A tile waterproofing membrane is a bonded liquid or sheet layer placed under thin-set tile in showers and wet areas, specified in the US to ANSI A118.10-2023 and in Europe to EN 14891 as type CM, DM or RM. The three European types stand for cementitious, dispersion and reaction-resin products, and British specifiers call the same job tanking.
The tile and grout above a membrane are not the water barrier: no tile grout, cement or epoxy, is the waterproofing layer. The membrane is, and ANSI A118.10-2023 asks it for a shear bond of at least 0.34 MPa (50 psi) at five test ages, while EN 14891:2017 asks for a tensile adhesion of at least 0.5 N/mm² (72.5 psi) and crack bridging of at least 0.75 mm (0.030 in). Tile membranes are one product class of the tile family within this reference to construction chemicals.
This page follows a specification: identity, mechanism, uses, properties and standards, selection, application, inspection, safety and VOC rules, alternatives, sourcing and the full shower assembly.
How we check: standards, codes and rules are read at the body that issues them, product values come from the data sheet named in the text, and each price carries its own source and date; the full method is in methodology and fact-checking.
The summary table below lists the attributes a specifier checks first on a tile waterproofing membrane.
| Attribute | Value |
|---|---|
| US standard | ANSI A118.10-2023 (load bearing, bonded, waterproof membranes, liquid and sheet) |
| EU standard | EN 14891:2017 (CEN current edition); EN 14891:2012 cited for CE marking and the declaration of performance |
| International (sheets) | ISO 13007-6:2020, bonded sheet waterproofing membranes beneath ceramic tiling |
| EU types | CM cementitious, DM dispersion, RM reaction resin |
| EU optional classes | O1 crack bridging at -5 °C (23 °F); O2 at -20 °C (-4 °F); P chlorinated water |
| Forms | 1K liquid (roller, trowel or spray); 2K cementitious; sheet with seam bands |
| Key minimums | Shear bond ≥ 0.34 MPa (50 psi) (ANSI); tensile adhesion ≥ 0.5 N/mm² (72.5 psi) and crack bridging ≥ 0.75 mm (0.030 in) (EN) |
| Installation standard | ANSI A108.13-2005 (reaffirmed 2021) |
| Hazards | Follow the chemistry: dispersion, cement or reaction resin; see the product SDS |
What Is a Tile Waterproofing Membrane?#
A tile waterproofing membrane is a continuous, load-bearing film or sheet bonded to the substrate that accepts thin-set tile directly, so the tile and grout above it are no longer the water barrier. Load-bearing means the membrane carries tile and traffic without shearing apart, which is why ANSI A118.10-2023 tests shear bond at five ages.
The membrane is one of three layers on a wet-area substrate, beside the thin-set mortar that beds the tile and the grout that fills the joints. Only the membrane standard tests waterproofness, and the full family of adhesives, grouts and membranes is set out under tile installation systems.
Liquid, cementitious, reaction-resin and sheet membranes: which forms exist?#
Four chemistries make up the class: acrylic or acrylic-polyurethane dispersions (DM), polymer-modified cementitious slurries (CM), polyurethane or epoxy reaction resins (RM) and polyethylene sheets. The four forms are listed below with the binder behind each one.
- Dispersion membranes (DM): one-component liquids based on acrylic polymers, applied by roller, trowel or spray, with optional mesh.
- Cementitious membranes (CM): two-component polymer-modified slurries, the tile grade of cementitious waterproofing.
- Reaction-resin membranes (RM): liquids based on polyurethane resins or epoxy resins and hardeners.
- Sheet membranes: polyethylene sheets bonded with thin-set and joined with seam bands.
Liquid forms build thickness on site, coat by coat, while a sheet arrives at a factory thickness and depends on its seams.
Regional names: shower membrane, paint-on membrane and wet room tanking#
Tile membranes carry four regional names that describe the same bonded layer. The table below lists each name with its region and meaning.
| Name | Region | Meaning |
|---|---|---|
| Shower membrane, paint-on membrane | US | Liquid or sheet membrane under shower tile; "paint-on" names the liquid form |
| Tanking, wet room tanking kit, liquid tanking | UK | Waterproofing under tile in bathrooms and wet rooms, sold as kits |
| Liquid-applied water impermeable product, type CM, DM or RM | EU (EN 14891) | The formal name in the standard and on the declaration of performance |
| Bonded waterproof membrane | Generic | Any liquid or sheet layer bonded under tile |
All four names point to the same product class and the same two standards.
