Included in our report are our visual observations, recommendations for follow-up evaluation, and conceptual repair recommendations.

Transcription

1 Ms. Pamela J. Irwin Community Management Associates 384 Ralph McGill Blvd Atlanta, GA Re: Phase I Condition Assessment Central City Condominiums Pool Deck Atlanta, Georgia Walter P Moore Project No. D Dear Pamela: Walter P Moore has completed a Phase I limited visual condition assessment of the pool deck structure associated with the Central City Condominiums located in Atlanta, Georgia. Our evaluation included review of the available construction documentation, limited visual review of the pool deck surface, crawl space beneath the pool deck, and concrete members supporting the pool deck area. This work was performed in accordance with our proposal dated April 11, Included in our report are our visual observations, recommendations for follow-up evaluation, and conceptual repair recommendations. Background The Central City Condominiums and associated pool deck (Photo 1) were constructed circa 2005 and are located in Atlanta, Georgia. The pool deck is located on the roof of the parking structure, and consists of composite metal deck supported on concrete masonry walls, which are in turn supported by a cast-in-place post-tensioned two-way concrete slab and cast-in-place concrete columns. We understand that residents and facility personnel have observed signs of deterioration such as concrete cracks in the pool deck surface and basin walls, and leaks in the structural slab soffit in the past. Scope of Work The evaluation was divided into two components. The scope of each component is detailed below: 1. Document Review: Perform a cursory review of the available construction documentation to develop an overall familiarity with the construction of the garage and pool deck structure. Our review of documents was limited to those aspects of the construction which may have a bearing on the elements under study. 2. Visual Observations: Perform an on-site visual observation of the pool deck surface, crawl space, and supporting concrete members to develop an overall familiarity with the PE AC H TR E E S TR E E T, NE 40 0 C O L O N Y S Q UA RE, S UI T E A TL A N TA, G E O R G IA P HO NE : F AX : W WW.W AL TE R P M O O RE. C O M

2 Page 2 of 9 construction, observe typical distress conditions and to evaluate probable causes behind the existing distress conditions. This report describes the existing conditions, field observations, and findings for each component of the evaluation. Document Review Walter P Moore had access to and reviewed the following documentation: Record Construction Drawings, Central City Condominiums, Lord Aeck Sargent Architecture, Pruitt Eberly Stone Structural Engineers, dated July 5, 2005 Pool Deck Ventilation Modifications, Central City Condominiums, Mayweather Enterprise, Inc., dated February 19, 2014 Record Construction Drawings Based on the Record Construction Drawings by Lord Aeck Sargent and Pruitt Eberly Stone, the Central City Condominiums were constructed circa The garage roof which supports the pool deck consists of a cast-in-place post-tensioned concrete two-way slab supported on cast-in-place concrete columns and cast-in-place concrete spread footings. The garage roof depresses 6 inches about the perimeter of the pool deck area. The slab soffit depresses an additional amount in the pool basin area, but the dimension of this depression is not indicated on the drawings. Additionally, the drawings indicate that the pool basin slab was to be mildly reinforced rather than posttensioned. The Record Construction Drawings appear to indicate that design of the pool deck and slab were to be a deferred submittal. As such, the Record Construction Drawings by Lord Aeck Sargent and Pruitt Eberly Stone do not provide details or sections showing the construction of the pool deck. Pool deck and slab drawings related to pool construction were not available for our review. Pool Deck Ventilation Modification Drawings Based on the Pool Deck Ventilation Modification Drawings by Mayweather Enterprise, the crawl space beneath the pool deck was modified circa 2014 in order to add three shutter mounted exhaust fans on the north side. However, the layout of concrete masonry partition walls depicted on the Proposed Floor Plan on Sheet A-3 does not appear to be consistent with the as-built condition. Visual Observations Representatives of Walter P Moore visited the site on May 10, 2017 to develop an overall familiarity with the pool deck structure and to perform a limited visual evaluation of the structural and nonstructural distress in the pool deck. Our visual observations are summarized in the following sections.

