Piers Under the Center of a Two-Story House Settle GENERAL INFORMATION Date of Site Inspections: 8/24 (9:15 - 11:55 AM), 8/31 (9:00 - 12:15 AM), 11/10 (4:00 - 4:30 PM) Weather Conditions: 8/24 (Overcast, 80°), 8/31 (Sunny, 70°), 11/10 (Sunny, 60°) Prepared for: Darrel & Kim Wilson People Present During the Field Inspections Mr. and Mrs. Wilson and William Stanton on 8/24 and 8/31. Mrs. Wilson and William Stanton on 11/10. Source(s) of Information Site observations Interviews with Mr. and Mrs. Wilson U.S. Soil Conservation Service Maps (see Appendix B) Purpose of the Investigation Determine cause (s) of cracks in the interior walls. Determine cause(s) of slope in the kitchen floor and other floors. Determine the cause(s) of the gap between the fireplace and den wall. Determine cause(s) of the displacement and slope in the front foyer. Determine cause(s) of the cracks in the exterior brick veneer. Determine the condition and adequacy of the foundation and first floor supports. Determine if there are any potential drainage problems. Make recommendations as to the type of structural repairs that are needed. Orientation Unless otherwise stated, all directions (left, right, rear, etc.) are in relation to an observer facing the front of the house. | Top | Table of Contents | BACKGROUND According to Mr. Wilson, the house had two previous owners. The first owner lived in the house for 27 years. The second owner lived in the house for 6-7 years and rented it for 3-4 years. The Wilsons purchased the house last year. Mr. Wilson thought that the wall cracks and sloping floors have existed for some time with the exception of the crack in the brick veneer on the rear elevation (Photo 2). He thinks that this crack occurred after they moved into the house. Mr. Wilson said that the previous owner recently had some repair work done on the sills and supports under the front foyer. The Wilsons had the french drain installed in the crawlspace. Mr. Wilson said, that after the drain was installed, the ground in the crawlspace dried out considerably. | Top | Table of Contents | DESCRIPTION The house is a two-story, wood- framed structure with brick veneer cladding (Photo 1). It does not have a garage. It has about 2200 sq. ft. of living space. The original structure is 37 years old. There is a laundry room ell on the right side of the house. An enclosed sunroom was added on to the rear of the house. The sunroom addition looks like it may be 10-20 years old. The house has a gable roof, with the ridge running from left to right. The interior finishes consist of sheetrock walls and ceilings, hardwood floors on the first floor, and carpeted floors on the second floor. The house sits on a lot that may have originally been a natural drainage swale, as the lot is somewhat low in relation to the streets on the front and left sides. There is satisfactory slope on all sides the house, however. Runoff water generally flows toward the rear and to the right of the lot. The roof is supported with rafters. The rafters have braces at the midspans. The braces bear on the wall in the center of the house; therefore, this wall carries most of the roof weight (see floor and crawlspace plans in Appendix C). The floor joists in the attic, second floor, and first floor run from front to back and are supported by the wall in the center of the house. The walls on the second floor generally line up with the walls on the second floor. The foyer, stairs, and bathrooms are in the center part of the house. Consequently, this is where the house weight is concentrated. The house has a pier and curtain wall type of foundation. The piers consist of 8"" x 16"" concrete blocks. The size and thickness of the footings under the piers is unknown. The curtain walls consist of a single wythe of brick. The fireplace and chimney are supported by a 2' x 15' foundation. The main girder in the center of the house consists of 2 - 2 x 12’s. The floor joists are 2 x 10’s. They are doubled at wall locations, and in all cases except one, there are piers under the midspans. The floor sheathing consists of 1 x 8 tongue and groove (T & G) boards laid diagonally. There is a french drain inside the crawlspace along the front and right foundation walls. The water is expelled with a sump pump. The floor joists under the kitchen support several pipes, ducts, and electrical wires. | Top | Table of Contents | METHOD OF INVESTIGATION First visit on 8/24 - At the beginning of the site visit, I interviewed Mr. Wilson about the history of the house and the structural conditions he had identified. In the company of Mr. Wilson, I then inspected the first and second floors and the four exterior elevations, paying particular attention to the problem areas pointed out by Mr. Wilson. I used a 4' carpenters level to check the levelness of the floor in the front foyer and kitchen. In addition, I took several photographs of the interior and exterior conditions. Second visit on 8/31 - With the help of Mr. Wilson, I measured the partition layout on the first and second floors. I also looked into the attic to observe how the roof was supported. We