Differential Settlement Causes Cracks in Expensive Split-Level Home GENERAL INFORMATION Date of Site Inspections: 10/18 @ 9:00 AM and 10/22 @ 3:30 PM Weather Conditions: Sunny, 65°, both days Prepared for: Jack and Lisa Wright People Present During the Field Inspections 10/18 - Mrs. Wright and William Stanton of Criterium-Stanton Engineers. 10/22 - Mr. and Mrs. Wright, Ryan Walters of Wallace's Pressure Grouting Services, Inc., and William Stanton. Source(s) of Information Interview with Mr. and Mrs. Wright Photographs of the family room supplied by the Wrights Purpose of the Investigation Inspect cracks in the brick veneer and interior walls. Determine if they are a structural concern. Determine the reason for the pressure grouting work that was done in the family room and if there are any present structural problems related to this work. Investigate the reason for the steel jack posts in the crawlspace. Inspect the leaning pier to see if it is a structural concern. Inspect the topography around the house and determine if there are any potential drainage problems. Orientation For purposes of the discussion that follows the front of the house is assumed to face north. | Top | Table of Contents | BACKGROUND According to the Wrights, the house was constructed in 1961. The house has had four owners, including the Wrights. The original owner occupied the house until 1983. The second owners occupied it until 1993. The third owners occupied it until June 1999 when they sold it to the Wrights. When they bought the house, the Wrights had it inspected by a home inspector. At the time, there were many overgrown shrubs and bushes around the house. The only cracks in the brick veneer that were visible were the ones over the garage door and some of the cracks on the front elevation. The home inspector did not think that these cracks were a structural concern. When the Wrights cut the overgrown bushes, they noted several additional cracks in the brickwork. About six weeks after they moved in, the Wrights decided to put a new carpet in the family room. When the old carpet was removed, they discovered pressure grouting holes in the floor. The previous owners did not disclose this information. Mrs. Wrights told me that when they bought the house, the door to the master bedroom was okay. Now it binds. In addition, they have recently noted cracks in the master bedroom walls. At our recommendation, Mr. Wright called the principal floor grouting companies in Charlotte to determine if one of them may have done the pressure grouting work. None of the companies had any records of doing the work in the recent past. | Top | Table of Contents | DESCRIPTION The house is a split-level structure, approximately 2700 sq. ft. in size (Photos 1-2). There is a detached two-car garage on the east end. Originally, there was a one-car garage under the east end of the house. The garage has been converted into interior space. The one-story section of the house has a pier and curtain wall foundation. The two-story section has concrete block foundation walls and a concrete slab-on-grade floor. The slab was poured after the foundation wall was constructed; therefore it is a separate structural component. The main house has a wood-frame with brick veneer cladding. The two-story section has a hip roof while the one-story section has a gable roof. There is an enclosed sunroom in the rear of the house. The sunroom has a slab-on-grade foundation. The ground pitches away sharply on the front and sides of the house. The ground in the rear pitches toward the house at a moderate slope. | Top | Table of Contents | METHOD OF INVESTIGATION insert into content values (1st Visit - At the beginning of the inspection, I interview Ms. Wright about the location and history of the conditions. I then inspected the interior of the house focusing my attention on the part of the house where the bedrooms are located. After that, I inspected the exterior walls, drainage in the rear of the house, and the crawlspace. insert into content values (2nd Visit - I met Ryan Walters of Wallace's Pressure Grouting Service at the site. In the company of Mr. Wright, Mr. Walters and I inspected the exterior walls of the house. We then inspected the garage and family room. Mr. Wright had pulled back the carpet in the garage allowing us to inspect the slab area adjacent to the wall between the garage and family room. While we were there, he uncovered one of the pressure grouting holes in the family room. In addition, we showed Mr. Walters photographs of the pressure grouting holes in the family room. After Mr. Walters left, I inspected a leaning pier in the crawlspace. | Top | Table of Contents | OBSERVATIONS There is a vertical hairline crack over the upper right corner of the door to the master bedroom. In addition, the doorframe is out of square about º"" and the door binds slightly. There is also a horizontal hairline crack at the top of the doorframe on the corridor side of the wall. This wall is directly over the wall separating the family room and garage on the lower level. It supports some of the roof load. There are vertical hairline cracks over the upper corners of the closet door in the master bedroom. The cracks have been patched and have reopened. This wall is directly over the wall separating the family room and garage on the lower level. There are two hairline vertical cracks over the door leading to the master bathroom. In the master bedroom, there is also a diagonal hairline crack in the lower