Investigation of Leaking Shower and Mold Growth

Investigation of Leaking Shower and Mold Growth
Multiple units in a high rise condominium had showers with leaks that caused damage to adjacent areas. The home owners association retained CTaSC to investigate what had caused the leaks, to determine if the showers were installed per industry standards, and to determine how best to remediate the problem.

The Problem

Investigation of Leaking Shower and Mold GrowthBackground: Multiple units in a high rise condominium had showers with leaks that caused damage to adjacent areas.  The home owners association retained CTaSC to investigate what had caused the leaks, to determine if the showers were installed per industry standards, and to determine how best to remediate the problem.Request:  CTaSC was asked to investigate and inspect the shower and bathroom floors to determine the cause of the leak and the extent of the damages, to determine if the installation met industry standards, and to determine how best to remediate the problems.

The Solution

Visual Inspection Findings: 
  • CTaSC first performed a visual inspection in various units of the condominium.  The following are our observations and process as we investigate this one particular unit.
  • There was obvious water damage on the walls that showed deterioration of the wall board.  The hardwood floors in the living room showed signs of warpage.
  • The bathroom floors outside of the shower showed high levels of moisture according to our electrical moisture meter.
  • Because there was evidence of a large area of microbial growth (mold) we contained the unit, everyone suited up with protective clothing and masks, and an air exchanger was installed.
Destructive Testing (DT):
  • Removing the tile over the shower pan dam showed that cement backer board was screwed over the waterproof membrane sheeting that penetrated and breached the membrane.   The screws had badly rusted.
  • A waterproof membrane seam in the corner of the shower pan was not properly welded and there was a gap to allow water to migrate out of the shower.
  • The waterproof membrane in the shower was not sloped to drain, but was negatively sloped away from the drain.  There was no pre-slope under the membrane.
  • On the tile floor outside of the shower the tile was installed over two layers of cement backer board over a sound control board made of a cardboard type of material that was open and hollow inside it.
  • Water had leaked from the shower and traveled through the sound board into adjacent rooms.
  • Water had migrated into the wall cavity that caused mold and deterioration of the wall board and rusting of the metal framing.
  • The drain did not have any weep hole protection and the weep holes were plugged that trapped water in the shower under the tile.
Conclusion: 
  • The shower was not properly constructed.  There was no pre-slope under the waterproof membrane so that water reaching the membrane would travel to the drain.
  • The weep holes of the drain were not protected and plugged so water that got below the tile had no way of reaching the drain.
  • The waterproof membrane was penetrated and improperly installed that allowed water to migrate outside of the shower area.
  • The bathroom floor tile assembly was not properly designed and installed to prevent water from migrating outside of the bathroom, which resulted in extensive collateral water damages.
Recommendations:
  • All of the tile had to be removed.  The shower floor had to be pre-sloped and then a liquid applied waterproof membrane was installed over it.
  • The drain weep holes had weep hole protection.
  • The tile was installed with 95% full thin-set contact with an ANSI A118.4 modified thin-set mortar adhesive.
  • The tile was grouted with a cementitious grout, and then sealed.
  • All transitions of the shower were properly flashed and filled with an ASTM C920 sealant.
  • All of the damages to the adjacent floors and walls had to be repaired or replaced.  This was a very expensive repair.

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