eApproximately 25m²\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003cdiv class=\"wwfs-important-box\"\u003e\n    \u003ch3\u003eOne Coat – Different Application Weights\u003c\/h3\u003e\n\n    \u003cp\u003eStopgap F77 is a one-coat system at both application rates. A higher relative humidity reading does not require two standard coats. Instead, the product is applied at a heavier coat weight using the supplied 1.5mm × 5mm trowel.\u003c\/p\u003e\n\n    \u003cp\u003eAfter trowelling, immediately back-roll the epoxy with a pre-coated paint roller to flatten the ridges and create an even, continuous and pinhole-free membrane.\u003c\/p\u003e\n\n    \u003cp\u003eVery absorbent surfaces can draw resin into the subfloor and leave a subdued finish. Where pinholes, weak areas or insufficient coverage remain visible, an additional application may be required.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\n  \u003ctable\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003cth\u003eProduct Type\u003c\/th\u003e\n        \u003ctd\u003eTwo-part epoxy waterproof surface membrane\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eAvailable Sizes\u003c\/th\u003e\n        \u003ctd\u003e7kg and 14kg kits\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eComponents\u003c\/th\u003e\n        \u003ctd\u003ePre-measured resin and hardener\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eColour\u003c\/th\u003e\n        \u003ctd\u003eGlossy black when correctly mixed and applied\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eMaximum Moisture Reading\u003c\/th\u003e\n        \u003ctd\u003eUp to 98% RH on suitable cementitious subfloors\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eUnderfloor Heating\u003c\/th\u003e\n        \u003ctd\u003eUp to 90% RH at an application rate of approximately 1.8m² per kg\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eWorking Time\u003c\/th\u003e\n        \u003ctd\u003eApproximately 30 minutes at 20°C once mixed and poured onto the floor\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eCuring Time\u003c\/th\u003e\n        \u003ctd\u003eFrom approximately 3 hours at 20°C\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eMinimum Floor Temperature\u003c\/th\u003e\n        \u003ctd\u003eAbove 10°C during application\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eApplication\u003c\/th\u003e\n        \u003ctd\u003eSpecified notched trowel followed immediately by back-rolling\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eSuitable Substrates\u003c\/th\u003e\n        \u003ctd\u003ePrepared, clean and absorbent concrete and sand\/cement screeds\u003c\/td\u003e\n      \u003c\/tr\u003e\n\n      \u003ctr\u003e\n        \u003cth\u003eIndoor Use\u003c\/th\u003e\n        \u003ctd\u003eYes\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch2\u003eHow to Apply Stopgap F77\u003c\/h2\u003e\n\n  \u003ch3\u003e1. Test the Subfloor Moisture\u003c\/h3\u003e\n\n  \u003cp\u003eUse an appropriate calibrated hygrometer to establish and record the relative humidity of the subfloor. The moisture reading determines the required application rate and coverage.\u003c\/p\u003e\n\n  \u003ch3\u003e2. Mechanically Prepare the Surface\u003c\/h3\u003e\n\n  \u003cp\u003eRemove laitance, surface treatments, weak material and contamination by suitable mechanical preparation. Power-floated concrete must be mechanically prepared to expose a clean, lightly textured and absorbent surface.\u003c\/p\u003e\n\n  \u003cp\u003eNew concrete and sand\/cement screeds should normally be left for a minimum of seven days before preparation and application of the membrane.