How Does a Bonded Membrane Keep Water Out of a Tiled Assembly?#
A liquid membrane forms a continuous film as it dries or cures, a sheet membrane is bonded to the substrate with banded seams, and both bridge small substrate cracks by elastic elongation. Water that passes the grout joints meets the membrane and runs on its surface to the drain. Continuity is the whole mechanism: one open seam or unsealed drain flange lets water past an otherwise intact film.
Elastic elongation keeps the film whole when the substrate moves. EN 14891:2017 turns it into a requirement, crack bridging of at least 0.75 mm (0.030 in), repeated at -5 °C (23 °F) for O1 and -20 °C (-4 °F) for O2. One liquid product, TEC HydraFlex, reports 750 % elongation and 1.72 MPa (250 psi) tensile strength under ASTM D751 as cited on its data sheet (TDS R0925). Elongation is not the EN crack-bridging result, so each value is read against the test that sets it.
Where Are Tile Waterproofing Membranes Used?#
Tile membranes are used wherever water stands on or runs over a tiled surface: shower walls, floors and benches, bathroom and wet-room floors, and pools, where EN 14891 adds class P for chlorinated water. The four uses are listed below with the page that covers each structure.
- Showers and wet rooms: walls, floors, benches and niches, the core use of ANSI A118.10-2023 and EN 14891 types CM and DM.
- Tanks with a tiled lining: covered among water-retaining structures.
- Swimming pools: class P products under pool tile, covered under swimming pool waterproofing.
- Balconies and terraces: tiled exterior decks with O1 or O2 crack bridging for frost, covered under balcony and terrace waterproofing.
Shower walls, shower floors and benches#
A shower needs the membrane on every wall and floor surface the water reaches, including benches, niches and the floor slope toward the drain. Benches and niches add corners, each a change of plane where the film is reinforced, and the floor adds the drain, where the membrane laps onto the drain body.
Seams, drains and changes of plane fail first, so they decide who installs the system. A residential shower is tile-setter work; a commercial wet area such as a locker room goes to a commercial waterproofing applicator who records thickness and flood tests.
Bathroom floors and wet rooms#
A bathroom or wet-room floor takes the same membrane as a shower floor wherever the floor is wetted. The membrane goes over concrete, a mortar bed, cement backer board or, where the membrane maker allows it, plywood. A wet room without a tray or curb extends the shower floor detail across the room and slopes it to one drain. Whether a code requires a membrane on a given bathroom floor is a question for the local code official.
Which Properties Define Tile Membrane Performance?#
Six properties define a membrane under ANSI A118.10-2023 (shear bond, breaking strength, seam strength, dimensional stability, waterproofness and fungus resistance), while EN 14891:2017 tests tensile adhesion, crack bridging and waterproofness. The ANSI set describes a membrane that holds tile, keeps its size and does not leak. EN 14891:2017 tests tensile adhesion after five conditionings (initial, water contact, heat aging, freeze-thaw and lime water) plus chlorinated water for class P. The two lists overlap only in waterproofness: no visible penetration after 48 hours under ANSI, and a test in Annex A.6.9 under EN.
Standard requirement or product value: how to read membrane numbers#
A requirement is the minimum every listed membrane must reach; a data-sheet value is one product's result in the same test. TEC HydraFlex (TDS R0925) prints shear bonds of 1.64 MPa (238 psi) at 7 days and 0.86 MPa (125 psi) after 100 days immersion, against the 0.34 MPa (50 psi) minimum of ANSI A118.10-2023. A higher result creates no higher class, because A118.10 sets one pass level per property. The 100-day immersion value matters most for a shower, since it shows the bond after long water contact.
Which Standards Classify Tile Membranes: ANSI A118.10, EN 14891 and ISO 13007-6?#
Two standard families govern tile membranes: ANSI A118.10-2023 for liquid and sheet membranes in the US and EN 14891 for liquid-applied products in Europe, while ISO 13007-6:2020 covers bonded sheet membranes. US installation follows ANSI A108.13-2005, reaffirmed in 2021, and the TCNA status page of 2026-09-10 lists both as current. ANSI A118.17, for field fabricated shower kits, is proposed and under development, not published. The full US series is listed under ANSI A118 standards for tile mortars, grouts and membranes.
