Water Entry & Water Damage to Buildings InspectAPedia® -
Guide to detecting and evaluating leaks and water entry into buildings
Foundation & Structural Damage due to Building Leaks & Water Entry
How to Dry Out Buildings after Flooding & Leaks, Prevent Further Damage, Mold, etc.
Basement / Crawlspace Water Removal & Leak Prevention Systems
Basement waterproofing & foundation coatings or sealants: Wet Basement or Wet Crawl Space Causes & Cures
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Here we discuss the causes of water entry, leak, or actual flooding of buildings, the damage that is caused, and how best to cure water entry problems on buildings. In the page top photo our client points to a flood line on the heating boiler expansion tank, showing us the high-water level reached in this building basement. Observing evidence of the frequency, extent, source, and causes of leaks, water entry, and actual building flooding is a critical step in evaluating a building as well as in planning the cure for building leaks, water entry, and mold.
Our page top photo shows our client pointing to flood lines on a heating system expansion tank, indicating that this building was subject to severe deep flooding.
We learned from neighbors that a nearby river had flooded this home and others in its neighborhood repeatedly over the 60 year life of the building.
Building Leaks, Water Entry, Flooding, Moisture: Diagnosis, Evaluation, Cure, Prevention - Key Concepts
Visual inspection of a the exterior and interior of a building can provide ample evidence of the history of leaks and water entry at a property. Even when a building is brand new, an experienced home inspector or waterproofing or de-watering contractor can spot conditions that are likely to lead to future leaks, water entry, flooding, and moisture or even mold problems at a structure.
Because building leaks, water entry, and flooding and their related damage, ranging from structural damage to costly mold damage are such a large topic, we divide our building water problem inspection, discussion, and advice into these major categories.
Three Degrees of Building Wetness
We also divide our wet building thinking into these degrees of severity:
Damp or moist conditions in a building: in most areas basements and crawl spaces are damp; certainly anywhere that we have masonry construction below ground level we can expect higher humidity and dampness; depending on the degree of moisture and other building conditions, damp or moist conditions can cause mold or other building problems.
Wet conditions in a building: some limited areas of a basement or crawl space floor have been or are regularly wet or showing puddles in some weather conditions, but water does not extend over the entire building floor.
Flood conditions in a building: water extends over the entire building floor, extending from a fraction of an inch to virtually filling the building and even flooding upper floor levels if a building is located in a flood plain or flooded area.
How Long Does It Take for a Building To Dry Out After a Flood or Leak
The length of time required for wet conditions in a building to dry out is quite variable, depending on multiple factors. The time for water to dry in a wall cavity can be substantial, depending on:
the original wetness level: Was the building flooded, was there a plumbing leak, is the moisture due to trapped condensation?
the building materials involved: more porous materials dry more rapidly and permit the cavities they cover to dry more rapidly
the amount of air movement in and out of wet or damp building cavities as well as along the outer surfaces of damp materials or wet building cavities (this is why we supplement use of dehumidifiers with area fans when drying out a building).
the permeability of building surface coverings: more porous materials dry more rapidly; building walls, floors, ceilings that include openings or cracks might dry more rapidly, but probably unevenly and unreliably nonetheless
temperatures and relative humidity outside the wet building cavities on all sides
other factors such as weather involving wind (and wind direction), intermittent rain or snow, etc.
A Comparison of the Effectiveness of Basic Building Dry-Out Procedures
We have inspected numerous buildings after flooding or severe plumbing leaks, and we have examined and tested the results of various building dry-out, "de watering", or "water extraction" methods used by contractors. Observations:
Even when drywall is measured (using a moisture meter) as "dry", we have pulled off wall baseboard trim to find visible water and soaking conditions in such locations. Readers who need to know how to properly respond to flooded buildings should see our series of articles beginning at FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP and also FLOOD RESPONSE CHECKLIST.
Simply operating a dehumidifier and/or fans will not remove moisture from wet building cavities fast enough to avoid a risk of hidden mold contamination.
Making small 2" diameter openings along the bottom of a wall, or even along the bottom and top of a wall between each wall stud pair in order to try to speed wall cavity dryout has proven ineffective and has resulted in severe mold contamination in some locations.
Strip cuts at the entire length of the bottom of walls in a room that has been flooded, removing the bottom 12" of drywall or plasterboard is often sufficient to dry out cavities that were not flooded to higher levels, but check for wet materials such as wet insulation at higher levels in the wall cavity and extend the strip cut higher as necessary.
Complete wall covering demolition indoors is often needed on at least one side of the wall to rapidly dry cavities that were wet from above, such as during a fire extinguishment, an upper floor plumbing leak, or severe building flooding. Similar approaches may be used for wet ceilings.
Wet carpeting needs to be removed and disposed-of;
Wet finish flooring that has buckled or moved will probably have to be demolished. Often it is possible to allow subflooring to remain in place if it is not water-damaged. See TRAPPED MOLD BETWEEN WOOD SURFACES for details.
Wet building insulation needs to be removed and disposed-of, not re-used.
Six Topics to Sort Out Building Leaks, Water Entry Cause, Cure, and Prevention
A series of detailed articles addressing these categories are listed below. Contact Us to suggest changes and additions to this material.
Present building condition: how wet or dry is the building, what building surfaces or cavities have become wet, what steps have already been taken or need to be taken to dry out the building. See WATER ENTRY in BUILDINGS for a discussion of sources of building leaks, moisture, and moisture related problems other than actual building flooding.
Building water entry damage control: what emergency steps should we take to minimize damage to a building that has suddenly been wet by leaks or flooding? (If your home has been flooded see FLOODS IN BUILDINGS-priorities first)
Building water entry history: Identify evidence of the leak, water entry, moisture, or flood history at the building.
Building water entry causes: identify building or site conditions likely to cause leaks, moisture, basement or crawl space water entry, or actual flooding at the building. Often on older buildings there has been a history of water entry and there may be multiple sources of water entry, confusing insurance claims as well as proper building repair procedures.
Building Leaks & water entry cures: what should we do, in what priority order, to stop recurrent water and moisture problems at a building?
Building water entry and flood damage prevention: what should we do at any building to prevent future leaks, condensation, water entry, or actual flooding at a building
Evidence of Prior Building Water Entry & Flooding
This home inspection client was not happy to learn that the home she had recently purchased had been the subject of recurrent basement and crawl space flooding.
Flood lines in a building indicate the depth of water entry. Careful observation of water and mud stains can also indicate the number of significant floods that have occurred as well as possibly their frequency.
Even after a post-flood cleanup it is usually the case that clues of a building's history of leaks and water entry can be found.
Links to Key Articles on Diagnosing & Curing Moisture and Water Problems in Buildings
Photo of a mud-clogged footing drain
Our client saved this partly-clogged footing drain that was excavated from around their nearly-new but very wet home to show how quickly soils can enter and block drainage at a property if the system was not properly installed.
Scroll down to see our links to building water-entry related articles on the detection, diagnosis, cure, and prevention of building water damage and water related problems such as rot and mold.
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Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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More Information on Building Diagnostic Inspections and Repairs
Links to more information on inspection, diagnosis, and repair of defects in foundations and structures
InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.
The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems
Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.
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