\u003c\/p\u003e\n\n  \u003ch3\u003e3. Repair or Pre-Smooth Where Required\u003c\/h3\u003e\n\n  \u003cp\u003eRough, uneven or damaged cementitious subfloors should be repaired or pre-smoothed before applying F77. Suitable products can include \u003ca href=\"\/products\/ball-stopgap-1200-pro-screed-bag-20kg-including-5l-liquid\"\u003eStopgap 1200 Pro\u003c\/a\u003e or another compatible Stopgap repair or smoothing compound selected for the substrate and required depth.\u003c\/p\u003e\n\n  \u003cp\u003eAny smoothing compound installed beneath the membrane must be fully dry and sufficiently strong before F77 is applied. Care should be taken to avoid pinholes within the pre-smoothed surface.\u003c\/p\u003e\n\n  \u003ch3\u003e4. Mix the Complete Kit\u003c\/h3\u003e\n\n  \u003cp\u003eAdd all of the hardener to the resin container. Mix using a suitable power whisk and low-speed drill for approximately two minutes, scrape the sides and base of the container, and then continue mixing for a further two to three minutes until a consistent colour and appearance are achieved.\u003c\/p\u003e\n\n  \u003cp\u003eDo not split the pack unless the resin and hardener can be measured in the manufacturer’s exact proportions. Incomplete mixing can leave soft, uncured areas and prevent the membrane from performing correctly.\u003c\/p\u003e\n\n  \u003ch3\u003e5. Apply Immediately\u003c\/h3\u003e\n\n  \u003cp\u003eOnce mixed, pour the product onto the prepared floor immediately. Leaving mixed epoxy inside the container significantly reduces its working time and can cause it to heat and cure rapidly.\u003c\/p\u003e\n\n  \u003cp\u003eFor readings up to 98% RH, spread the membrane using the supplied 1.5mm × 5mm trowel at approximately 1.8m² per kg.\u003c\/p\u003e\n\n  \u003cp\u003eFor readings up to 85% RH, use a STYCCOBOND A2 trowel at approximately 2.5m² per kg.\u003c\/p\u003e\n\n  \u003ch3\u003e6. Back-Roll the Membrane\u003c\/h3\u003e\n\n  \u003cp\u003eImmediately back-roll the applied F77 using a pre-coated roller. This flattens the trowel ridges and helps form an even, glossy, continuous and pinhole-free coating.\u003c\/p\u003e\n\n  \u003ch3\u003e7. Allow the Membrane to Cure\u003c\/h3\u003e\n\n  \u003cp\u003eAt approximately 20°C, F77 can fully cure in around three hours. Cooler temperatures will extend the curing time. Do not proceed until the entire surface is hard, fully cured and tack-free.\u003c\/p\u003e\n\n  \u003ch2\u003eWhat Goes Over Stopgap F77?\u003c\/h2\u003e\n\n  \u003ch3\u003eF77 Followed by a Smoothing Compound\u003c\/h3\u003e\n\n  \u003cp\u003eOnce the F77 has fully cured, apply \u003ca href=\"\/products\/f-ball-stopgap-p141-primer-5l\"\u003eStopgap P141 Primer\u003c\/a\u003e neat before installing most Stopgap smoothing compounds. P141 dries to a hard, textured surface that promotes adhesion between the non-absorbent epoxy membrane and the smoothing compound.\u003c\/p\u003e\n\n  \u003cp\u003eA typical system is:\u003c\/p\u003e\n\n  \u003cp\u003e\u003cstrong\u003ePrepared cementitious subfloor → Stopgap F77 → neat Stopgap P141 → compatible Stopgap smoothing compound → flooring adhesive → floor covering.\u003c\/strong\u003e\u003c\/p\u003e\n\n  \u003ch3\u003eStopgap 1200 Directly Over F77\u003c\/h3\u003e\n\n  \u003cp\u003e\u003ca href=\"\/products\/ball-stopgap-1200-pro-screed-bag-20kg-including-5l-liquid\"\u003eStopgap 1200 Pro\u003c\/a\u003e can be applied directly to fully cured Stopgap F77 within 24 hours of the membrane curing, without first applying P141.\u003c\/p\u003e\n\n  \u003cp\u003eThe 24-hour period is the maximum direct-application window and not an additional waiting time. For example, where the F77 becomes fully cured and tack-free after approximately three hours, the 24-hour window starts from that point.