Tanking a cellar—applying a continuous waterproof coating to interior walls and sometimes the floor—typically costs $8-$18 per sq. ft. of treated surface, or about $5,000-$12,000 for a modest basement project. The final price depends on wall and floor area, surface preparation, water pressure, local labor rates, and whether drainage or repairs are needed.
In U.S. estimates, the work is often described as interior basement waterproofing or cementitious waterproofing rather than cellar tanking.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| Installed tanking | $8/sq. ft. | $13/sq. ft. | $18/sq. ft. | Per treated wall and floor surface |
| Typical project total | $3,500 | $8,000 | $16,000 | Roughly 300-900 sq. ft. of surface |
| Wall-only application | $6/sq. ft. | $10/sq. ft. | $15/sq. ft. | Preparation and coating; no floor system |
| Drainage add-on | $40/linear ft. | $75/linear ft. | $140/linear ft. | Interior perimeter channel and related work |
Assumptions: U.S. dollars, ordinary access, sound foundation, contractor-installed system, and no major structural repair.
What a Typical Cellar Tanking Project Costs
Most straightforward jobs land between $5,000 and $12,000, with treated surface area—not floor area alone—driving the estimate. A 300-sq.-ft. basement floor with 7-ft. walls may have roughly 700-850 sq. ft. of combined floor and wall surface. At $8-$18 per sq. ft., that can mean $5,600-$15,300 before unusual repairs, although a wall-only treatment can cost less.
Lower quotes generally cover accessible masonry, limited patching, and a standard cementitious coating. Mid-range projects may include removal of old finishes, joint repairs, multiple coating layers, and floor-to-wall junction treatment. High estimates are more likely when the substrate is damaged, access is restricted, the room needs extensive clearing, or water pressure calls for a more involved design.
Contractors may calculate the price using wall area, floor area, or a combined treated-surface measurement. Ask the estimator to show the measured square footage and identify exactly which surfaces are included. A quote based only on the basement’s floor footprint can be misleading if walls are also being tanked.
Materials alone are often about $1.50-$4 per sq. ft. of treated surface, depending on coating type and required layers. The remainder covers preparation, skilled labor, protection, equipment, and business overhead. Typical scope: sound concrete or masonry, local patching, and a compatible waterproof coating.
How Coatings, Repairs, and Labor Shape the Quote
Surface preparation and labor commonly account for more of the bill than the waterproofing compound itself. A contractor should list prep, coating, junction detailing, and any separate drainage work rather than presenting one unexplained lump sum.
| Quote component | Typical price | What it covers | Pricing basis |
|---|---|---|---|
| Materials | $1.50-$4/sq. ft. | Primer, cementitious coating, reinforcement, and sealants | Coating surface |
| Labor | $4-$9/sq. ft. | Preparation, application, and cleanup | 10-12 hours for a small room; more for larger areas |
| Equipment | $150-$600 | Mixers, grinders, ventilation, and protective setup | Per project |
| Repairs and disposal | $300-$2,000 | Loose plaster removal, crack patching, and debris hauling | Depends on condition and volume |
| Permits or inspections | $0-$500 | Local review when required for associated work | Jurisdiction and project scope |
Labor rates often run $50-$100 per hour per worker, but contractors commonly price tanking as a complete installation. A two-person crew may spend one to three days on a modest project, with extra time needed for grinding, drying, multiple coats, or careful detailing.
Waterproofing may require multiple application and curing stages. If a quote promises same-day completion, check whether it accounts for substrate drying and product instructions. A cheap coating price may omit crack repair, floor-to-wall coves, protection of stored items, or cleanup.
Why Wall Height, Water Pressure, and Surface Condition Matter
Two cellars with the same floor size can receive very different estimates when wall height, moisture pressure, and substrate condition differ. A 7-ft. basement with a 30-by-40-ft. footprint has about 980 sq. ft. of wall surface before openings are deducted; an 8-ft. wall adds roughly 140 sq. ft. More wall area means more preparation and coating, even though the floor footprint stays unchanged.
Water entry also affects the design. Occasional dampness or seepage through sound masonry may be addressed with surface treatment and joint detailing. Persistent water pressure, a rising water table, or active leaks can require an interior drainage channel and sump pump instead of—or in addition to—a coating. A perimeter drain can add roughly $40-$140 per linear foot, and a sump system may add $1,200-$3,500 installed.
Cracks wider than about 1/8 inch, moving joints, deteriorated mortar, and flaking coatings need assessment before tanking. Patching may add $10-$30 per linear foot for straightforward cracks; structural movement or extensive masonry rebuilding costs more. Applying a coating over loose or contaminated material risks failure and should not be treated as a legitimate low-cost shortcut.
Surface area and access are practical thresholds too. Projects under 300 sq. ft. may still face a contractor minimum of $1,500-$3,000, while areas above 1,000 sq. ft. can qualify for a lower unit price if the work is repetitive and access is easy. Finished rooms may require extra removal and reinstallation work.
How Regional Labor Rates Shift Basement Waterproofing Prices
Local labor and access can move a tanking quote by roughly 10%-30% from a typical mid-market estimate. In lower-cost rural markets, standard installation may fall near $8-$12 per sq. ft.; in many suburban markets, $10-$16 is common; dense, high-cost metro areas can reach $14-$22 or more for difficult jobs.
