Black  moldy sub basement (C) D Friedman D Grudzinski Impact of Wet Moldy Basement on Other Building Areas

  • BASEMENT MOLD WATER IMPACT - CONTENTS: Photographs show examples of a wet, moldy, rotted-framing sub basement that served as a moisture problem source for the whole building. How to inspect & test for mold in building basements. How to inspect & test for moldy basement insulation or basement contents & stored items
  • POST a QUESTION or READ FAQs about the effect of wet basements and moldy basements on other building areas: movement of moisture and mold contamination through buildings

Wet moldy basement guide: this article describes the effects of a wet moldy basement on the rest of a building.

This article includes photographs and text illustrating a very wet, moldy, rotted-framed sub-basement inspected by David Grudzinski, a Cranston RI professional home inspector and member of ASHI and NACHI. Page top photo of a rotting, flooding, moldy sub basement, courtesy of Mr. Grudzinski.

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BASEMENT WATER & MOLD IMPACT: how moisture & mold from a wet basement or crawl space travel up through the building living area and into the building attic or roof cavity

Moldy sub basement, rot, flooding (C) David Gruzinski Daniel Friedman

At BASEMENT MOLD we described visual clues that you can spot in a building basement or crawl space that show the leak history, water sources, and moisture sources in a building.

Mr. Grudzinski's photograph (left) shows severe rot and structural damage found in a building sub basement that had been exposed to periodic flooding. Moisture from this area traveled upwards through the rest of the building where it was also a key contributor to ATTIC MOLD.

Grudzinski's page top photo (above) shows more collapsing framing as well as mold growth. This sub basement was dangerous even to enter, and conditions there apparently indicated a threat of structural collapse of the floor above.

"In the basement of home, a small door in the floor was found. There was a sub basement. The form were still present. The rot and mold was extensive. This white mold was al over, and the room was very humid. " - D.G.

Wet moldy rotting sub basement (C) D Friedman D Grudzinski

Grudzinski found the sub basement so wet, in fact, that his camera lens fogged up between photos, as he demonstrates in this photograph.

"Some of the forms used to pour the sub basement were still in place.

Some rotted and fell. Notice the fog.

In the time it took to take 2 pictures, the camera fogged again."

Careful examination of these clues, such as leak stain patterns, can also make clear whether water is entering a basement from the ground level (maybe bad gutters and downspouts?) or from a lower source such as ground water or a hidden spring.


"As you can see form the water mark, this sub basement has been subjected to flooding, [probably recurrent flooding.] "

Moldy wet basement (C) D Grudzinski D FriedmanMore on basement or crawl space leak prevention and drying out procedures can be read at CRAWL SPACE DRYOUT - home.

If there is visible mold on other basement, sub basement, or crawl space surfaces, don't forget to also check

  • the condition of the occupied spaces above for mold or other IAQ problems that may be caused or aggravated by wet building conditions - MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
  • the conditions in the building attic or roof spaces where moisture may be trapped - see ATTIC MOLD CAUSES
  • the condition of building insulation in those areas that during a mold remediation the insurance company, mold consultant, or mold remediator may want to leave in place because it "looks clean".
  • the overall condition of the building for evidence of rot, and insect damage, structural movement, or even risk of structural collapse

Photograph of extensive basement Stachybotrys chartarum contamination -  © Daniel Friedman

In the photograph shown here, not only was there extensive Stachybotrys chartarum contamination visible as "black mold" on the basement drywall, a special vacuum test of the fiberglass insulation in this basement ceiling disclosed high levels of Aspergillus versicolor, Aspergillus sp., & Penicillium sp..

Basements and crawl spaces that have been wet or exposed to high moisture are common reservoirs of hidden mold such as moldy insulation.


Photo - Daniel Friedman.


This article is part of our series: MOLD in BUILDINGS which describes how to find mold and test for mold in buildings, including how and where to collect mold samples using an easy, inexpensive, low-tech but very effective mold testing method.

The wet conditions in this sub basement formed the principal moisture source in the building above, leading to a moldy attic that we describe at ATTIC MOLD CAUSES.


Continue reading at MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD or select a topic from the More Reading links or topic ARTICLE INDEX shown below.

Readers should also see ATTIC MOLD, see CRAWLSPACE MOLD, and BASEMENT MOLD.

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