Examples of Waterproofing a Foundation
1. Liquid Rubber Foundation Waterproofing Membranes
are elastomeric polymerized coatings made from liquid rubber – the same quality material your car tires are made from.
Advantages: They are easy to apply, quick to dry, cold applied. You can do it by yourself, by using sprayer, roller or trowel. The liquid cures into an elastic rubber coating, able to fill up current small holes and bridge possible future cracks in foundation wall as the building settles down. Rubber is flexible. They also usually come with a long warranty, and many are environmentally friendly with low solvent content, or solvent free. Very economical.
Disadvantages: Possibility of inconsistency in coverage, but the newest products will help you to determine the “right” thickness by the intensity of color, i.e. if you apply the product and you see any lighter patches, you just add more liquid. Additional surface preparation and curing may be required. If there are bigger cracks or holes in the structure you have to fill in with cement or other trowel-grade material before applying the overall coating. Also some of the liquid membranes require longer curing times for the concrete before they can be applied to insure proper bonding.
2. Hot applied Liquid Rubber Foundation Waterproofing:
It’s a rubberized asphalt compound that forms a strong, flexible monolithic waterproofing membrane. Can be also applied on roofs.
Advantages: Adheres to virtually any structural surface. Ideal for rough uneven surfaces. Monolithic, free of seams, watertight, eliminates water migration and buildup of moisture. Offers strong protection because of the way it has to be applied.
Disadvantages: The surface has to be primed by primer first. The cost is higher because the product has to be applied in layers – basically you apply first coat of hot liquid rubberized asphalt, then you have to quickly firmly press on the fabric reinforced sheet into that hot layer, then apply a second coat of hot liquid waterproofing. Also, depending on the local building code you may have to apply 2 or 3 of these sheet layers. Because of this, the elasticity is low. And because it is Hot you have to be very careful – the best is to have it applied by a certified specialist.
3. Sheet membranes
The most common are self-adhering rubberized asphalt membranes composed of rubberized asphalt laminated to a waterproof polyethylene film.
Advantages: The biggest one is the consistent thickness because they are “pre-made” to a required standard. Mechanically strong, and resistant to hydrostatic pressure. Cover even the bigger holes or damaged areas.
They can be applied to concrete, metal, wood or masonry surfaces.
Disadvantages: Harder to apply because of their very high “stickiness”, also the cost for in-place is higher. Application requires at least 2 people to put in on properly. Requires lots of additional work = additional cost. If there are irregularities on the surface you want to put a sheet on they have to be smoothed first with some coat to make the surface even. You also would need to learn of joint treatment, lap joints, corners, penetration, priming, patching etc. And once the piece is down you won’t get it back up in reusable condition.
4. Cementitious Waterproofing
Is a cement based flexible waterproofing membrane? It can consist of Portland cement, sand, acrylic mixture, plasticizer and other active waterproofing chemicals to increase its durability and effectiveness.
Advantages: Very easy to use, just mix the powder with water according to manufacturer’s recommendation, and apply with brush or trowel. Very accessible - available from suppliers of masonry products, or specialized dealers. Paintable. Also comes in a variety of colors. In most cases one coat is sufficient, although some areas may be needing a use of the reinforcing mesh. Low cost. Corrosion and weather resistant. Can be applied as a positive or negative side waterproofing.
Disadvantages: No flexibility – cement does not stretch, so as the structure settles down there are the possibilities of the future cracks. Before applying the surface has to be free from protrusions, gaping cracks, oils, paints, water repellents and any other foreign material that could act as a bond breaker. Holes must be filled with approved block filler.
5. Bentonite Waterproofing
is a Bentonite clay below-grade foundation waterproofing product which consists of sodium Bentonite clay sandwiched between 2 layers of woven and no-woven puncture resistant polypropylene fabric. Comes as a clay panels and sheets.
Advantages: Can absorb tremendous amount of water. And as it takes the water in the clay swells and pushes itself into cracks and voids where it stays permanently as a barrier against the water. It is flexible and resistant to most chemicals. Non-toxic, non-polluting. No fumes. Can be applied in cold weather.
Disadvantages: Because of the way the clay works the seal does not form until the foundation is backfilled and the water reaches the Bentonite material, which means you cannot confirm the integrity of the seal.
Damp proofing is the traditional method of protecting a foundation. Sealer is a damp proofing membrane that stops water vapor from passing through a foundation wall and into the basement area. It can be used on either poured concrete or masonry block construction and forms a smooth continuous barrier.
**If such a basement is constructed of masonry block or concrete and not reinforced properly, such a damp proofing might not be the best product to protect you against water infiltration when cracks come about due to stress, movement or just plain fatigue from hydrostatic pressures, poor drainage and poor backfill. **
When plans call for dry basement living space, a membrane or liquid can do the job if it’s installed right
The most commonly specified sheet materials are self-adhering rubberized asphalt membranes. These 60-mil-thick membranes are composed of rubberized asphalt laminated to a waterproof polyethylene film. The asphalt side is incredibly sticky but is covered by a release paper, which you remove during application.
The first time you work with this material, it’ll drive you crazy because it sticks to everything. But you’ll be surprised how fast you can move with it once you develop a rhythm. It takes two people, one on top to smooth it out and stick it down, the other on the bottom to pull off the paper. You’ll have many details to learn about surface preparation, priming, patching, joint treatment, terminations, lap joints, penetrations, and corners.
Because they’re so sticky, these membranes can be pretty unforgiving. Once a piece is down, you won’t get it back up again at least not in reusable condition. However, the system allows easy repairs of holes, fish mouths, puckers, and wrinkles. You’ll patch holes or damaged areas with a piece of membrane placed right over the first layer. With a fish-mouth or wrinkle, all you do is slit the raised area, press it down flat, and cover it with a patch.
A chief advantage of sheet membranes is their consistent thickness. Because they’re manufactured to exacting tolerances, you can be sure of the 60-mil coverage. These membranes also have good elongation.
A higher in-place cost is one of the main disadvantages of sheets. The cost of the material itself is likely to be greater on a square-foot basis than the liquid membranes. Labor cost is also higher, because of the entire cutting, handling, reinforcing, and detailing you have to go through during installation.
Not everyone agrees, however, that sheet membranes lessen the quality-control risk. A rubberized liquid forms a continuous, seamless coating, whereas a sheet membrane results in many seams, with the potential for a poor seal. If you’re applying these materials, make sure your lap joints are tight and properly detailed. Make correct use of the manufacturers mastic or other accessories. For example, one manufacturer requires you to apply a bead of mastic to every lap joint within 12 inches of a corner when using its product.
Hope this might help to understand some basement water proofing basics.
This does not even touch the parameters of the waterproofing technology.