One of the most common drainage problems that I encounter throughout the year is poor rain drain discharges and gutter systems running water into crawlspaces or basements. The homes built before the 1970’s-80’s seldom have adequate rain drain discharge systems connected to the gutters to vent the roof water. To make matters even worse the homes seldom had french drains installed. Many of these homes have suffered with poor drainage for decades as a result. The basement or foundation exterior walls have deteriorated. The window well sashes and other surrounding wood has dryrot. The concrete foundation has usually started to crumble to dust. Let’s explore this subject and shed some light on the cure for this problem.
The most common rain drain discharge system in those days, constructed to vent the roof water from the gutter system on the home, was a system constructed of tile lengths about 18″ long. The tiles were placed into a crude dirty ditch and butted together in hopes that, when backfilled with dirt, the water would stay in the pipe that was formed by putting these tiles end to end in loose soil backfill. No french drains are also a common finding on these older homes.
Naturally the dirt ran between the tiles, which were made of clay pottery or concrete, clogging the pipe. The described system almost always plugged up in the short or long term depending on how well they were butted together and the amount of water put into them.
The payoff for the homeowner, and the home, was water leaching out throughout the system, between the tiles, along the foundation wall where they were placed. Saturation and hydrostatic pressure next to the home where the downspouts were put into the system caused leaking of roof water.
The constant overflowing of the system at the foundation where the gutters were put into the pipe started to open channels in the dirt next to the foundation where the water could very quickly run into the basement or crawlspace. Most commonly there were no french drains installed to collect this overflowed water.
The homes built in the early 1900’s have many times suffered such deterioration of the foundation concrete walls that they now must be plugged, patched, and skim coated at best, or replaced altogether at worst. This can be a very expensive reconstruction for the homeowner to fund.
The method of plumbing a rain drain discharge in modern terms uses an abs plastic glued pipe and sometimes solid ads flex pipe to contain all the downspout water in a solid pipe as it travels to the vent, which is usually a drywell or a daylighted vent placed well away from the foundation area.
The solid pipes are constructed to lay on a grade of approximately 2″ per 10 lineal feet which slopes on the bottom of a hand excavated french drain also containing a perforated pipe for the collection of the groundwater that collects near the foundation wall when it rains hard.
If you own an older home and have your downspouts venting into the old type of rain drain discharge system that I described containing the tiles, I highly recommend that your downspouts be plumbed into a solid pipe system. The installation of french drains should also be part or your groundwater drainage program for best results to vent rainwater collecting near the foundation wall. The value of your home can be adversely affected by the improper discharge of large amounts of downspout gutter water from your roof.
Make sure your gutter systems are up to date as well with no leaks. I do not recommend gutter covers or helmets because while they are marketed with the hype that less gutter cleaning is required, depending on the amount of roof shingle layers on the roof, the helmets allow the water from hard rains to run mostly over the gutter system all together causing a water fall next to your foundation and saturation and hydrostatic pressure that promotes leaking below grade.