Frequently Asked Questions

Answers to the most common questions about SEMCO waterproofing, sealers, cleaners, and application. For shipping, returns, and payment questions, see our policy pages.

What is SEMCO Liquid Membrane?

SEMCO Liquid Membrane is a single-component, water-based liquid rubber waterproofing and anti-fracture membrane. You roll, brush, or spray it on and it cures into a seamless, flexible waterproof barrier for wood, concrete, metal, and many other surfaces, above ground or fully submerged.

Is it truly waterproof or just water-resistant?

It is fully waterproof. Once cured it forms a continuous, seamless elastomeric membrane with no seams or joints for water to penetrate, and it is rated for permanent submersion when applied at the correct thickness.

What surfaces can it be applied to?

It bonds to concrete, plywood and natural wood, stone, metal and aluminum, ceramic tile, CMU/concrete block, fiberglass, ICF, drywall, and RV roofing. The surface must be clean with moisture content under 3%, and no separate primer is required.

How many coats do I need?

Two coats minimum for standard above-ground waterproofing, to a total of about 30 mil. For fully submerged applications like pools and fountains, apply three coats at about 20 mil each, totaling about 60 mil.

How much does it cover?

One gallon of Liquid Membrane covers roughly 100 to 250 sq ft at two coats, depending on surface porosity. The 5-gallon pail is the most cost-effective size per square foot.

How long does it take to cure?

You can usually recoat within about 1 to 2 hours at 70F and 50% humidity. Full cure takes about 5 to 10 days depending on temperature and humidity, and submerged surfaces need a minimum of 6 to 7 days before filling with water.

Can I apply SEMCO products myself?

Yes. SEMCO products are designed for DIY use. Liquid Membrane goes on with a half-inch nap roller, brush, or airless sprayer, and the key to success is proper surface prep and even coats.

How do I prepare the surface?

Clean the surface with the appropriate SEMCO cleaner: Power Cleaner for oil and grease, Nu-Lift Cleaner to etch concrete and remove efflorescence, and Stone Soap for general cleaning. The surface must be clean, sound, and under 3% moisture before coating.

How flexible is it? Will it crack?

Liquid Membrane is highly elastomeric with up to 1300% elongation, so it stretches and bridges cracks instead of cracking with the substrate, holding up on decks, roofs, and foundations through movement and freeze-thaw cycles.

Is it UV-stable and can it be left exposed?

Yes. Liquid Membrane is fully UV-resistant and suitable for permanently exposed exterior applications, so it does not require a protective topcoat to survive sunlight.

Can SEMCO be used for pools, ponds, and fountains?

Yes. Liquid Membrane is a low-VOC, water-based membrane rated for permanent submersion, widely used to waterproof swimming pools, koi ponds, and fountains. Apply three coats to about 60 mil and allow the full 6 to 7 day cure before filling.

Are SEMCO products eco-friendly?

Yes. SEMCO products are water-based and low-VOC, and the companion cleaners such as Stone Soap are biodegradable, making them suitable for interior and exterior use with normal ventilation.

What colors are available?

Liquid Membrane comes in about 15 colors, including Semi-Clear, White, Rockslide Grey, Black Pearl, Cove Blue, Sandy Beige, Sequoia Brown, Barn Red, Hunter Green, and SEMCO Orange, and PreStain offers a full decorative-concrete color range.

Is there a warranty?

SEMCO Liquid Membrane carries a 5-year standard limited warranty, extended to 10 years on non-traffic surfaces, when applied correctly over properly prepared surfaces.

Ordering & Payments

What payment methods do you accept?
We accept VISA, MasterCard, American Express, Discover, and PayPal.
Can I change an order I have already placed?
Contact support during business hours as soon as possible. Once an order has shipped we are unable to make changes to it.

Shipping

When will I receive my order?
Orders placed before 8:00am PST on weekdays ship the same day; orders after 8:00am ship the next day, and weekend orders ship the following Monday. Expect delivery within 3 to 5 business days from our Las Vegas warehouse.
What do I do if I never received my order?
First check the tracking with the carrier. If the delivery still cannot be located, email us at info@semcoworks.com and we will help track it down.
What do I do if I received a defective order?
Photograph the defect and email the images to info@semcoworks.com so we can review it for replacement eligibility.

Returns & Refunds

What is the return policy?
You have 30 days from receipt to request a return. Items must be in original condition with intact packaging and proof of purchase. Only unopened liquids can be returned, with a 25% restocking fee; opened packages incur a 40% fee. Special orders and pigmented or color products are non-returnable, and international shipping fees are non-refundable.
How long does a refund take?
Once we receive and inspect the returned item, the refund is initiated immediately. Most credit card providers then take about 5 to 7 business days to post it.

