Article on How to waterproof concrete roofs by Dr. W. C. Ames PhD.

Waterproofing concrete with roof coatings is an important task on concrete structures for roof repair and preservation. Many roofs throughout the world are constructed using poured concrete. These structures are usually made with reinforced steel. They are inexpensive but require a great deal of maintenance to keep them from leaking since they shift, move, and dissolve easily. The problem with concrete is that it IS concrete. Concrete is made up from several ingredients including calcium carbonate and sand. Calcium Carbonate is a plentiful substance that comes from the dead skeletons of sea life. These plentiful substances dissolve quite easily in very wet environments unless they are protected.

The Ames® Company specializes in the making of specialty rubber and plastic coatings that extend the life of concrete. These products stretch with the concrete and form a waterproof membrane. Unfortunately, untreated concrete cracks and dissolves in many geographic areas where there is a great deal of rain. In the wintertime, water leaks into the untreated cracks and freezes and expands substantially damaging your concrete building.

Before beginning any project, read all instruction labels. Always run a test patch first in an inconspicuous area, to ensure that proper adhesion and drying occurs and the product works to your satisfaction.

Usually a concrete structure is composed of four walls of poured concrete and a poured concrete roof. Walls and parapet walls, both outside and inside, over the roof need to be water proofed. Both outside walls and inside walls should always be considered to be a part of your waterproofing tasks. The building should be thought of as a total building envelope. If you have stucco on the outside of the building, use Ames “Super Primer” and then “Paint & Prime®” to waterproof the stucco or concrete surface.

PREPARE THE SURFACE
How to fix flat roofs or concrete roofs with “roof coatings” is really a simple process even for the “do it yourselfer”. The first thing you should do is to power wash the entire surface area of the roof, which will remove most of the loose material. Use caution, so as not to damage any interior areas due to roof leakage that are inside the building. In certain situations, a shot-blaster may be needed to roughen the surface. In addition, it might be a good idea to fill any large cracks and crevices with mortar.

PRIME THE SURFACE
After preparing the surface you will need to prime the roof with Ames Pure Acrylic Plastic primer, “Super Primer”. Super Primer will dry rapidly and will flow into the cracks and crevices of the concrete rooftop. It will bond to the concrete with remarkable adhesion. Super Primer has an affinity for concrete and it actually glues together and strengthens old concrete surfaces. Read all instruction labels before beginning. Always run a test patch first in an inconspicuous area, to ensure that proper adhesion and drying occurs and the product works to your satisfaction.

SEAM TAPE
Next, seam tape all remaining cracks larger than one-eighth of an inch. Seam tape with “Ames Peel & Stick” Seam tape. This tape comes in 2 inch, 4 inch, and 6 inch widths by 50-foot rolls. This rubber tape contours easily to the surface and will stick with the most remarkable adhesion to the primed surface. The seam tape will be difficult to remove from here on out.

TOPCOAT THE SURFACE
Apply at least two gallons per 100 sq. ft. of “Super Elasto-Barrier” or similar Ame's product. Finally, apply two to three gallons per 100 sq. ft. of Ames Maximum Stretch elastomeric acrylic plastic coating. Super Primer, Seam Tape, Super Elasto Barrier, and “Maximum-Stretch” are an unbeatable combination for concrete roofs. This five-gallon per 100 sq. ft. system will cost about $1.40 per square foot on average.

DRAINAGE
Proper drainage is also an important factor on concrete roofs. With this application, you will be substantially strengthening the concrete with the pure acrylic plastic Super Primer. Followed by the rubber “Super Elasto-Barrier”. Be sure to apply seam tape where the vertical and horizontal concrete joints meet at the parapet roof and wall joints. The parapet wall and cap also need to be water proofed. This combination of coatings, as well as the outside of the parapet wall, should be waterproofed with Ames “Paint & Prime”.

ROOF DECKS
If the surface is a roof deck application and you wish to walk on your roof, then you can apply Ames “Safe-T- Deck” non-skid durable plastic paint as your final coat. This product comes in a variety of colors. Lighter colors are best for areas in high heat. Dark colors in the northern hemispheres.

We at Ames wish you the best in your application.

The drawing below describes a basic product application.