A water repellent reduces the tendency of concrete or masonry to absorb rainwater. A waterproof coating may be designed to resist a continuous water barrier or hydrostatic pressure. Those are different performance claims, and using the wrong term can lead homeowners to expect a clear penetrating sealer to fix a leak it was never designed to stop.
Water Repellency
Penetrating silane/siloxane treatments typically make pore surfaces hydrophobic so rainwater beads or absorbs more slowly. Current Sika penetrating sealers emphasize water repellency, breathability and protection from moisture or chloride intrusion while leaving little visible surface film.
Waterproofing
Some coatings are tested for much more severe exposure. Current DRYLOK Extreme, for example, publishes ASTM D7088 hydrostatic-pressure resistance and states a 15 psi pressure rating. That is not a normal performance claim for a clear penetrating driveway sealer.
Wind-Driven Rain Is Another Category
Manufacturers may also publish wind-driven-rain testing for above-grade walls. That can be relevant to Florida block, brick and stucco, but it still does not mean a coating repairs failed flashing, openings, roof/wall transitions or active cracks.
| Problem | Typical product question |
|---|---|
| Rain soaking into porous above-grade masonry | Would a breathable penetrating water repellent reduce absorption? |
| Below-grade hydrostatic pressure | Is the chosen system specifically rated for the pressure and side of application? |
| Water entering around a window/door/flashing joint | What failed in the assembly? A broad wall coating may not be the repair. |
| Concrete slab vapor transmission | What does the floor/coating manufacturer allow? Surface water repellency is a different issue. |
Marketing Words Are Not Test Methods
Look for the technical claim behind words such as “weatherproof,” “waterproof,” “water-resistant” and “water repellent.” What test was used? On what substrate? At what film thickness or application rate? Was the product tested against absorption, wind-driven rain, hydrostatic pressure or something else?