November 2, 2015 Melissa A. Malcolm Library Director Lapeer District Library 201 Village West Dr S Lapeer, MI 48446 RE: Structural Conditions Assessment of Current Lapeer District Schools Administration Building 250 Second Street, Lapeer, Michigan Dear Ms. Melissa Malcolm; It was a pleasure meeting with you and Ms. Jan Watz at 250 Second Street, Lapeer, Michigan on October 7, 2015. Thank you for coordinating the access to the building. The district staff were very helpful in the information and access they provided me to complete the evaluation of the building, including sets of drawings of the building s design and additions. For the purposes of this report, the building stretches in the north-south direction; the main door we entered is on the west elevation. Digital photographs taken of the building during the survey are included with this report. The original building was designed in 1951; only the mechanical plans were available of this portion of the building; although they provided a lot of insight into the structural system of the building. The original building footprint is a rectangle with a thin western projection for offices and entry into the original school building. The building is primarily a single story building, with a raised roof area for the original multipurpose room (the current board room). The roof over the original building is a gabled roof structure with a flat portion at the center that is dropped below the high point of the gabled sides. There is no basement; there are minimal crawl spaces or utility tunnels. In 1964, a north addition and a small extension to the west were constructed. The west addition now serves as the board room and storage closet spaces. In 2007, when the district repurposed the school for administration offices, a large renovation of the building took place. However, minimal changes were made to the overall building structure; most of the changes were with window/door systems and mechanical systems. Below is a description of the conditions observed with potential explanations for the distresses. A list of recommendations is also provided at the end of the report, given with a general sense of priority to the recommendations. Overall, the building structure is in good condition with few areas of concern. The building, from a structural engineering standpoint, could be repurposed as a library, with consideration given for loadings of the floors over the tunnels and crawl spaces.
The conditions assessment is visual in nature; destructive access to the structure was not obtained (finishes were not removed to verify the structure). Dropped ceiling tiles were not removed as original ceiling finishes were observed in the original building where the ceiling tiles were not installed. Only the structural system were evaluated on site. Hazardous materials, mechanical, life safety systems are not reviewed as part of this scope of work. Observations: The original building is simplistic in design with classrooms on the east and west sides of the building and a corridor between. The corridor is a non-load bearing wall constructed of concrete masonry units (CMU). Thin, horizontal cracking was observed in the CMU in the small closets in nearly each of the original classrooms. These closets are now furnace or storage rooms for the office use. The horizontal cracks in these interior walls infer that the bottom of the wall has settled downward. This settlement may have occurred shortly after construction of the building or many years later. Some of the cracks have been infilled with a sealant (caulk). This sealant should be removed and all of the cracks should be repointed. If the cracks reform, we will know that the settlement is still active and can address the situation with appropriate measures. In the Men's and Women's Bathrooms in the original building there is a significant horizontal crack along the bottom of the tile walls that create the plumbing chase between the restrooms. These walls are most likely undermined from plumbing piping, water leaks, or insufficient structure. The cracks should be repointed, and the potential for mud jacking the slab may be worth more investigation. Again, if the cracks do not reform, the settlement is old, and no further work is required. In the plumbing chase, the wall construction was exposed to be the 4" clay tile observed on the bathroom walls with a nominal 4" CMU structural backup. The northern wall of the plumbing chase is a bearing wall. The wood rafters, spanning north-south, are lapped over this wall. The roof system of the original building is constructed with nominal 2x rafters that span north-south to either masonry bearing walls as observed in the plumbing chase, or beams that are spanning east-west, following the slope of the east and west sides of the roof. The beams are supported on the exterior walls and steel I columns on the interior. The 1964 addition roof structure is of open web steel joists spanning between the CMU bearing walls. Nearly all of the north wing walls are bearing walls. In the west wing, the storage closet and bathroom, ceiling tiles were exposed that may contain asbestos; a materials professional should be consulted on this. Water staining was observed in isolated areas on the ceiling tiles. Specifically, in the following rooms: Closet south of the Men's Room in the Original Building Center Corrridor, opposite of the East Entry Corridor Mail Room (Room just north of the East Entry Corridor) Lapeer School District Administration Building 250 Second Street Page 2 of 8 Structural Conditions Assessment Lapeer, Michigan November 2, 2015
