Interior Waterproofing Systems for Crawl Spaces & Foundations
Manage recurring interior water with drainage, sump systems and foundation-wall water-control components designed around where the water enters and how it can be discharged.
Interior Waterproofing May Be Appropriate When
The correct system depends on how water reaches the interior and where it can be collected.
- Water appears along a foundation wall
- Water collects along the crawl-space perimeter
- Standing water returns after rainfall
- Exterior excavation is impractical
- Water needs to be routed to a sump basin
- An existing interior system needs improvement
Interior Waterproofing Is About Controlling the Water Path
An interior system does not stop rain from falling or make a structure immune to water. It provides a controlled way to collect and manage water that reaches the interior side.
Water may appear along foundation walls, through joints, beneath a crawl space or at low points inside the structure.
Depending on the source, the system may include an interior French drain, sump basin, pump, wall drainage or vapor-control materials, and a defined discharge route.
The final design should be based on the actual conditions rather than a fixed package or tier.
What We Evaluate
- Where the water first becomes visible
- Foundation-wall condition
- Floor and crawl-space low points
- Existing drains or sump systems
- Interior elevation and drainage route
- Available gravity discharge
- Need for pumped discharge
Collect the Water and Give It Somewhere to Go
A complete interior system considers collection, routing and final discharge.
Identify the Entry Point
Determine where recurring water is entering or appearing inside the structure.
Collect the Water
Use drainage components positioned along the identified water path.
Route It
Move the collected water toward gravity discharge or a sump basin.
Discharge It
Route collected water to the selected exterior discharge location.
The System Can Combine Several Different Components
Not every project requires every component.
Interior French Drain
Perimeter or targeted drainage used to collect water entering or accumulating inside the structure.
Sump Basin
Receives water from the drainage system where gravity discharge is not practical.
Sump Pump
Moves collected water through solid discharge piping to the selected outlet.
Wall Drainage
Wall drainage or protection materials may help direct interior wall seepage toward the drainage system where appropriate.
Vapor Protection
Crawl-space vapor-control materials may be incorporated once liquid-water conditions have been addressed.
Solid Discharge Piping
Carries collected water away from the structure without intentionally collecting surrounding soil water.
Collect Water Along the Interior Perimeter or Low Areas
An interior French drain may be used when water repeatedly enters along a foundation wall or accumulates in a predictable path beneath the structure.
The drainage trench can contain perforated pipe, clean aggregate and filter fabric where specified before routing toward gravity discharge or a sump basin.
The location and extent of the drain should match the water path rather than automatically surrounding the entire structure.
Learn About Interior French Drains →A Typical Interior Drain May Include
- Excavated drainage trench
- Perforated drain pipe
- Clean drainage aggregate
- Filter fabric where specified
- Sump or gravity connection
- Specified finish or patching
Pump the Water When Gravity Discharge Is Not Available
A sump system is commonly used when collected water cannot leave the structure effectively through gravity alone.
Interior drainage routes water into the basin. The pump then moves that water through solid discharge piping toward the selected exterior outlet.
A sump pump is only one component. It works best when the surrounding drainage system gives water a defined path to the basin.
Learn About Sump Pump Integration →Sump System Components May Include
- Sump basin
- Submersible pump
- Interior drain connection
- Check valve where specified
- Solid discharge piping
- Selected exterior discharge location
Interior Waterproofing Is One Option — Not the Only Option
Water Already Reaching the Interior
Interior drainage may make sense when recurring water is entering or collecting inside and needs a controlled path to discharge.
Water Against the Outside Foundation
Exterior waterproofing may make more sense when the primary problem is repeated exterior saturation against an accessible foundation wall.
Multiple Water Sources
Some properties require exterior drainage, foundation waterproofing, interior drainage or more than one approach to address separate water paths.
Build the System Around the Water Path
Inspect
Identify where water appears and evaluate surrounding conditions.
Diagnose
Determine the likely water path and which system components may be appropriate.
Design
Establish the collection route, sump location and discharge plan.
Install
Install the drainage, basin, pump or wall components included in the project.
Finish
Complete discharge, patching and other specified finish work.
Different Approaches to Different Water Paths
Interior Water Management
Manages water after it reaches the interior side of the foundation or crawl space.
- Interior French drainage
- Sump pump systems
- Wall drainage where appropriate
- Interior collection and discharge
Exterior Foundation Waterproofing
Treats accessible exterior foundation surfaces and exterior drainage conditions before water reaches the interior.
- Exterior excavation
- Foundation surface preparation
- Waterproof membrane
- Drainage or protection board
Interior Waterproofing Manages Water — It Does Not Make a Structure Floodproof
Interior drainage and sump systems are designed around conditions identified during the evaluation and the areas included in the written project scope.
They do not prevent plumbing failures, blocked outlets, extreme rainfall, changing grades, neighboring runoff, power outages, equipment failures or every possible future source of water.
The purpose of the system is to provide a controlled collection and discharge path for the water conditions being addressed.
Liquid Water and Humidity Are Different Problems
Interior Waterproofing
Interior drainage and sump systems are designed to collect and route liquid water.
When standing water is present beneath a crawl space, the drainage system should generally be established before the final encapsulation liner is installed.
Crawl Space Encapsulation
Encapsulation addresses ground vapor, wall vapor and crawl-space humidity after liquid-water management has been addressed where necessary.
Drainage and encapsulation can work together as separate components of a complete moisture-control system.
View Crawl Space Encapsulation →Coverage Depends on the System Installed
Qualifying interior waterproofing or drainage projects may include written workmanship coverage when identified in the project documents.
Sump pumps and other manufactured equipment remain subject to applicable manufacturer warranty terms.
View Warranty InformationImportant Warranty Distinction
Standalone interior drainage, waterproofing and sump-pump work does not automatically receive the 40-Year Transferable Limited System Warranty.
That warranty is reserved for qualifying premium encapsulation systems when specifically identified in the written warranty documentation.
Interior Waterproofing FAQ
What is interior waterproofing?
Interior waterproofing generally refers to systems that collect, manage and discharge water after it reaches the interior side of the foundation or crawl space.
Do I need a sump pump?
Not always. If an appropriate gravity discharge exists, a pump may not be required. Where gravity drainage is impractical, a sump basin and pump may be used.
Is interior waterproofing better than exterior waterproofing?
They address water differently. The appropriate approach depends on the source, access, foundation conditions and available drainage options.
Can interior waterproofing be installed before encapsulation?
Yes. When recurring liquid water is present, drainage and sump work are commonly addressed before the final encapsulation liner is installed.
Will an interior system stop every future leak?
No. The system is designed around the water sources and areas included in the project scope. Future conditions outside that scope can still affect the structure.
Can you waterproof only one problem wall?
In some situations, a targeted scope may be appropriate. The final recommendation depends on the water path and surrounding conditions.
Interior Waterproofing Service Area
Serving homeowners throughout Greenville, Spartanburg, Anderson, Pickens, Greenwood, Laurens and surrounding Upstate South Carolina communities.
Water Entering Along a Crawl Space or Foundation Wall?
We can evaluate where the water is appearing, how it is moving through the structure and where it can be discharged, then build the waterproofing scope around the actual conditions.