INVESTIGATION OF SUNKEN FLOORS

Description of the Property

For purposes of the discussion that follows, the front elevation of the condominium building is assumed to face east. The condominium building is located in the Meadowbrook Development along the rear part of a 20-30 acre site. The site slopes steeply from front to rear. The condominium building is about 100 feet from the Meadowbrook creek. The condominium building has three levels and contains 8 condominium units. The White residence is located in the southeast corner of the building and occupies the second and third floors (photo 1 in Appendix B).

The building is a wood frame structure with hardboard siding and a gable roof that spans from front to rear. The condominium units are separated from each other by firewalls that run from the ground level to the roof. The building has a crawl space foundation. The foundation walls, piers, and footings are poured concrete. The exterior wood frame walls and interior firewalls are supported by concrete foundation walls. The interior walls of the condominium units are supported by a combination of concrete walls and concrete piers. The first floor framing consists of 6 x 12 wood girders that span between the piers and 16" deep wood floor trusses (photos 2-5). The upper floors are supported by wood trusses which in turn are supported by exterior and interior stud walls. All wood floor trusses are parallel with the front of the building. The interior bearing walls on the three levels line up with one another and the main supports in the crawl space. The upper level condominium units (including the White Residence) have cathedral ceilings.

Background

Ms. White purchased the condominium in December, 1993. At that time, she had a pre-purchase inspection performed by ABC Home Inspection Service (see report in Appendix E). In their report, ABC noted that some of the interior concrete foundation walls had settled. They attributed the settlement to unstable soil under the footings. They observed water ponding against the foundation walls and indicated that the water was affecting the bearing strength of the soil. They also noted that the floors in the first floor master bedroom (the bedroom opposite the stairs) and loft bedroom were out-of-level. And they noted several settlement and stress cracks in the walls and ceilings.

Soon after Ms. White purchased the condominium, she approached the Meadowbrook Board of Directors about correcting the structural problems. No effective actions were taken by the Board until about a year later when they hired Jones Engineering to investigate the problem (see Jones Report dated April 17, 1995 in Appendix E). Jones Engineering observed cracks in the wall between the first floor bedroom (the bedroom opposite the stairs) and adjacent bathroom as well as excessive deflections in the bedroom floor. They attributed the structural problems to settlement of the piers under the wall and inadequate superstructure framing. (The superstructure is the framing system above the foundation.) The Board of Directors ordered Jones Engineering to prepare plans and specifications to fix the problems. Jones Engineering prepared contract documents that called for resupporting the girder under the wall between bedroom opposite the stairs and the bathroom with new concrete piers, strengthening the floor trusses on either side of the girder, strengthening the wall, and jacking up the wall (see Remedial Repair Instructions dated June 19, 1995 in Appendix E). The repairs that were made to the piers and girders are shown in photos 2 - 5.

The repairs did not fix the problems in Ms. White’s condominium (see White letter to the Board dated May 15, 1997). The Board of Directors hired Jones Engineering to perform a follow-up inspection of her condominium. Jones Engineering noted several cracks over the tops of doors, cracks between the walls and cathedral ceilings, and visible deflections in the floors of the bedroom opposite the stairs and the loft bedroom. They also noted slopes in a bathroom floor (see Jones Engineering Report dated July 10, 1997 in Appendix E). They indicated that some additional structural movement occurred since the repairs, but they did not think it was caused by the repairs or further settlement. They attributed the additional damage in the condominium to thermal expansion and contraction of the roof system. They went on to suggest that one way to fix the out-of-level floors is to apply a self-leveling slurry.

Purpose of the Investigation

A primary objective of the investigation was to document the extent of the structural defects in Ms. White’s condominium. This part of the investigation entailed identifying and location and severity of:

• Out-of-level floors.
• Out-of-square door frames.
• Out-of-plumb walls.
• Cracks in the walls.

A second objective of the investigation was to determine the causes of the defects and if the defects are related to the foundation settlement and subsequent repairs to the main supports and bearing walls. A third objective was to gain enough understanding about the problems so that recommendations could be made on how to make repairs.

Method of Investigation

The evaluation was conducted by William A. Stanton, P.E. and Paresh D. Patel, Assistant Engineer. An initial site visit was made by William Stanton, during which the structural defects were observed and Ms. White was interviewed concerning the history of the problems. The crawl space was inspected during this visit. Photos were taken of the cracks in the condominium and structural repairs in the crawl space. During the visit, Ms. White provided Mr. Stanton with several reports and other documents related to the problems dating back to June 1995.

In the next phase of the investigation, measurements of the rooms on the second and third floor levels were made so that floor plans could be drawn. Measurements were made to the nearest .10 feet. At the same time, measurements were made of the floor elevations on the two levels. A TOPCON RL-50 rotating laser was used and measurements were made to the nearest .01 feet. Elevations were taken on one, two, and four foot grids, depending on the severity of the sags and slopes in the floors. At the same time, the door frames were measured for plumbness with a plumb bob suspended from the top of the doors. The walls were also checked with the plumb bob.

In the third phase of the investigation, calculations were performed to reduce the laser readings to elevations (see spreadsheet in Appendix C). CAD drawings were made of the room layouts. The floor elevations were plotted on the CAD drawings as 0.2 inch contour interval lines. CAD drawings were also made of the door frames and walls. The CAD drawings are in Appendix A.

