Someone has suggested "How to waterproof a concrete house", and this article will offer some methods of waterproofing that a fairly handy homeowner should be able to have good success with. That being said, a true concrete house is probably more waterproof than any other common type of structure to begin with, and only cracks, joints, or window and door openings should require attention.
Step 1
Determine if you concrete house needs waterproofing. Core-formed concrete, precast concrete panels, and ICF, or Insulated Concrete Form wall construction is essentially more waterproof than most other construction methods to begin with, and the exterior is usually coated more for appearance than weatherproofing.
Step 2
Select the type of exterior waterproofing membrane you wish to use. There are a number of durable, attractive, and fairly simple to apply coatings available. For a stucco-like finish, an EIFS (exterior insulated finish system) finish coat can be applied directly to the concrete, filling any voids, floating out minor irregularities, and creating a good moisture resistant surface. This is applied with a trowel, and comes in 5 gallon buckets premixed and tinted to your preferred color. There are a number of paints which will seal concrete and masonry construction, as well as membrane applied waterproofing, and elastomeric coatings.
Step 3
Prepare the walls for the coating you have selected. This should include: Caulking, to fill any expansion joints or larger cracks up to 1/4 inch, with a good quality polyurethane caulking, grinding off any rough, uneven concrete, and thoroughly cleaning the surface of any loose material, oil, or dirt.
Step 4
Apply the finish system you have selected to the wall according to the manufacturer's directions. With an EIFS system, you mix the material in the bucket it comes in with a paddle mixer and drill motor, and apply it to the wall directly with a plastering trowel, keeping the thickness fairly uniform, and floating it off with a Styrofoam block or rubber float to create a uniform surface and texture. Other products may be sprayed, brushed, or rolled on with a paint roller.
Step 5
Use a chemical waterproofing material that has silicone, siloxethane, or other sealants if you are simply sealing or resealing a finished wall system like stucco. These products do not effect the finished appearance greatly, offer good performance if the surface is retreated at manufacturer's recommended intervals.
Step 6
Apply a suitable roof sealer to your roof if you have a cast in place concrete roof. This is an unusual situation, but there are homes with cast in place concrete roof systems, and typically, roofing cement and fiber reinforced roll roofing is applied to the roof to prevent water intrusion. If the house doesn't have sufficient slope to allow water to drain off the roof in a rain event, you may have to apply tar or a synthetic waterproofing membrane directly to the concrete, or use a seamless rubber roofing system. These products are more suitable for professional contractors to use.
Tips
- Check the VOC (volatile organic compounds) labelling on the material you select for this project. Some jurisdictions limit VOC releases and strictly enforce compliance.
- Below grade (underground) construction is more problematic as far as waterproofing is concerned. Many basements built in areas where snow accumulation is common have chronic water seepage, leaving them damp and necessitating installation of sump pumps and dehumidifiers to dry them out.
Warnings
- Read and follow manufacturer's instructions carefully. These products may have volatile chemicals, fumes, and other dangerous byproducts during application.
- Use appropriate safety equipment, such as safety glasses and respirators.
Things You'll Need
- Tools for cleaning the surface to be treated, possibly including a grinder with a masonry grinding wheel, a pressure washer, brush, and water.
- For applying waterproofing, a trowel, rubber float, paint brushes or roller.
- Caulking gun and caulk for filling larger cracks.
