How To Waterproof A Basement Under Front Porch

How To Waterproof A Basement Under Front Porch

A front porch that sits directly over your basement is more than a porch because it also does the job of a roof. Unfortunately, that means you have to deal with all the issues of a porch and a basement roof in one and plan for both.

What is the best way to waterproof a basement under your front porch? I will walk you through all the options for fixing leaks, whether they come from the deck or walls, and share the best choice.

The best way to waterproof a basement under your front porch is a layer of ice and water sealant under a set of interlocking waterproof tiles. This is a smart option because the tiles are also simple to remove and replace individually. Accessibility will allow you to repair any damage or leaks much more easily and quickly in the future.

Basement Leaking Under Front Porch: (5 Fast Fixes)

When your basement is directly under your front porch, you need to take extra steps to avoid leakage.

Options like putting up a roof over your porch and hiring someone to add exterior vinyl sheets are just a couple of examples of how to prevent leaks.

Below is a list of all the ways you can approach this issue with step-by-step instructions on how to make each repair.

1 – Ice and Water Seal Under Tiles

To apply ice and water seal, sometimes called snow and water seal, you need to expose the subflooring layer on your deck.

You will be placing this protective membrane over the whole surface.

Once you’ve done that, using waterproof wooden tiles that interlock will make a beautiful, easy to repair, and highly leakproof porch over your basement.

  1. Strip everything off the porch except the boards that make up the sub-floor.
  2. According to Homeowners Hub, “IBC 1507.2.8.2 Ice dam membrane. In areas where there has been a history of ice forming along the eaves, causing a backup of water, a membrane that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet shall be used in lieu of normal underlayment and extend from the eave’s edge to a point at least 24 inches (610 mm) inside the exterior wall line of the building.” These directions are designed for roofing, but when your porch is over a basement, it is a roof. Don’t let the wording trip you up.
  3. Once you’ve laid both layers of bitumen sheet, make sure the porch edges are nailed or screwed back in place.
  4. Laying interlocking waterproof wooden tiles is a relatively simple process. You should start against the edge of your home and work outward toward the edge of the porch.
  5. When you reach the edge, mark and cut any pieces that extend beyond the border, so they fit without hanging off.

2 – French Drain

When the problem isn’t the porch itself leaking down into the basement but rather the water buildup around it when there’s precipitation, a different solution is called for.

Seal any cracks in your basement walls and ceiling first. You should do this when it is sunny and warm if possible.

The steps below will help you add a French drain that moves the water away from your basement and house foundations.

  1. Most Fench drains are 8 inches to 2 feet deep. However, you may need to dig deeper around the basement to get the water away from the walls. Ensure that there is a moisture barrier around the basement before you get started. The barrier can be a membrane or a painted-on option.
  2. Your drain will need to drop 6″ for every 50 ‘, so mark out where you will place your drainage trench(s).
  3. Dig out a trench to the requisite depth. According to HGTV, “Proper trenches run parallel to buildings and horizontally across slopesThe trench should be at least 2 feet wide and can be as deep as 6 feet for a basement or as shallow as two feet for a slab-on-grade home.”
  4. Add 3′ of gravel.
  5. Add landscape fabric lining with a 10′ overhang on both sides.
  6. Place your pipe and cover it with about 5′ of gravel.
  7. Wrap your plastic over the pipe, making sure it overlaps.
  8. Fill your trench with sand and then topsoil.
  9. Add a bed of stones around the open end of the pipe where the water comes out.

3 – Exterior Vinyl Sheets

Exterior vinyl sheets are the easiest but often most expensive option to prevent your basement leak under the front porch.

Unfortunately, I cannot give you the steps here because you’ll need a professional to do the installation.

Exterior vinyl sheeting over your existing porch will keep out water, but it requires a license to purchase and apply.

4 – Paint-On Sealant

The quickest and most high-maintenance solution is easier than you think. Using a paint-on sealant on your porch and any exposed basement walls is a project you can do in an afternoon.

The downside is that you will need to do this to a bare, unfinished basement, and you may need to reapply periodically to keep your waterproofing intact.

Unfortunately, this fix is better as a temporary stopgap than a permanent plug.

  1. Apply masonry sealant to bare interior walls of the basement. Allow this to dry for 1 to 2 days or as directed. A suitable masonry sealant will help keep out moisture.
  2. Choose your sealant product. There are lots of waterproof paints and Flex-Seal products to choose from. I recommend finding out what works best in your area, as the climate will affect the application and longevity of your sealant.
  3. Place drop cloths on the floor and put on a mask, goggles, and other safety equipment.
  4. Paint the entire interior wall space of your basement from floor to ceiling. Allow the paint or other sealant coating to dry completely and reapply in a couple of days.
  5. Finally, coat your porch deck in a durable outdoor sealant as well.

5 – Porch Roof

Sometimes the solution is to look up instead of down. Building a roof over your porch can help keep the porch dry and prevent leaks into the basement.

This fix is helpful when the leak is close to where the porch and house connect.

You will still need to seal any cracks from the inside but keeping water or snow from reaching the problem area should prevent future drips.

  • Check your local building codes and apply for a building permit as needed. Some areas don’t require a permit if your project costs less than $1000.
  • Check to see if your porch is level and evaluate the existing roof to decide where to make your installation. It’s vital to ensure the top covers the whole porch and has a proper drainage channel.
  • Purchase the boards, tools, ladder, particle board, shingles, and sealant you need for your project.
  • Build your support posts first. These will hold up the entire project. Typically supports go at the corners, and for large porches, they may be needed every few feet, per your area’s building code specifications.
  • Frame out the roof. I recommend checking out this excellent video from Bob Vila to see the process if this is your first time doing a project like this.
  • Attach the valley board and top plate.
  • Attach your rafters.
  • Cover the roof with plywood and then add a moisture sealant layer.
  • Add shingles and proper drainage around the edges.

Helpful Tips To Know About How To Waterproof A Basement Under Front Porch

All leaks are unpleasant, but basement leaks are the worst.

If you don’t want to turn your underground space into a pool for breeding mold and mildew, you’ll have to put n some work sealing your porch or diverting water elsewhere.

Here are a few helpful tips to know about how to waterproof a basement under your front porch.

  • You can also try replacing the subflooring on your porch with plywood. Then cover it with EDPM rubber. You can add whatever decking you want over the rubber for a finished porch.
  • Many people have a leaky basement under their front porch because the original designer of their home or a subsequent DIY enthusiast who worked on it didn’t understand that the porch is also a ceiling. Not only do you need water sealant, but it should be framed and built like any other ceiling.
  • The solution you use should be based on where your leaks come in. Not all porch leaks happen through the ceiling of the basement. Sometimes it’s the walls.

Final Thoughts

No one wants a leaky basement. When your porch is part of the ceiling for an underground or partially underground basement, it’s essential to ensure that you treat your porch deck like a ceiling.

You’ll need water barriers and a well-designed system for channeling the runoff so that it doesn’t eat away at your home’s foundations and the basement.

Fortunately, you can add French drains and a porch roof or work with various sealants to achieve a nice dry space underneath.

Don’t be afraid to combine the methods above to help guarantee a pleasant, leakproof basement in the future.

Drew Thomas

My name is Drew Thomas and I’m the creator of Fun In the Yard, your one stop site for all your outdoor games, sports, party activities, outdoor gear, and lawn & gardening tips.

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