Homeowners may be faced with the task of coating concrete surfaces in basements to create more inviting living areas. Due to its composition, concrete contains a great deal of water, which makes coating these surfaces challenging. In general, construction standards for covering concrete surfaces require preliminary preparation before drywall compound or other coatings can be successfully applied for long wear and attractive results.
Concrete is composed of cement, aggregate and and up to 20 percent water. This large amount of water helps the components in cement to form strong bonds within the material in a process called hydration. Unfortunately, it also creates problems in that water can continue to be absorbed into the concrete long after the material has set. When applying coatings of any kind to concrete surfaces, you must take into account the tendency of concrete to absorb and release moisture.
Drywall compounds are designed to creating a smooth surface on drywall seams and corners for the application of paint or other coating materials. Most often, drywall in installed on top of the concrete surface, and the compound is then applied over the drywall. Occasionally, compounds are applied directly to the concrete, but this can be risky, with cracking or peeling occurring in some cases. The vast array of drywall compounds available can make the job of choosing a coating for concrete more confusing. Read labels and recommendations carefully to determine if the compound can be used directly on concrete.
Types of Drywall Compounds
Drywall compounds can range from standard products used to finish wallboard to more sophisticated formulas that have a variety of applications. Manufacturers offer a “lightweight” drywall compound material that can be applied to concrete surfaces. Setting-type joint compounds are made of polymers and plaster of Paris, which undergo a chemical reaction when wetted that creates a hard and durable surface.
Preparing Concrete for Drywall Compound Application
Due to its moisture content, concrete must be treated before covering it with drywall compounds, or the water within the material will react with the coatings. This is true not only for drywall compounds but also for paint, plaster, stucco or other coatings. The reaction can be so extensive as to necessitate complete removal of the coating and re-application after treating the concrete surface. A concrete sealer or primer is generally recommended to prevent water from reacting with the coating compound.
Applying the Drywall Compound
Allow the concrete to cure for at least 60 days before applying drywall compound. Remove dust and surface contaminants from the concrete before application. Apply a priming agent such as Kilz or other concrete sealer and allowed it to dry before using the surface coating material.
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