\u003c\/p\u003e\n\n  \u003ch3\u003eDirect Bonding Wood Flooring with STYCCOBOND B95\u003c\/h3\u003e\n\n  \u003cp\u003eF. Ball STYCCOBOND B95 wood flooring adhesive can be applied directly to a fully cured Stopgap epoxy waterproof surface membrane within 24 hours of the membrane curing, provided the surface is smooth enough to receive the flooring and all other installation requirements are satisfied.\u003c\/p\u003e\n\n  \u003cp\u003eA direct wood-flooring system can therefore be:\u003c\/p\u003e\n\n  \u003cp\u003e\u003cstrong\u003ePrepared cementitious subfloor → Stopgap F77 → STYCCOBOND B95 → suitable wood flooring.\u003c\/strong\u003e\u003c\/p\u003e\n\n  \u003cp\u003eIf the subfloor requires levelling, the correct system would normally be F77 followed by P141 and a suitable smoothing compound before the wood flooring adhesive is applied.\u003c\/p\u003e\n\n  \u003ch3\u003eUsing Bona or Another Manufacturer’s Adhesive\u003c\/h3\u003e\n\n  \u003cp\u003eDo not assume that a Bona or other third-party wood flooring adhesive can be bonded directly to Stopgap F77 simply because it is a reactive or silane-based adhesive.\u003c\/p\u003e\n\n  \u003cp\u003eUnless the adhesive manufacturer has confirmed the exact combination in writing, the safer mixed-manufacturer system is:\u003c\/p\u003e\n\n  \u003cp\u003e\u003cstrong\u003eStopgap F77 → Stopgap P141 → compatible Stopgap smoothing compound → selected wood flooring adhesive.\u003c\/strong\u003e\u003c\/p\u003e\n\n  \u003cp\u003eThis provides a conventional prepared smoothing-compound surface for the adhesive and avoids relying on an unconfirmed direct bond between products from different manufacturers.\u003c\/p\u003e\n\n  \u003ch2\u003eP141 Primer or Kiln-Dried Grit?\u003c\/h2\u003e\n\n  \u003cp\u003eEpoxy damp proof membranes have traditionally sometimes been blinded with clean kiln-dried grit while the epoxy is still wet. The grit becomes embedded in the resin and creates a mechanical key for a subsequent smoothing compound.\u003c\/p\u003e\n\n  \u003cp\u003eFor most modern F. Ball installations, the cleaner and simpler system is to allow F77 to cure fully and then apply \u003ca href=\"\/products\/f-ball-stopgap-p141-primer-5l\"\u003eStopgap P141 Primer\u003c\/a\u003e neat. P141 contains recycled uPVC particles and dries to a textured surface designed specifically to promote adhesion to non-absorbent substrates, including Stopgap waterproof surface membranes.\u003c\/p\u003e\n\n  \u003cp\u003eDo not add or broadcast grit unless it forms part of a project-specific specification or has been recommended by F. Ball Technical Services. Using P141 avoids loose or poorly bonded aggregate and makes it easier to achieve a controlled, consistent surface.\u003c\/p\u003e\n\n  \u003ch2\u003eRecommended Levelling Compounds\u003c\/h2\u003e\n\n  \u003cp\u003e\u003cstrong\u003e\u003ca href=\"\/products\/ball-stopgap-1200-pro-screed-bag-20kg-including-5l-liquid\"\u003eStopgap 1200 Pro\u003c\/a\u003e\u003c\/strong\u003e – A two-part smoothing compound particularly suited to refurbishment work. It can be applied directly to cured F77 within the specified 24-hour window.\u003c\/p\u003e\n\n  \u003cp\u003e\u003cstrong\u003e\u003ca href=\"\/products\/ball-stopgap-300hd-screed-25kg-smoothing-compound\"\u003eStopgap 300 HD\u003c\/a\u003e\u003c\/strong\u003e – A heavy-duty smoothing compound for preparing internal subfloors in demanding domestic and commercial areas. Apply over cured F77 using the correct primer and system guidance.\u003c\/p\u003e\n\n  \u003cp\u003e\u003cstrong\u003e\u003ca href=\"\/products\/ball-stopgap-700-superflex-20kg\"\u003eStopgap 700 Superflex\u003c\/a\u003e\u003c\/strong\u003e – A flexible, fibre-reinforced smoothing compound for suitable timber, steel and mixed subfloor installations. Apply only as part of the correct specified build-up.