Bad sump pump instlallation (C) D Friedmamn Crawl Space Waterproofing
How to Prevent Crawl Space Water Entry

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Prevent future crawl space water entry by crawl space waterproofing methods:

How to keep water from entering a building crawl space in the first place.

Here we summarize the approach to preventing water from leaking into a building crawl area. The place to start is with an outside inspection for sources of leaks into the crawl area, but we also discuss using a sump pump to lower the water table under and around the building.

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How to Keep Out Crawl Space Water & Moisture - Exterior Measures for Crawl Space Moisture Control

Wet crawl space unsafe to enter (C) Daniel FriedmanWe noted earlier that it is almost always preferable to keep water from entering a building rather than allowing it to enter and then working to get rid of it. Here we refer to articles giving more detail on measures to keep unwanted roof runoff or surface or even subsurface water from entering a basement or crawl space.

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Inspect the roof drainage system, gutters and downspouts to be certain that roof spillage is not ending up by the building foundation.

Defects in handling roof runoff is the number one source of basement and crawl space dampness and water entry.

Start outside the building: inspect the building roof drainage system and surface grading to be sure that roof runoff is not spilling where it is trapped against the crawl space foundation walls.

The articles listed just below provide ample detail for more complete water entry source, cause & cure investigation for a crawl space.

Key building water entry diagnosis and cure articles:

How to Install & Use Sump Pumps in Crawl Spaces

Bad sump pump instlallation (C) D FriedmamnIn a crawl space where there is standing water, dehumidification and dry-out efforts will be ineffective. We need first to get rid of standing water and second (as discussed previously) keep water from entering the crawl area.

It's always better to keep water out of buildings than to let it come in and then try to get rid of it. But some building sites and conditions may still justify one or more sump pumps in the crawl space. Earlier we stressed the importance of making sure that the crawl space floor drains to one or more points where as sump pump can be installed if needed.

Not like this! We cannot show all of the ways to foul up a sump pump installation in one article, but our photo at left is particularly disgusting. Don't just throw a sump pump into a low area in the floor. The resulting lake will continue to damage the rest of the building.

A sump pump can, by lowering the water table under a crawl space floor, reduce the chances of water entering the crawl space through the lower foundation walls or floor. We have used this method with success in areas of seasonally wet soils, but we would not add a sump pump installation to try to dry out a crawl area (or basement) before first fixing all outdoor water entry sources possible.

Otherwise you may find you are simply cycling water: pumping it out of the crawl area only to have the same water cycle back into the structure.

At SUMP PUMPS GUIDE we discuss types of sump pumps and how they should be connected to electrical wiring and to drainage destinations. Keep in mind that the time you are most likely to need a crawl space sump pump is during hurricanes or tropical storms or in northern climates during times of heavy snow melt.

During a storm is just when electrical power may be lost. If your electrical power is not reliable you should consider a battery-operated backup sump pump system with enough capacity to keep the pump(s) running until power is restored.

Also see MOLD CLEANUP - MISTAKES to AVOID for a master list of the principal ways that people foul up mold cleanup projects.


Continue reading at CRAWL SPACE GROUND COVERS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


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