then went into the crawlspace where we inspected and measured the structural support system. Mr. Wilson assisted me part of the time. Third visit on 11/10 - Mr. Wilson was not present during this visit. With the help of Mrs. Wilson, I measured the plumbness of the fireplace with a 4' carpenter’s level. I then went outside and measured the verticality of the brick veneer using a ladder and plumb bob with a 12' string. | Top | Table of Contents | OBSERVATIONS Interior The center of floor in the front foyer is sunken in. From the dining room going in a leftward direction, the floor slopes down 1?"" in 8'. From the living room going in a rightward direction, the floor slopes down æ"" in 4'. In addition, there is a ?"" gap between the baseboard on the front wall and the floor. There is also a 1/32"" wide crack in the ceiling over the front of the stairs. Mr. Wilson said the crack is new. There is a hump in the kitchen floor at the door to the laundry room. The hump is created by a sharp downward slope in the kitchen floor. I measured a slope of 1"" in the first 4'. In addition, the kitchen floor sags in the middle. Mr. Wilson said that a few months ago, a water hose in the refrigerator broke, and the water ran across the kitchen floor to the center of the house. The refrigerator is located by the door to the laundry room. Mrs. Wilson told me that when she puts marbles on the floors for their cats to play with, the marbles roll toward the center of the house. This evidence seems to indicate that the center of the house is lower than the rest of the house. On the second floor, there are slopes in the floors, but they are not as noticeable as on the first floor. Two doors in the bearing walls (the walls that run from left to right) bind in their frames slightly. The doors are located in the center part of the house. The stairs from the first to the second floor seem slightly out of level and askew. In the den, there is a ?"" wide gap between the ceiling molding and fireplace. There is also a tapered gap between the wall molding and fireplace. The gap between the wall and fireplace is ?"" at the bottom of the wall and æ"" at the top of the wall. I measured the verticality of the fireplace with a plumb bob. The face of the fireplace leans inward 1/8"" in 3'. Although the gap between the wall molding and fireplace seems to indicate that the fireplace leans outward, it actually leans inward slightly. The discrepancy can be explained by the fact that the º round molding strip is not plumb. There is a vertical hairline crack in the front living room wall. It is goes from the upper left corner of the window to the ceiling and from the windowsill down to the floor. Exterior On the left side of the front elevation, there is a 1/8"" wide crack between the window frame and steel lintel angle. The crack is in the upper right corner of the window and is opposite the crack on the inside wall. On the rear elevation, there is a v-shaped step crack in the top of the brick veneer wall where the storage ell joins onto the main house. The crack starts at the upper left corner of the ell and angles downward to the main house. The crack is about 3/16"" wide at the upper left corner and 1/16"" wide at the main house. There is also a 1/64"" wide step crack in the base of the brick veneer on the main house, where the ell joins the main house. The crack starts about 3-4' up on the wall and angles down to the ground. The exterior wall on the left side of the house where the fireplace is located leans outward ?"" in 12'. Crawlspace The ground in the crawlspace was dry during my visits. Part of the ground is covered with a polyethylene vapor barrier. A corrugated plastic drainpipe has been recently installed along the front and left foundation walls. The drain is in a shallow trench filled with crushed stone. The pipe does not appear to slope uniformly. It is likely that water will collect in low places in the drain. There is a low area under the front foyer. The drain probably does not remove water that collects in this area. There are water stains on some of the piers, 3""-4"" up from the ground, indicating that water has ponded around the piers. In addition, one of the piers is not plumb. It may have been moved around by swelling and shrinking of the soil, as the moisture content changed. The floor joists have some mildew discoloration but are in sound condition. The discoloration indicates that the moisture level in the crawlspace was somewhat high at one time. The sill bands seem to be in almost new condition, as though they were recently replaced. The main girder in the center of the house is also in very good condition. I did not observe any rot or moisture damage in the floor framing. The piers are generally in good condition. Almost all of them are plumb and centered under the girders. The fireplace foundation seemed to be in good alignment, and I did not observe any cracks. There is a girder (2 - 2 x 12ís) under the door leading from the laundry room to the kitchen. The girder spans about 12' overall, but there is a masonry pier in the center of the span, so the effective span