These ranges are directional rather than fixed regional tariffs. A high-cost city can still have competitive bids, while a remote property may pay extra for contractor travel, material delivery, or limited crew availability. Older northeastern and midwestern homes can also require more masonry preparation, but that condition—not the region by itself—is what should appear in the scope and price.
Compare quotes from contractors familiar with local foundation types and groundwater conditions. Check whether sales tax, disposal, drainage, and any required inspections are included. When one bid is much lower, ask whether it treats the same area, includes equivalent prep, and specifies a compatible coating system.
When Interior Tanking Needs a Drain or Different Repair
Tanking is not a universal fix for water intrusion, so the right comparison is the cause of the leak and the full remedy price. A cementitious coating can control moisture moving through suitable masonry, but it may not stop water that is entering under strong hydrostatic pressure or through an active floor-wall joint.
For persistent seepage, an interior perimeter drainage system with a sump pump may cost $4,000-$12,000 for a typical basement, depending on perimeter length, floor cutting, pump equipment, and discharge routing. It manages water by collecting and directing it rather than trying to block it at the wall. Some installations combine drainage with wall coatings or a vapor-control finish.
Exterior excavation and waterproofing can cost about $100-$250 per linear foot of foundation wall, with a small project commonly reaching $8,000-$20,000 or more. It can address water at the outside wall but may involve landscaping removal, access limitations, and backfill. For isolated hairline cracks in otherwise dry walls, professional injection may cost $500-$1,500 per crack or repair visit, subject to crack length and access.
Ask for a diagnosis before choosing by price alone. A contractor should identify where water enters, whether it appears seasonally, and whether the foundation moves. A coating warranty is useful only when its written conditions match the actual source of moisture and the proposed preparation.
Three Cellar Sizes Show How Quotes Add Up
These examples use installed rates and typical U.S. conditions; they are planning budgets, not guaranteed bids. Each estimate includes coating and ordinary preparation but excludes major structural repairs, unusual drainage, and extensive finish replacement.
| Scenario | Measured scope | Labor assumption | Estimated total |
|---|---|---|---|
| Small utility cellar | 450 sq. ft. of wall surface at $9-$13/sq. ft. | Two workers, about 12-16 crew-hours | $4,050-$5,850 |
| Average basement, walls and floor | 800 sq. ft. at $11-$16/sq. ft. | Two workers, about 24-32 crew-hours | $8,800-$12,800 |
| Large, older masonry cellar | 1,100 sq. ft. at $14-$20/sq. ft. | Two or three workers, about 40-60 crew-hours | $15,400-$22,000 |
The small example assumes accessible walls and limited patching. The average example includes both surfaces, so its area is not the basement footprint. The older cellar example allows for more grinding, mortar repair, and careful junction treatment, but not a full drainage system. Adding 50 linear feet of channel at $40-$140 per foot could add $2,000-$7,000.
For a quote comparison, request the same details from each bidder: measured area, coating system and number of layers, crack repairs, floor-wall detailing, drying time, cleanup, and exclusions. Ask whether the total is fixed or subject to changes after demolition reveals hidden damage.
Which Preparation Choices Can Lower the Tanking Bill
Controlling access, repair scope, and material upgrades is usually safer than cutting out essential preparation or coating layers. Clear stored items before the crew arrives if the contractor permits it; moving furniture and shelving can add $200-$800, while a full basement cleanout may cost $500-$2,000.
Keep the work area accessible and agree in advance on who removes old paneling, carpet, or plaster. DIY removal may save $300-$1,500, but only when the material is safe to handle and the contractor approves the preparation. Older finishes can contain asbestos or lead; testing and qualified removal may be necessary, and disturbing suspect materials can increase costs and health risks.
Limit the treated area only when a qualified inspection confirms that water is confined to a specific zone. A partial coating may cost less upfront, but stopping at an arbitrary wall line can leave vulnerable joints untreated. Conversely, avoid paying for full-room tanking when a documented, localized defect can be repaired reliably.
Compare at least three itemized bids for the same scope. Confirm the coating’s intended use, required substrate condition, number of coats, warranty exclusions, and whether drainage is needed. Choose standard-grade products that meet the site requirements rather than adding premium finishes that do not improve waterproofing performance.
How Scheduling and Drying Time Affect the Final Price
Most small tanking jobs take two to five working days on site, but curing and preparation can extend the calendar schedule. A wall-only application on sound masonry may be completed more quickly than a combined wall-and-floor system that needs grinding, crack treatment, and several coats.
Contractors may charge a 10%-25% premium for urgent scheduling, weekend work, or a short-notice leak response. The premium can be higher when emergency service includes water extraction or temporary protection, which is separate from tanking. Scheduling during a contractor’s slower period may help avoid rush fees, but seasonal discounts are not guaranteed.
Moisture and temperature conditions can affect product application and drying. Ask how long the cellar must remain clear, when flooring or wall finishes can be reinstalled, and whether ventilation or dehumidification is included. Reinstalling finishes too soon can trap moisture or conceal a coating problem, potentially creating a larger repair expense.
Get the projected start date, number of site visits, curing intervals, and payment milestones in writing. A deposit should correspond to the contract terms and applicable local rules; avoid paying the full price before the specified work and cleanup are complete.