In the fourth phase of the investigation, information was gathered about residential construction performance standards. The National Association of Home Builders (NAHB) Research Center was consulted during this phase. Also, several warranty performance standards were reviewed. And, during this phase, more background information dating back to December, 1993 was received from Ms. White and reviewed.

The final phase of the investigation consisted of analyzing the above information and writing the report.

STRUCTURAL DEFECTS

Out-of-Level Floors

The table below summarizes the floor elevations by room. The elevation differences (column 4) were obtained from CAD Drawings 1 in Appendix A. The NAHB Performance Standard for floor elevation difference is 0.50" in 20 feet or .025" per foot (see NAHB Performance Standards in Appendix D). The allowable elevation difference (column 5) was obtained by multiplying the room dimension with the asterisk by 0.25. The defect factor is column 4 divided by column 5. The defect factor is a measure of the severity of the slope or sag in the room. The factor should not be over 1.00 to meet the NAHB standard.

Four door frames are noticeably out-of-square. The doors are designated as D 1 - D4. All the out-of-square doors are located around the master bedroom and adjoining bathrooms. The worst door frame is the door to bathroom 3. It is 3/4" out-of-square. Ms. White reported that she had to sand the tops of some of the doors because they bound in the frames.

Out-of-Plumb Walls

The eight foot high wall between the bathroom 1 and bathroom 2 is noticeably out-of-plumb. The top of the wall leans 1-1/2" toward the back wall of the condominium. Walls that are out-of-plumb more than 3/4" in 8 feet are defective according to NAHB standards.

Cracks in Walls

There are several severe stress cracks in the walls (photos 6 - 8 in Appendix B). There are diagonal cracks over the door between the bedroom by the stairs on the first level and bathroom 3 (photos 6 & 7). There are also diagonal cracks over the door between the loft sitting room and loft bedroom. These doors are in walls that are located approximately over one another and over the main support that was repaired (photos 2 - 3). The cracks are shear cracks. They were caused by vertical displacement of the wall.

There is also a severe structural crack at a corner of the opening in the wall in the loft bedroom. The opening in the wall overlooks the living/dining room below. This crack is also a shear crack. It was caused by vertical displacement of the wall. The crack is located approximately over the other main support that was repaired.

There is also a narrow crack between the cathedral ceiling and wall for the bedroom by the stairs. This crack may have been caused by upward movement of the roof supports due to thermal expansion and contraction forces.

The floor at the back of Ms. White’s condominium is 0.8" - 1.4" lower than the floor at the front. The NAHB performance standard is 0.71". The elevation data indicates that the middle and back foundation walls of the condominium building may have settled about an inch relative to the front foundation walls. This difference in elevation may be accounted for by the steeply sloping site (more weight is on the rear wall) and the possibility that the soil nearest the creek does not have as good bearing capacity as the soil further up the hill.

The slopes in the master bedroom, living/dining room, and loft sitting rooms vary uniformly from front-to-back. The respective slopes are 1.00", 1.00", and 0.80". According to the NAHB Standard, the slopes should not be any more than about 0.33". When walking across these rooms, a person has the sensation of walking down or up a slight grade.

In several rooms, the slopes are accompanied by sags in the floors. The condition is worse in the bedroom by the stairs, bathroom 3, and the loft bedroom. As well as the slopes, there are pronounced depressions in the floors of these rooms. In the downstairs bedroom, the floor pitches down 1.8" in five feet. In bathroom 3, the floor pitches down 0.8" in three feet. In the loft bedroom, the floor pitches down 0.8" in five feet. In these rooms, the depression is unsightly and causes problems. For example, Ms. White has placed blocks under the legs at the foot of the bed in the loft bedroom.

In our opinion, the depressions are caused by structural deficiencies in the floor trusses and settlement of the foundation. The depressions may have also been exacerbated by the jacking work that was done on the main supports. The jacking may have only lifted the trusses at their supports. The sags are so severe that it is likely that the floor trusses have been damaged. The floor trusses should be examined before any attempts are made to level the floor with a leveling compound or slurry. This will entail taking up the floor sheathing in the rooms. If the trusses are damaged, they should be reinforced or replaced.

The cracks in the walls were caused by settlement of the foundation and/or subsequent jacking operations. The cracks can be easily repaired and should not reappear if the building has stopped settling. The out-of-square door frames may have been caused by settlement or poor workmanship. The out-of-plumb wall is a result of poor workmanship.

Recommendations

Repairs to the White condominium probably involves the following work:

• Structural reinforcement or replacement of several floor trusses.
• Reframing several door frames.
• Rebuilding the out-of-plumb wall in the bathroom.
• Leveling several of the floors.

The cost of doing this work could range from $10,000 to $25,000, depending on the amount of major structural repairs (such as replacing floor trusses) that need to be made.

The observations described in the report are valid on the date of the investigation. The opinions are based on visual evidences of readily accessible areas. No invasive or destructive testing was performed. The investigation was not for the purpose of determining compliance with North Carolina State Building Codes. The report was prepared for the exclusive use of Barbara White and her successors and assignees. Criterium-Stanton Engineers does not intend any other individual or party to rely upon the report without our express written consent. If another individual or party relies on the report, they shall indemnify and hold Criterium-Stanton Engineers harmless for any damages, losses, or expenses they may incur as a result of its use.

Respectfully submitted,

William A. Stanton, P.E.