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How to Fix a Leaky Basement

leaky basement dampening drywall
If you notice water in your basement, it’s important to take care of it right away. Leaks won’t disappear, and the longer they go untreated, the worse they get. Wondering if you can fix it yourself? Let’s explore how to fix a leaky basement from the inside, and when it’s time to call in a professional hand.

Determine Where the Moisture is Coming From

First, you need to determine whether the moisture is coming from the outside or inside of your home. Once you’ve found the source, you can begin waterproofing your basement.
One simple, handy trick is to duct-tape a piece of aluminum foil onto your basement wall. Leave it for 24 hours, and then check to see if moisture has condensed on the outside of the foil. If it has, the moisture is coming from inside. If moisture has condensed on the wall underneath the foil, then the source is probably from outside.
You can also check for possible leak sources. For example, you may look to see if the soil around the foundation is sloped towards the house, if there are cracks in the wall, if pipes are covered in condensation, or if the ducts on your dryer are leaky.

Water Coming From An External Source

water from downspout pooling near home

Does Your Basement Leak After it Rains or Snow Melts?

When it rains, most of the water will run down from your roof or siding onto the ground around the house. Improperly drained gutters may cause water to collect around the foundation. Over time, this can form a depression in the soil around the base of the house. As snow and ice melt, water may also leak into your basement along the foundation.

Need Basement Waterproofing?

MT Drains & Plumbing offers basement waterproofing services in Toronto and the surrounding area. If you need help identifying the source of your leaky basement give our team a call and get a free inspection and quote.

Use a Downspout Extension to Keep Water Away from Your Foundation

Downspout extensions connect to your existing downspout to redirect rainwater away from the foundation of your house. We recommend that you use a four- to six-foot downspout extension to channel water runoff. Some downspout extensions can fold or roll up, so you can still finish yard work, such as mowing the lawn, without hassle. Another option is the installation of a catch basin to transport water away from your home.

home with earth sloping away from foundation

Slope Soil Around Your Home Away from the Foundation

Over time, erosion from rainfall can collect water around your foundation, which could let water into your basement. Use a level to check the ground’s elevation around the base of your house. Take note if you see depressions in the soil which slope towards your home.
Create a slope that descends away from your house, this is called land grading. This slope should be at least ten feet wide and should drop six inches. You can build this slope by moving soil towards the foundation, or bringing in new dirt, concrete, clay, or recycled asphalt. This incline will carry water away from your home naturally, rather than channelling it into your basement.

Use a 6-mil Poly to Prevent Water from Soaking Around the Foundation

Putting down 6-mil poly, a vapour barrier, along the foundation of your house, can add extra protection against leakage. Run the 6-mil poly along the slope. You can cover this sheet with mulch or grassy soil for aesthetic reasons if you want.
Why Is There a Crack in the Basement Wall?

Patch Up Holes and Cracks Along the Foundation

There are a few methods out there for foundation crack repair. While no patch is guaranteed to last forever, some materials have more advantages than others. Hydraulic concrete, urethane, and polyurethane polymers can bond to wet surfaces, making them an easier solution than epoxy, which only sets if the wall is dry.
Hydraulic concrete is a popular solution for basement foundation crack repair. It is applied by making an inverted ‘V’ shape at the affected area with a chisel or an angle grinder. The concrete is then added into the carved-out space before it sets into the wall.

Coat Your Basement's Concrete Walls with a Waterproofer

Basement waterpoofing sealants such as DRYLOK can block moisture coming in from outside. You should only apply waterproofer directly to the brick or stone, and not over paint. Waterproofer goes on like primer, but you want to make sure that it’s coated thick enough to be effective.

Install a Drainage System Under Your Basement Floor

Drainage systems are expensive, but they are one of the most effective ways to moderate moisture in the long term. Professional installation typically costs between $3,000 and $8,000. If you wish to do it yourself, you should be aware that this process usually involves cutting concrete.
To install a drainage system, you will need to cut out slabs of concrete along the foundation of your house. Then you will dig an inward-sloping trench away from the foundation, after which you will lay down a drainage tube that connects to your sump-pump. You’ll fill in the trench with stones, which is then covered over by concrete.

Apply a Drainage Mat Under the Floor to Make it Drier & Warmer

A drainage mat or dimple mat is a hard plastic sheet that looks a bit like an egg carton. It comes in rolls, which are laid on the concrete floor of your basement. You can lay down finished flooring over the top. These dimple mats can make your floor drier and warmer by locking out moisture and cold air.
Moisture can easily form on the concrete subfloor because concrete is a porous material sitting on damp ground. Dimple mats can block this moisture from your finished floor. They can also protect against cold drafts by forming an air pocket between the basement flooring and its concrete under-layer.
basement sump pump cover

Install a Sump Pump to Connect with Your Drainage System

You should install a sump pump to carry water out of your basement during thaw or rainfall. This is an essential element of your basement drainage system, as the pump will redirect water flow to protect your basement from flooding. Sump pump installation can be done professionally or DIY, though the process requires a lot of hard labour, including breaking the concrete floor with a jackhammer.
It’s always best to have a back-up system for your sump pump. In case of failure or power outage, a battery back-up sump pump can protect your home from flooding.

Water Coming From An Internal Source

dryer in basement

Prevent Build-up of Humidity from Dryer Vents & Showers

Basements naturally have a lot of moisture due to the dampness of the soil surrounding them. Try to reduce internal sources of moisture as much as possible.
Leaky dryer vents can be a source of interior moisture. Use aluminum tape to seal any leaks coming from holes or joints in the pipe. If you have a shower in your basement, you should install an exhaust fan to help with ventilation. Run the fan during and after showering.
many uninsulated copper pipes

Prevent Condensation from Cold Pipes with Insulation Foam

You may notice moisture beading along the outside of cold, metal pipes. This issue is easy to solve and inexpensive. Buy an insulation foam tube and make a slit down the side so that it fits around the pipe, then seal up the opening.

Insulate Your Walls to Prevent Condensation in Cold Climates

Concrete contains a high amount of moisture. Insulation could go a long way in reducing the moisture level of your basement. There are a few insulation options available, though rigid foam tends to be the least expensive. Use at least 1 ½ thick foam board panels.

Basement Still Leaky? Call MT Drains & Plumbing

If you’ve explored all the above and are still seeing mystery moisture in your basement, give us a call for a free no-obligation consolation. We’ll come investigate and see if we can get to the bottom of things. We offer our plumbing services to Concord, Toronto, Barrie, Richmond Hill, MarkhamOshawa, Newmarket, Aurora, Vaughan.


Paul S

Paul has more then 20 years in basement waterproofing and plumbing projects experience. Looking for an advice from an expert plumber? Make sure to read Paul's articles about residential waterproofing and plumbing projects in Toronto.

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