An In-Depth Look At Waterproofing Your Home

Arguably the most overlooked home renovation by far has to be waterproofing. The reality is you can’t blame homeowners for wanting that new fancy kitchen or bathroom, as it is aesthetic to the eye and used everyday. Kitchens and bathrooms also add tremendous resale value, but what good is resale value if your basement is flooded or even worse you are staring down the barrel of six-figure foundation repair. Having a proper waterproofed home is essential if you have a below grade basement either built-up of concrete block or a poured concrete foundation. The science is simple. When your home is built untouched or “virgin” soil is excavated in order to create the homes footing’s and foundation walls. Once this process is complete the trench that was dug out beside the foundation walls are back filled with soil. This soil is referred to as “active” soil because it is compacted significantly less than the virgin soil, which has been compacting since the beginning of time. There is no competing with father time. Active soil’s looser compaction allows for water to move more freely and since water likes to choose the path of least resistance this becomes a problem for your home’s foundation and subsequently your basement.

Over the years methods to protect your home’s foundation and basement have improved dramatically. Waterproofing theory, technology, and products are all light years a head of what they once were, ensuring for better-protected foundations and dryer basements. Two main approaches exist when waterproofing. You can either waterproof from the exterior of the home or you can waterproof from the interior of the home. Both methods are considered to be highly effective with either personal preference and situational nuances being the key deciding factors. So I know you are probably thinking, I’m not an expert how am I supposed to know what I prefer or what a situational nuance is, well this answer is not so simple. This is why professional General Contractors and Waterproofing Contractors exist. Personal preference really means the method that the contractor prefers to use. There has been an ongoing debate as to what the preferred approach is and still the procedure has not been standard. This is for a number of reasons, but in our humble opinion we believe that they both work because the reality is that if nothing is done the related problems as previously mentioned can be disastrous. It’s safe to say that in Toronto and Southern Ontario Canada as a whole, the exterior approach is most commonly used. The answer to this will come to light when we examine both approaches in some detail, interior and exterior waterproofing.

From our experience interior waterproofing is still widely used and is the recommended method in situations when exterior excavation is not desired. For example, perhaps a new deck was built in front of the wall needed waterproofing or a fresh asphalt driveway was just installed the year before and any disruption would leave a patch where the excavation took place. Maybe budget is a major consideration and typically interior waterproofing is less costly than exterior waterproofing. The theory behind interior waterproofing is that when water penetrates the foundation wall and the gap between the footing and the foundation wall the water is directed into an interior drain tile and flows to a sump pump, which is then pumped out of the house. (Drain tile or a “weeping” tile and sump pumps will be discussed soon in detail). This is where is gets a little dicey. As mentioned above water is expected to penetrate the foundation walls through this approach. So right away this indicates that the interior waterproofing approach is geared towards flood prevention and not necessarily complete home protection. The main concern with that is that water has destructive salts in it that will degrade the concrete over time.  It would take a long time, but this is still something to be aware of. To combat this masonry paint can be used on the walls and the floor to prevent complete penetration, but water will still penetrate that concrete.  A German company claims to have developed a penetrating slurry product that will seal micro cracks, resist salt, sulfate, and chloride damage, and prevent any further damage, but this product is not available in Canada. I wonder why? In fact there are tons of companies out there claiming to have the most revolutionary interior waterproofing systems, but the reality is that the capillary action of water can work to erode foundations over time, so while interior waterproofing definitely has its merit when it comes to basement flooding prevention, the best course of action is to protect your homes concrete foundation and manage water flow with the exterior method.