SEMCO Liquid Membrane

How does SEMCO Liquid Membrane bridge cracks?
It has up to 1300% elongation, meaning it can stretch up to 13 times its original length without breaking, so it stretches over substrate movement and temperature changes instead of cracking.
Can I apply SEMCO Liquid Membrane on bare cinderblock?
Yes. Clean it with the recommended cleaners, make sure it is completely dry, then apply a minimum of two coats by roller.
What is the coverage of SEMCO Liquid Membrane?
Approximately 200 to 250 sq ft per gallon at two coats, about 20 mil per coat. Submerged applications use three coats at roughly 100 to 150 sq ft per gallon.
Can tile be applied on top of SEMCO Liquid Membrane?
Yes. Apply the Liquid Membrane as the primary waterproofing layer, then set tile over it with mortar or thin-set.
Can I paint over SEMCO Liquid Membrane?
Yes. We recommend a urethane-based or water-based acrylic paint.
How do I apply SEMCO Liquid Membrane?
Preparation varies by substrate, but in general clean thoroughly and let the surface dry, then apply with a half-inch nap roller at about 40 mil total (minimum two coats) or an airless sprayer at 2,500 to 3,300 PSI. Submerged applications need three coats at 20 mil each with a 6 to 7 day cure.
Why does SEMCO Liquid Membrane discolor when it contacts water?
Discoloration is a sign the membrane has not fully cured yet. It does not affect the waterproofing performance and clears as the membrane finishes curing.
How do I apply the Fabric Reinforcement?
Apply a generous coat of Liquid Membrane, press the fabric into it while wet while avoiding bubbles, wait 10 to 15 minutes, then apply a thin encapsulating coat over the fabric.
Does SEMCO Liquid Membrane need more coats for submerged applications?
Yes. Submerged applications require a minimum of three coats, or a total thickness of about 45 to 60 mil, with a 6 to 7 day cure before water exposure.
Is SEMCO Liquid Membrane UV-stable and can it be left exposed?
Yes. It is fully UV-resistant and suitable for permanently exposed exterior applications, so it does not need a protective topcoat to survive sunlight.

Natural Shield

What is Natural Shield and how does it work?
It is a water-based penetrating sealer made from silane and siloxane. It soaks into the pores of the substrate, where a chemical reaction forms a solid, breathable, water-repelling membrane.
On which substrates can Natural Shield be applied?
Any porous surface such as brick, natural stone, grout, and concrete. It is not suitable for painted or already-sealed surfaces.
How do I apply Natural Shield and how many coats?
Prepare the surface and make sure it is completely dry, then apply a minimum of three coats with a quarter-inch nap roller, HVLP, pump, or airless sprayer (size 17 tip). Apply the first three coats wet-on-wet without letting them dry between coats.
Will Natural Shield change the look of my surface?
No. Because it penetrates rather than coats, treated surfaces keep their natural color and texture.
Does Natural Shield make surfaces slippery?
No. As a penetrating sealer rather than a film-forming one, it does not change the look or feel of the surface.
Can I use Natural Shield on cinder block or vertical walls?
Yes. It works well on cinder block, helping the wall repel water and reducing efflorescence. Fill any cracks first.
How much coverage do I get per gallon?
It varies by surface: about 150 to 250 sq ft per gallon on polished concrete and 300 to 350 sq ft on stamped concrete, at three coats.
Is Natural Shield eco-friendly and easy to clean up?
Yes. It is a ready-to-use, water-based formula, and clean-up is simply SEMCO Stone Soap and water.

Crystal Coat

Do I need to strip old wax or finish before applying Crystal Coat?
Existing wax should be removed first. Beyond that, Crystal Coat is designed to go directly over existing sealed surfaces.
What floors can I use Crystal Coat on?
Hardwood, laminate, and VCT or linoleum indoors, plus concrete, marble, natural stone, terrazzo, and commercial-grade tile.
What do I apply Crystal Coat with?
A standard household microfiber mop, with no sprayers, buffers, or specialty tools required.
How long does Crystal Coat take to dry?
About 45 minutes before it is safe to walk on, and a full 24 hours before placing heavy objects on it.

Titan Shield Gloss

What kind of sealer is Titan Shield Gloss?
A single-component, water-based polyurethane-hybrid sealer. It goes on milky white and dries to a clear gloss finish.
What surfaces can I apply Titan Shield Gloss to?
Concrete, micro-toppings, pavers, block, wood, polished and stamped concrete, masonry, artificial stone, and X-Bond microcement.
How much coverage do I get from one gallon of Titan Shield Gloss?
About 150 to 200 sq ft per gallon at three coats on polished concrete, artificial stone, or masonry; stamped concrete covers more, around 200 to 300 sq ft per gallon.
How long does Titan Shield Gloss take to dry and cure?
Each coat is dry to the touch in about 20 to 45 minutes, and full cure is typically around 48 hours at 72F.
Can I use Titan Shield Gloss indoors and outdoors?
Yes. It is UV-stable, so it holds up in direct sunlight without yellowing.
How do I apply Titan Shield Gloss?
Test the surface pH (ideal 6.8 to 7.8) and apply a minimum of three coats to about 6 to 8 mil, using an airless sprayer (size 17 tip, 850 to 1,000 PSI at 18 inches) or a quarter-inch woven roller in a single direction.

