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LATICRETE 9235 Coverage Calculator: How Many Gallons Do I Need?
Enter the area and choose how you are installing it. LATICRETE's data sheet DS-236 (revision DS-236-1026) gives about 100 sq ft per gallon for each coat of 9235 liquid. A full waterproofing job is a fabric-reinforced system: one coat to bed the fabric, one to saturate it and one to seal the surface, so the calculator counts three coats by default. Interior cement board and drywall walls may skip the fabric and the third coat. The calculator then picks the 2 gallon kits and 6 gallon pails to buy.
LATICRETE 9235 Waterproofing Membrane coverage
| Application | Coats | Per gallon, each coat | Per gallon, all coats |
|---|---|---|---|
| Full waterproofing with fabric (3 coats) | 3 | 100 sq ft (9.3 m²) | 33.3 sq ft (3.1 m²) |
| Interior cement board or drywall walls, no fabric (2 coats) | 2 | 100 sq ft (9.3 m²) | 50 sq ft (4.6 m²) |
| Crack isolation strip with fabric (2 coats) | 2 | 100 sq ft (9.3 m²) | 50 sq ft (4.6 m²) |
Source: LATICRETE Product Data Sheet DS-236: 9235 Waterproofing Membrane (North America), DS-236-1026, read 2026-10-18.
How the calculation works
gallons = area × (1 + waste ÷ 100) × coats ÷ sq ft per gallon per coat
Every coat goes over the whole area, so two coats at 80 sq ft per gallon use as much liquid as one coat at 40. The rate depends on what the membrane is for: the data sheet lists a heavier rate for code-listed waterproofing than for crack prevention alone. The calculator then picks the fewest pails that cover the job without leaving more than one small pail of liquid unused, so a job needing 3 gallons gets one 3.5 gallon pail rather than three 1 gallon pails. Extra passes over corners, seams, drains and pipe penetrations are not included; raise the waste figure if you have many of them.
Worked example
A 100 sq ft area, Full waterproofing with fabric (3 coats), with 10% extra: 100 × 1.1 = 110 sq ft. The data sheet calls for 3 coats at 100 sq ft per gallon each, so 110 × 3 ÷ 100 = 3.3 gallons (12.5 L). In the pail sizes on sale, buy 2 × 2 gal pail kits (4 gal).
LATICRETE 9235 Waterproofing Membrane key specs
| Product type | Waterproofing membrane |
|---|---|
| Package | 2 gal (7.6 L) pail kit and 6 gal (23 L) pail |
| Coverage (data sheet) | about 100 sq ft per gallon per coat (about 0.01 gal per sq ft, 0.4 L/m² per coat); packaging figures: 6 gal pail about 300 sq ft (27.8 m²), 2 gal pail kit about 75 sq ft (7 m²) |
| System | liquid rubber polymer with LATICRETE Waterproofing/Anti-Fracture Fabric embedded: coat, fabric, saturating coat, then a sealing coat once dry to the touch; lap fabric seams about 2 in (50 mm) |
| Fabric | 300 sq ft (27.8 m²) roll 38 in (965 mm) wide for the field; 6 in (150 mm) × 75 ft (23 m) roll for cracks, coves, corners and seams; drains get a 38 × 38 in square |
| Film thickness | wet coat 15–22 mils (0.4–0.6 mm) each (coverage chart T-10810 shows 20 mil); about 0.02 in (0.5 mm) when cured |
| Drying and flood test | each coat dry to the touch in about 1–3 hours at 70°F and 50% RH; thin-set tile once the last coat is dry to the touch; 7 days before flood testing, thick bed mortar, epoxy or moisture sensitive flooring; keep rain off for at least 5 days |
| Temperature | surface 45–90°F (7–32°C) during application and for 24 hours after |
| Crack isolation | non-structural cracks up to 1/8 in (3 mm); strip at least three times the tile width; not over structural cracks, expansion joints or cracks with vertical movement |
| Standards | ANSI A118.10 and A118.12; ICC-ES ESR-1058; IAPMO File 3524 (shower pan liner); TCNA "Extra Heavy" service per ASTM C627; 2.9 perms (ASTM E96 inverted water); UL GREENGUARD Gold |
| Not for | vapor barrier or steam rooms on its own, particle board, luan, Masonite or hardwood floors, single layer wood floors, under self-leveling underlayments or plaster finishes, negative hydrostatic pressure, primary roofing over occupied space; do not leave uncovered in sun or weather for more than 30 days |
| Packaging | 6 gal (23 L) pail and 2 gal (7.6 L) pail kit; 2 year shelf life stored between 32°F and 110°F (the coverage line of the data sheet swaps the litre figures of the two sizes) |
What 9235 Waterproofing Membrane is
9235 Waterproofing Membrane is LATICRETE's long-established fabric-reinforced liquid membrane. The liquid is a cold applied rubber polymer that you put on with a paint brush or a heavy nap roller, and it is used together with LATICRETE Waterproofing/Anti-Fracture Fabric bedded into it. Cured, the whole system is only about 0.02 in (0.5 mm) thick, load bearing and flexible, and tile, stone or brick can be set straight onto it with a latex or polymer fortified thin-set.
