KTA Solutions

Failing Wood Flooring

 

Problem:  Failing Wood Flooring

Description:  A free-standing retail building with a concrete floor was taken over by another retailer.  The remodel included polishing the concrete in the main aisles and the installation of wooden flooring in areas around the perimeter.  In less than a year, the wooden flooring showed significant wear in heavy traffic areas.  The Owner asked for an examination to determine the cause of the problem.  The following is a summary of the types of testing and analysis undertaken by KTA to examine problems of this nature.

NOTE: The conclusions provided below cannot be interpreted as being relevant to other failures, even if they are similar in appearance. Likewise, the tests identified below may or may not be relevant or adequate for the investigation of other failures.

Field Sampling/Analysis:

  1. Significant wearing of the flooring was visible in heavy foot-traffic areas.   In seating areas, the scraping of chair legs created deep gouges in the wood.  Flooring away from heavy traffic areas was fine and retained its desired texture and appearance.
  2. When scraped with a knife, the surface stain was removed, revealing an off-white wood substrate.
  3. Lower shelves in the area in question exhibited a fine power-like material.
  4. The flooring had the appearance and color of Spruce.

Conclusion:

            The flooring was confirmed to be Spruce.  In low traffic areas Spruce is fine, but it is too soft for use in high traffic areas or in locations where physical scraping of the surface is likely (e.g., sliding chairs across the floor while seated.  The surface of the floor is being abraded away from repeated contact with shoes.  The fine dusting on the lower shelves is an indication of the nature of the deterioration. The solution in heavy traffic areas is routine oiling of the floor or removing and replacing it with a more robust flooring material such as oak.  The oiling will not prevent gouging by chair legs.  The solution here is to overlay the areas beneath the chairs with mats or to replace the flooring.  The application of a surface coating to the flooring is not recommended due to the underlying softness of the wood.

 

Improperly Installed Surface Mounted Flashing

Problem:  Flashing Deficiencies

Description:  A masonry building in Ohio was experiencing leaking underneath a drive under canopy.  Leaks were occurring over entrance/exit doors and also storefront windows of conference rooms and offices.  The leaks were causing a nuisance to customers entering and exiting the building during rain and were also contributing to coating failures underneath the canopy.

The drive under canopy was a pre-manufactured structure erected independent of the main masonry building.  The canopy consisted of a structural steel framing and a light gage parapet wall with a metal panel facade.  The roof of the canopy consisted of standing seam panels that were underhung from the structural steel frame above.  A field fabricated flashing system was installed between the main building and canopy.  In addition, overflow scuppers were installed in the main building wall just above the canopy and drained onto the canopy.  The following is a summary of the types of testing and analysis undertaken by KTA to examine problems of this nature.

NOTE: The conclusions provided below cannot be interpreted as being relevant to other failures, even if they are similar in appearance. Likewise, the tests identified below may or may not be relevant or adequate for the investigation of other failures.

Field Sampling/Analysis:

  1. Visual Observations – The flashing system between the main building and canopy was visually inspected.  Fabricated sheet metal flashing was installed between the masonry building and canopy.  The flashing system was one piece that spanned from the masonry wall to underneath the standing seam roof panels.  The flashing was mostly flat and butted the masonry wall.  The top edge of the flashing was not cut into the masonry wall. The top of the flashing contained a thick bead of sealant material.  The sealant material was found to be cracking and separating at the top of the flashing.  Sealant material was also found to be missing in the grooves of the scored block.
  2. Spray Rack Test – A water spray rack test similar in principle to the method in ASTM E1105, Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors and Curtain Walls by Uniform or Cyclic Static Air Pressure Difference was performed.  The spray rack was placed directly above the canopy and sprayed onto the masonry wall.  A steady stream of water was applied to the surface at 5 gallons/square foot/hour through spray nozzles held 12 inches from the surface.  The purpose of the spray rack test was to replicate the leaking underneath the canopy above the doors and windows so that a controlled examination of potential causes could be made.  The test immediately showed that leaks were coming from deficiencies in the flashing system.

Conclusion:

            The single piece flashing system was inadequate to prevent leaks from occurring underneath the canopy.  It is likely the flashing system was originally designed to be a two piece flashing system and only the base flashing was installed; the counterflashing was omitted.    The top edge of the base flashing was simply caulked in an attempt to make it shed water.  Movement between the canopy and building, and movement of the flashing itself caused the sealant to crack and separate over time, allowing rain water to run down the wall beneath the canopy.