Women's Room in the North Wing Conference Room in the North Wing (west interior room of the north side of the North Corridor) In the mechanical room, significant cracking and water staining was noted on the CMU walls, especially on the east and south walls of the room. There are vertical cracks in the south wall that align with the corners of the chimney on the other side of the wall. Cracking in the southern end of the eastern wall may be related to support of the masonry above the original opening to the crawl space on the opposite side of this wall. Storage items in this corner prevented a full evaluation, or even verification that the crawl space access was still present. Some cracking was observed in the current storage room, mainly where the 1964 western extension joins the original building. The joint between original and addition is cracked in both walls and floor. This is a typical condition where additions meet pre-existing structures. Relatively minimal cracking was observed in the 1964 addition walls in this area, especially in the western corners of this room. On the exterior, the brick veneer is in good condition mostly. There are small areas where mortar is missing or the brick is spalled. Most areas are near downspout locations. A steel plate has been installed at the base of the east wall at a downspout location. The brick is spalled at this location, full height of the wall. The steel plate may be a 'backsplash,' to protect the brick from further damage. The condition of the brick behind the plate is unknown. The brick in this area of this downspout will require replacement in the future. Several downspouts are discharging directly against the building. Vegetation was observed in the drainage system on the flat roof over the central corridor in the original building. The stone window sills are missing mortar in their joints; some have shifted; several have been replaced. Steel lintels over louver openings in the walls are beginning to corrode and rust jack the brick veneer. The lintels should be cleaned and painted; the mortar joints repointed. It is interesting to note that the brick has header courses every sixth course in both the original building and 1964 addition. The header courses, traditionally tie the individual wythes of brick masonry walls together by rotating the bricks in these header courses 90 degrees from the typical running bond. With a CMU structural backup, the header courses may be purely architectural detail as metal wall ties typically join the brick and CMU wythes together. Removal of the brick would be required to verify which condition was constructed. At the southeastern corner, the grade is sloping down toward the building here, and when combined with the overall slope of the grade, creates an area where rain and snow melt will pond. Vertical through brick cracking is occurring in the eastern "wing" of the southern wall. The brick is significantly spalling at the top of the wall. Two potential causes for these distresses are that the soils are being washed away from the water collecting in this area, or that the wing wall is insufficient to withstand the corner wind loads acting on this cantilevered wall portion of the wing. The vertical cracking may be a Lapeer School District Administration Building 250 Second Street Page 3 of 8 Structural Conditions Assessment Lapeer, Michigan November 2, 2015
result of wind loads acting on the cantilevered wall section, creating a negative bending situation that the brick cannot support, thus cracking as the tension stresses increase. With the assumed brick veneer on both sides of the 'wing' wall, the wall is a nominal 12 inches wide, leaving a mere 4 inches of structural backup. If the brick is built integral with the structural backup (assumed 4" CMU), if the brick is a structural element not just a veneer finish, the wind load resistance is much higher. It is recommended to repair the crack, improving the drainage and monitoring for recracking. If when the crack is repaired, the construction method of the wall can be verified, that knowledge can be applied to a proper final solution to prevent this crack from recurring. On the west elevation, south of the west wing of the building, there is a horizontal crack just above grade, just above the header course. This crack is unusual; potentially related to frost heave of the foundation below. The foundation system for the original building may be a poured concrete trench foundation. It is common for these foundations to have "mushrooming" or overflow at the top of the foundation pour. The mushroomed top create horizontal projections that the frost in the ground can act against, pushing the foundation up out of the ground. As the frost melts, the foundation may settle back down, creating the crack in the wall. The foundation in this area could be exposed on the exterior to verify this assumption. The crack should be repaired regardless to keep the structure weathertight. On