\u003c\/p\u003e\n\n  \u003cp\u003e\u003cstrong\u003e\u003ca href=\"\/products\/ball-stopgap-fast-track-30-16kg-rapid-set\"\u003eStopgap Fast-Track 30\u003c\/a\u003e\u003c\/strong\u003e – A rapid-setting smoothing compound for time-sensitive installations. Use over F77 only with the required primer and in accordance with the current technical data.\u003c\/p\u003e\n\n  \u003cdiv class=\"wwfs-advice-box\"\u003e\n    \u003ch3\u003eNeed Help Choosing?\u003c\/h3\u003e\n\n    \u003cp\u003eThe correct system depends on the subfloor, moisture reading, floor covering, underfloor heating and whether the surface requires repair or levelling. Contact our flooring specialists before ordering if you are unsure which F. Ball products are required for your installation.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"wwfs-important-box\"\u003e\n    \u003ch3\u003eImportant Information\u003c\/h3\u003e\n\n    \u003cul\u003e\n      \u003cli\u003eStopgap F77 must be applied to a clean and absorbent cementitious substrate.\u003c\/li\u003e\n      \u003cli\u003eDo not apply it directly over old bitumen adhesive residue.\u003c\/li\u003e\n      \u003cli\u003eDo not describe old black adhesive residue as a suitable base simply because F77 is an epoxy product.\u003c\/li\u003e\n      \u003cli\u003eMastic asphalt is a finished flooring substrate made using bitumen and aggregate; it is not the same as a thin layer of bitumen adhesive residue.\u003c\/li\u003e\n      \u003cli\u003eSound asphalt normally requires an appropriate smoothing-compound system rather than direct application of F77.\u003c\/li\u003e\n      \u003cli\u003eFor bitumen adhesive residues, \u003ca href=\"\/products\/ball-stopgap-1200-pro-screed-bag-20kg-including-5l-liquid\"\u003eStopgap 1200 Pro\u003c\/a\u003e may be suitable where the residue is firm, thin and well bonded, subject to full preparation guidance.\u003c\/li\u003e\n      \u003cli\u003eDo not bridge structural or movement joints with F77.\u003c\/li\u003e\n      \u003cli\u003eApply the membrane across the entire floor and terminate it correctly at the wall damp-proof course.\u003c\/li\u003e\n      \u003cli\u003eThe floor temperature must remain above 10°C during application.\u003c\/li\u003e\n      \u003cli\u003eThe underfloor heating system must be fully commissioned before installation.\u003c\/li\u003e\n      \u003cli\u003eUnderfloor heating should be switched off for 48 hours before, during and for 48 hours after installation of the membrane, smoothing compound and floor covering.\u003c\/li\u003e\n      \u003cli\u003eRecommission underfloor heating gradually to prevent thermal shock.\u003c\/li\u003e\n      \u003cli\u003eAlways follow the latest F. Ball Technical Data Sheet and relevant British Standards.\u003c\/li\u003e\n    \u003c\/ul\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"wwfs-small-print\"\u003e\n    \u003cp\u003eCoverage and curing times are approximate and depend on the temperature, substrate texture, porosity, application technique and site conditions. The specified coverage rate must not be exceeded. Product specifications and manufacturer recommendations can change, so always consult the latest technical information before use.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n\u003c\/div\u003e","brand":"Bona","offers":[{"title":"7kg","offer_id":56345719374203,"sku":null,"price":160.62,"currency_code":"GBP","in_stock":false},{"title":"14kg","offer_id":56345719406971,"sku":null,"price":160.62,"currency_code":"GBP","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0560\/7309\/3177\/files\/F77-Kit.webp?v=1784737929","url":"https:\/\/wiltshirewoodflooringsupplies.co.uk\/products\/f-ball-stopgap-f77-epoxy-damp-proof-membrane","provider":"Wiltshire Wood Flooring Supplies","version":"1.0","type":"link"}