Water problems in a Cape Cod basement come in two very different kinds. One is ordinary: rain and groundwater find a crack, a low spot or a failed gutter, and the basement gets damp or wet after storms. The other is the ocean: storm surge and coastal flooding that no drain tile or sump pump will hold back. A waterproofing contractor can fix the first. For the second, the answers are elevation, flood vents, insurance and design, and a good contractor will tell you so before taking your money.
Is your basement in a flood zone?
Start with the maps. The countywide Flood Insurance Rate Maps now in force for every Cape town took effect on July 16, 2014, along with the flood study behind them. You can look up your address, and see its map panel's effective date, on FEMA's Map Service Center, or ask your town's building or conservation department, which will have the maps.
What you are looking for:
- VE zones along the open coast, where waves are expected. If your lot is near the shore in Chatham, Harwich, Falmouth or Provincetown, check whether any of it falls in one.
- A zones, where water rises without strong waves. Ask the same question about low streets near harbors and marshes in Barnstable or Wellfleet.
- The Coastal A Zone and the Limit of Moderate Wave Action (LiMWA). The 10th edition of the Massachusetts building code uses these lines, as WHOI Sea Grant's guide explains, and they change what a renovation must do in the area just landward of the VE zone.
A house in one of these zones may already carry flood insurance; Barnstable County's flood insurance brochure gives the average Cape premium as about $1,300. If your basement takes water during coastal storms, talk to the building department about what you can do under the floodplain rules before you hire a waterproofing crew.
What actually works for groundwater and rain?
For the ordinary kind of water, the usual fixes, roughly from cheapest to most expensive, are:
- Grading and gutters. Soil that slopes toward the foundation and downspouts that dump at the corner are the most common causes of a wet basement. Fixing them costs little.
- Crack repair. Injected sealant for isolated cracks in poured concrete.
- Interior drainage and a sump. A perimeter drain cut into the slab, leading to a sump pump that lifts water out.
- Exterior excavation and membrane. Digging down to the footing to coat and drain the outside of the wall. This is the costliest and, on a tight lot, sometimes impractical.
Ask each contractor to explain why they recommend the step they do, and whether a cheaper step should come first. On an empty house, ask about a high-water alarm that reaches your phone.
Does a sump pump discharge near wetlands need approval?
It can. The state's Wetlands Protection Act gives town conservation commissions authority over work in and near wetlands, coastal banks and other resource areas, and over activities that alter them. A new discharge pipe running toward a marsh in Orleans or a pond in Brewster, or regrading near a coastal bank, may need a filing first. A sump line also should never be tied into a septic system, which is designed for wastewater only.
Ask the contractor where they plan to send the water and whether they have worked with the conservation commission in your town.
How does a crawl space differ from a basement?
Many Cape houses sit on crawl spaces, a low space between the soil and the first floor. Crawl spaces get damp in a different way from basements: moisture rises from bare soil, and in summer warm, humid air coming through foundation vents condenses on cooler surfaces underneath. The signs are a musty smell in the house, mold on joists, sagging insulation and a damp feel to floors above.
Common fixes include a heavy plastic vapor barrier over the soil, sealed at the walls; closing vents and conditioning the space; and a drain and sump where water actually pools. Which of those fits depends on the house and on whether it is in a flood zone, where open vents may be required to let floodwater pass through. Ask the contractor how they would treat your crawl space, whether that affects any floodplain rule, and how they would protect plumbing in the space from freezing in an empty house.
What alarms does an absent owner need?
If you are away from the house for weeks at a time, a pump failure or a power outage can turn a dry basement into a wet one without anyone knowing. Ask the contractor about a water alarm that sends a text, a battery backup pump, and a test you or a caretaker can run each month. In towns such as Sandwich, Dennis and Eastham, where many houses are empty all winter, that alarm is cheaper than the cleanup it prevents.
Is waterproofing covered by the HIC law, and what deposit is reasonable?
Yes. Waterproofing your home is home improvement work, so the contractor must be registered; you can search the Contractor Hub by name or registration number. The home improvement contract statute sets the rules for the agreement:
- A written contract for anything over $1,000, signed by both of you.
- A cap on money up front: one-third, with an exception only for goods made or ordered for your job. Pumps, pipe and crushed stone are stock items, so the exception rarely applies here.
- Start and completion dates, the full scope and materials, the price and payment schedule.
- Any permit, the contractor's registration number, and the notice that you may cancel by midnight of the third business day.
Be wary of a waterproofing sales visit that ends with a same-day discount for signing on the spot. You have three days to cancel, and that right exists for exactly that kind of pressure.
Where does an interior drain and sump fall against the Cape Cod calculator?
A typical basement waterproofing job comes to about $7,150 to $14,100 on the market's calculator; the Cape Cod waterproofing cost page shows how wall length and method change it. Exterior excavation, a long perimeter or a second sump runs higher. Gutter and grading fixes run far lower and are worth trying first.
Get more than one opinion. Waterproofing is a trade where the diagnosis drives the price, and two contractors can look at the same damp wall and recommend a simple gutter repair or a drainage system costing many thousands. A second inspection from a different company in Barnstable or Yarmouth is often free, and worth asking for.
Questions for every waterproofing contractor
- What is causing my water, and what is the cheapest fix that would work?
- Is the house in a flood zone, and does that change your recommendation?
- Where will the sump discharge, and does it need conservation approval?
- What does the warranty cover, and does it transfer?
- Does the system have a backup pump and an alarm?
