Can-Do Guide®: Dampproofing Foundations Dampproofing vs. Waterproofing A contractor must provide for adequate drainage around the building or retaining wall. If rainwater is able to drain away, then the “dampproofing” techniques outlined here will be sufficient to keep water from entering or damaging the structure in most cases. (Check local building codes). On the other hand, if the ground tends to become saturated with water frequently or if you have standing water around the structure for part of the year, you need to consult a professional waterproofing contractor. Choosing the Right Foundation Coating There are two types of foundation coatings to choose from: water-based asphalt emulsion coating, and solvent-based asphalt coating. Choose water-based Henry® 107 Asphalt Emulsion. Henry 107 is a protective coating that will last longer than solvent-based coatings, but needs to be applied under good conditions. The surface must be very clean, and you must have two days of dry, warm weather (over 50°F). Asphalt emulsions become water resistant only after drying thoroughly. Do not apply if the air temperature is below 60°F, or if there is threat of rain or temperatures below 40°F within 48 hours. Make sure the entire job is fully cured before backfilling with dirt, and avoid scraping or damaging the coating. Choose solvent-based Henry 201 Asphalt Roof Coating or Henry 101 Unfibered Roof & Foundation Coating. For better adhesion, choose Henry 201—its fibered base gives it added body and better grip to vertical surfaces. With Henry 201 or Henry 101, you will have no worries about low temperatures or rainfall after application. Solvent-based coatings can be applied in colder temperatures (as low as 32°F), can be rained upon within two hours of application, and can actually eat through a fine layer of dust to “grab” the surface. Coating Your Foundation Before coating, the surface must be clean and in good repair. Fill all holes, cracks, and joints with cement mortar so the surface is as smooth as possible. - Moisten the concrete wall with a fine mist of water.
- Apply a priming coat of Henry 107 diluted 20% with water, at a rate of 1.5 gallons per 100 square feet with a 4-knot soft-bristle brush. Avoid over-brushing.
- Allow the first coat to dry completely. Do not moisten surface before applying the finish coat.
- Apply the finish coat at full strength (do not dilute), at a rate of 3 gallons per 100 square feet.
Drying time for each coat is 8 to 12 hours in warm, dry weather. Cool and humid weather can extend the drying time of each application to a week or more. Test for dryness in the slowest drying area by rubbing the surface vigorously with wet fingers. The coating is dry if no stain transfers to your fingers. For waterproofing/dampproofing with Henry 107, email Henry Technical Services, or call them at 1-800-486-1278 for additional application instructions. | 
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To dampproof with Henry 201 or Henry 101: - Apply a priming coat of Henry 201 or Henry 101 at a rate of 1.5 to 2 gallons per 100 square feet with a soft-bristle brush. Do not thin.
- Allow the first coat to dry completely.
- Apply the finish coat at a rate of 1.5 to 2 gallons per 100 square feet.
Allow each coat to cure overnight before applying a second coat or backfilling with dirt. While solvent-based coatings must be applied to a dry surface, they will not wash off or be damaged by rainfall before they are cured. IMPORTANT: No dampproof coating will work if it is damaged or scraped off when backfilling, or if the foundation wall itself cracks. Recommended tools: | 
