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How Much Does it Cost to Waterproof a Basement?

Updated: May 11

You’ve just come home from work and your wife is yelling at you from the basement about a leak. Great. So your mind instantly jumps to money - how much? Assuming water is coming through your walls, you want to know how much does it cost to waterproof a basement?


A contractor will charge roughly $6,000 for an interior drainage system including a sump basin. That price drops if you already have a sump basin. Exterior waterproofing for a whole house starts at around $10,000 and goes up for larger homes.


Like we just said, these prices vary widely. Why? Well, if you have a leak in one spot on your basement wall, but the rest of the walls are fine, then you might choose only to waterproof that one side of your basement. Or you might not need an interior drainage system for the entire perimeter of your basement.


Below we’ll go over the costs and try and explain why some waterproofing options are more expensive than others, and how you might be able to save some $$ if you are forced to hire someone to do interior or exterior waterproofing in your house.


Before You Hire a Contractor...

Before you re-mortgage your home and pay someone to do exterior waterproofing on your home, check out our articles about easy ways to waterproof your home.


After you’ve taken the time to implement those quick fixes, and you still have water in your basement, then you likely need more serious waterproofing.



Now, if you are handy and want to waterproof yourself, then check out our articles on exterior basement waterproofing DIY and DIY interior basement waterproofing system.


If you are curious about how much it costs to do these renovations, then see below. We’ll go over materials costs plus general markups contractors will add on to the cost of the job.


Remember, while this is a DIY website, we still advocate for using licensed, reputable general contractors for work that you don’t feel comfortable doing. After all - that’s what we do, too!


And all contractors will mark up their estimates by the same general percentages - it’s how they make their living. Much of the skimming comes on materials cost and labor. More on that later.


How Much Does it Cost to Waterproof a Basement?

As mentioned above, there are two methods of waterproofing that actually work: interior and exterior. Both require full exposure of either interior or exterior walls, which means there is tons of prep to do before you actually waterproof.


Let’s take a look at the various methods and how much they can cost you.


Interior Waterproofing

Interior waterproofing works because you cover the entire perimeter of your interior basement walls with a waterproof membrane, sealed at the top, and embedded in concrete in the bottom.


This virtually guarantees that you will never have water in your basement again.


But, this guarantee comes at a cost. While the average cost of these repairs runs around six grand, it can vary widely because some folks opt to only do one or two walls instead of their entire perimeter.



If you have a 1000 square foot house, you have a rectangle that is probably somewhere along the lines of 45’ x 20’. Based on that size, let’s outline the costs:


Costs (Materials)

  • At least two rolls of 6 ‘ x 65’ dimpled membrane - $350

  • 4” PVC Drainpipe, 100’ - $200

  • Sump pit - $50

  • Sump pump - $300 (with battery backup, $450)

  • 1.5” sump pump outlet with check valve - 25”

  • Gravel - $20

  • Concrete - $100


Labor/Extra Costs

  • $750 and up/day


Interior waterproofing can be done by two people, and usually takes two full days, minimum. If there are no obstructions to be moved, such as walls, posts, or other impediments, then two days is a reasonable time to complete the task.


If you need a sump pump pit dug out, then you are likely looking at three days of labor, minimum.


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Avoid this - waterproof your basement.

If you are opting for interior waterproofing, you can save greatly on costs by taking down perimeter walls and removing any flooring, which will save the contractor time and reduce their estimate.


In general, expect to pay in the neighborhood of over $1000 per day for labor. A three-day interior waterproofing job that includes a sump pit installation will cost you about $5000.


A total basement interior waterproofing project will not cost under $3000, and most projects will be $4000 and up.


It is possible to interior waterproof one or two interior basement walls, which would reduce costs significantly. This is a great option if you actually know where your wall is leaking.


How Long Will It Take?


Expect this to take a minimum of three days for a full basement. One day will be entirely devoted to hammering out the concrete, removing material, and lugging concrete bags and other equipment into the basement.


If you have a full-size basement window that can open, you can save time.


The secovnd day will involve installing the membrane, the drain, backfilling with gravel, then pouring the concrete over it all and smoothing it out to make it flush with the existing floor.


If there is a third day, it will be to clean up and let the concrete dry. If you need a sump pit, then you can definitely expect a third day, and perhaps a fourth since not only will they need to dig a pit, but also route drainage line through a wall and potentially out and underground for a bit - requiring a trench.