3 Page 3 of 9 Pool Deck Surface & Pool Basin Our visual observations pertaining to the pool deck surface and pool basin are as follows: Separation between the pool coping and adjacent slab of up to 3/8 inch was observed on the south side of the pool basin, and separation up to 1/8 inch was observed on the east side of the basin (Photo 2-4). Separation between the pool basin wall and pool coping of up to 1/4 inch was observed on the north side of the pool basin, and separation of up to 1/8 inch was observed on the east and west sides of the basin (Photo 5-7). Joints between pool coping and the adjacent slab appear to have been grouted rather than sealed with a chemically resistant flexible sealant material. The existing grout was typically cracked or failed in the areas where separation between the coping and slab was observed. Horizontal cracks of approximately to inch were observed at several locations in the pool basin walls (Photo 8-9). Cracks in the concrete floor surface of approximately 0.01 to inch were observed throughout the pool deck area, especially adjacent to the trench drain and the corners of the pool basin (Photo 10-11). Cracks in the pool coping tiles of approximately inch were observed on the north and west sides of the pool basin (Photo 12). Deteriorated pool deck coating was observed throughout the pool deck (Photo 13). An area of the pool deck adjacent to the north side of the pool basin appears to have been repaired in the past (Photo 14). Crawl Space Our visual observations pertaining to the crawl space beneath the pool deck are as follows: The pool deck construction appears to consist of composite metal deck welded to steel angles at the bearing end, which are attached to concrete masonry walls. The walls are supported by a concrete slab (garage roof). Evidence of water infiltration was visually apparent on the concrete masonry walls at several locations throughout the crawl space (Photo 15). The shelf angles on top of the concrete masonry walls as well as the composite metal deck soffit were typically corroded at the bearing ends. Section loss in the angles was visibly apparent at several locations (Photo 16). Evidence of corrosion was observed in the soffit of the composite metal deck at isolated locations (Photo 17). Standing water was observed at several locations on the north and east sides of the crawl space (Photo 18). The existing coating on the concrete masonry walls and concrete floor slab has deteriorated in several areas of the crawl space (Photo 19).

4 Page 4 of 9 Concrete Members Our visual observations pertaining to the concrete slab soffit and columns as viewed from the garage beneath the pool deck are as follows: It appears that weep holes have been drilled near the top of the vertical face of the pool basin slab depression (Photo 20). Many of these weep holes are partially or completely obstructed by efflorescence (Photo 21). Horizontal cracks in the vertical face of the pool basin slab depression were observed on the north, east, and south sides of the slab depression. Evidence of water leakage in the form of efflorescence was observed in several of these cracks (Photo 22). Cracks in the slab soffit in the depressed pool basin area were observed at isolated locations (Photo 23). PT anchor pockets were observed on the exterior face of the concrete slab (Photo 24) Analysis & Discussion The distress observed in the Central City Condominiums pool deck structure appears to be primarily the result of differential thermal movement and water infiltration. Both rain and pool water appear to be infiltrating through the pool deck surface due to a combination of the following factors: 1. Gaps about the perimeter of the pool basin. Separation between the pool coping and adjacent slab, or between the basin wall and coping, has allowed water to infiltrate into the space between the pool basin and adjacent concrete masonry wall. Causes of the observed separation are discussed in the sections below. 2. Deteriorated pool deck coating. Pool deck coatings serve to create a waterproof barrier at the surface of the pool deck. Over time, these coatings tend to wear and may begin to debond from the substrate, allowing water to infiltrate into the crawl space. 3. Cracks in the pool deck surface. Cracks in the concrete pool deck surface provide a direct path for water to infiltrate to the steel elements below. 4. Deteriorated CMU wall and structural slab coating. The waterproof coating on the walls and slab in the crawl space beneath the pool deck serves to prevent water from infiltrating into the concrete members below. This coating has deteriorated in many areas, providing a path for moisture infiltration into the structural slab. Distress conditions which have, or may arise from water infiltration due to these factors are discussed in the following sections.

