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WATER ENTRY IN BUILDINGS
AGE of MOLD - Old is the Mold?
BASEMENT CEILING VAPOR BARRIER
BASEMENT MOLD WATER IMPACT
BRICK WALL DRAINAGE WEEP HOLES
BUCKLED FOUNDATIONS due to INSULATION?
BUILDING DAMAGE ASSESSMENT & REPAIR
CONDENSATION on WINDOWS & SKYLIGHTS
DEW POINT TABLE - CONDENSATION POINT GUIDE
EFFLORESCENCE, Salts & White / Brown Deposits
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOD DAMAGED FOUNDATIONS
FLOOD VENTS & FLOOD PORTS
FLOODS IN BUILDINGS-mold
FLOOR DAMAGE DIAGNOSIS
FOOTING & FOUNDATION DRAINS
FOUNDATION BULGE or LEAN MEASUREMENTS
FOUNDATION CRACKS & DAMAGE GUIDE
FREEZE-PROOF A BUILDING
FROST HEAVES, FOUNDATION, SLAB
HUMIDITY LEVEL TARGET
ICE DAM PREVENTION
MOISTURE CONTROL in BUILDINGS
MOLD INFORMATION CENTER
NOISE / SOUND DIAGNOSIS & CURE
ODORS & SMELLS DIAGNOSIS & CURE
SEWAGE BACKUP, WHAT TO DO
SEWAGE BACKUP TEST & CLEANUP
SEWAGE BACKUP PREVENTION
SEWAGE PUMP CLOG DAMAGE
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
SWEATING (CONDENSATION) on PIPES, TANKS
TOILETS, INSPECT, INSTALL, REPAIR
TRAPS on PLUMBING FIXTURES
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in BUILDINGS
WATER ENTRY in BUILDINGS
WINTERIZE A BUILDING
How to diagnose the cause of & how to cure building leaks & water entry: key concepts for an effective approach to building, basement, or foundation leaks & waterproofing, how to dry out a wet or flooded building, how to determine a building's leak history, and the age of leaks & water damage. This series of articles explains the causes of building water entry, leaks, or actual flooding of buildings and describes how to fix building water entry problems. We describe the damage that is caused by flooding, water entry, or smaller leaks, and we explain how best to cure water entry problems in buildings using a series of measures to keep water out of the building basement or crawl space (or other areas), how to get rid of water or wet conditions in a building, and how to correct building damage, mold, rot, etc. caused by water entry.
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Building Leaks, Water Entry, Flooding, Moisture: Diagnosis, Evaluation, Cure, Prevention - Key Concepts
We include a series of detailed "how to" articles for stopping and fixing building water damage. 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.
If your building has been flooded by hurricane, tropical storm, burst pipe, or other water problems, see FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP.
Also see BASEMENT LEAKS, INSPECT FOR where we describe procedures for finding evidence of the frequency, extent, source, and causes of leaks, water entry, and actual building flooding - a critical step in evaluating a building as well as in planning the cure for building leaks, water entry, and mold.
The most basic advice we can give on stopping or preventing basement or crawl space water entry is that it's best to find where and why water is leaking into the structure and to correct that source - usually it's outside the home. If there are reasons that you really cannot address the water problem at its source, a second best approach is to choose among various methods for keeping water out of the building at the last minute - from inside, combined with steps to dry out or remove excess indoor moisture or water, combined with avoiding generating excessive moisture by proper handling of moisture coming from indoor activities.
Here we begin a article series on drying out a wet basement or crawl space and keeping it dry.
Our photos below show the basement dry-out procedure for a New York home that had water entry from a foundation wall leak. Because a finished floor had been put down over wood sleepers, it would have been virtually impossible to dry out this space without pulling up the flooring. The contractor also removed the bottom foot of all drywall to permit inspection of wall cavities for leak signs. It was that step that allowed us to trace this basement soaking to a single foundation wall crack.
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:
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.
Carson Dunlop Associates' sketch (left) shows common measures to control roof and surface runoff to get water away from the building. In general this is the first step in stopping or preventing wet basements or crawl spaces.
Detailed Investigation to Determine the Extent of Basement Water Entry
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.
Three types of wet-building events
Often one can easily spot the difference between
In our photo above, our screwdriver has pushed easily in to its handle through the bottom of a wood post set into a concrete floor. Look closely and you can see water lines about five inches up from the floor on this post bottom and much lower water stains on the bottom of the stair stringer in the upper right of the photo. Give careful thought to the conclusions you'd draw from this example. Even without basement flooding a wood post set through a concrete floor slab is likely to suffer rot or insect damage at its hidden end.
See BASEMENT LEAKS, INSPECT FOR for more clues indicating the history of water into a building's lowest floor.
Distinguish Among Recent Water Entry or Flooding & Old or Chronic Water Entry & Flooding in a Building
Our photo at above left shows me finding significant mold contamination behind paneling that itself looked perfectly clean; the floor trim in this basement was also intact and it was difficult to find clues suggesting prior flooding and certainly there was no evidence of chronic water entry. But the owner's daughter had immediate breathing difficulties and asthma attacks immediately on entering this basement area - in fact her reaction started when she opened the door to the basement. On reviewing the history of the home the owners noted that more than a decade before there had been a burst sewer line and sewage backup that wet the basement floors. All exposed surfaces were cleaned, dried, disinfected within 24 hours. But no one thought about the wetting that had occurred within the wall cavities and behind the paneling.
