Everything You Need to Know About French Drains.
If your basement is damp or flooding, you often have a drainage problem in your yard. A french drain is one possible solution to remove excess water before it can damage your home.
What problems can a French drain fix?
If water is collecting in your basement, a french drain is often a great solution to save your property from damage. Properly installed, a french drain can help keep your basement dry and prevent future water damage.
Collected water is usually the result of poor drainage. Two common drainage problems are caused by building a home near the bottom of a slope and having a high water table on the property. The type of soil around your home can also play a big role in allowing water to collect around the foundation.
Once installed, a French drain will collect water and carry it away to a better location like the storm drains near your house.
How are French drains installed?
Installing a French drain takes five steps:
- A trench is dug around the foundation of a building with drainage problems. The trench may be from a foot to six feet deep depending on where the foundation of the home sits.
- A special pipe with holes to collect standing water is laid in this trench. It is put in the trench on a grade, with the pipe running to a lower point away from your home.
- This pipe is then covered with a foot of gravel which will draw in water from the surrounding soil.
- A layer of special filtering fabric is laid down over the gravel to protect the system from clogging.
- Finally the trench is filled back in with the original top soil and made level with the ground around it.
How do French Drains work?
A french drain creates a hidden path in your yard that carries water away from your basement. It attracts water by surrounding the basement with an trench filled with gravel. Instead of flooding your basement, water is drawn into this gravel-filled trench that slopes away from your home. Perforated pipes inside this trench then carry this water further downslope, to the storm drains or a lower point on the property.
French Drain Design
French drains can be built inside or outside of the house, but outside the house is most common. A french drain installed as part of new construction can easily be laid outside the basement, following the foundation of the house. Sometimes a drain inside the basement will be required. Both drains have the same mechanical design. A trench will be dug, lined with a perforated pipe, and filled with gravel. Each design has some unique features, but they both serve the same purpose.
Some Common Questions About French Drains:
How long do french drains last?
Properly installed drains use advanced plastic sheeting called geotextile to protect the drainpipe from a blockage. French drains can last decades before needing maintenance. If your home requires a sump pump, a high-quality model will last around ten years before needing replacement.
What is an exterior french drain?
An exterior french drain is installed by digging a trench at the level of your foundation. It will be covered by several feet of soil. These systems are prone to clogging over the years as sediment from the soil above builds up in the drain pipes. To combat this, installers may surround the drainage pipe with a water permeable barrier, similar to the weed-guard fabric sold at garden centers. Exterior installations rarely require a drainage pump.
Are french drains from France?
No. French drains are actually an American invention, just like french fries. A Massachusetts farmer and postmaster named Henry Flagg French designed the system and popularized it in an 1859 book called Farm Drainage. The design became widespread in the US and Europe, and people came to know gravel-and-pipe drainage systems as “French Drains”.
What’s an interior french drain?
An interior french drain is installed by jackhammering around the edge of your basement to create a trench between the exterior wall and the floor slab. This trench is filled with gravel and a drainage pipe like an exterior drain. These pipes drain to the sump in your basement, and a sump pump will be installed to drain the water to the sewer system as it fills. Once installed, the drain is cemented over again, with a small gap left along the wall to collect any infiltrating water. These systems are best installed as a first step when finishing a basement.
What are vertical french drains?
Some property flooding problems can be resolved by digging a small well with an auger and filling it with gravel. These are sometimes called vertical french drains, but aren’t suitable for basement water problems.
What kind of pipe do french drains use?
French Drains can use two types of pipe:
- Flexible corrugated polypropylene pipe is more economical for exterior runs and larger installations. This pipe can be bought with a sediment sock already installed. These pipes are cheaper, but they aren’t as durable, prone to changing slope, and harder to clean should they become clogged.
- Interior installations often use rigid 4-inch PVC pipe. This can be set up with an access point for a rotor-rooter machine to clean sediment and will last indefinitely at the same slope it was installed at.
Your contractor will help you choose the best option for your installation.
Are french drains and ground gutters the same thing?
No. French drains and ground gutters serve two different purposes. A french drain is placed to relieve water that is penetrating the lowest level of your home. A ground gutter is placed under the drip point of your roof to collect rainwater runoff in cases where a rooftop gutter is unwanted or impractical. Both systems use a trench with sunken pipe, but the specific design and locations are different.
What is the best slope for a french drain?
A french drain needs to have at least a 1% slope. That means it goes deeper by 1 inch for every 8 feet of pipe.
How deep will my french drain be?
A french drain trench is about a foot deep and half a foot wide.
Should my gutters connect to the french drain?
No. The french drain is only designed to absorb excess groundwater. Draining any other system into the french drain will overload it and potentially cause more drainage issues than you already have.
French Drains: Before and After
A french drain can help turn a swampy basement into a dry livingspace. The installation won’t leave any permanent scars on your property. Here are some before and after pictures:
French Drains are a Valuable Addition to Your Property
If you have water problems in your basement, a french drain is the smartest investment you can make. Left unattended, a wet basement will cause tens of thousands of dollars in damage, threatening the health and safety of the home’s residents. The cost of repairing mold and water-damaged walls and floors far outweighs the cost of installing a french drain. And if you decide to sell your home, a wet basement will hurt your property values. Dry Basement Solutions has the tools and experience to fix your swamped basement. Don’t wait till your damp basement becomes a lagoon. Make the smart choice and give them a call to explore your options for a dryer basement today!