So what exactly does exterior waterproofing entail? In a basic sense it’s digging a trench beside the wall you wish to waterproof, fixing the wall, covering it with a protective material, replacing the drain tile, and backfilling. This being the most common approach we figured we would break it down in detail to better educate. First off before excavating beside the wall you are going to waterproof it is highly advisable to call before you did. Actually in Ontario it’s the law to get utility locates before you dig, so for more information on this check out on1call.com. Once you have your locates you can now begin excavation. Excavation by machine is preferred as it is much easier, faster, thus less costly, but If you have restricted access usually around less than four feet width or if there is delicate obstacle in the way such as an air condition or back up generator then hand digging will be the only option. Once the trench is dug down right below the footing it’s time to clean and prep the wall. This part of the process will incorporate hydraulic cement to seal any foundation cracks that can lead to a larger problem over time. Once this is complete, Tar can be applied to the wall to protect the foundation acting much like masonry paint. Finally a PVC membrane, commonly referred to as “dimpleboard” is installed which acts to wick all water away guiding it into the newly replaced drain tile, which should sit directly below the foundation’s footing. Drain tiles come in three common types corrugated, filter fabric pipe, and PVC with holes. The type that is most recommended is the filter fabric pipe as it prevents soil from entering and leading to a clogged pipe. If any windows are located along the wall being waterproofed new window wells should be properly constructed with vertical drain tiles in order to prevent basement flooding through the window. As an extra layer of support to the newly waterproofed wall a composite membrane consisting of a rubberized asphalt compound laminated to a high-density polyethylene film such as Blueskin can be applied between the tar and the dimple board. This fabric will act as an extra protective layer if any water ever manages to get through the dimple board, which is highly unlikely if properly installed, but the requests are out there. Depending on the location of your home, your budget, and overall desire to never have any issues for a thousand years, a very costly and labor intensive redundant interior-exterior drain tile system can be installed, which will ensure that if there even is a blockage on one side (Interior or exterior) the water will not become a problem. This is not the norm by any means and in 99% of cases we would consider it over kill, but it is still worth mentioning. It is completely related to water-soil saturation levels. Finally, It is important to note that when backfilling the trench, concluding your waterproofing process, some time should be given to allow the active soil to compact over time before applying sod or walkways and driveways. If the finishing material is applied to early such as an interlock stone walkway, it will sink, resulting in more work.

So where does all of the water go once it enters the drain tile system. That depends. Once upon a time in the city of Toronto a home’s drain tile system could be connected to the city run-off drains, but in 2012 that all changed with the introduction of the City of Toronto’s Storm Water Action Plan. Along with the mandatory downspout disconnect residents are not permitted to allow newly installed drain tiles to be connected to the city sewers. The only options are to be lucky and have the necessary slope to your property where drains can be sloped away from the house allowing water to free flow out or if you are not so fortunate you have to install a sump pump to force the water out.

A sump pump as its name suggests is a pump that sits in a basin in the floor called a sump, which collects water. There are two styles of sumps, a drain attached sump pit in which all of the water collected in drain tile system flows to the basin and then is pumped out, or a seepage sump pit which deals with preventing flooding through the basements concrete floor slab. A sump pit can incorporate both, but a seepage sump is imperative if there is a lot of ground water. The idea behind this is that hydrostatic water pressure forces water up through the concrete slab. A seepage sump will alleviate that pressure and collect the water so it can be pumped out. There are a variety of different pumps available on the market including a pedestal pump, submersible pump, and sealed pumps. These pumps operate in a similar manner to a toilet in that they utilize a float that is used to instate the pumping action. Different float mechanisms pump out different desired amounts of water. Sump pumps also come in different horsepower ratings allowing water to be moved father distances away from the house as desired. Thanks to the City of Toronto’s newly instituted Basement Flooding Protection Subsidy Program homeowners can receive a rebate on installing a backwater valve, a rebate for the foundation Drain (Weeping Tile) pipe severance and capping, and a rebate for replacing or installing a new sump pump. Every sump pit should have a cover on it to protect against someone stepping into it, blocking out bad odours, and protecting against harmful Radeon, which is a radioactive, colourless, odourless, tasteless naturally occurring noble gas dangerous to humans.

If you have any questions regarding waterproofing or the City of Toronto’s Basement Flooding Protection Subsidy Program please don’t hesitate to contact at Grand Building and Contracting at 416-546-9051 or email us at info@grandbuilding.ca. We are always here to help.

Waterproofing - City of Toronto