Inside or Outside? How Metro Detroit Homeowners Can Tell Which Basement Waterproofing Fix Fits Their Leak

Exterior basement waterproofing by Mansour's Innovations on a Southeast Michigan home

Interior basement waterproofing by Mansour's Innovations in Southeast Michigan

Mansour's Innovations logo. Family-owned waterproofing, excavation and plumbing contractor in Shelby Township, Michigan

Southeast Michigan sits on poorly drained lakeplain clay. A Shelby Township contractor explains when interior drain tile works and when to dig outside.

SHELBY TOWNSHIP, MI, UNITED STATES, November 8, 2026 /EINPresswire.com/ -- Ask three waterproofing companies how to fix a wet basement and a homeowner can get three different answers. One says dig outside. One says drain tile inside. One says seal the crack.

All three can be right, said Imad "Matt" Mansour, owner of Mansour's Innovations, a family-owned waterproofing, excavation and plumbing company in Shelby Township. It depends on where the water is coming in.

"The water tells you where it's coming from," Mansour said. "Our job is to read it before we sell anybody a system. Sometimes it's a crack or a downspout, and that's a small fix."

Why basements here get wet

Much of Southeast Michigan is old lake bottom. Michigan State University's Natural Features Inventory describes the region as "poorly drained glacial lakeplain," often with clay underneath. Clay soaks up water and gives it up slowly. After heavy rain or a spring thaw, water collects in the looser soil that was backfilled against the foundation and presses on the wall and under the floor until it finds a way in.

Where it gets in tells you which fix fits.

Water through a single crack or tie-rod hole

If the wall is dry except along one crack or a few small holes from the concrete forms, the fix is usually injection from inside. Polyurethane or epoxy is pumped into the crack until it fills the full thickness of the wall. There is no digging and no drain system.

Water along the bottom of the wall or the floor edge

Dampness along the bottom of the wall after rain or snowmelt, white powder on the lower rows of block, and peeling paint near the floor usually mean water is building up at the footing. That is what interior drain tile is for.

Crews cut a strip of floor along the walls, dig down to the footing and lay perforated pipe in washed stone, sloped to a sump pit. On block walls, small weep holes are drilled into the bottom row of block so water trapped inside the block can drain out. A membrane on the wall directs any water that comes through down into the drain instead of across the floor. The floor is then poured back. Most jobs take two to four days.

Mansour said interior drain tile is a common fit for the 1960s and 1970s block-wall ranches around Utica and Auburn Road in Shelby Township.

Water through the wall in many places

When a wall leaks in many places, when the water table is high, or when a finished basement would have to be torn out to work from inside, the better fix is often exterior waterproofing.

After MISS DIG marks the buried utilities, the crew digs along the outside of the wall down to the footing, cleans and repairs the wall, and applies a waterproofing membrane thick enough to bridge small cracks as the wall moves. New drain tile goes in at the footing in washed stone, carried to the sump or another outlet. The soil goes back in layers and is graded away from the house. Exterior work stops water before it touches the wall, but it takes longer, usually five to ten days, and it disturbs landscaping next to the house.

When neither is the answer

A horizontal crack or a wall that bows inward is not a leak problem. It means soil is pushing on the wall, and drain tile won't stop that. It needs a structural assessment first.

Water that comes up through a floor drain during a storm is usually the sewer, not groundwater, and needs a different fix entirely.

"A full system isn't the answer for one leaking crack, and a patch isn't the answer when water is coming in all along the footing," Mansour said. "Get somebody to look at where it's actually wet."

What homeowners can check themselves

Before calling anyone, Mansour suggests looking at the outside of the house. Downspouts should empty at least 6 feet from the foundation, and soil should drop about 6 inches over the first 10 feet away from the wall. Fixing either can make a real difference in a borderline basement.

Drain tile and membrane work from Mansour's Innovations carries a 25-year transferable limited warranty. The sump pit and pump are not covered by that warranty and carry the manufacturer's warranty.

The company has published details on its interior and exterior waterproofing, foundation crack injection and sump pump services on its website.

About Mansour's Innovations

Mansour's Innovations is a family-owned waterproofing, excavation and plumbing contractor based in Shelby Township, Michigan, serving Macomb, Oakland and Wayne counties since 2014. Owner Imad "Matt" Mansour has more than 20 years in the trade, and the crew has completed more than 1,600 projects. The company holds a 4.9-star rating on Google, is licensed, bonded and insured, offers free estimates and answers emergency calls 24/7.

Imad Mansour
Mansour’s Innovations
+1 586-345-7292
Info@mansoursinnovations.com