SEMCO Liquid Membrane™ Waterproofing

You’ll need: Nu-Lift Cleaner · Stone Soap

Basement walls and floors carry mineral deposits, efflorescence — that white chalky bloom — and old residue. None of it lets a coating bond.

1. Remove loose paint, dust and debris. Scrape anything flaking.
2. Wet the surface, then apply Nu-Lift Cleaner and work it in with a stiff bristle brush to lift mineral deposits and efflorescence.
3. Rinse with fresh water.
4. Follow with Stone Soap to remove the residue Nu-Lift released and rebalance the surface pH, then rinse again.
5. Let it dry completely — hours, not minutes. This is the step people rush.

You’ll need: Fabric Reinforcement · Liquid Membrane

Hairline cracks need nothing — the membrane spans those on its own. Anything wider will reopen and telegraph through unless it’s reinforced.

1. Fill large cracks first with foam or hydraulic filler.
2. Apply a generous coat of Liquid Membrane over the crack.
3. Lay Fabric Reinforcement into the wet coating and press it flat.
4. Wait 10–15 minutes.
5. Coat over the fabric again to fully encapsulate it.
6. Let it dry to the touch before moving on.

Tape anything not being coated — frames, fixtures, pipe collars, the edge of a floor you’re stopping at.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

You’ll need: Liquid Membrane · ½" nap roller

1. Check any pre-treated areas from step 2 are fully dry.
2. Stir the product well. Pigments settle, and unstirred product gives uneven color.
3. Apply a thin, even coat over the whole surface including the pre-treated areas.
4. Wait for the recoat window: it’s ready when you can walk on it without leaving residue, and can’t leave a fingerprint. Roughly 25–45 minutes at 72°F.
5. Apply the second coat perpendicular to the first. Both coats go on the same day.
6. Let it dry to touch — roughly 1–2 hours at 70°F and 50% humidity.
7. Inspect for pinholes, voids and thin spots. It dries lighter, which makes them easier to see. Touch up with more membrane.

Initial cure is at least 7 days, and longer if the coats went on thick or the air is humid. Keep water off it for the whole window — the surface needs to be fully cured and hard before it sees any.

Floors only · walls need nothing

The membrane is rated for light foot traffic. If your floor will carry regular walking, furniture, shelving, appliances or storage, add a topcoat about 2 days after the last coat of membrane — not as soon as it’s dry to touch.

• Titan Shield Gloss — a water-based polyurethane hybrid and the tougher of the two. Three coats, roughly 150 sq ft per gallon. Choose it for heavy traffic or heavy objects standing on the floor.
• SEMCO Sealer MATTE — the same protection without the shine. Two coats, roughly 120 sq ft per gallon. Choose it for a finished basement where gloss would look wrong.

You’ll need: Nu-Lift Cleaner · Stone Soap

1. Excavate to the footing where you can, or as deep as the problem goes.
2. Remove soil, roots, loose mortar and anything flaking. Old tar can stay if it’s sound.
3. Apply Nu-Lift Cleaner, work it in with a stiff brush, rinse.
4. Follow with Stone Soap to clear the residue and rebalance the surface pH, then rinse again.
5. Let it dry completely. A wall that has been underground holds moisture — give it more time than you think.

You’ll need: filler · Fabric Reinforcement · Liquid Membrane

1. Fill large voids with foam or hydraulic filler and let it cure.
2. Cracks up to ¼" the membrane bridges on its own — a customer about to buy cement for a hairline crack found he didn’t need it.
3. Anything wider, or any joint that moves: coat, lay in Fabric Reinforcement, wait 10–15 minutes, coat over it.
4. Do the same at the footing junction, around bulkheads and along the sill plate line.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

1. Stir well — pigments settle and unstirred product gives uneven color.
2. ½" nap roller on flat concrete; a masonry brush for block, stone and stucco.
3. Two coats on smooth poured concrete, three on block or stone, four to five on ICF foam.
4. Recoat when it holds no fingerprint — a day apart is common in cool weather.

Initial cure is at least 7 days, and longer if the coats went on thick or the air is humid.

Every surface needs the right cleaner pair. Here is the rule.

