Wet basements in Maine come from a few familiar sources: spring snowmelt that sends water against fieldstone foundations, a high water table on sandy lots, roof runoff dumped right at the wall, and the occasional heavy rain that overwhelms everything. A waterproofing contractor will offer to stop the water. In Maine, a good one will also ask about the other thing that comes up from the ground: radon.
Why does every Maine basement need a radon answer first?
Because radon is not a regional problem here. The Maine CDC's radon FAQ says that at least 25% of the homes tested in any part of the state have radon problems, and puts it bluntly: "It doesn't matter if you're in Kittery or Madawaska, Eastport or Jackman." The worst problems turn up in homes built on sand and gravel rather than on ledge.
That matters for waterproofing in two ways. First, many of the same cracks and gaps that let water in let soil gas in, and sealing them changes how air moves in the basement. Second, a perimeter drain and a sump pit, the standard waterproofing system, are also the backbone of the most common radon mitigation design. A contractor who installs a drain and an open sump pit with no cover, in a house with a high radon reading, has missed an easy chance to do both.
So test first. You can do the test yourself, and the CDC says that's allowed for an owner or occupant. A tester working for someone else must be registered with the state, and at a sale an independent registered tester is required.
Should the basement be tested before it's finished?
Yes, and before the waterproofing contract is signed. A finished basement in Windham or Brunswick with drywall over the foundation walls is far harder to fix if a later test finds high radon. With the walls open, a mitigation contractor can run a pipe from under the slab and out with little disruption.
Tell your waterproofing contractor the radon result, and ask:
- Will the sump pit have a sealed, airtight lid?
- Can the perimeter drain be connected to a mitigation fan later?
- Will any wall membrane leave a path for soil gas to be drawn off?
If the contractor doesn't understand the questions, consider a company that does both kinds of work, or have a radon contractor review the plan.
Where can the pumped water go?
A sump pump has to send water somewhere, and that is partly a local question. Maine doesn't license waterproofing companies, but a sump discharge tied into a drain line, a sewer or a septic system is plumbing, and in Maine plumbing is permitted through the town's Licensed Plumbing Inspector. Groundwater pumped into a septic system adds load the system wasn't designed for, so ask before anyone connects to it.
The common answer is a discharge line to daylight, well away from the foundation and not toward a neighbor's lot or a road. In winter, that line can freeze. Ask how the contractor will protect it, whether it has an overflow outlet near the house, and what happens when the outside end is buried under three feet of snow in Fort Fairfield or Orono.
Before the job, ask the town office whether the planned discharge needs a permit. It's a five-minute call.
Inside drain or outside excavation?
Interior systems, a drain channel cut into the slab along the walls with a sump, are the most common answer and the least disruptive. Exterior excavation, which digs the foundation out to apply a membrane and a footing drain, is often the better fix on a fieldstone or block wall but can cost much more and disturb landscaping, steps and walks.
Any exterior excavation is digging under Maine's Dig Safe law, and the excavator has to give notice in the window 23 M.R.S. §3360-A sets: a minimum of three business days before the work, and not earlier than thirty calendar days before it. Ask the contractor to confirm who places the call and when.
Before paying for either, look at what the gutters and grading are doing. A downspout that empties at the foundation of a house in Auburn or Lewiston can put hundreds of gallons against the wall in one storm. Big rain and snowmelt events are what reveal the weak spots; the NWS office in Gray issues flood and storm warnings for most of the state.
What happens to the sump when the power goes out?
A sump pump is only useful while it runs, and in Maine the power tends to fail during exactly the storms that fill the pit: a spring nor'easter with heavy rain on melting snow, or an ice storm that brings lines down for days. Ask the contractor what backup they offer and what it costs:
- a battery backup pump in the same pit, and how many hours it can run
- a high-water alarm that sounds, or sends a text, when the main pump can't keep up
- a second pump on a separate circuit in a basement that floods often
- an inlet for a generator, which is electrical work for a licensed electrician
Ask also how often the pump should be tested and replaced, and whether the warranty requires a service visit. A pump that sits idle through a dry summer and then seizes in April is a common failure. A simple test, pouring a bucket of water into the pit each spring and fall, catches most of them.
What should a waterproofing warranty actually promise?
Waterproofing companies sell on warranties, often "lifetime" ones. Read the document, not the brochure:
- What is covered. Water through the walls only, or also through the floor, around windows and at the wall-floor joint?
- What you must do. Annual service visits, a working sump, a backup battery?
- Transferability. Does it pass to a buyer if you sell? Is there a fee?
- The remedy. Does the company only come back to fix the system, or does it cover damage to finished space?
In Maine the contract itself also carries a warranty for work above $3,000: the Home Construction Contracts Act requires a clause promising work free of faulty materials, built to the applicable code and done skillfully (10 M.R.S. §1487). That statutory clause is in addition to whatever the company offers.
How should a waterproofing job be priced and paid?
The Maine calculator default for a typical waterproofing job is about $6,850 to $13,500; the Maine waterproofing cost estimate explains what it assumes. Interior drains on a straightforward slab sit lower; exterior excavation, ledge and long runs sit higher.
Because jobs this size are well above $3,000, Maine requires a signed written contract and limits the first payment to a third. A contractor who leaves the required terms out of a covered contract risks a finding of an unfair trade practice under §1490. Waterproofing salespeople sometimes push same-day signing with a discount; take the contract home, compare it with another bid from a contractor in Sanford, Old Town or wherever you live, and read the warranty first. As the Attorney General's page notes, no state license stands behind these companies, so the paper does.
