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How to Waterproof a Basement without Digging

Jun 18, 2014 • By Matthew Stock.

No Digging

Mention “basement waterproofing” to the average homeowner and their first thought is often of big piles of dirt ringing the perimeter of their house, followed quickly by visions of dollar signs. 

Of course, there are situations where the best way to waterproof a basement is from the outside and exterior waterproofing work usually does require excavation.  Installing an exterior waterproofing membrane, for example, requires that the affected wall, or the entire foundation in bad cases, be dug up all the way down to the footings leaving a wide enough trench for technicians to work in.

Although an exterior waterproofing membrane is an extremely effective way to keep a basement dry, it certainly isn’t the only way.  Since water in the basement is one of the most common home maintenance problems, many homeowners seek alternatives that can be done without digging.  There are a number of ways to waterproof a basement permanently and cost-effectively that can be done inside the basement and, even though one method does require a little shovel-work, it’s minor compared to digging up the outside of the house.

Why Not Dig Up the Outside?

Most homeowners want to avoid digging up the outside of their foundation if at all possible and there are some good reasons for that:

Cost – Excavation work for basement waterproofing is done right next to the foundation and may extend as far as the entire perimeter of the house.  The close proximity to the home usually rules out the use of heavy equipment so all the digging is done by hand and the cost of labor to excavate adds significantly to the overall price tag of the job.  Also, the excavation must be back-filled by hand when the work is done.

Damage to Landscaping or Hardscape– Most homeowners who take pride in their homes have added some type of landscaping around the house, including flowers, shrubs, small trees and decorative items.  In most cases, these plantings will need to be moved or removed to accommodate the excavation and replaced after the digging has been backfilled.

Also, it’s common to have patios, decks, sidewalks and other landscaping structures built next to a house and these, too, will have to be removed and replaced to allow the excavation.

Inconvenience – Let’s face it, although a professional basement waterproofing contractor will work as quickly as possible, the homeowner who needs exterior waterproofing work will be living with a trench around the house (or a portion of it) for several days. 

What are the Alternative Methods that Don’t Require Outside Digging?

A significant number of techniques are available to basement waterproofing contractors that can be done on the inside of the basement to repair seepage problems permanently:

  • Crack Injection
  • Interior Drain Tile
  • Sump Pumps and Back-ups
  • Crawl Space Encapsulation

Crack Injection

The most common type of residential foundation found in the United States is one constructed of poured concrete.  These foundations have largely replaced masonry foundations except in areas that are too far from ready-mix concrete plants for poured foundations to be viable.  Because they are monolithic they tend to resist lateral pressure better than masonry foundations, although both types of construction are strong and supportive enough to build on.

Even with their lateral strength, poured concrete foundations can still crack from lateral pressure and these cracks can admit water into the basement.  These non-structural cracks are generally narrow, less than 1/8 inch, and occur at random.  As long as they are accessible, these cracks can be repaired permanently from the interior.

To repair the crack, a technician begins by using a  wire brush to clean dust, debris and aggregate from it and may need to chisel open any tight spots.  Once the crack is prepared, he installs plastic injection ports at regular intervals along its length and covers the crack with a coat of quick-drying epoxy to hold the ports in place and create a barrier over the inside.

When the epoxy has cured, the technician starts at the top of the crack and injects each port with expanding polyurethane that will fill the crack completely and extrude just enough on the exterior to form a small cap over the crack.

After the polyurethane has cured, it remains flexible to absorb minor foundation movement and prevent the crack from re-opening.

Interior Drain Tile

Interior drain tile is one of the most versatile methods of basement waterproofing as it is used to stop seepage through floor cracks and through the cove joint between wall and floor and also to manage seepage coming through masonry walls. 

Of course, installing interior drain tile does require some digging but it is minimal and takes place on the inside of the basement where it is easily ignored and quickly repaired.

