Waterproofing a Concrete Wall with Ames Blue Max

Protect it With a Continuous Waterproof Membrane

Water leaks through a concrete wall can lead to serious issues over time, from mold growth and damp odors to structural deterioration. Fortunately, stopping those leaks and protecting your wall for the long haul is simple with Ames Blue Max® Trowel Grade and Blue Max® Original Blue.

Both products are part of Ames’ professional-grade waterproofing line, engineered to create a flexible, seamless membrane that keeps water out for good. Whether you are sealing a basement wall, foundation, or retaining wall, following these steps will help you get long-lasting results.

#1 PREP THE SURFACE
Pressure wash, scrape, and remove any loose material

Start by cleaning the wall thoroughly. Remove dirt, debris, efflorescence, old paint, or any loose or flaking material that could prevent good adhesion. A clean, dry, and sound surface ensures that Blue Max® bonds tightly to the wall, creating a continuous waterproof membrane.

If you are dealing with heavy contamination or mold, use a concrete cleaner or mild detergent before pressure washing. Allow the surface to dry completely before moving to the next step.

Two men working on a roof, inspecting the edge and surface.

Apply Blue Max Trowel Grade to a concrete wall using a putty knife

#2 FILL CRACKS AND VOIDS
Use Blue Max® Trowel Grade to fill cracks or voids over 1/8 inch

Inspect your wall for cracks, holes, or rough areas. Any opening wider than 1/8 inch should be patched with Blue Max® Trowel Grade. This thick, paste-like version of our classic Blue Max® formula is perfect for filling and leveling imperfections before applying your main waterproof coating.

Apply it directly with a trowel or putty knife, pressing it firmly into the crack or joint. Smooth the surface to ensure it blends evenly with the surrounding area. Allow the patched areas to cure before moving on.

#3 APPLY THE FIRST COAT
Apply Blue Max® Original Blue at 1 gallon per 100 sq. ft. per coat

Now it’s time to start building your waterproof membrane. Apply the first coat of Blue Max® Original Blue using a brush, roller, or airless sprayer. Work it into the concrete surface to ensure full penetration into pores and small imperfections.

Blue Max® goes on blue and dries to a dark, flexible, rubberized finish that seals out moisture completely. Make sure your first coat is even and consistent across the entire area.

#4 INSPECT FOR COVERAGE
Inspect the surface for even coverage and ensure coating has fully dried.

Once the first coat has cured, inspect your wall for any missed spots or thin areas. The surface should have a uniform color and texture. If you notice light or thin patches, touch them up before applying the second coat.

Drying time will vary depending on temperature and humidity, but generally, you’ll want to wait until the coating is dry to the touch and no longer tacky. (Blue Max will remain tacky even once dry. You will just want to wait until it is dry to the touch.)

#5 APPLY THE SECOND COAT
Apply another coat of Blue Max® at the rate of 1 gallon per 100 sq. ft. per coat
The second coat is where the real strength comes in. Apply it perpendicular to the first coat for best coverage. This cross-layer technique helps eliminate pinholes and ensures a thick, continuous membrane that moves with the structure without cracking or peeling.

Once cured, you’ll have a heavy-duty waterproof barrier that resists hydrostatic pressure and keeps moisture out permanently.

Construction site with a dome structure and workers under a cloudy sky.

#6 TOPCOAT WITH YOUR LATEX PAINT OF CHOICE
After the final coat of Blue Max® has fully cured, you can paint over it with a quality latex paint if you prefer a decorative finish. The paint helps protect the coating from UV exposure (if applied above grade) and gives your wall a clean, finished look.

Man spraying blue paint on a roof under a clear sky.

And That’s It!

Your wall is now sealed, waterproof, and protected against future leaks. 💪

Whether you are tackling a basement moisture problem or reinforcing a retaining wall, Ames Blue Max® Trowel Grade and Blue Max® Original Blue give you professional results that last for years.