Sealer Matte

What is SEMCO Sealer Matte?
A single-component, water-based polyurethane-hybrid sealer that acts as both sealer and hardener. It goes on white or milky and dries to a natural matte finish.
How is Sealer Matte different from Titan Shield Gloss?
They share the same chemistry and vehicle-traffic rating. Sealer Matte dries to a natural, non-reflective matte look, while Titan Shield Gloss dries to a visible gloss.
How much coverage do I get from one gallon of Sealer Matte?
About 120 to 160 sq ft per gallon at a minimum of two coats on polished concrete or artificial stone; stamped concrete covers more, around 220 to 270 sq ft per gallon.
Do I need a separate primer with Sealer Matte?
No. Sealer Matte is self-priming and works as both sealer and hardener.
Can I use Sealer Matte outdoors?
Yes. It is UV-stable and will not yellow or fade in sunlight, for application between about 50F and 90F.
How long does Sealer Matte take to dry and cure?
The first coat is dry to the touch in about 30 to 45 minutes. Full cure can be as fast as 18 hours at 90F, or up to 48 hours at 45F.
Will Sealer Matte hold up to vehicle traffic?
Yes. It is rated for commercial and industrial vehicle traffic, just like Titan Shield Gloss.

PreStain Color

Is PreStain a paint or a stain?
It is a stain, not a paint. PreStain penetrates into the pores of the substrate and reacts with it chemically.
Can I use PreStain indoors?
Yes. It is low-VOC, odorless, and non-toxic, so it is suitable for occupied interior spaces.
What surfaces can I use PreStain on?
Concrete, masonry, brick, stucco, wood, and composite materials, both interior and exterior.
Do I need to seal PreStain after applying it?
Light foot traffic needs no sealer. For heavier use such as furniture, regular foot traffic, garages, or vehicle traffic, apply a SEMCO sealer over it.
Will my surface look like a solid, uniform color?
No, and that is intentional. PreStain produces a translucent finish that lets the natural texture show through; additional coats increase color saturation.
Can PreStain go on damp or below-grade surfaces?
Substrate moisture must be 3% or below at the time of application. Mitigate any constant dampness first.

Projects & Applications

How do I waterproof a basement from the inside?
Clean the walls with SEMCO cleaners, repair cracks, and confirm moisture is under 3%, then apply two coats of Liquid Membrane to about 30 mil. It works on interior walls and floors as a moisture barrier and on exterior foundations.
How do I waterproof a swimming pool?
Apply SEMCO Liquid Membrane directly to pool plaster, gunite, or concrete at three coats totaling about 60 mil, and allow the full 6 to 7 day cure before filling with water.
How do I waterproof a wood deck or balcony?
Strip old coatings or sand with 60-grit, then apply two coats of Liquid Membrane and add Fabric Reinforcement at seams and high-movement joints. Its flexibility lets it move with the boards without cracking.
How do I waterproof a roof?
Apply SEMCO Liquid Membrane directly to roof tiles, asphalt, or flat roofs to form a seamless membrane. Its high solar reflectance also helps reflect heat and reduce cooling costs.
How do I seal and protect a garage floor?
Clean and etch the concrete with SEMCO cleaners, optionally add color with PreStain, then apply a SEMCO sealer such as Titan Shield Gloss. Add the Non-Skid Additive for traction.
How do I waterproof a fountain or water feature?
Apply SEMCO Liquid Membrane at three coats to about 60 mil for submerged use and allow the full 6 to 7 day cure before filling. The Color Activator can be added for richer color.
How do I waterproof a retaining wall?
Use the SEMCO Waterproofing Kit built around Liquid Membrane: prep and clean the wall, repair cracks, reinforce joints with Fabric Reinforcement, and apply the membrane to stop seepage.
Can I waterproof my RV roof with SEMCO?
Yes. Liquid Membrane is an easy-to-apply, water-based way to seal RV roofs and stop leaks, and its flexibility lets it move with the vehicle without cracking.

General

How is SEMCO Liquid Membrane different from products like DRYLOK?
It is a flexible, elastomeric liquid-rubber membrane with up to 1300% elongation rather than a rigid masonry sealer, so it moves with the surface and works across wood, metal, tile, fiberglass, and concrete, including submerged use. Rigid masonry waterproofers are generally limited to concrete and block and can crack where the substrate moves.
Are SEMCO products eco-friendly?
Yes. SEMCO products are water-based and low-VOC, and the companion cleaners such as Stone Soap are biodegradable, making them suitable for interior and exterior use with normal ventilation.
Is there a warranty on SEMCO Liquid Membrane?
It carries a 5-year standard limited warranty, extended to 10 years on non-traffic surfaces, when applied correctly over properly prepared surfaces.