ANSI A118.10-2023 requirements for bonded membranes#
ANSI A118.10-2023 requires at least 0.34 MPa (50 psi) shear bond at 7 days, after 7 days immersion, at 4 and 12 weeks and after 100 days immersion, plus 1.17 MPa (170 psi) breaking strength. Four further requirements complete it: seam strength of at least 1.40 N/mm (8 lb per inch width), dimensional stability within 0.7 % length change, no visible water penetration after 48 hours, and no support of mold growth. The standard is printed in the TCNA compilation of ANSI A108, A118 and A136.1, July 2026 edition. The table below sets it beside EN 14891.
| Property | ANSI A118.10-2023 | EN 14891:2017 | Note |
|---|---|---|---|
| Bond | Shear ≥ 0.34 MPa (50 psi) at 7 d, 7 d immersion, 4 wk, 12 wk, 100 d immersion | Tensile adhesion ≥ 0.5 N/mm² (72.5 psi) initial, water contact, heat aging, freeze-thaw, lime water; also after chlorinated water for class P | Shear and tensile are different tests |
| Breaking strength | ≥ 1.17 MPa (170 psi) | No requirement | Strength of the film or sheet |
| Seam strength | ≥ 1.40 N/mm (8 lb/in) | No requirement | Sheets and banded seams |
| Dimensional stability | ≤ 0.7 % length change | No requirement | Size change in service |
| Waterproofness | No visible penetration after 48 h | Test in Annex A.6.9 | Both test water passage |
| Crack bridging | No requirement | ≥ 0.75 mm (0.030 in) at standard conditions; O1 at -5 °C (23 °F); O2 at -20 °C (-4 °F) | Movement over cracks |
| Fungus resistance | Shall not support mold growth | No requirement | Wet-area hygiene |
| Status | Current (TCNA, 2026-09-10); A118.17 proposed | CEN current; CE marking and DoP cite EN 14891:2012 under the EU Construction Products Regulation | Sheets: ISO 13007-6:2020 |
EN 14891 types CM, DM and RM and classes O1, O2 and P#
EN 14891:2017 sorts liquid-applied products into types CM, DM and RM and adds optional classes O1 (crack bridging at -5 °C (23 °F)), O2 (-20 °C (-4 °F)) and P (chlorinated water). Every type must reach 0.5 N/mm² (72.5 psi) tensile adhesion in every conditioning and 0.75 mm (0.030 in) crack bridging at standard conditions. Published on 2017-02-14 by CEN/TC 67/WG 3 under mandate M/102, it supersedes EN 14891:2012 and its corrigendum at CEN and drops the single "O" class of 2012.
The CE mark follows a different edition. The European Commission's summary list of harmonised standards under Regulation (EU) No 305/2011, dated 2026-02-09, cites EN 14891:2012, so a declaration of performance refers to the 2012 edition. Regulation (EU) 2024/3110 applies from 2026-01-08, and standards cited under 305/2011 stay valid until their family moves under an implementing act of the new regulation. A CEN systematic review enquiry on the 2017 edition ran from 2025-10-13 to 2026-10-14. The full test regime is set out under EN 14891 liquid-applied waterproofing under tiles.
Is an ANSI A118.10 membrane the same as an EN 14891 product?#
No: ANSI A118.10 tests shear bond and seam strength of liquid and sheet membranes, while EN 14891 tests tensile adhesion and crack bridging of liquid products, so a match between them is indicative, not legal equivalence. The indicative mapping pairs A118.10 with EN 14891 for liquids and ISO 13007-6:2020 for sheets, and one claim does not establish the other.
How do you check a membrane claim on a data sheet, listing or DoP?#
Five checks confirm a membrane claim, whatever the brand. They are listed below in reading order.
- Read the standard and edition: ANSI A118.10-2023, or EN 14891 with type and class.
- Find an ANSI result for every A118.10 row, all five shear ages included.
- Check the EN type and class on a declaration of performance citing EN 14891:2012 under the EU Construction Products Regulation.
- Record any listing number, such as IAPMO certification 2212-25024 or ICC-ES ESR-2467 (effective August 2026, re-examination in one year).
- Note the wet film thickness and coats behind the claim, since a liquid meets its standard only at the tested thickness.
Brand comparisons between two shower membranes are answered the same way: both are judged against A118.10, and neither is ranked here.
