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Interior vs Exterior Basement Waterproofing

When waterproofing is discussed, two words come up again and again: interior and exterior. This guide to interior vs exterior basement waterproofing explains the difference in general terms. Basements are uncommon across most of California, so the choice usually arises in older homes, where a basement was built before modern drainage and sealing were common. This page compares interior exterior basement waterproofing in general terms, so the difference is clear before a visit.

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The [basement waterproofing and flood prevention](/basement-waterproofing-flood-prevention/) page describes the service in general terms. Both approaches are described here in general terms only, because the methods depend on the basement and are not claimed in this guide.

The basic difference

The basic difference is where the work is done. Interior waterproofing deals with water from inside the basement, while exterior waterproofing deals with water from outside it. One works on the inside faces of the walls, the other on the ground and walls outside.

Neither approach is better in general terms. The right one depends on the basement, the ground around it, and where the water is coming from, and that is a matter for a professional to advise on, in person.

Interior waterproofing in general terms

Interior approaches, in general terms, manage water that has already reached the basement. They may involve sealing the inside faces of walls, collecting seepage, or directing it to a sump pump. The work is done inside, so the ground outside is not disturbed.

Interior work is often less disruptive than exterior work, and it can be the first step for a basement where the water comes through the walls. Whether it suits a particular basement is decided on the visit.

Interior vs Exterior Basement Waterproofing — California basement water damage guide

Exterior waterproofing in general terms

Exterior approaches, in general terms, keep water from reaching the basement in the first place. They may involve drainage around the outside of the walls, grading the ground so water runs away from the house, or sealing the outside faces of the walls.

Exterior work is usually a bigger job, because it involves digging and the ground around the house. It is often considered where the water comes from outside in large amounts, or where interior work alone has not been enough.

What each approach deals with

Interior work deals with seepage and water that has already entered, while exterior work deals with the water before it arrives. A basement with water seeping through its walls is a different problem from one where ground water pools against the outside of the walls.

The source of the water decides the approach, in general terms. A professional looks at where the water comes from, how the ground slopes, and what the walls are made of before advising on either approach.

Can the two be combined

In general terms, the two approaches are not rivals; they can work together. Interior work can manage the water that gets through, while exterior work reduces how much water arrives in the first place. Whether a combination suits a particular basement is a matter for a professional.

What matters is that the choice is made for the basement in question, not from a general rule. A basement with a failed sump pump needs a different answer from one with water seeping through its walls.

Arranging a waterproofing conversation

To arrange a visit, call California Basement Water Damage Co. at (877) 624-0105. A professional can look at the basement in person, talk through the interior and exterior approaches in general terms, and explain which would suit that home.

Interior and exterior work are not rivals, and the visit is where the right mix is chosen for the basement in question.

Key Takeaways

The basic difference is where the work is done.
Interior approaches, in general terms, manage water that has already reached the basement.
Exterior approaches, in general terms, keep water from reaching the basement in the first place.
Interior work deals with seepage and water that has already entered, while exterior work deals with the water before it arrives.
In general terms, the two approaches are not rivals; they can work together.
To arrange a visit, call California Basement Water Damage Co.

Your Next Step

If this guide matches what you found at home, the next step is a visit — not a guess. Call and describe what you found, and the visit is arranged from what you describe. The Basement Waterproofing & Flood Prevention page explains what that service covers, the Basement Flooding Cleanup page covers a related part of the job, and the services hub lists every service in one place.

While you wait, do not enter a flooded basement and do not touch switches, plugs or appliances in standing water. Floodwater is not safe water — keep pets and children clear of it.

Keep the guides on this site bookmarked: the first guide, the signs guide, and the preparation guide cover the checks worth repeating — after moving in, and after heavy rain.

Basement water damage help is available across California. See basement water damage cleanup in Fall River Mills, CA for one local example, or find your town on the service areas page.