How Much Does Basement Waterproofing Cost in Maryland?

A complete interior perimeter drainage system runs roughly $100 to $160 per linear foot. A typical single-family basement needs about 120 linear feet, which puts most complete systems between $12,000 and $18,000, with the middle of that range around $14,500. Sump pumps and exterior work are priced separately and the numbers are below. Almost every waterproofing site answers this question with "a few thousand dollars into the low five figures," which is wide enough to be useless. Here are the actual numbers we work from in Harford and Baltimore County.

The short answer, in a table

Work	Price
Interior perimeter drainage	$100 to $160 per linear foot
Typical single-family basement (about 120 linear feet)	$12,000 to $18,000, most often near $14,500
Sump pump replacement	About $1,000 installed
New sump pump where there was not one before	About $2,500 installed
Battery backup pump	$2,000 installed, in addition to the pump
Exterior excavation and waterproofing	Quoted per project. See below for why

These are Maryland numbers, current as of 2026, for the work we actually do. They are not a national average and they are not a lead-generation range.

Why interior systems are priced by the linear foot

An interior perimeter system is a trench cut along the inside edge of your basement slab, a perforated pipe bedded in stone, and a sump pump that moves the collected water out of the house. The cost tracks the length of trench, not the floor area, which is why a linear foot is the unit and square footage is not.

Linear feet means the run of wall being drained, measured along the base of the wall. If you are draining the full perimeter of a 30-foot by 30-foot basement, that is 120 linear feet. Most single-family homes we quote land near that figure, which is where the $12,000 to $18,000 range comes from.

You do not always drain the whole perimeter. If only one wall leaks and the cause is clearly on that side of the house, a partial run is a legitimate scope and it is priced the same way, per foot. Ask any contractor quoting you a lump sum what their number is per linear foot and how many feet they are proposing. If they cannot answer that quickly, the quote is not built on anything.

Why the range runs from $100 to $160

The bottom of the Maryland market is around $100 a foot. A number of good companies price there and so do some that are not good. We are usually at $150 to $160, and we would rather explain that than bury it.

What separates one quote from another is rarely the trench. It is what is under it, what is done with the water once it is collected, what happens outside the house, and what the warranty is worth when you have to use it. A system that is priced to be the cheapest bid has to save that money somewhere, and it is generally saved in places you cannot see once the concrete is back down.

Sump pumps and battery backups

Any interior drainage system needs a pump. The system collects water at the footer and a pump is the only thing that moves it up and away from the house.

• Replacing an existing sump pump: about $1,000 installed. The pit and the discharge line already exist, so you are paying for the pump and the labor.
• Adding a sump pump where there was not one before: about $2,500 installed. The pit has to be cut into the slab and a discharge line run, and that is most of the work.
• Battery backup: $2,000 installed, on top of either of the above.

The backup is worth explaining properly, because most homeowners picture a spare part in a box. It is a second pump, plumbed in alongside the first, kept trickle-charged off mains power so the battery is full when it is wanted. Lose power and it takes over. Keep power but take on water faster than the primary pump can move, and both run at once.

It is the single upgrade we recommend most often, for an obvious reason: the storms that flood basements are the same storms that take the power out. A pump with no electricity is a hole in your floor. Two thousand dollars against a finished basement full of water is not a close call.

Exterior excavation: why there is no per-foot number here

Exterior waterproofing means digging down the outside of the foundation to the footer, cleaning the wall, applying a membrane, and rebuilding the drainage so water is carried away before it can load against the wall.

We are not going to publish a per-linear-foot price for it, because linear feet is the wrong unit. Depth is what drives the cost. A wall that goes down four feet and a wall that goes down eight feet are the same length and nowhere near the same job: the volume of soil, the shoring, the machine time and the restoration all scale with depth, not run. Access matters too. A crew that can get a machine to the wall is a different price from a crew digging by hand between a house and a property line.

So exterior work is quoted per project after someone has seen it. We would rather tell you that than post a number that turns into a different number when we arrive.

What we can tell you is what it does and does not buy you, which is covered in detail on our interior vs. exterior waterproofing page, and in the warranty section below.

What the warranty covers, and what it is worth

Warranty is the part of a waterproofing quote that costs nothing to promise and everything to honor, so it is worth reading closely on every proposal you receive, including ours.

• Interior drainage: lifetime warranty, for the life of the structure. It transfers to a new owner when you sell. The new owner contacts us within 30 days of the sale with their details and there is a $150 administrative fee to put the warranty in their name. That is set out in the contract rather than left to a conversation.
• Exterior waterproofing: a five-year workmanship warranty, and no warranty against water inside the basement. We will not pretend otherwise. A membrane on the outside of a wall, applied correctly, does not stop water travelling underneath the wall and coming up through the cold joint. Nobody can guarantee a dry basement from exterior work alone, so we do not, and we would treat anyone who does with some suspicion.
• Structural and foundation repair: lifetime. Carbon fiber carries a manufacturer's lifetime warranty on the material, and we add a lifetime labor warranty from Drift on the work itself.

Transferability is the part homeowners underestimate. A lifetime warranty that dies the day you sell is a warranty for however long you happen to stay. Ask whether it transfers, what the new owner has to do, and what it costs them.

What makes a basement cheaper or more expensive to fix

Two houses on the same street can be thousands apart. The usual reasons:

• How much of the perimeter needs draining. One wall is not four walls, and the per-foot price is the same either way.
• Whether the basement is finished. Finished walls and flooring have to come out along the trench line and go back afterwards.
• Foundation depth, on exterior work. The single biggest variable in an excavation quote.
• Access. Whether a machine can reach the wall, or whether the work is between a house and a property line.
• Where the water can be discharged to. A short run to daylight is cheap. A long run, or a lot with nowhere obvious to send water, is not.
• What is already there. An older interior system that has silted up is sometimes corrected rather than replaced, which is a smaller job than starting from nothing.

How to compare three quotes without guessing

You are going to get quotes that differ by thousands and you will not be able to tell why from the cover page. Ask all three of these:

• What is your price per linear foot, and how many feet is this quote? Any real system has both numbers behind it.
• What exactly is warranted, for how long, and does it transfer if I sell? Get the answer in writing, and get the difference between interior and exterior spelled out.
• What is happening outside the house, and is the pipe perforated? If a contractor is putting perforated pipe or a French drain against your foundation, ask where the water goes once it enters that pipe and what stops it coming back out along the way. It is the question that separates people who have thought about it from people who have not.

Before you spend anything

Some wet basements are not waterproofing jobs. Downspouts discharging next to the foundation, ground sloping toward the house, and full gutters cause a real share of the leaks we get called about, and all three are cheap to fix. If that is your situation we would rather tell you than sell you a system.

If you are not sure which situation you are in, start with why is my basement wet, which walks the same diagnostic sequence we use on an inspection. If you want eyes on it, we offer a free virtual inspection: send photos of what you are seeing, we talk it through, and you get a diagnosis and a ballpark range before anyone schedules a visit.