Installing interior drain tile begins by removing a section of basement floor about one foot wide along the perimeter of the basement where the drain tile is to go.  After removing the concrete, a trench is dug to a level even with the bottom of the foundation footing, which should be no more than 12 inches below the floor.

The bottom of the trench is filled with washed gravel to serve as a porous space for water to move through.  The drain tile, which is actually corrugated plastic pipe that is perforated between corrugations, is encased in a “sock” of filtration fabric and laid on top of the gravel.  Once all the sections of pipe have been connected and fitted to the basin of a sump pump, more washed gravel is poured on top, completely embedding the pipe.  The concrete floor is then replaced.

When installed as described, interior drain tile never requires maintenance.  It prevents seepage by alleviating the hydrostatic pressure under the foundation that would otherwise force water in through floor cracks or the cove joint and carries the water to a sump pump to be discharged from the basement.

If interior drain tile is to be used to manage seepage coming through a foundation wall, either from porous concrete or blocks or deteriorated or cracked mortar joints, it is installed the same way, right up to the last step.  When replacing the concrete floor in these circumstances, a small gap is left between the wall and floor to allow the seepage to flow to the drain tile.  This gap can be covered by a plastic baseboard with openings at the top for drainage.

Not required but recommended, the homeowner may also choose to install a vapor barrier on the wall to cover the seepage and help direct it to the drain tile.

Sump Pumps and Back-up Pumps

The sump pump is considered the heart of any basement waterproofing system and it’s important to keep that heart beating for a dry basement.

The best sump pump set-up will work in conjunction with the interior drain tile described above.  There are homes that have sump pumps without an interior drain tile system but the pumps typically are situated in a low point in a basement and will remove water only from that relatively small area.  Coupled with interior drain tile, a good sump pump will drain the entire foundation and eliminate the possibility of new points of seepage cropping up.

When it comes to choosing a sump pump, the expected volume of water and the height of the discharge from the house are important factors to consider.  A low-volume pump may be OK in dry areas but most homes in the Midwest should be equipped with higher volume pumps to handle the influx of water from a heavy summer thunderstorm or spring snowmelt.  The pump must also be rated to match or exceed the “head height” of the system – the amount of vertical travel between the pump and the discharge point.  An underpowered pump just won’t get the water out of the house.

A back-up sump pump is a great idea that can be easily installed inside the basement.  There are battery-only systems, dual-power (AC-DC) systems and dual-power, dual-pump systems for the ultimate in protection.  Battery-only systems protect against power failures, dual-power systems against power or pump failures and dual-power, dual-pump systems ensure equal run times between pumps to prevent excessive wear-and-tear, as well as providing AC-DC back-up.

Crawl Space Encapsulation

Homes that do not have a full-height basement (or only a partial one) are likely to have crawl spaces, which are just like short basements with the same potential for seepage or more, considering that many have only dirt floors.  Crawl spaces can provide badly needed storage space in most homes but only if they are dry, clean and protected against seepage.

Many builders will leave a crawl space with only roofing felt or a thin sheet of plastic covering the dirt, which is completely inadequate to keep out water.  Further, crawl spaces can suffer the same water problems as full basements and can be fixed by the same methods, including interior drain tile, sumps pumps and crack injection.

One great way to seal off a crawl space from seepage and turn it into usable storage space is to encapsulate it.  A semi-rigid plastic underlayment is installed on the floor and is then sealed to insulating material covering the walls up to the floor joists of the first floor above.  Thus encapsulated, the crawl space will remain dry and bright and will not only be usable but will no longer be a potential source of humidity and mold in the rest of the home.

Of course, no matter what method of interior basement waterproofing is right for a home, the homeowner will need the advice and assistance of an experienced basement waterproofing contractor to implement it.  At U.S. Waterproofing, we have been waterproofing basements since 1957, on both the interior and the exterior, and have a list of more than 300,000 satisfied customers to testify to our capabilities.  Why not ask for our free advice if your basement is showing signs of seepage?

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