You can install plastic or metal gutter extensions if water is being deposited near your house by downspouts.
Extensions aren’t the best long-term solution, especially if you’re going to trip over them or run over them with a lawnmower. Underground drain pipes are invisible and can move a lot of gutter runoff farther away from your house.
The cost of digging a trench and installing a pipe to drain water is $10 per foot for landscapers or waterproofing contractors.
When you notice water dripping into the basement through cracks or gaps around plumbing pipes, you can plug the openings yourself with hydraulic cement or polyurethane caulk for less than $20.
Generally, plugs work when there is merely a hole that water oozes through, either from surface runoff or from damp soil. But if the water is coming up through the floor, or at the joint where floor and walls meet, the problem is groundwater, and plugs won’t do the trick.
In case your gutters are working and you’ve sealed obvious gaps, but water still seeps into your basement or crawl space from high on the foundation walls, the surface water isn’t draining away from the house as it should.
The foundation of your house should sit on a “crown” of soil that slopes at least six inches in all directions over the first 10 feet.
The soil around the foundation settles over time. A shovel and some dirt can help you rebuild it. A cubic yard of a clay-loam mix from a landscape supply house costs between $30 and $40 (plus delivery) and is sufficient for a layer measuring 2 feet wide by 3 inches deep along 57 feet of foundation.
Your home’s siding overlaps its foundation slightly, so building up the crown could bring soil, and rot and termites, too close to the siding. A minimum of 6 inches is recommended. Make a berm (a mound of dirt) or a swale (a wide, shallow ditch) to divert water before it reaches your house.
For small areas, berms are easy to build; you can hire a landscape contractor for a few hundred dollars. It makes less sense to build berms on larger projects because too much soil will have to be delivered. Dig a swale instead (about $1,000). Once your landscaping has taken hold, berms and swales can make your yard more attractive.
If water is leaking into your basement low on the walls or at the seams where walls meet the floor, your problem is hydrostatic pressure pushing water up from the ground.
Check if you have footing drains, underground pipes installed when the house was built to carry water away from the foundation. The basement floor should have a manhole or drain or a cleanout pipe capped a few inches above the floor.
The clogged drains can be flushed with a garden hose if the cleanout is open. For about $600, a plumber with an augur can do the job if this doesn’t work.
Install a curtain drain to divert water that’s traveling underground toward your home if you don’t have working footing drains.
Curtain drains are shallow trenches – two feet deep and 1.5 feet wide -filled with gravel and perforated piping that catch water uphill of your home and carry it downhill to a safe distance.
In areas with trees or shrubs, consider installing solid pipe to prevent roots from growing into the piping and clogging it. Prices range from $10 to $16 per linear foot.
If you can’t keep subsurface water out, you’ll have to channel it from the inside.
Lay perforated pipe in the hole and saw a channel around the perimeter of the floor to create an interior drainage system. Drainage from the pipe is collected in a tank near the basement’s low point and pumped out of the house by a sump pump.
Starting at about $3,000, an interior system is the best and least disruptive option in an unfinished basement with easy access. It’s also a good choice if your yard is filled with mature landscaping that digging an exterior drainage system would destroy.
The walls cannot be waterproofed by installing an interior drainage system. You need an exterior system for that: a French drain to relieve hydrostatic pressure, and exterior waterproofing to protect the foundation.
If you have a foundation with numerous gaps, this may be the best solution. In addition, it keeps the mess and water outside, so you won’t have to tear up your finished basement.
Additionally, you may need to remove decks and walkways, as your yard will take a beating.