How Do You Choose a Tile Waterproofing Membrane?#
Choose a tile membrane by the standard the project cites, then by form and detail: an A118.10 product for US work, an EN 14891 type and class for European work. Class P applies where the water is chlorinated, and O1 or O2 where crack bridging must hold at -5 °C (23 °F) or -20 °C (-4 °F). The standard fixes which tests the product must pass; the form fixes how the work is detailed and checked.
The applicator follows from the job. A residential shower or bathroom is installed by a tile setter who places membrane, thin-set and tile in one sequence, while a commercial wet area, pool surround or tiled terrace calls for a commercial waterproofing applicator.
Liquid or sheet membrane: which suits which detail?#
A liquid membrane follows any shape and is checked by wet film thickness; a sheet membrane brings a factory thickness and is checked at every seam. The table below compares the two forms detail by detail.
| Detail | Liquid membrane | Sheet membrane | Check |
|---|---|---|---|
| Niches and benches | One film around corners, band at changes of plane | Cut and folded pieces, each joint banded | Continuity at every corner |
| Flat wall field | Two coats by roller, trowel or spray | Large sheets bonded with thin-set | WFT readings; full bond of the sheet |
| Drain and corners | Band embedded in the first coat around the flange | Preformed corners and drain collars | Lap onto the drain body |
| Exterior or cold areas | EN 14891 O1 or O2 crack bridging | Sheet system to the maker's exterior rules | Class on the DoP |
| Inspection | Wet film thickness gauge, coat by coat | Seam check, sheet by sheet | Flood test after cure for both |
Many niches favor a liquid; large flat walls favor a sheet's fixed thickness.
When is a tile membrane the wrong product?#
Three situations call for another product, listed below with the product that does the job.
- Grout as the barrier: no grout waterproofs, including epoxy tile grout.
- Movement without water: a moving floor in a dry area needs crack isolation to ANSI A118.12-2014 (reaffirmed 2024), one of the uncoupling and crack-isolation membranes.
- Tank or pool structure: the shell holds water on its own first, with class P under tile, as set out under swimming pool waterproofing.
How Is a Tile Membrane Applied? Substrate, Thickness, Coverage and Cure#
A tile membrane performs only at its specified film thickness over a sound substrate. Application therefore fixes four things: substrate and moisture, reinforcement at seams and changes of plane, wet film thickness, and the time and temperature before tiling.
Substrates and backer boards (ANSI A118.9 and A118.18)#
Tile membranes go over concrete, mortar beds, cement backer board and, where the maker allows it, plywood. ANSI A118.9-2023 covers cementitious backer units and ANSI A118.18-2023 foam core backer boards, both current substrate standards (TCNA, 2026-09-10). A board system's waterproofing claim is read against A118.10 on its own data sheet, never inferred from the backer board standard.
Slab moisture is limited by the membrane maker, not by the test method. ASTM F1869-23 measures the moisture vapor emission rate and ASTM F2170-19a the in-situ relative humidity, and neither sets a pass or fail value; the product table under temperature lists one maker's limits and its mortar-bed cure period. Both methods are covered under concrete moisture testing.
Seams, drains and changes of plane#
Seams, drains and changes of plane are reinforced with the band or fabric of the same membrane system before the field is coated. The band goes into the wet first coat of a liquid membrane, and the second coat covers band and field together; sheet systems use preformed corners, seam bands and drain collars. Board joints, corners, bench edges, pipe penetrations and the drain flange all get this treatment, because the substrate moves there.
Wet film thickness and coverage per mil#
Liquid membrane coverage follows from wet film thickness: 1 L spread at 1.27 mm (50 mil) WFT covers 0.787 m² (32.1 ft² per US gal), whatever the solids. The identity is 1,604 ft² per US gallon at 1 mil and 100 % volume solids, or m²/L = 1,000 x volume solids / DFT in µm, and DFT equals WFT times volume solids.