• EPDM, rubber, shingle, torch-down — Prep B: Power Cleaner then Stone Soap. Power Cleaner cuts through grease, weathering and chalk; Stone Soap clears the residue and rebalances the surface pH.
• Metal, concrete decks, gutters — Prep D: Nu-Lift then Stone Soap. Nu-Lift chemically etches the surface and lifts oxidation; Stone Soap clears the residue and rebalances the surface pH.
• Plywood or timber — Prep E: sand with 60-grit. No cleaner; wood absorbs water.
• Unknown coating — Prep C: Power Cleaner then Nu-Lift.

1. Clear debris, moss and loose granules first.
2. Apply the cleaner, work it in with a stiff brush, rinse thoroughly.
3. Follow with Stone Soap — it clears the residue and rebalances the surface pH — then rinse again.
4. Let it dry completely before you coat.

You’ll need: Fabric Reinforcement · Liquid Membrane

Roofs leak at joins, not in the field. Treat every one of them before you coat the surface.

1. Apply a generous coat of membrane along the seam, lap, edge or around the penetration.
2. Lay Fabric Reinforcement into the wet coating and press it flat.
3. Wait 10–15 minutes.
4. Coat over the fabric to fully encapsulate it, and let it dry to touch.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

You’ll need: Liquid Membrane · ½" nap roller · extension pole

1. Check the reinforced areas from step 2 are fully dry.
2. Stir the product well — pigments settle, and unstirred product gives uneven color.
3. Apply a thin, even coat across the entire surface.
4. Recoat when it holds no fingerprint — roughly 25–45 minutes at 72°F.
5. Second coat perpendicular to the first. Both coats the same day.
6. Inspect for pinholes and thin spots; it dries lighter, which makes them easier to see.

Dry to touch in about an hour. Initial cure is at least 7 days — longer with thick coats or high humidity. Apply between 50–90°F, out of direct sun.

• EPDM, TPO, fiberglass — Prep B: Power Cleaner then Stone Soap.
• Aluminum or metal — Prep D: Nu-Lift then Stone Soap. Nu-Lift chemically etches the surface.
• Previously coated or unknown — Prep C: Power Cleaner then Nu-Lift.

1. Sweep off debris and wash away road film.
2. Apply the first cleaner, work it in with a soft brush, rinse thoroughly.
3. Follow with the second, rinse again.
4. Let it dry completely before you coat.

You’ll need: Fabric Reinforcement · Liquid Membrane

1. Coat around the penetration generously.
2. Lay Fabric Reinforcement into the wet coating and press it flat.
3. Wait 10–15 minutes, then coat over it to encapsulate.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

1. Check the reinforced areas are fully dry.
2. Stir the product well — pigments settle and unstirred product gives uneven color.
3. ½" nap roller, thin and even. Second coat perpendicular to the first, same day.
4. Inspect for pinholes and thin spots — it dries lighter, which makes them easy to see.

Dry to touch in about an hour. Initial cure is at least 7 days — longer with thick coats or high humidity. Apply between 50–90°F, out of direct sun.

Prep E · 60-grit · no cleaner

1. Pressure wash to remove dirt, algae and loose fibres.
2. Sand off every trace of old stain, sealer or paint with 60-grit. The coating bonds to bare timber, not to what was on it.
3. Vacuum or blow off all dust.
4. Let the wood dry fully — days, not hours, after washing. Wood holds water long after the surface looks dry.

You’ll need: Fabric Reinforcement · Liquid Membrane

End grain is the thirstiest part of any board and the first place rot starts. Treat it before you coat the field.

1. Coat the joint, board end or transition generously.
2. Lay Fabric Reinforcement into the wet coating and press it flat.
3. Wait 10–15 minutes, then coat over it to encapsulate.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

1. Stir the product well — pigments settle and unstirred product gives uneven color.
2. First coat goes into the timber and will look thin. That’s the wood drinking it, and it’s normal.
3. Recoat when it holds no fingerprint. Run each coat perpendicular to the last.
4. Three coats on bare wood. Inspect for thin spots — it dries lighter, which makes them easy to see.

Wait about 2 days after the last coat of membrane, then seal: three coats of Titan Shield Gloss or two of Sealer MATTE, about 6–8 mil per coat, with Non-Skid Additive mixed in. The membrane still needs its full 7-day cure before heavy use.

1. Drain fully. Check with a pool professional first if your water table is high — an empty shell can float.
2. Remove failed plaster, chalking gelcoat or any coating that is letting go.
3. Let the shell dry out properly. Days, not hours.