Data sheet DS-236 lists it for swimming pools, fountains and water features, shower pans, stalls and tub surrounds, bathrooms and laundries, spas and hot tubs, kitchens and food processing areas, terraces and balconies over unoccupied space, countertops and facades. It meets ANSI A118.10 for waterproofing and ANSI A118.12 for crack isolation of non-structural cracks up to 1/8 in, has an ICC-ES report (ESR-1058) and an IAPMO listing as a shower pan liner, and carries a TCNA "Extra Heavy" service rating. Suitable substrates include concrete, cement mortar beds and plaster, masonry, cement backer board, existing ceramic tile and stone, cement terrazzo, self-leveling and patching compounds, exterior glue plywood indoors, and gypsum wallboard indoors in areas that are not wet.
Coverage: per coat, not per pail
The data sheet gives the rate in its installation notes: each wet coat is 15 to 22 mils thick and uses about 0.01 gallon per sq ft, which is about 100 sq ft per gallon per coat. Separately, under "Approximate Coverage", it lists 300 sq ft for the 6 gallon pail and 75 sq ft for the 2 gallon pail kit. Those two figures are not the same rate. 300 sq ft from 6 gallons is 50 sq ft per gallon, which matches two coats. 75 sq ft from 2 gallons is 37.5 sq ft per gallon, closer to three thinner coats. LATICRETE's coverage chart T-10810 for the kit shows 75 sq ft at a 20 mil wet coat, with two 6 inch fabric rolls.
The installation section is clear that a full waterproofing job is more than two coats. You bed the fabric in a liberal coat, apply another liberal coat to saturate it, let that dry to the touch and then apply another liberal coat to seal the entire surface. That is three passes of liquid over the field, and the coves, corners, seams, drains and penetrations get pre-treated with a further 8 inch wide band before the main application. The calculator therefore defaults to three coats at 100 sq ft per gallon. If you are working on interior cement board or drywall walls, the data sheet lets you leave out the fabric and the third coat, so pick the two coat option for those walls. A crack isolation strip, which is liquid, fabric and liquid only over the crack, is also two coats.
How the calculator works
Area times one plus the waste allowance gives the area to treat. Multiply by the number of coats and divide by 100 sq ft per gallon to get gallons of liquid. The calculator then picks the fewest containers from the two sizes on sale, the 2 gallon pail kit and the 6 gallon pail, without leaving more than one kit's worth of liquid unused. A 100 sq ft shower floor and walls with 10 percent waste and three coats needs 3.3 gallons, which is two 2 gallon kits; 300 sq ft at three coats is 9.9 gallons, which is two 6 gallon pails.
Because the default is the full three coat rate, the result will usually be higher than you would get by dividing by the pail label. That is deliberate. Running out before the sealing coat means a second trip and a joint in the work. If you know your coats are going on thin, you can compare with the two coat option, which gives the same answer as the 300 sq ft per pail label.
Measuring a shower or floor
Add the floor, every wall surface you will waterproof, the curb and any niche or bench. A 3 × 5 ft alcove shower with three walls coated to 7 ft is 15 sq ft of floor plus (5 + 3 + 3) × 7 = 77 sq ft of walls, 92 sq ft in total. If the walls are cement board you could split it: 15 sq ft of floor and curb at three coats and 77 sq ft of wall at two coats comes to about 0.5 + 1.5 = 2 gallons before waste, so one 2 gallon kit is tight and two kits is the safe buy. Done entirely at three coats it is about 2.8 gallons, still two kits. The pre-treatment bands come on top in both cases, so keep the waste figure at 10 percent or more if the room has many corners, pipes or a niche.
Fabric is bought separately. The 38 inch roll covers about 300 sq ft of field; allow for the 2 inch overlap at seams. The 6 inch × 75 ft roll is used for every crack, board joint, cove and corner, folded in half at coves and corners and run 3 inches up the wall.