Data-sheet rates must agree with that arithmetic, as the table below shows. LATICRETE HYDRO BAN states 0.38 to 0.56 mm (0.015 to 0.022 in) wet per coat, two coats, and an approximate yield of 23.2 m² (250 ft²) per commercial unit, which the identity turns into 1.79 to 2.62 m²/L (72.9 to 106.9 ft²/gal) per coat. A rate that does not match its thickness is queried before ordering, and gauge practice is covered under wet and dry film thickness measurement.
| Item | Value | Basis |
|---|---|---|
| Coverage identity | 1,604 ft²/US gal at 1 mil; m²/L = 1,000 x VS / DFT (µm) | 100 % volume solids, theoretical |
| 1.27 mm (50 mil) WFT | 0.787 m²/L (32.1 ft²/gal) | Theoretical, any solids, per coat |
| 0.635 mm (25 mil) WFT | 1.57 m²/L (64.2 ft²/gal) | Theoretical, any solids, per coat |
| 0.38 to 0.56 mm (0.015 to 0.022 in) WFT, LATICRETE HYDRO BAN (data sheet) | 1.79 to 2.62 m²/L (72.9 to 106.9 ft²/gal) | Theoretical, calculated from the printed wet thickness, per coat |
| LATICRETE HYDRO BAN (data sheet) pack yield | 23.2 m² (250 ft²) per commercial unit; 4.65 m² (50 ft²) per mini unit | Approximate, two coats, as printed |
Temperature, drying and time to tile#
One liquid membrane (TEC HydraFlex) takes tile 1 to 3 hours after application at 21 °C (70 °F) and is flood tested once its second coat has turned fully dark, 2 to 12 hours. Drying depends on temperature, relative humidity, substrate porosity and airflow, so a time stated at 21 °C (70 °F) is a reference point, not a promise for a cold site. The table below lists the values printed on two data sheets, each with its temperature.
| Temperature | Product (data sheet, edition) | Step | Time or limit |
|---|---|---|---|
| 21 °C (70 °F) | TEC HydraFlex (TDS R0925) | Tile after application | 1 to 3 h |
| 21 °C (70 °F) | TEC HydraFlex (TDS R0925) | Flood test when the second coat is fully dark | 2 to 12 h |
| Varies with temperature, RH, porosity, airflow | TEC HydraFlex (TDS R0925) | Drying | 2 to 12 h; keep liquid from freezing |
| Not stated | TEC HydraFlex (TDS R0925) | Green concrete | From 3 days |
| 21 °C (70 °F) | LATICRETE HYDRO BAN (data sheet) | Wet mortar bed cured before membrane | 72 h |
| Not stated | LATICRETE HYDRO BAN (data sheet) | Second coat | After the first coat has changed color (sage to olive) |
| Not stated | LATICRETE HYDRO BAN (data sheet) | Concrete moisture | ≤ 283 µg/(s·m²) (5 lb/1,000 ft²/24 h) per ASTM F1869-23 or ≤ 85 % RH per ASTM F2170-19a |
Color change is the cure indicator on both products and gives a visual hold point before the second coat or the flood test. Outside the 21 °C (70 °F) reference, the maker's temperature window on the data sheet governs.
How Are Tile Membranes Inspected, and Why Do Showers Leak?#
Tile membranes are accepted on film thickness, continuity and a flood test after cure. Leaking showers trace back to four faults: an under-thickness film; unsealed seams, drains or changes of plane; a skipped flood test; or grout treated as the barrier. Each fault is cheap to catch before tiling and costly after, because finding it later means removing tile. Wet film readings are taken coat by coat and seams checked visually; no reference method edition for shower flood tests is stated here, and the procedure is covered under membrane leak detection and flood testing.
The table below lists five failures with their cause and the check that catches each one.
| Failure | Cause | Check |
|---|---|---|
| Under-thickness film | WFT not checked | Wet film gauge, coat by coat (wet and dry film thickness measurement) |
| Leaks at seams, drains or corners | No band or fabric, or band not embedded | Visual check of every change of plane and the drain flange |
| Leak found after tiling | Flood test skipped | Flood test after cure (membrane leak detection and flood testing) |
| Water under the tile bed | Grout treated as the barrier | Specification review: membrane named under the tile |
| Soft or damaged film | Tile set before the membrane reached its cure | Color-change indicator where the product has one; time and temperature on the job record |
What Health, Safety and VOC Rules Apply to Tile Membranes?#
A tile membrane's hazards follow its chemistry: dispersion (DM) products carry the line of their polymer class, cementitious (CM) components carry the portland cement classification, and reaction-resin (RM) products carry epoxy or diisocyanate rules. The table below lists each classification or rule with its instrument and date.