the west elevation, there are four steel columns supporting the roof overhang. The columns are all rusting at the base of the columns. The columns should be cleaned with a wire brush, inspected for significant deterioration, repaired if needed, and repainted. The brick above this roof overhang on the south elevation of the west wing is missing mortar, spalling, potentially shifting. The distress seems to be on horizontal lines, separated by five courses of brick. The metal brick ties connecting the brick to the structural CMU wythe behind may be corroding and causing this distress. Removal of the bricks in this area to properly address this concern is recommended. Simple repointing and repair will only be a temporary fix if it is the corrosion of the metal ties causing the distress. Similar brick movements and distresses were observed in the upper courses of brick on the tall chimney stack. Up to 18 courses of the outer wythe of brick may require rebuilding on at least two sides of the chimney, if not all four. On the north addition, the CMU foundation wall is exposed at the window locations. With no brick veneer at the window locations, the exterior edge of the wall is inset of the exterior edge of the CMU foundation wall. At least one of these locations, the cores of the CMU are exposed; they are ungrouted and allowing moisture into the foundation wall system. It is surprising that no distresses were noted with this situation as of yet. The cores should be cleaned, grouted solid, and ideally capped to prevent water from entering the wall structure. Lapeer School District Administration Building 250 Second Street Page 4 of 8 Structural Conditions Assessment Lapeer, Michigan November 2, 2015
Analysis: The structural analysis of the system is limited to the first floor system, as that is the only area that would change loading criteria if the building is repurposed as a library. The roof and walls are still supporting the same wind and snow loads regardless of the use of the building. The structural concrete slab over the crawl space in the original building (below the east entry corridor mainly) is adequate for 100psf live load, based on its original and current use only. Building codes have traditionally required first floor corridors of schools to safely support 100psf live load (people, furniture, movable loads). If structural drawings showing the steel reinforcement sizes and spacings are located, a safe allowable live load of the concrete slab over the crawl space can be provided. The structural concrete slab over the utility tunnels in the north addition are adequate to safely support 100psf if constructed as shown on the design drawings. Stacks of books should be kept free of the perimeter of this addition, off of the utility tunnel slab. The remaining floor areas are concrete slabs on grade. The soil below the slabs is unknown (its stiffness); this is required to complete any sort of numerical analysis of the concrete slab. The thickness of the slab is also unknown; it is assumed to be a 4-inch thick slab on grade. Traditionally, for 100psf, a 4-inch concrete slab on grade is adequate. For a 150psf, as required for library loads in current codes, traditionally a 5-inch thick concrete slab on grade is recommended. Some settlement was observed in the building, mainly at unsupported (as per the mechanical drawings) masonry walls. The sustained weight of the masonry, combined with the insufficient support (the slabs should have been thickened below these walls) leads to the settlement observed. Even if the interior walls are a minimal 4-inch nominal masonry, the direct pressure on the slab and soil below the wall is greater than 150psf. Therefore, if the relatively minor settlement cracks observed in the closet walls are the greatest distress observed under the constant weight of the masonry wall, the existing concrete slab on grade should be sufficient to support safely the 150psf code required live load for library use. As discussed above, some of the masonry walls are bearing walls for the roof structure. In other areas, such as the main corridor walls in the original building, are non-bearing walls. However, a portion of these walls are providing lateral restraint from wind loading on the building. If the desire is to remove nearly all of the interior walls to create an open space, a structural engineer should be involved in the design process to ensure the lateral stability of the building is not compromised in this effort. Lapeer School District Administration Building 250 Second Street Page 5 of 8 Structural Conditions Assessment Lapeer, Michigan November 2, 2015