You’ll need: Nu-Lift Cleaner · Stone Soap · Fabric Reinforcement

1. Apply Nu-Lift Cleaner to lift scale, waterline deposits and calcium. Rinse.
2. Follow with Stone Soap to clear the residue and rebalance the surface pH. Rinse again.
3. Coat cracks over ¼" and the floor-to-wall cove, lay in Fabric Reinforcement, wait 10–15 minutes, coat over it.
4. Let everything dry before the field coats.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

1. Stir the membrane well, then mix in one Color Activator per container — matched to the same size and color.
2. Roller on the flat, brush into the cove, corners and around fittings.
3. Recoat when it holds no fingerprint. Three thin coats, not thick ones.
4. Inspect for pinholes and thin spots before you stop — on a shell this size one missed patch is the leak.

Initial cure is at least 7 days, and longer if the coats went on thick or the air is humid. Fill only after that.

1. Drain it fully. If there are fish, move them before you start.
2. Remove any failed coating — the membrane bonds to sound substrate, not to something already letting go.
3. Let it dry out properly. Concrete that has held water for years holds it in the pores too. Days, not hours.

You’ll need: Nu-Lift Cleaner · Stone Soap

1. Pressure wash if the surface takes it.
2. Apply Nu-Lift Cleaner and work it in to lift mineral deposits and old waterline staining. Rinse.
3. Follow with Stone Soap to clear the residue and rebalance the surface pH. Rinse again.
4. Let it dry completely before coating.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

1. Stir well — pigments settle and unstirred product gives uneven color.
2. Roller on the flat, brush into corners, cracks and around any fittings.
3. Recoat when it holds no fingerprint. Three coats for submerged work.
4. Check the waterline and the base especially — those are where leaks reappear.

Initial cure is at least 7 days, and longer if the coats went on thick or the air is humid. Owners who waited report no leaks; the ones who rushed are the ones who redid it.

You’ll need: a degreaser · Nu-Lift Cleaner · Stone Soap

1. Degrease oil and transmission stains first. No coating bonds to oil, and Prep D isn’t a degreaser.
2. Wet the slab, apply Nu-Lift Cleaner and work it in with a stiff brush to lift efflorescence and mineral deposits.
3. Rinse thoroughly.
4. Follow with Stone Soap to clear the residue and rebalance the surface pH, then rinse again.
5. Let the slab dry completely. Concrete holds water long after the surface looks dry.

You’ll need: Fabric Reinforcement · Liquid Membrane

1. Fill anything wider than ¼" with a suitable filler first.
2. Coat the crack or joint generously, lay Fabric Reinforcement into the wet film, press it flat.
3. Wait 10–15 minutes, then coat over it to encapsulate.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

1. Stir well — pigments settle and unstirred product gives uneven color.
2. ½" nap roller on an extension pole; cut in the edges with a brush.
3. Recoat when it holds no fingerprint. Second coat perpendicular to the first, same day.
4. Inspect for pinholes and thin spots before you stop.

Wait about 2 days after the last coat of membrane, then seal: three coats of Titan Shield Gloss or two of Sealer MATTE, about 6–8 mil per coat, with Non-Skid Additive mixed in. The membrane still needs its full 7-day cure before heavy use.

You’ll need: Nu-Lift Cleaner · Stone Soap

1. Remove soil, moss, loose mortar and anything flaking.
2. Wet the wall, apply Nu-Lift Cleaner and work it in with a stiff bristle brush to lift efflorescence and mineral deposits.
3. Rinse with fresh water.
4. Follow with Stone Soap to clear the residue and rebalance the surface pH, then rinse again.
5. Let it dry completely. A retaining wall holds moisture — give it more drying time than you think.

You’ll need: Fabric Reinforcement · Liquid Membrane

Mortar joints move more than the block does, and the joint where the wall meets its footing moves most of all.

1. Repoint anything that has failed before you coat.
2. Coat the joint generously, lay Fabric Reinforcement into the wet film, press it flat.
3. Wait 10–15 minutes, then coat over it to encapsulate.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

1. Stir the product well — pigments settle and unstirred product gives uneven color.
2. ½" nap roller on the flat, a masonry brush into the joints and corners.
3. Two coats on an exposed face; three on the buried side, on timber, or in a planter.
4. Recoat when it holds no fingerprint. One customer applying at 50°F got two to three hours between coats and finished in a day.