5 Page 5 of 9 Thermal Movement Separation between the pool coping and adjacent slab, or between the basin wall and coping, were observed about the perimeter of the pool basin. This separation appears to be the result of differential thermal movement between the pool deck slab, basin wall, and structural slab. These elements will tend to experience thermal movement due to cycles of heating and cooling, expanding as temperatures rise and contracting as temperatures fall. Furthermore, these elements will tend to experience different levels of thermal expansion and contraction due to differences in materials and exposure. The joints between the pool deck slab, pool coping, and basin wall were observed to be grouted. Grouted joints are quite rigid and tend to restrain thermal movement. The restrained movement induces tensile forces in the grout, eventually leading to grout cracking or failure and the observed separation. Gaps between the pool coping and adjacent slab, and between the basin wall and coping, should be sealed with a chemically resistant flexible joint sealant material in order to accommodate thermal movement and mitigate moisture infiltration. Pool Deck Surface Water which infiltrates through the pool deck surface will eventually reach the steel elements below, such as metal deck on which the concrete is cast, steel angles at metal deck bearing ends, and embedded steel reinforcement. Prolonged exposure to moisture will lead to the initiation of corrosion in these steel elements, as was observed in both the metal deck and steel angles. Additionally, the presence of chloride ions in concrete tends to result in initiation and acceleration of steel corrosion. It is likely that water which infiltrates the concrete will be chloride-laden due to the presence of chlorine ions used to kill bacteria in the pool water. During the corrosion process, steel elements may experience a localized volumetric increase of 3 to 7 times that of its original cross section. The tensile stresses generated by this increase in cross section will tend to manifest in the surrounding concrete as cracks, delaminations, and spalls in the future. Corrosion and steel section loss in the metal deck and steel angles were typically observed at bearing ends. This corrosion and section loss will continue if left unaddressed and may lead to loss of structural capacity. Corrosion in the vicinity of the connections between the steel angle and metal deck, or steel angle and supporting concrete masonry wall, may cause the connections to break, leading to structural instability. Corrosion of the steel angles and metal deck at bearing ends may pose a life safety hazard if left unaddressed. Repairs of the steel angle and metal deck corrosion should be implemented with priority. Deteriorated pool deck coating should also be replaced in order to mitigate moisture infiltration and corrosion related distress in the future.

6 Page 6 of 9 Crawl Space and Structural Slab Water which infiltrates through the pool deck slab tends to pond in several areas of the crawl space for prolonged periods of time. Since the coating on the concrete masonry walls and structural slab has deteriorated in many areas, this standing water eventually infiltrates into the concrete slab or through horizontal-to-vertical joints at the base of the walls. Prolonged exposure to moisture will result in corrosion of the embedded reinforcing steel in the structural slab, which has likely led to the cracking observed in the vertical face of the slab depression, as well as in the slab soffit. Once the concrete has cracked, water is able to migrate more easily through the slab, eventually exiting through the crack and resulting in the observed efflorescence. Mitigation of corrosion in embedded reinforcing steel is necessary in order to prevent concrete distress, steel section loss, and potential loss of structural capacity in the future. Additional testing should be performed in order to understand the current extents and severity of corrosion related distress in the steel reinforcement. Post-Tensioned (PT) Anchors Adjacent to Pool Slab Although the Record Construction Drawings indicate that the pool structural slab was to be mildly reinforced, the surrounding slabs were to be post-tensioned (PT). Additionally, the Record Construction Drawings indicate that PT anchors exist about the perimeter of the pool slab depression. Furthermore, it is likely that water which has infiltrated the concrete slab may have also reached the PT anchors and initiated corrosion. PT tendons and anchors are essential structural components which must be maintained and protected from moisture in order to ensure adequate load carrying capacity of the slab. Even small amounts of corrosion in the PT anchors or PT tendons may result in anchorage failures and/or tendon breaks which leads to a partial loss of structural capacity in the future. Additional investigation including non-destructive testing and exploratory openings in the structural slab should be performed in order to understand the location and condition of the PT anchors in the vicinity of the pool. Weep Hole Efflorescence In addition to migrating through the pool deck slab, water is also able to infiltrate into the space between the pool basin and adjacent concrete masonry wall through gaps between the pool coping and adjacent slab, as well as between the pool basin wall and coping. Based on our visual observations of the underside of the structural slab, it appears that weep holes have been installed to allow water to drain from this area. Since construction drawings of the pool deck area were not available, it is not known whether these weep holes were part of the original construction or were added at a later date. Many of these weep holes were observed to be clogged by efflorescence and should be cleaned periodically in order to allow drainage. A supplementary system to catch water draining from these weep holes may be installed to prevent leakage onto vehicles below.