right corner of the window over the garage. The crack has been patched and has reopened. There are two vertical hairline cracks over the door leading to a childís bedroom in the front of the house. In addition, Mrs. Wright told me that were vertical cracks over the door leading from the kitchen to the front foyer. These cracks are not visible. On the southwest corner of the main house, the ground next to the foundation is flat. In addition, the land in the rear of the house slopes toward this point. Water draining off the backyard will pond next to the foundation at this location, seep into the soil, and get into the crawlspace. There are diagonal step cracks in the brick veneer over the old garage door opening (Photo 4). The cracks originate at the ends of the lintel beam and form a triangular-shaped wedge over the opening. The cracks are about º"" wide and have been repointed. In the rear elevation, at the juncture of the crawlspace foundation and slab-on-grade foundation, there a 1/8"" wide crack in the brick veneer that extends from the ground up to the roof eave. There is a diagonal crack in the brick veneer in the southwest corner of the main house. It is v-shaped and runs from the ground on the left side of the window toward the upper right corner of the window (Photo 5). The crack is hairline width at the ground and about 1/8"" wide at the corner of the house. In addition, the right jamb of the window frame has separated about 1/8"" from the brick. This joint has been caulked in the past. On the front elevation, there is a v-shaped crack between the part of the house that is on the crawlspace foundation and the part that is on the slab-on-grade foundation (Photo 6). The crack proceeds upward from the ground and follows the joint between the door frame and brick and edge of the roof eave and brick. It is hairline width at the ground and about ?"" wide at the roof eave. On the front elevation, under the window in the northeast corner, there are two diagonal cracks in the brick veneer. The first crack is a hairline crack that starts at the corner of the house at the ground and extends to the lower left corner of the window. The second crack is about º"" wide and extends from the lower right corner of the window to the ground. This crack has been pointed up with mortar. On the front elevation, at the window to the left of the front stairs, there are two diagonal cracks. The first crack runs from the lower right corner of the window to the ground on the left side of the window. The second crack runs from the lower right corner of the window to the stairs. The cracks are about º"" wide and they have been repointed. The ground in the crawlspace was dry during the times that I visited the site. A foundation drain has been installed in the crawlspace partly along the south wall of the house and between the one-story and two-story sections. The water is removed with a sump pump. In the front part of the crawlspace, steel jack posts have been installed under some of the beams to give them extra support. One of the posts is somewhat askew. I dug down several inches around one of the posts to see if it was sitting on a poured concrete footing. I was not able to dig deep enough to determine if it had a concrete footing or not. One of the masonry piers under the main girder supporting the house is out of plumb (Photo 3). The girder does not bear solidly on the pier. The pier is located on the edge of a steep slope, and there is a crack in a mortar joint at the base of the pier. By all appearances, the pier has shifted out of position. There are several cracks in the front stair unit, and the mortared joints have loosened up in several places. Approximately 20 random pressure grouting holes were made in the concrete floor in the family room. The slab surface is level; however, it is about ?"" lower than the top of the perimeter foundation wall. This is an indication that it may have settled slightly in the past. There is no evidence that any pressure grouting work was done on the garage floor slab or that the wall between the garage and family room was underpinned. | Top | Table of Contents | FINDINGS AND CONCLUSIONS The cracks in the interior wall between the master bedroom and hallway were probably caused by subsidence of the wall. It also caused the door to bind. The cracks are not very wide, indicating that the subsidence was probably under ?"". It was probably caused by settlement of the footing under the wall below. The footing is carrying a moderately heavy load because the walls support the roof and second floor. Given the age of the house, I would expect very little future settlement. Underpinning is not warranted at this time. The cracks in the wall (interior and exterior sides) over the old garage door opening were caused by deflection in the lintel beam (header) over the opening. The beam is slightly undersized. It is large enough to support the load, but not large enough to do so without excessive deflection. Consequently, the cracks occurred. Further deflection is not expected. The vertical cracks over the childís bedroom door and door leading to the kitchen were probably caused by thermal movement of the sheetrock and not settlement. These are not a structural concern. The crack in the brick veneer on the southwest corner of the house was probably caused by swelling and shrinking action of the soil under the footing. This is a serious concern. Further movement is likely to occur unless steps are taken to direct water away from