| Topic | Rule or classification | Instrument and date |
|---|---|---|
| Acrylic and styrene-acrylic polymers (DM) | No Annex VI entry for the polymer class; see the product SDS (isothiazolinone-preserved products may carry H317) | CLP; ECHA |
| Portland cement (CAS 65997-15-1, EC 266-043-4) (CM) | No Annex VI entry; ECHA C&L notified classification: H315, H317, H318, H335; see the product SDS | ECHA C&L notifications |
| Soluble chromium (VI) in cement | At most 2 mg/kg (0.0002 %) of the total dry weight of the cement when hydrated | REACH Annex XVII entry 47 |
| Cr(VI) in US construction | OSHA 1926.1126 (PEL 5 µg/m³) does not apply to portland cement exposures | 29 CFR 1926.1126(a)(3) |
| Liquid epoxy resin (CAS 25068-38-6) (RM) | Harmonised CLP Annex VI (index 603-074-00-8): H315, H317, H319, H411; hardeners: see the product SDS | CLP Annex VI |
| Polyurethane resins and prepolymers (RM) | No Annex VI entry for the class; see the product SDS; isocyanate monomers 4,4'-MDI, HDI, TDI, IPDI and H12MDI each harmonised with H334 and H317 | CLP Annex VI |
| Diisocyanates at 0.1 % by weight or more | Label since 2022-02-24; training before professional use since 2023-08-24, renewed at least every five years (diisocyanates rules) | REACH Annex XVII entry 74, Regulation (EU) 2020/1149 |
| Quartz (crystalline silica) (CAS 14808-60-7), where the SDS lists it | No Annex VI entry; product-specific, see supplier SDS (ECHA C&L: no majority; not classified 27.5 %, H372 25.2 %, H373 18.8 %, H350 7.7 %) | ECHA |
| Respirable crystalline silica, US construction | PEL 50 µg/m³ 8-h TWA; action level 25 µg/m³ | OSHA 29 CFR 1926.1153, effective 2016-06-23 |
| California Proposition 65 | "Silica, crystalline (airborne particles of respirable size)", cancer, listed 1988-10-01 | OEHHA list |
| VOC, South Coast | No waterproofing membrane category; label category or Default 50 g/L (0.42 lb/gal) | SCAQMD Rule 1113, amended 2016-02-05 |
| VOC, New York | Waterproofing membranes 250 g/L (2.09 lb/gal) | 6 NYCRR Part 205, state effective 2020-01-11 |
Cementitious and reaction-resin components#
Portland cement (CAS 65997-15-1) has no Annex VI entry; ECHA C&L notified classification: H315, H317, H318, H335; see the product SDS. REACH Annex XVII entry 47 limits soluble chromium (VI) to 2 mg/kg (0.0002 %) of the cement's dry weight when hydrated, so packs with a reducing agent carry a packing date and storage period. OSHA 29 CFR 1926.1126 and its 5 µg/m³ Cr(VI) limit do not apply to portland cement exposures under paragraph (a)(3). Quartz (crystalline silica) counts only where the product SDS lists it, and then OSHA 1926.1153 applies.
Reaction-resin membranes carry skin sensitizers. Liquid epoxy resin is harmonised under CLP Annex VI index 603-074-00-8, and polyurethane products with 0.1 % by weight or more diisocyanates need entry 74 training before professional use since 2023-08-24. Once sensitized, a worker reacts to very small amounts, so uncured epoxy or isocyanate product never touches bare skin.
VOC limits for tile membranes#
SCAQMD Rule 1113 (amended 2016-02-05) has no waterproofing membrane category, so a liquid membrane falls to the category its label claims or to Default at 50 g/L (0.42 lb/gal). New York's 6 NYCRR Part 205, approved by EPA on 2022-08-11 (87 FR 49571), sets waterproofing membranes at 250 g/L (2.09 lb/gal). The thin-set and grout above fall under SCAQMD Rule 1168 (amended 2022-11-04) at 65 g/L (0.54 lb/gal) each, less water and exempt compounds. As one product's value, TEC HydraFlex states 7 g/L (0.058 lb/gal), or 12 g/L (0.10 lb/gal) less water (TDS R0925). Other categories are compared under VOC limits for construction chemicals.