is 6'. Because of the size of the girder and the short span, there is hardly any deflection in the floor at this location. The 2 x 10 floor joists under the kitchen span about 13'. They are in good condition, but they sag excessively. There is a significant amount of weight on the joists from the ducts, pipes, and wires that are hanging from them. Most of the weight comes from the sheetmetal ducts and fiberglass insulation that is wrapped around the ducts. Normally, fiberglass insulation is lightweight, but in this case, it is somewhat heavy because it has absorbed moisture from the surrounding air. Four girders under the front foyer extend from the front of the house to the main girder in the center of the house. The girders support the walls around the foyer and the stairs. Three of these girders do not have piers under them where they attach to the main girder. They are just supported on the girder ledger strip. Three of the girders have piers at midspans; one spans the entire distance without any intermediate support. On the left side of the foyer, new joists have been sistered onto the sides of the old joists. The ends of the old joists along the front wall were cut. They no longer extend to the sill band. The old joists were cut in order to install a new sill band on the foundation wall at the front entrance. Pressure treated lumber was used. Probably the original sill band had rotted due to water that seeped in around the front entryway. The tops of the floor joists under the front foyer have been trimmed to accommodate the mortar bed for the slate tiles in the foyer. | Top | Table of Contents | FINDINGS AND CONCLUSIONS Appendix B and Appendix D contain information from soil survey maps of Mecklenburg County. The maps were published by the United States Department of Agriculture, Soil Conservation Service (SCS). They indicate that the soils where your house is located are MkB soils. The surface layer typically consists of sandy loam about 7"" thick. The subsoil is clay 27"" thick, and the underlying material is clay loam 45"" thick. Below this, to a depth of 65"", it is loam. The soil has slow permeability. The plasticity index of the clay ranges from 20-45, indicating a moderate shrink-swell potential. In some areas, the soil has been altered, and is covered with more than 20"" of fill. My interpretation of this information is that the soil is satisfactory to build on, but precautions must be taken. The plasticity index is high enough to cause shrinking and swelling problems if the soil is allowed to go through cycles of being wet and dry. The shrinking and swelling forces can cause cracks in walls and unevenness in floors. In addition, there is a potential for settlement where fill material exists. Usually, filled land is not as firmly consolidated as native soil. The loads on the piers and footings are highest in the middle third of the house, because this is where the bathrooms, stairs, and the majority of the interior walls are located. When the house was built, the footings under the piers in this area were probably not oversized to accommodate the higher loads. Normally, the bearing capacity of the soil is high enough so it does not matter. In your case, however, it is possible that the soil under the house contains fill material. The bearing capacity of the fill sometimes is not very high. If so, the soil will tend to compress more where there are higher loads. This may account for why the center part of the house seems low. The hump in the kitchen floor is caused by the difference in the way the floor by the laundry room is supported and the kitchen floor is supported. The 4 x 12 girder under the door to the laundry room is not deflecting, while the 2 x 10 joists under the kitchen floor are deflecting (sagging) a lot. The joists under the kitchen floor sag excessively for three reasons: (1) the 13' span is somewhat long, (2) they are supporting heavy mechanical equipment, and (3) creep deformation. Wood that is overstressed for long periods with sustained loads such as mechanical equipment will seriously deform. Wood will retain its springiness under a short-term load and bounce back into position when the load is removed. However, wood loses its springiness under a long-term load and bows permanently. The phenomenon is exacerbated when moisture is present. In my opinion, creep deformation is the major cause of the excessive sag in the floor. The girders and joists under the front foyer support slate tiles, a mortar bed, two-story walls, and the stairs. There is a lot of weight on the joists and girders. According to my measurements, the low point in the foyer is located 5' to the right of the wall between the living room and front foyer. This point is over the girder that does not have an intermediate support. In addition, a header is attached to this girder (see Crawlspace Plan in Appendix C). The girder is deflecting more than the adjacent girders because of the heavy floor loads and lack of intermediate support. This is why the floor slopes toward this point. The lack of proper support is also the cause of the stairs being slightly