The terms water and basement are two terms you don’t want to hear in the same sentence as a homeowner. Sure if it is going through piping and water systems to provide water for the space that fine; otherwise you prefer it remain outside the space. Contractors will seal masonry walls during construction of the space to help prevent leaking and will install interior/exterior drain systems (known as French drains). These are installed at the footer level to help pump water away. It is best to install these drains during basement construction, but a standalone system can be installed later on, if not done during the initial construction phase.
It should be below floor level and as close to basement walls as possible. This will help block trenching and pouring of water onto basement floors; depending on regulations/codes, trenches might be below the footer level which extends inside the basement space. With the first option, water which leaks through the walls is captured and will run down to an open trench. In the second scenario it also catches water from the footer, but will require more floor space in your basement for installation purposes.
Material requirements –
Perforated PVC is the typical material used for the French drain system. The flexible pipe typically measures 3 to 4” in diameter, and comes with mesh socks to help catch debris. Another type of drain comes in rigid perforated sections, which are assembled in order to fit the area you will place the drain in your basement. In the trench below the basement, pea gravel is used to act as a natural filter. Concrete can cover/conceal the drain, removable metal grids can also be installed by contractors for such purposes.
Collection pit –
One or both French drains will open into a collection pit; the water has to go somewhere, and this is where it will drain when flooding occurs. A sump pump then pumps the water out and into the ground’s surface away from your basement space. Electricity is required for the sump pump to operate, so an outlet in a utility room or nearby room is required as well. For free flowing water, the collection pit should be deeper than your French drains, so water collection doesn’t occur below the space.
Exterior water draining –
If installation is taking place in an existing basement then the issue of water entering the space is already present. A French drain will divert this water, it will not prevent the water from leaking to the basement walls, which is what is probably occurring in the space. Water from outside will find its way in through cracks in the basement walls, and when the wet soil freezes it will expand and place additional pressure on those walls. Drilling weep holes is one option to alleviate some of the pressure, and these are placed at the bottom of the basement. They will have tubes running through the holes to divert water away, and push it away from the French drains which are being installed.
Ground water reduction –
Your end goal is to keep water away from basement walls, so you need to relocate foundation plantings away from your basement space. This can be done by installing guttering downspouts, which will carry the water away from your home and basement. You will do this by raising the level of the yard around its foundation. This will grade the yard away from the foundation of the basement, and help reduce water flow towards the space. It will also help to encourage water to drain away from the home, which can eventually help with prevention of flooding.
DIY or hire a professional contractor? –
It isn’t complicated to install a French drain in an existing basement, but electric power, a jackhammer, electric saw, and other supplies are required to break the basement walls. Although it will save you some money doing it yourself, it is best to check with building inspectors prior to beginning, to ensure there are no obstructions in your way when you do begin the work. Local codes might also prevent drainage from a sump pump, into municipal sewers. If sump pump wiring has to be done, it might require hiring a professional basement waterproofing company to perform more complicated tasks.