Recommendations: As stated above, the building, structurally, can support the library floor loadings. The following recommendations are given to ensure the building is maintained. The distresses as noted create a baseline from which they can be monitored for further movement. At minimum, these distresses should be reviewed on an annual basis until they are repaired properly. The greatest concern is the exterior masonry. However, most of this is general repair of a 50+ year old building. The recommendations provided below are schematic in nature; further review, research, analysis and/or design may be required. They are provided as at a minimal, practical, and ideal level, with the later levels building upon the previous. Minimal Repair: 1) Verify the assumed 4-inch thickness of the concrete slab on grades. If the thickness is less than 4-inches, consult with a professional structural engineer before proceeding with any further design of the building as a library. 2) Monitor the thin, horizontal cracking was observed in the CMU in the small closets in nearly each of the original classrooms. 3) Tuckpoint the significant horizontal crack along the bottom of the tile walls that create the plumbing chase between the Men's and Women's Bathrooms in the original building. 4) Determine source of water staining was observed in isolated areas on the ceiling tiles; verify it is old staining or repair as required. 5) Remove storage items in the southeast corner of the mechanical room to verify the crawl space access was still present. Verify the condition of the opening, and the underside of the concrete slab in the crawl space. 6) Monitor the minimal cracking observed in the 1964 addition walls, especially in the western corners of the storage room (old kitchen). 7) Maintain and direct water away from the building with the gutter and downspout systems. 8) Repoint the brick masonry where mortar is missing or cracked to keep the building weathertight. 9) Repair the crack on the east end of the south wall, improve the grading in this area, and monitoring for recracking. a. If when the crack is repaired, the construction method of the wall can be verified, that knowledge can be applied to a proper final solution to prevent this crack from recurring. 10) On the west elevation, south of the west wing of the building, tuckpoint the crack to keep the structure weathertight. 11) On the west elevation, clean, re-inspect, reinforce if required, and repaint the four steel columns supporting the roof overhang. 12) Remove a select area of the brick above the western roof overhang on the south elevation of the west wing to verify wall construction detailing and to properly address the distress. Lapeer School District Administration Building 250 Second Street Page 6 of 8 Structural Conditions Assessment Lapeer, Michigan November 2, 2015
13) Up to 18 courses of the outer wythe of brick may require rebuilding on at least two sides of the chimney, if not all four. 14) On the north addition, at the exposed CMU at the window locations; the cores should be cleaned and grouted solid. Practical Repair: 15) Repoint the thin, horizontal cracking observed in the CMU in the small closets in nearly each of the original classrooms. Remove the caulk in isolated areas and re-create the mortar bond between the CMU courses. 16) Investigate further the potential for underpinning or mud jacking the concrete slab in the Men's and Women's Bathrooms in the original building in the areas that are supporting the interior masonry walls. 17) Consult a materials professional on original ceiling tiles that were exposed that may contain asbestos. 18) Repoint the vertical cracks in the south wall of the Mechanical Room that align with the corners of the chimney on the other side of the wall. 19) Repoint the cracks in the east wall of the Mechanical Room. 20) Repoint, reset or repair the stone window sills as required at each location to make the walls weathertight. 21) Clean and repaint the exposed steel lintels over louver openings in the walls. Ideal Repair: 22) Remove the steel plate that may be a 'backsplash' to protect the brick from further damage from the downspout. Inspect and repair the brick masonry as required. 23) Removal of the brick veneer is required to verify if the wythes of masonry were built with header courses or metal ties. Corrosion of the metal ties may be a cause of cracking in the masonry. 24) Expose the foundation on the west elevation, south of the west wing of the building to verify if frost heave is a cause of the horizontal crack in this area. 25) On the north addition, at the exposed CMU at the window locations; cap and/or flash the cores to prevent water from entering the wall structure. 26) If structural drawings showing the steel reinforcement sizes and spacings are located, a safe allowable live load of the concrete slab over the crawl space can be provided. 27) Keep stacks of books free of the perimeter of the North Addition, off of the utility tunnel slabs, unless these slabs are reinforced to achieve the 150psf safe allowable live load capacity. 28) If the desire is to remove nearly all of the interior walls to create an open space, a structural engineer should be involved in the design process to ensure the lateral stability of the building is not compromised in this effort. Lapeer School District Administration Building 250 Second Street Page 7 of 8 Structural Conditions Assessment Lapeer, Michigan November 2, 2015
Thank you for the opportunity to assist on this project. Please let me know if you have any questions or concerns. I wish you the best of luck in your decision to repurpose this building or build new. Respectfully, Cheryl Early, P.E. Associate Engineer Enclosure cc: Ms. Janet Watz, Board Chair, Lapeer District Library (via email) Lapeer School District Administration Building 250 Second Street Page 8 of 8 Structural Conditions Assessment Lapeer, Michigan November 2, 2015