How much will it cost to install a French drain in my basement?
As a basement waterproofing contractor, the two questions I get asked most frequently are “What is a French drain?” Which is followed by “How much does a French drain cost?”
There are different types of French drains, just as there are different contractors and different ways to do the same job. The cost of a French drain from a contractor who digs a shallow channel will vary from the cost of a French drain from a contractor who installs a deep channel system. They’re both French drain systems, but there’s quite a difference between the two. A deep channel French drain relieves more hydrostatic pressure – the pressure of groundwater pushing against your basement floor – than a shallow French drain system.
Installing a French drain system with a sump pump in your basement is similar to having a construction job going on inside your house. If your basement is finished or has lot of belongings in it, there will be a lot of preparation work that needs to take place before construction begins. The perimeter of the basement floor must be cleared at least 5 feet from the basement walls. The basement walls themselves must be cleared to the bare foundation to a minimum height of at least 2 feet. Performing this preparation work yourself, rather than having a contractor perform it, can result in significant cost savings.
What is a French drain?
First we do the prep work, moving your stuff and covering it with plastic, then laying tarps across the floor. The inside perimeter of the floor, the floor that touches your basement’s exterior walls, is cut approximately 1 foot from the wall. Then a deep channel trench is excavated and pitched.
If your basement walls are constructed of cinder block, where possible, we tap the lowest course of block and install weep holes to drain water from the walls. Then fully slotted, non-biodegradable, high density polyethylene drainage pipe (also known as HDPE pipe) is installed in the trench to deliver water to the sump area.
To discharge the water, we install a 3,000-gallon-per-hour submersible pump in a covered polyethylene liner. Typically for a basement with a perimeter of less than 124 feet, only one sump pump is needed, but two sump pumps are usually installed basements with perimeters ranging from 125 to 249 feet.
Next, polydrain wallboard is installed over the bottom of the perimeter wall and over the entire trench in the basement. Then the wallboard and drainage pipe are covered in gravel and the basement floor is re-cemented back to its original level.
Finally, we do the cleanup work, sweeping the floor clean, removing all debris from your property and removing the plastic covers from your belongings.
How much does a French drain cost?
At our company, the cost of a French drain system depends on the size of your basement. It’s calculated by the number of linear feet around the perimeter of your basement. So, if your basement measures 36 feet wide and 24 feet wide, your perimeter footage would be 120 feet (36 feet + 24 feet + 36 feet + 24 feet = 120 feet).
Here are some average costs for a French drain installation from A-1 Basement Solutions in 2012. These prices, of course, are subject to change in the future:
- 100-foot perimeter basement (25 feet wide by 25 feet long) is about $6,000 including one sump pump
- 130-foot perimeter basement (30 feet wide by 35 feet long) is about $7,000 including two sump pumps
- 150-foot perimeter basement (40 feet wide by 35 feet long) is about $8,000 including two sump pumps
- 180-foot perimeter basement (40 feet wide by 45 feet long) is about $9,000 including two sump pumps
- 200-foot perimeter basement (50 feet wide by 50 feet long) is about $10,000 including two sump pumps.
As every project is different, these numbers should be a general guideline to use. For example, if your house has a 140-foot perimeter, you can generally figure the cost to be between $7,000 and $8,000 for a French drain system with two sump pumps.
About this Angie's List Expert: Doug Lynch provides a basement waterproofing from Westfield, N.J., where he lives with his wife Kelli. Doug teaches the Adult School class “Keeping Your Basement Dry” in six different towns to educate people how to have healthy basements. Doug is the owner of A-1 Basement Solutions in Scotch Plains, N.J., and the author of the popular Basement School blog.
As of January 23, 2013, this service provider was highly rated on Angie's List. Ratings are subject to change based on consumer feedback, so check Angie's List for the most up-to-date reviews. The views expressed by this author do not necessarily reflect those of Angie's List.