askew. The ?"" gap between the floor and front wall in the foyer is probably due to the new joists not being as wide as the old joists. In photo 11, it can be seen that the bottoms of the old joists are about ?"" lower than the bottoms of the new joists. When the new sill band and joists were installed, the old joists probably slipped down and were never raised back up to the correct position. The gap seems too wide to attribute to shrinkage of the new joists, but this could be the cause or could have contributed to the problem. While the new foundation drain apparently is working to some extent and has dried out the ground in the crawlspace, it was not installed very well. I am concerned that water can still pond around the piers under the front foyer and cause the soil to expand. When it dries out, the soil will contract. The swelling and shrinking action can cause the piers in this area to move around. It is important to keep water out of the soil around the piers. Movement of the piers probably caused some of the unevenness in the floor in the front foyer. The molding strip not being vertical can explain most of the v-shaped gap between the fireplace and wall. The ?"" gap between the fireplace and ceiling is harder to explain. On the exterior side, the brickwork leans outward slightly. On the interior side, the brickwork leans inward slightly. No perceptible movement has occurred in the fireplace foundation. All and all, the evidence does not conclusively point toward the wall leaning out more than normal (?"" in 12' is within normal tolerances), or the footing under the fireplace tipping. In my opinion, the gaps are partly caused by the center of house being somewhat low in relation to the outside walls. The crack between the window frame and steel lintel angle was probably caused slippage of the wall framing when the rotted sill band in this area was replaced. The brick veneer is supported on the foundation, while the window frame is supported on the sill band. Since there are no cracks in the brick veneer around the window, it is unlikely that the foundation settled. Since the crack in the brick veneer on the rear elevation is new, it probably was not caused by settlement. It is more likely that it was caused by the soil shrinking as a result of the new foundation drain that you had installed. As long as the moisture content of the soil remains stable, the crack probably will not get any worse. The crack is not wide enough at present to be a structural concern. | Top | Table of Contents | RECOMMENDATIONS The foundation drain should be reinstalled so that it has a constant pitch back to the sump pump. The drain should be installed in such a way that it drains the low area under the front foyer. Alternatively, fill can be placed in the low area. A pier should be added under the midspan of the girder that is located 5' to the right of the wall between the living room and foyer. Piers should also be added where the girders that run from front to back intersect the main girder in the center of the house. The joists in the front foyer need to be raised up ?"" or so to get them back into their original position and close the gap between the floor and wall. A drop beam should be installed under the midspans of the joists under the kitchen floor. The floor sheathing should then be removed and the tops of the floor joists shimmed with 2 x 4ís to create a level floor. Alternatively, it may be possible to leave the present floor sheathing in place and install a leveling compound over the surface of the floor. Some of the sag can probably be removed by jacking up the floor after the drop beam is in place. I am not too optimistic that this can be done successfully, however, because I think the joists have taken on a permanent set. At the same time this work is done, new ductwork should be installed. A floor level survey should be performed to determine the elevations of the entire first floor. Using the elevations as a guide, the first floor should be jacked up and shimmed to make it level. The jacking and shimming should be done after the new piers and drop beams are in place. The width of the crack in the brick veneer in the rear elevation should be monitored for a period to ensure that no more foundation movement is occurring. Once it ascertained that the movement has stopped, the crack should be repointed with mortar. In the meantime, the crack should be filled with resilient caulk to keep water out. | Top | Table of Contents | ESTIMATED COSTS Item Cost Reinstall the foundation drain $1,500.00 Add four piers under the girders in center of house $3,000.00 Raise the floor in the front foyer $1,500.00 Install a drop beam under the kitchen floor. Relevel the floor. Relocate ducts. $3,000.00 Perform a floor level survey $500.00 Jack up and shim the entire first floor $2,500.00 Total Cost $12,000.00 | 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. Wilson 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. | Top | Table of Contents | William A. Stanton, P.E. | Top | Table of Contents | | Structural Inspections | Residential & Commercial Services |