Application notes from the data sheet
- Surface temperature must be 45 to 90°F during application and for 24 hours afterwards. Damp surfaces are fine; hot, dry ones should be dampened first.
- Cement mortars must cure 7 days at 70°F before the membrane goes on, and new concrete must be at least 14 days old with moisture emission no higher than 5 lb per 1000 sq ft in 24 hours or 75 percent relative humidity.
- Each coat is dry to the touch in about 1 to 3 hours at 70°F and 50 percent relative humidity. Inspect the last coat for pinholes and thin spots and fix them with more liquid.
- Thin-set tile can go on once the final coat is dry to the touch. Allow 7 days at 70°F before flood testing and before thick bed mortar, screeds, epoxy adhesives or moisture sensitive flooring, and keep rain and water off for at least 5 days.
- It is not a vapor barrier, so steam rooms need a separate one, and it must not be used over expansion joints, structural cracks or cracks wider than 1/8 in.
9235 or HYDRO BAN?
LATICRETE also makes HYDRO BAN, a fabric-free membrane at the same 100 sq ft per gallon per coat but only two coats in the field, so it covers about 50 sq ft per gallon finished against about 33 for 9235 at three coats. HYDRO BAN can be flood tested 2 hours after it cures rather than 7 days. 9235 is still specified on many commercial and pool projects where the reinforcing fabric is wanted. Compare price per finished square foot and the time you can wait before tiling, not price per gallon.
Check before you buy
Every number here comes from LATICRETE data sheet DS-236, revision DS-236-1026, and coverage chart T-10810-FD-1125, read in October 2026. Coverage varies with the substrate profile, and LATICRETE revises data sheets without notice, so check the sheet that comes with your pail and call LATICRETE technical services at 1-800-243-4788 ext. 1235 if your job is unusual. Get local building code approval before using it as a shower pan liner.
FAQ
How many square feet does a gallon of 9235 cover?
About 100 sq ft per coat. How much finished membrane that makes depends on the number of coats. LATICRETE's main waterproofing method is three coats with fabric, which works out to about 33 sq ft per gallon. The data sheet's packaging figures are more generous: 300 sq ft for the 6 gallon pail is 50 sq ft per gallon, the same as two coats, and 75 sq ft for the 2 gallon kit is 37.5 sq ft per gallon. This calculator uses the three coat rate by default so you are not short on the sealing coat.
Why three coats? The pail label says 300 sq ft.
The installation steps in data sheet DS-236 call for a liberal coat to bed the fabric, a second liberal coat to saturate it, and, once that is dry to the touch, another liberal coat to seal the whole surface. The crack isolation section says the same thing: if waterproofing is needed, a third coat goes over the entire area. At 100 sq ft per gallon per coat, three coats over 300 sq ft would take 9 gallons, not 6. If you work with thinner coats at the low end of the 15 to 22 mil range you may get closer to the pail figure, so treat 300 sq ft as a best case and choose the two coat option only where the data sheet allows it.
How much fabric do I need?
The calculator only counts liquid. For the field, a 38 inch wide roll covers about 300 sq ft; with the 2 inch seam laps the data sheet asks for, plan on about 6 percent more fabric than floor and wall area. Add 6 inch wide strip for every cove, corner, board joint and crack, folded in half at coves and corners and flashed 3 inches up walls, and cut a 38 × 38 inch square for each drain. LATICRETE's coverage chart pairs the 2 gallon kit with two 6 inch × 75 ft rolls.
Can I leave out the fabric on shower walls?
On interior walls built with cement backer board or gypsum wallboard, the data sheet allows the fabric and the third coat to be left off the main application, which is the two coat option in the calculator. Coves, corners, seams and board joints still have to be pre-treated with liquid and 6 inch fabric first. Floors, shower pans, pools, exterior work and any substrate that is not cement board or drywall get the full fabric system. Check with your local building authority before using it as a shower pan liner.
How long before I can tile or flood test?
Each coat is dry to the touch in about 1 to 3 hours at 70°F and 50 percent relative humidity. Tile, stone or brick can go on with a latex or polymer fortified thin-set as soon as the last coat is dry to the touch. Wait 7 days at 70°F before flood testing, and before covering it with thick bed mortar, screeds, epoxy adhesive or moisture sensitive resilient or wood flooring. Cold or wet weather lengthens all of these. That is much slower than HYDRO BAN, which LATICRETE allows to be flood tested 2 hours after it cures.
LATICRETE and LATICRETE 9235 Waterproofing Membrane are trademarks of their owner. This page is an independent estimate based on the published data sheet; check the bag label before mixing.