the corner. It is important to keep water out of the soil in this location. As it is now, the ground around this corner of the house invites water. In addition to improving the drainage in this area, you may want to consider installing a heavy duty plastic barrier 3-4"" under the surface of the ground. The vertical cracks on the front and rear elevations at the juncture of the crawlspace foundation and slab-on-grade foundation and the other cracks on the front elevation are related to the same cause. The cause is subsidence at the northeast corner of the house. This corner has probably settled about 1"", causing the two-story section to rotate about an axis at the base of the cracks. Because of the age of the house, it is unlikely that much more settlement will occur. In fact, the point of equilibrium may have already been reached. Just to be on the safe side, we recommend that you monitor the width of the crack on the front elevation for a few years. You can simply measure it three or four times a year with a tape measure or use a crack monitoring device that you can purchase at most hardware stores. If the crack gets any wider, you probably should consider underpinning the northeast corner of the foundation with helical piers. They cost about $1500 each and you probably would need about five piers. The steel jack posts in the crawlspace may not be needed, since the beams seem to be of adequate size to support the loads. The previous owners may have installed them because they experienced some movement in the floors at these locations. It certainly will not do any harm to leave them in place. You should check to see that they have concrete footings though. Without solid footings, they are not much good. The leaning masonry pier is a serious structural concern since it supports a very heavy load. You would not want this pier to fail. We recommend that you have a new one installed immediately. The footing for the new pier should be deep enough so there no chance of it being undermined by the slope. When a new pier is installed, the contractor needs to carefully shore the girder to ensure that adequate support is maintained at all times. The loose bricks in the front stairs should be repointed to keep out water. If water is allowed to penetrate the bricks it can freeze in cold weather and cause further damage to the bricks. We are not sure why the previous owners had the floor in the family room pressure grouted. Since the holes were made in a random pattern, the purpose was probably to level the slab rather than raise it up. The work was done well since the floor slab is very level and in good condition. Probably the slab jacking was done several years ago. If so, the repairs have stood the test of time and future settlement is no longer a structural concern. | Top | Table of Contents | RECOMMENDATIONS Take steps to keep water out of the soil in the southwest corner of the house. Monitor the width of the crack at the juncture of the crawlspace foundation and slab-on-grade. If it widens, consider underpinning the northeast corner of the house. Check to see if the steel jack posts have concrete footings. If not, install them. Replace the leaning and cracked masonry pier with a new pier. Repoint the inactive cracks and caulk the active cracks in the brick veneer. Repoint the bricks in the front steps. Investigate who did the pressure grouting work in order to see when it was done. | Top | Table of Contents | ESTIMATED COSTS Item Cost Regrade ground at southwest corner. Install moisture barrier $1,000.00 Replace leaning pier $1,500.00 Repoint and caulk bricks $1,000.00 Underpin NE corner (not necessary at this time) $7,500.00 Install concrete footings under jack posts (if needed) $500.00 Total Cost $11,500.00 | Top | Table of Contents | LIMITATIONS The observations described in the report are valid on the date of the investigation and were made under the conditions noted in the report. We prepared the report for the exclusive use of Mr. and Mrs. Wright and their 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. The report is limited to the visual observations we made during our inspection. We did not remove surface materials, furnishings or equipment, undertake any digging or excavation, or perform any destructive or invasive testing. Accordingly, we cannot comment on the condition of systems and components that we could not see. In addition, we are not responsible for conditions that were not within the scope of our services at the time of inspection. We did not assess the stability of the building or the underlying foundation soil since this effort would require excavation and destructive testing. We did not perform any computations or engineering analysis as part of this evaluation, nor did we conduct a comprehensive code review. This report should not be considered a warranty of condition, and no warranty is implied. The costs that we have given to remedy deficiencies are estimates only. They are based on our general knowledge of building systems and the construction industry. When appropriate, we have relied on standard references, such as R.S. Means Building Construction Cost Data. For items for which no standard guide exists (e.g., structural repairs), we have used our own cost records. Costs may vary significantly from estimates and competitive quotations from repair contractors. | Top | Table of Contents | William A. Stanton, P.E. | Top | Table of Contents | | Structural Inspections | Residential & Commercial Services |