What Are the Alternatives to a Bonded Tile Membrane?#
Five product classes compete with a bonded tile membrane, and each wins where tile is not the finish, the structure holds water, or the problem is movement rather than water. The table below lists them after a first row for the whole waterproofing family.
| Alternative | Chemistry | When it wins | Standard |
|---|---|---|---|
| waterproofing membranes and systems | 13 types, sheet, liquid and crystalline | Waterproofing beyond tile: roofs, basements, decks | Per type |
| cementitious waterproofing | Rigid or flexible polymer-modified cement slurry | Tanks, basements and walls without tile | EN 14891 CM under tile |
| liquid-applied waterproofing membranes | Polyurethane, acrylic, bitumen and hybrid films | Roofs, decks and buried walls | ASTM C836/C836M-18(2022) under a wearing course; ASTM C957/C957M-25 with integral wearing surface |
| sheet waterproofing membranes | Modified bitumen, PVC, TPO, EPDM, HDPE | Below grade and roofs | Per sheet type |
| uncoupling and crack-isolation membranes | Polyethylene sheet with cavities and fleece; elastic liquid films | Movement under tile without a water load | ANSI A118.12-2014 (reaffirmed 2024); A118.20 proposed |
| swimming pool waterproofing | Membrane systems for immersed tile | Pools and chlorinated water | EN 14891 class P |
Pools and terraces stretch the tile membrane rather than replace it: a pool takes a class P product over a watertight shell, and a terrace takes O1 or O2 crack bridging for frost.
Tile Membrane Forms, Packaging and Sourcing#
Tile membranes are sold as one-component liquids, two-component cementitious kits and sheets with matching seam bands, and buyers compare them on the declared standard, the listing and the thickness basis behind every coverage figure.
Comparing declarations rather than brand claims is the method set out under construction chemicals manufacturers and suppliers.
The five items a membrane quote should carry are listed below.
- State the standard and edition: ANSI A118.10-2023, or EN 14891 with type and class on a DoP.
- Name the IAPMO or ICC-ES listing number, where one exists.
- Give the wet film thickness per coat, coats and volume solids behind every coverage figure.
- List the accessories: seam bands, preformed corners, drain collars and fabric.
- Attach the data sheet, the SDS and the VOC statement with its method.
Installer skills belong to the same decision. ACT (Advanced Certifications for Tile Installers), created by IMI, BAC, CTEF, NTCA, TCAA and TCNA, includes a membranes module and a shower receptors module.
Where Does the Membrane Sit in a Tiled Shower Assembly?#
The membrane sits between the substrate and the thin-set mortar, and above it modified mortars set the tile with at least 95 % mortar contact in wet areas (ANSI A108.5-2023 practice). Dry interior areas need at least 80 % contact, with all tile edges supported, and grout fills the joints without adding waterproofing. The four layers are listed below from the bottom up.
- Substrate: concrete, a sloped mortar bed, cement backer board (ANSI A118.9-2023) or foam core board (ANSI A118.18-2023).
- Membrane: liquid or sheet, to ANSI A118.10-2023 or EN 14891, continuous into the drain.
- Thin-set mortar: modified (ANSI A118.4-2023) or improved modified (A118.15-2023), H for large and heavy tile; see tile adhesive classes and large and heavy tile mortars.
- Tile and grout: tile grout or epoxy grout, which resists stains but does not waterproof.
Tile waterproofing FAQs#
Three questions come up most around membranes and the layers next to them.
Is there such a thing as waterproof grout?#
No: neither cement grout (ANSI A118.7) nor epoxy grout (A118.3) is a waterproofing layer, and an epoxy grout maker states it is no replacement for a membrane.
LATICRETE's data sheet DS-681 states that its epoxy grout "is not a replacement for a waterproofing membrane"; strength, stains and cost of both grouts are compared under epoxy grout vs cementitious grout.
What is dry pack mortar in a shower floor?#
Dry pack mortar is the cement and sand mortar bed that forms the sloped shower floor under a bonded membrane. It gives the floor its fall to the drain, and the membrane goes on once the bed has cured to the membrane maker's requirement.
Does a waterproofing membrane also isolate cracks?#
Not always: crack isolation is a separate standard, ANSI A118.12-2014 (reaffirmed 2024), with Standard and High Performance grades, so a membrane isolates cracks only when it declares both. A118.12 asks for a point load of at least 454 kg (1,000 lb) and crack isolation of at least 1.6 mm (1/16 in) for Standard and 3 mm (1/8 in) for High Performance.