The recommendation to repair the leaks above the canopy included modifications to the flashing system.   Modifications included removal of sealant above the base flashing to allow unrestricted movement of the base flashing and the masonry wall.  A detail was developed illustrating a new counterflashing to cover the base flashing.  Prefabricated surface mounted flashings were not an option due to the deep grooves in the scored block.   The detail included cutting in a groove slightly deeper than the grooves in the scored block.  The new flashing detail showed a 90 degree bend at the top of the flashing with another upward bend along the entire edge to create a “friction fit” into the cut groove.  The new counterflashing overlapped the existing base flashing.  Fasteners of like material as the counterflashing were specified to be installed in oversized holes and sealed with urethane sealant.  The cut groove was specified to be sealed with a hybrid urethane sealant material.

Damp CMU In-Fill Insulation

 

Problem:  Damp CMU In-Fill Insulation

 

Description:  A single-wythe CMU building was less than 1 year old when blocks on the back wall were damaged and the faces had to be replaced.  When the replacement work started, the contractor notified the owner that the spray polyurethane foam insulation (SPF) in the block cavities was damp.  The owner requested an examination of the insulation around the building to determine if the problem was widespread.  The specified SPF was low density open-cell, 0.8 lb/ft3.  The following is a summary of the types of testing and analysis undertaken by KTA to examine problems of this nature.

NOTE: The conclusions provided below cannot be interpreted as being relevant to other failures, even if they are similar in appearance. Likewise, the tests identified below may or may not be relevant or adequate for the investigation of other failures.

 

Field Sampling/Analysis:

 

  1. Visual Observations – Small, isolated patches of efflorescence were visible on the exterior walls at random, but nothing stood out visually to suggest that the block and/or insulation were damp.
  2. Infrared Thermography – IR thermography was used to examine the building walls.  The images showed clear indications of thermal bridging in portions of all walls.  The results of the IR thermography were used to select test locations for in-depth moisture measurements.

 

  1. Moisture Content – Moisture readings were taken around the building.  Since the purpose of the assessment was to determine whether the in-fill insulation was damp, destructive testing was used.  Two ¼” diameter holes were drilled though the mortar joints or block faces.  Special probes designed in the KTA machine shop were inserted into the holes and connected to a conductivity moisture meter.  The probes allowed for a determination of the presence of moisture at the outer face of the blocks, the interior cavities of the blocks (the insulation), and the inside back faces of the blocks.

    Test sites were selected based on the thermal imaging results in order to obtain moisture readings in areas that did and didn’t exhibit thermal bridging.  In locations where the entire height of the wall appeared to be the same by IR imaging, testing was typically performed at 3 heights (ground level, 10 to 12 feet up from the ground, and below the upper bond beam).   The moisture testing showed mixed results: the in-fill insulation in some block cavities was damp, some was dry, and some of the block cavities were void of insulation altogether.  In some cases, the moisture content was so high that damp insulation was adhered to the probes when removed from the block.

 

  1. Optical Borescope – A borescope was used to view the inside of random wall cavities in areas where the moisture testing indicated that no insulation was present.  The borescope assessment confirmed that the cavities were empty.

 

  1. Samples – A few 1” diameter cores were drilled through the block face in both dry and damp locations and the insulation removed.  Each sample of insulation was double bagged and sealed to prevent the ingress or egress of moisture.

 

Laboratory Analysis:

  1. Samples of damp insulation were weighed upon receipt, dried in an oven, reweighed, and the percentage of moisture by weight of the insulation determined (the mass of moisture per unit mass of dry material).  Samples contained up to 226% of their weight in moisture.
  2. The insulation had open cell properties based upon the rate of absorption that was observed.  Open cell, low density foam had been specified.

Conclusions:

 

While damp insulation was expected to be present to some extent based on the contractor’s initial observations, the investigation revealed a finding that the owner didn’t anticipate – many of the cavities, either in total or in part, were missing insulation.  The IR thermography indicated that thermal bridging was occurring.  Since thermal bridging can be caused by damp insulation or missing insulation, the destructive moisture tests and borescopes were used to investigate the walls further.  It was estimated that insulation was missing in the upper ½ to ¼ of approximately 25% of the wall cavities up to the bond beam.  In areas of thermal bridging where insulation was present, the insulation was damp.  In areas where thermal bridging was not visible, the insulation was dry.  Where the insulation was damp, the moisture content was extremely high as determined by laboratory testing, and because paint is present on both the interior and exterior sides of the walls, there is no opportunity for it to dry.

 

Determining the source of the moisture was not part of the scope of services, but it is not uncommon to find both missing and damp in-fill insulation in single-wythe CMU construction.  Common causes of damp insulation range from deficiencies in roofing, flashing, and sealants; poor wind-driven rain resistance of the exterior coating; cracks in the mortar and block; and air infiltration/exfiltration leading to condensation in un-insulated block that runs down the cavity to dampen the insulation beneath.