What is weeping tile?
Weeping tile is a perforated pipe that forms a continuous ring around your foundation at the footing level. Generally if you have a full basement the weeping tile will be placed on the outside of your foundation just below your basement floor level. The purpose of this pipe is to collect all the ground water that flows to your foundation and then runs down the exterior of the foundation wall until it reaches the footing. The footing is the concrete base that your basement wall sits on, think of an inverted “T”. the weakest point of any foundation form a waterproofing perspective is the connection point between the wall and the footing. Since these are poured in two separate instances there is a seam between the two. Even tho concrete is very strong it tends to be very porous and absorbs water, it also does not seal or bond to itself very well once it is cured so when the wall is poured ontop of the cured footing it creates an easy place for water to force its way into your basement if your weeping tile is not functioning properly.
There is a lot of science involved in water and foundations and it generally refers to hydrostatic pressure. The simple explanation is that the ground outside your basement is full of water and the inside of your foundation is full of air, the water pressure outside of the foundation can become greater then the air pressure inside which in turn forces the water through any cracks or seams in the foundation where you would then in turn see a puddle of water or perhaps worse inside of your home. Minimum code requires that a foundation be damp proofed which is generally achieved by spraying tar on the outside of the foundation prior to backfill. This is often confused with waterproofing. Damp proofing simply slows down the process of the concrete absorbing additional ground water however if you have a crack or seam in the foundation and hydrostatic pressure builds up then water will find its way in.
The job of weeping tile is to prevent hydrostatic pressure from building up, this is achieved by creating a way for water to easily be directed away from the foundation IE; it is easier for the water to flow into a hollow pipe then to force its way inside your home. In older homes, pre 1985 generally you will find that the weeping system is built by laying a gravel base around the foundation, laying out individual pieces of clay tile pipe 1 foot long spaced apart 1 inch between pieces the to cover all of this in 6 more inches of gravel. The space allows water to enter the pipe and the gravel creates an easy place for water to flow and also acts as a filtration system for the water helping to prevent sediment and dirt from clogging the weeping pipe. The downside to clay tile was that the spaces between the pipes made it easy for tree roots to grow into and in some cases would actually plug off the pipe completely creating a dam and in turn now causing water to easily flow to this gravel bed with nowhere to go. Depending on the age of the home the weeping pipe was either routed to the homes sewer line, storm line or a sump pit where a pump would then pump the water to the storm line or outside of your home to drain onto the lawn.
In the 80’s weeping tile was transitioned to a black corrugated pipe which is what most people are accustomed to seeing this pipe was less susceptible to root infiltration however it does have some drawbacks.
- it is very soft and flexible and requires a good amount of stone minimum 6 inches of cover to help protect the pipe from being crushed.
- The inside of the pipe is corrugated (ribbed) which helps to create strength while still keeping its flexibility it is also continuous which prevents roots from entering however once sediment and dirt finds its way into the pipe the ribs actually help to hold the sediment inside the pipe and over time this builds up nd reduces the effectiveness of the pipe.
The number one cause of failure of this black corrugated weeping pipe is not enough stone being placed ontop which in turn allows the pipe to become partially crushed and also does not allow enough area for the water to be filtered which in turn carries more sediment into the weeping system. The third item to note is that generally weeping tile is installed with not slope around the whole house with the exception of a small area when the pipe is lowered down to meet the connection point for the sump pit or storm line. It works on the principal that as water builds up it will flow to this one low spot but with the corrugated ribs it also makes it very easy for sediment to build up.
The picture below is of a corrugated weeping pipe that did not have enough stone cover and was also not properly tied into the sump pit, this system is 15 years old and has caused numerous flood in the basement of the home.
Our solution to all these problems is a combination of better products and a little bit of common sense we ellminate all these problems by addressing each component individually and creating and system that functions effectively to waterproof your foundation and also direct water away from the home.
We excavate down to the bottom of your foundation and existing weeping tile in order to expose the wall and address the different issues.
We pressure wash the foundation to remove any dirt from the wall, in this case we also had to remove some previous crack sealing material that appeared to be a tar membrane below the windows.
We use a propane torch to thoroughly dry the foundation
We apply a primer to the foundation wall to help the Blueskin waterproofing membrane properly adhere to the wall, at this point we also address any large cracks of holes in the foundation with the appropriate repair method.
We apply the Blueskin waterproofing membrane taking care to wrap overtop of the footing to ensure a good seal, in cases where the footing is too rough to adhere too we will use a foundation waterproofing tar such as aquablock to create a good seal and also create a surface for the Blueskin to bond too.
We apply a dimple membrane, the function of this is two part, one is protects the blue skin from being damaged by the backfill and two it creates an air space between the foundation wall and the ground surrounding the home which helps to relive hydrostatic pressure. In the event water enters behind the dimple membrane it allows an area for water to flow down and enter the weeping system. The membrane is fastened to the wall using specially designed clips which u can see in orange and concrete nails, the Blueskin is self sealing so as the nails drive through it seals around them to prevent water from entering through the penetration.
The stone base and weeping pipe is set into place, you will notice that the pipe we use is actually rigid PVC pipe with perforations, there are a few reasons for this; one the pipe is more durable and less prone to crushing, two in the event a blockage occurs your can auger or use high pressure jetting to clean the system without risk of damage to the pipe, three the interior of the pipe is smooth and allows for better flow and finaly we are able to place a proper slope on the pipe to enable better flow. You will also notice we have inserter a “T” fitting to allow a verticle pipe to be installed under the window which allow water accumulation from window wells to be directed into the weeping system as well.
Once the stone base is laid and the pipe set in place, we will then cover the pipe with a minimum of 6 inches of washed rock to create a good area for water to easily enter and flow to the weeping system, we then cover the stone with a filter cloth to help prevent sediment from entering the weeping system and causing issues later on down the road. Its at this point that we also install 10 inch cardboard tubes overtop of the verticle pipes that go to the window wells these cardboard tubes are the filled with clear stone as well in order to hold in place a stone drainage channel during backfill which will allow for very effective drainage of your window wells during large rain storms and snow melt.
At this point we are ready to begin backfill and compaction the orginal ground we be placed back into the trench with care not to damage the system that has been installed it will be placed in lifts and then compacted in order to prevent the ground from settling. Once the trench is half way filled the trim strips will be installed ontop of the dimple membrane which prevents dirt from falling in behind the membrane the window wells will also be secured to the home and once backfill is complete those will also receive a layer of crushed stone the last step will be to create a good slope on the ground away from the house to help direct surface water away from the foundation and then finally landscaping and cleanup will be completed. It should be noted on this particular installation the home owner requested to have the dimple membrane and Blueskin terminated lower the usual to allow for parging to be applied on the foundation wall, generally the dimple and Blueskin would extend up above final grade.
As with all projects preparation and use of the proper products required to complete the desired outcome is key, no two jobs are the same and there are many different common practices used in order to waterproof a foundation however we have found this method to achieve the best results and when done correctly this repair will last the lifetime of your home as with any repair especially one of this magnitude the goal is to do it right the first time to never have to do it again! If you are experiencing flooding, moisture problems or water infiltration into your home give us a call for a free consultation and let us show you how we can be of service to you!