Overall, expect a bunch of noise and mess for two days. If you are only having one wall, or two, done, you’ll be pleasantly surprised by how quick the process is, especially compared to exterior waterproofing.



Exterior Waterproofing


Exterior waterproofing is when you dig up your entire basement foundation from the outside, wrap it in a waterproof membrane, install a weeping tile attached to an interior sump pump, put dimpled membrane over the adhesive waterproof membrane, then backfill.


When excavating the exterior of your home, one of the most important considerations is how much of your structure is actually below grade.


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Dimpled Membrane

If it’s only a few feet, then the job becomes substantially faster and cheaper. If it’s 5’ or more, then you’ll pay accordingly.


Using the same type of house profile as above - a 45’ x 20’ rectangle - we’ll go over the associated costs that go with an exterior waterproofing of your home.


Costs (Materials)

  • 3 rolls (or more) of self-adhering composite membrane - $600

  • Primer for self-adhering membrane - $50

  • At least two rolls of 6 ‘ x 65’ dimpled membrane - $350

  • Dimpled membrane flashing, sealant, and fasteners - $200

  • Gravel - $1500 (depending on how below-grade your basement is…)

  • Excavator rental - $400 (or more)

  • Drainpipe and permeable fabric - $400

  • Removal of clay/soil (optional) - $400

Labor/Extra Costs

  • $750 and up/day


One of the biggest cost factors when waterproofing the exterior of your foundation is the amount of material that will have to be removed.


Using the dimensions outlined above, let’s say your home is 4’ below grade, on average. Excavating one side and replacing it with drainage gravel - which is what will be done - will require almost 18 tons of gravel - and that’s just for one side. Use a gravel calculator to help.



To do the entire house, you’ll need almost 50 tons of gravel. In other words, you’ll be charged nearly $2000 dollars just for rocks.


But why can’t you just backfill what the contractor takes out? Well, if you are excavating in the first place, then you likely don’t have a nice layer of gravel against your house to drain water, otherwise, you’d likely not have the water problems that caused the entire issue in the first place.


Clay-based soils do not drain well, trapping water against foundations and pushing it into homes. It needs to be removed from against your foundation walls, and replaced with gravel that drains easily.



The gravel will allow your water to drain into the drainpipe, which will lead to an existing sump system in your house.


This estimate is basing calculations on applying self-adhering membrane to your foundation walls in addition to delta membrane. This is a double-walled option that will ensure that zero water ever gets into your house. Ever.


Keep in mind contractors will likely do just one or the other, but not both unless you ask. The cost is more, but the peace of mind is more than worth it.


If you were to just do one - self-adhering membrane or delta wrap - then we’d choose the delta wrap.


Delta wrap is extremely strong, and the sealant that binds the pieces of wrap together, in our experience, seems to last. Self-adhering membrane is susceptible to nicks from rocks and gravel when they move.


How Long Will it Take?

A crew of three can do one 40’ wall in a day - but that’s a 12 hour day. Expect the entire house to take at least 4 days, if not an entire work week.


Again, if you opt to only do one or two foundation walls, the time frame will be shorter.

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Excavating the entire house takes time - and money.

If your basement is shallow - only a few feet below grade - the time it may only take a couple of days to finish the entire home.


1 day to excavate and clean, the other to install the membranes and backfill.


Keep in mind this install is weather dependent. Self-adhering membrane needs a primer to attach to - and the primer cannot go on your walls if it is wet.


Many contractors will have tarps and scrap wood to allow workers to carry on in the rain if necessary, but this will still extend install time.


Conclusion

Waterproofing your basement is expensive - period. There’s a reason every contractor in town advertises for it - it’s fast for them and the margins are good. Plus, everyone needs it especially up north with all the freeze and thaw.


You can mitigate much of those costs by doing the job yourself. Check out our DIY exterior waterproofing and DIY interior waterproofing articles for more help - it’s not as complex as you think!


And remember, don’t forget that before you waterproof, you’ll need a building permit. Check your local building code office to find out more.


Thanks for taking the time to read this article - and I wish you the best of luck in your next waterproofing project. Please drop us a line for suggestions and or any other feedback you might have for the article.


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Too often, homeowners throw up their hands and call a contractor.

Don't do that. Come to our site first - you can fix your basement with a little knowledge and a few tools.

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