Water infiltration through concrete basements, foundations, and below-grade walls is one of the most common and costly home problems in areas with high water tables or significant rainfall. Effective waterproofing stops water before it enters the structure, protecting against mold growth, structural degradation, and finished basement damage. The five picks below cover the main product categories, from crystalline treatments to elastomeric coatings, for new construction and remediation on existing concrete.
| Product | Best For | Rating |
|---|---|---|
| Drylok Extreme Masonry Waterproofer | Basement interior walls | 4.6/5 |
| Xypex Concentrate | Deep crystalline waterproofing | 4.7/5 |
| KILZ Interior/Exterior Basement Waterproof Paint | Budget interior coating | 4.4/5 |
| UGL Drylok Fast Plug | Stopping active leaks first | 4.5/5 |
| RadonSeal Plus | Below-grade slabs | 4.6/5 |
Drylok Extreme Masonry Waterproofer - Best for Basement Interior Walls
Drylok Extreme is rated to resist 15 PSI of hydrostatic pressure, which is roughly equivalent to a 33-foot column of water, making it appropriate for most residential basement wall waterproofing from the interior side. The white coating applies with a brush or roller in one or two coats and bonds chemically to concrete block and poured concrete walls. It is also mold-resistant and paintable once cured, making it practical as both a functional waterproofing layer and a base for a finished basement. Coverage is approximately 75 to 100 square feet per gallon depending on surface porosity.
Search for Drylok Extreme Masonry Waterproofer on Amazon
Xypex Concentrate - Best Deep Crystalline Waterproofing
Xypex uses crystalline chemistry to penetrate into concrete and form needle-like crystals that fill the capillary pores and micro-cracks within the concrete matrix. Unlike surface coatings that can delaminate, crystalline waterproofing becomes part of the concrete structure and continues to self-sealing minor cracks that develop after application. Xypex is used in commercial and infrastructure construction for tunnels, water treatment plants, and foundations. For serious residential applications, it is the highest-performance option available in a DIY-accessible format. It applies as a slurry coat and requires surface preparation and damp curing after application.
Search for Xypex Concentrate Crystalline Waterproofing on Amazon
KILZ Interior Exterior Basement and Masonry Waterproof Paint - Best Budget Coating
KILZ offers the most accessible entry point into basement waterproofing with a formula that handles light to moderate moisture on concrete block and poured concrete walls. For basements without severe hydrostatic pressure, where the primary concern is seasonal dampness and condensation rather than active water intrusion, KILZ is a cost-effective solution. It applies easily and dries relatively quickly. Its pressure resistance is lower than Drylok Extreme or crystalline products, so it is not suitable as a primary waterproofer on walls with active seepage, but as a preventive treatment on currently-dry basement walls, it provides meaningful protection at an accessible price.
Search for KILZ Basement Waterproof Paint on Amazon
UGL Drylok Fast Plug Hydraulic Cement - Best for Stopping Active Leaks First
Before applying any coating or membrane to a leaking wall, active water entry points must be stopped. Drylok Fast Plug hydraulic cement is the first-step product for this, setting in 3 to 5 minutes and expanding to lock out flowing water through cracks, holes, and pipe penetrations. It is applied to the leaking area first, allowed to set, and then the full wall treatment (Drylok Extreme, Xypex, or similar) is applied over it once all active entry points are sealed. Skipping this step causes coatings to fail as water pressure lifts them from behind the sealed surface.
Search for Drylok Fast Plug Hydraulic Cement on Amazon
RadonSeal Plus - Best for Below-Grade Slabs
RadonSeal Plus uses a reactive deep-penetrating silicate formula designed for basement floors and other below-grade horizontal surfaces where vapor transmission through the slab is the primary concern. It penetrates deep into the concrete, reacts with the free lime and calcium silicate compounds, and creates a permanent crystalline barrier within the slab. Unlike film-forming floor sealers that require regular reapplication, RadonSeal Plus does not require repeat treatments. It also reduces radon infiltration through the slab, which is a secondary benefit for homes in radon-prone areas. Compatible with most concrete floor coatings applied afterward.
Search for RadonSeal Plus Concrete Sealer on Amazon
How to Choose a Concrete Waterproofing Product
Start by diagnosing the source and severity of the moisture problem. Active water seeping through cracks requires hydraulic cement first, then a rated waterproof coating. Dampness or condensation without active seepage is handled adequately by standard masonry waterproofers. For chronic hydrostatic-pressure situations, crystalline products offer the most durable long-term solution. Always clean the wall surface thoroughly and repair any structural cracks before applying any waterproofing system. Applying waterproofer over a dirty, painted, or flaking surface guarantees failure regardless of product quality.
For related reading, see best concrete water sealers and best concrete wall crack fillers. Review our full evaluation process at /methodology.
Frequently asked questions
What is the difference between waterproofing and water-sealing concrete?+
Waterproofing is intended to stop water under hydrostatic pressure from penetrating the concrete, while water sealing repels surface moisture and incidental water contact. True waterproofing products are rated for below-grade applications where water pressure exists from the soil side of the wall. Water sealers protect against rain, surface moisture, and occasional wetting but are not sufficient for basement walls with water pressure against them. The product label should specify whether it is rated for below-grade or hydrostatic-pressure applications.
Can I apply waterproofing to the inside of a basement wall if the water source is outside?+
Yes, but the effectiveness depends on the product type. Crystalline waterproofing products like Xypex and Kryton work from the negative side, meaning they can be applied to the interior face and still block water pushing from the exterior. Standard paint-on coatings and elastomeric products are less reliable from the negative side under sustained hydrostatic pressure and can delaminate. For serious exterior water intrusion, exterior-side waterproofing is always more effective when accessible, but interior crystalline treatments are the practical solution for existing structures.