Our photo at below left shows door and floor trim removed from a home that had experienced a single-event flood from a burst toilet tank. Notice that although these trim components had been wet, there are no stains, no rot, no mold evident in the picture. This suggests that these components had not been subjected to recurrent flooding or wet floors.
At below left, we have removed (without damaging it) floor baseboard trim to show the absence of any water stains on both the hidden side of the trim as well as on the drywall behind it. This area has not been wet since these materials were put in place. At below right, we have two clues of prior water entry: the stains and fungal growth on the back side of the plastic baseboard molding trim and on the wall surface behind it; and while plastic baseboard trim is widely used (e.g. in kitchens and baths and some commercial areas), in a finished residential basement above a tile or concrete floor, its use may indicate that previously people got sick of dealing with wet floor problems there.
Watch out: mold growth in a building may be quite recent (just a few days old) to months or even years. Some mold growth details and growth structures can suggest that there has been a long-standing mold contamination problem in a building.
See AGE of MOLD - Old is the Mold? for details.
At below left, the thick mold on the underside of the pantry shelf occurred following a single event building flood in a home that was left unattended for weeks or longer. But if you find rot on wood structural members, floor sills, or on the back side of floor baseboard trim (Photo below right), then this component and this building area has been wet repeatedly and over a long time.
Here we illustrate how to sort out among four wet floor cases:
Our photo at below left illustrates carpet tack strips that have in our OPINION never been wet more. Notice also there are no water stains on the OSB subfloor around the tack strip, BUT the surface itself looked a bit rough - a condition that can be caused by water. That rough surface of the OSB made us decide we needed to look further under this carpet. What we found is shown in our second photo, below right. There was evidence of what appeared to be a single-event flood.
Notice the water stains on the tack strips in the upper photo areas as well as water stains on the subflooring. This sequence illustrates the danger of too-hasty spot-checks for water entry. In the photo at below right, in that picture's lower left corner you can see that the owner had installed new carpet tack strips in some areas when a previously-wet carpet was replaced. That's what our first photo at below left had discovered.
Let's not pretend we can be more certain about building water entry history than is appropriate to the evidence at hand. At below left, to me the carpet tack strip looks like one that remained wet for some time - the nails are quite rusty and black stains have spread into the wood of the tack strip. But I don't see rot nor significant damage at the wall itself. This could have been a single event wet floor that stayed wet for longer than just a few days; or there may have been more than one wet floor event. I'm uncertain.
In contrast, our photo at below right illustrates carpet tack strips that have in our OPINION almost certainly been wet more than once. Also note the rust stains on the bottom of the carpet itself.
But here is a water entry case that we can sort out. At below left I've pulled back carpet in a corner (that's the easiest place to pull up wall-to-wall floor carpeting without tearing it) to show dark stains and damage to the tack strips and some stains on the back of the carpeting itself. To me this looked like chronic water damage. Now taking a close look at the bottom of the baseboard trim at the floor-wall juncture (photo below right), you can see unequivocal evidence of chronic water entry: the bottom of the floor trim is rotted. This was not a single-event wet floor.
Key building water entry diagnosis and cure articles:
I am scheduling a pre-purchase home inspection and my real estate agent asked a question about moisture detection: he wants to know if the home inspector will check the moisture level in Sheetrock? - C.W., New York, NY.
Reply: ... it depends ...
Moisture meters, particularly pin-type probing moisture meters that detect moisture by sending an electrical signal between two probes inserted into a material (such as the time-tested Delmhorst™ twin-point electronic resistance moisture meter shown at left) are one of the first tools that many building inspectors purchase after a flashlight, ladder, and screwdriver.
Relying on any test instrument, as we discuss at GAS DETECTOR WARNINGS , is not a good substitute for a careful inspection. While using a moisture meter is a popular tool among home inspectors and building environmental inspectors or "mold investigators", and a useful one, the visual inspection of a building for leak history is much more critical than a general "check" using a moisture meter.
After all, the building could have had a history of leaks in the past, as well as hidden rot, insect damage, or mold, related to leaks or trapped moisture, but the leak spot could happen to be dry at the time of testing.
Absence of evidence of moisture when using a moisture meter in a building is not evidence of absence of a history of building leaks, and there is a long list of visual clues that readily tell the story of a building's leak history or the risk of building flooding. .
So properly a moisture meter is, in our opinion, useful principally to confirm that a leak is current. We also find moisture meters useful, particularly radio-signal based non-probing moisture meters such the Tramex™ electronic moisture encounter, to check for hidden leaks behind ceramic tile walls in bathrooms and kitchens where probing is impossible.
Tramex also makes pin-type moisture meters.
And certainly "spot checks for moisture" done randomly at a building would be nonsense.
In a field study we conducted in February 2004 we compared the effectiveness of various methods to test for moisture in the walls of a home reported to have suffered leaks from ice dams at its roof eaves. We surveyed the inside surface of building exterior walls of the entire second floor front and rear building surfaces using the popular tools and methods - the results are reported at MOISTURE METER STUDY.
Home buyers and home owners are right to worry about building leaks and moisture - water where we don't want it is at the top of the list of sources of building problems. If you have a particular reason to be suspicious about something be sure to let the inspector know.
Watch out for "show and tell" tools that impress the client but are a poor substitute for doing a good job.
Frequently Asked Questions (FAQs) about diagnosing and curing wet basements & crawl spaces in buildings & about determining the age &history of building leaks & water damage
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Technical Reviewers & References
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