Dry to touch in about an hour. Initial cure is at least 7 days — longer with thick coats or high humidity. Apply between 50–90°F, out of direct sun.

• Cement or backer board — fixed soundly, joints taped, screws flush and dust-free. No cleaner needed.
• Plywood or wood — sand with 60-grit. No cleaner; wood absorbs water and chemistry.
• Existing tile — Nu-Lift then Stone Soap to remove soap residue, water deposits and mold, then rinse and dry.

You’ll need: Fabric Reinforcement · Liquid Membrane

1. Coat the joint generously, lay Fabric Reinforcement into the wet film, press it flat.
2. Wait 10–15 minutes, then coat over it to encapsulate.
3. Do this at every board joint, all inside corners, the wall-to-pan junction, the curb, niche corners and around the drain flange.

Each coat: 15–20 mil. Keep every coat in that range — thicker traps moisture and stays tacky, thinner leaves the membrane short of waterproof.

1. Stir well — pigments settle, and unstirred product gives uneven color.
2. Brush into screw heads, seams, corners and niches; roller the flat areas.
3. Two coats on board, three on bare wood. Recoat when it holds no fingerprint.
4. Inspect under a light. Look for pinholes, voids and thin spots — a customer specifically used a work light to find them, and touch-ups were easy.

Once dry, set tile straight onto it with standard thinset. Several customers tiled the next day; one reported mortar bonding to it as if it were concrete.

You’ll need: Stone Soap · stiff nylon brush · pump sprayer

Prep A is for dirt and grime, and for new concrete that has fully cured (about a month).

1. Sweep or blow off loose debris.
2. Mix 1 part Stone Soap to 4 parts water.

1. Lightly dampen the surface with water first — it stops the cleaner soaking deep into the pores.
2. Apply the Stone Soap mix with a pump sprayer and let it sit 2–3 minutes.
3. Scrub with a nylon brush or scrub machine.
4. Rinse well and make sure no residue is left.

Let the surface dry completely before any SEMCO coating goes on — below 3% residual moisture.

You’ll need: Power Cleaner · Stone Soap · nylon brush · pump sprayer

Prep B is for grease, oil, weathering and tough build-up — and for EPDM, TPO, shingle and bitumen roofs, and for re-prepping cured SEMCO membrane before an extra coat.

1. Power Cleaner: 1 part to 4 parts water.
2. Stone Soap: 1 part to 4 parts water.

1. Lightly dampen the surface with water.
2. Apply the Power Cleaner mix with a pump sprayer and let it sit 2–3 minutes.
3. Scrub with a nylon brush or scrub machine.
4. Rinse well until no residue is left.

Repeat the same steps with the Stone Soap mix. It lifts the chemical residue Power Cleaner leaves behind and rebalances the surface pH.

Let the surface dry completely — below 3% residual moisture — before coating.

You’ll need: Power Cleaner · Nu-Lift Cleaner · nylon brush · pump sprayer

Prep C is for surfaces with a non-water-based coating, or one you can’t identify.

1. Power Cleaner solution 1: 1 part to 4 parts water.
2. Nu-Lift solution: 1 part to 1 part water.
3. Power Cleaner solution 2: 1 part to 9 parts water.

1. Lightly dampen the surface with water.
2. Apply Power Cleaner solution 1, let it sit 2–3 minutes, scrub, and rinse well.
3. Repeat with the Nu-Lift solution.
4. Finish with Power Cleaner solution 2, then rinse until no residue is left.

Let it dry completely, then coat a small test patch before the full job.

You’ll need: Nu-Lift Cleaner · Stone Soap · nylon brush

Prep D is for efflorescence, mineral deposits and oxidation — basements, block, brick, stucco, weathered concrete — and for metal, which Nu-Lift etches so the coating bonds.

1. Remove loose paint, dust and debris.
2. Lightly wet the surface with water.

1. Apply Nu-Lift Cleaner undiluted and let it sit 2–3 minutes.
2. Scrub with a nylon brush or scrub machine.
3. Rinse well.

1. Mix 1 part Stone Soap to 4 parts water, apply and let it sit 2–3 minutes.
2. Scrub, then rinse until no residue is left.

Stone Soap clears the residue Nu-Lift released and rebalances the surface pH.

Let it dry completely — hours, not minutes — to below 3% residual moisture.