Average Cost Estimate
An interior french drain in your basement is the most effective way to keep your basement dry and prevent flooding. Similar to an outside french drain system, installing an interior french drain requires digging a trench roughly 18-48 inches deep around the perimeter walls of your basement to collect any water that is pressing against the foundation. You will also need to install a sump pump to collect and remove any water that is collected by the drain system. Along with sealing your basement walls, installing a french drain in your basement will prevent flooding and gives you peace of mind knowing that your basement is properly waterproofed. This is especially important to homeowners who are using the basement as a living area or for storage of important belongings.
This page of Costimates focuses on the cost to install a basement french drain. We’ll help you understand the different factors that go into the cost of this project, including the price of supplies and estimated labor time that will be involved. Throughout this page you’ll be able to estimate the cost of installing a french drain in your basement and if you can do this project yourself or if you should hire a professional. Finally, we’ll share costs found across the web, as well as actual pricing from other homeowners who have had a system installed in their own basement.
Product and Supplies Cost Details
Interior French Drain Price Factors
An interior french drain installation will require heavy construction in your basement and determining the cost will depend on the following factors:
- Depth of Drain Trench – Depending on your situation, the depth of the drainage trench can be shallow (18-24 inches) or deep (48-60 inches). The deeper the trench, the more you’ll pay in labor costs.
- Number of Sump Pumps – 125 linear feet is about the most a single sump pump can handle effectively. If you have a larger basement with more than 125 linear feet of trench drain, you’ll likely need a second sump pump, and all electrical and plumbing to go along with it.
- Size of Basement – The cost of installing a french drain relates directly to the size of the basement. A larger basement will require more materials and more digging.
- Condition of Basement – You will be digging through the floor roughly a foot out from the interior walls. If you have a finished basement you will need to consider the cost of replacing anything affected by this, including flooring and walls. If you are hiring somebody to do the job you can save money by clearing out a 4-5 foot area around the perimeter of your basement to cut down on prep time.
Cost of Installation Supplies
To determine the cost of supplies needed to install your french drain you will need to determine the linear distance of your basement walls.
- $60 – $70 per 100 feet | 4″ perforated drain pipe – A drainage pipe is placed in the trench to collect water and guide it into your sump basin.
- $20 per cubic foot | Drainage gravel – This will be used to fill your trench before placing the drainage pipe. You’ll need approximately 2 square feet of gravel per linear foot of trench.
- $250 – $500+ | Sump pump – Your sump pump will remove the water collected by your drain. The quality and efficiency of your pump will determine the overall cost.
- $40 – $60 | Sump pump basin – This container will collect the runoff water and house the sump pump.
- $5-10 | Plastic couplers to connect pieces of drain pipe.
- $3 – $5 per square foot | Concrete – The last step of the process involves replacing the concrete on top of the drainage trench.
- $70 – $120 per day | Powered concrete wet saw, to cut straight edges before breaking out the floor.
- $80 per day | Jackhammer rental, to break up the concrete slab for removal.
Permits, Inspection, and Interior French Drain Installation Costs
Installation of a french drain in your basement will require extensive digging below your homes foundation. You will need to check your local laws on drainage system installation to determine if this project will require a permit or inspection.
- $50 – $200 ea. | Local permits (if required). You will likely require electrical, mechanical and plumbing inspections.
- $0 – $75 | While you won’t usually find utility wires or pipes under the floor in your basement, it never hurts to make this call. It’s usually free.
Installation Labor Factors
Basement french drains may sound like a simple process but there are a few factors that should be considered when it comes to the labor involved:
- Length of drain – The most important labor factor will be the length of the drain itself. Larger basements will obviously require more work.
- Number, or type of sump pumps – If your basement is large enough to require more than 1 sump pump you will need to factor in the extra time involved in digging the area for each basin.
- Basement Access – Since you will be filling the trench with gravel, there will be a large amount of dirt and concrete that needs to be removed from the basement. Having easy access through a hatch door will drastically cut down the time involved in debris removal.
- Condition of Basement – If you have a finished basement, there will be work involved with carpet or flooring removal, and any other finished part of the basement that needs to be removed to facilitate the french drain installation.
- Access to Utilities – The sump pump(s) is going to need electrical power to run, as well as a drain pipe to pump the water into. An electrician and plumber may need to come in and run service to the sump pump.
Average Outdoor French Drain Installation Cost
- $60-$80 per linear foot – Estimated cost for a professional to install a french drain in your basement.
Completed Installation Time
- 2 – 4 Days | Installation of an interior french drain in your basement by a professional.
- 4 – 6 Days | DIY-ers have reported spending 2-3 weekends on this project.
DIY or Hire a Pro
This is a job for Pro’s unless your basement is not finished, and you have the ability to devote time to getting it done quickly. You’ll need specialty power tools to complete this job, so make sure you have a truck and several friends for the hard work of cutting the concrete floor, jack hammering out the concrete, and driving many wheelbarrows of stone and drainage rocks back into the trench after you’ve prepared for it.
- Prepare thoroughly with plastic and other materials to prevent dust and airborne debris from getting the rest of your home filthy.
- Get your wheelbarrow driver license and several wheel barrows – you’ll need them.
- Call in favors from friends, you can’t have too much help for this project.
I installed basement french drains back in the 80’s when I worked for a septic system / site work company. I would not do this job again if you paid me!
Installed Costs from Around the Web
Compare french drain installation costs around the web at other leading cost comparison sites.
Costs Submitted by Homeowners and Pro’s