7 Page 7 of 9 Conclusions Based on the results of our document review, visual observations, and analysis, the following conclusions can be drawn: The distress conditions observed onsite appear to be primarily the result of thermal movement between the pool basin wall, pool coping, and pool deck slab, as well as corrosion due to water infiltration; Corrosion may be accelerated due to the presence of chlorides ions to kill bacteria in the pool water; and Corrosion of both mild reinforcement and post-tensioning elements in the structural slab is likely and additional testing should be performed to understand the extents and severity of corrosion related distress. Conceptual Recommendations Based on the results of our document review, visual observations, analysis, and conclusions, we believe that additional investigation and testing is required in order to determine the nature and extents of structural distress in the pool deck area of the Central City Condominiums. Our conceptual recommendations for additional structural investigation and waterproofing repairs are described in the following sections. Additional Investigation: Our recommendations for additional investigation are as follows: Perform exploratory openings in the structural slab to review the condition of embedded steel reinforcement and post-tensioning elements (tendons and anchors); Perform laboratory materials testing including chloride ion content analysis to understand the chloride levels in the structural slab and how they may influence the likelihood of corrosion; and Perform non-destructive testing at selective locations on the structural slab soffit to understand the extents of mild-reinforcement corrosion related distress. Perform non-destructive testing at selective locations on the pool deck surface, crawl space, and slab soffit to confirm the as-built configuration of the pool deck surface to design the needed repair solutions; Structural Recommendations: The following recommendations for structural repairs should be implemented following the above recommended additional investigation. Our recommendations pertaining to the structural systems of the pool deck are as follows: Repair metal deck and steel angles Perform PT repairs, as needed based on Additional Evaluation recommended above.

8 Page 8 of 9 Waterproofing Recommendations: The following recommendations for waterproofing repairs should be implemented following the above recommended additional investigation. Our recommendations pertaining to the waterproofing systems throughout the pool deck are as follows: Replace the pool deck coating on the pool deck surface; Replace cracked pool coping tiles; Seal gaps between the pool coping and adjacent slab, and between the basin walls and coping, with a chemically resistant flexible joint sealant material; Replace the coating on the CMU walls and structural slab in the crawl space beneath the pool deck; Clean efflorescence from weep holes in the structural slab; and Install a drainage system beneath the weep holes to mitigate water leakage on vehicles below. Opinion of Probable Repair Costs Based on the unknown components related to the as-built construction of the pool deck and the need for additional structural evaluation and testing, we feel that an opinion of probable repair costs cannot be accurately projected at this time. An opinion of probable repair costs will be provided based on the results of additional investigation. Limitations This report has been prepared to assist Community Management Associates in understanding the nature and type of distress investigated in this limited pool deck review and determine a future course of action. Walter P Moore assessed specific issues relevant to the distress observed in the pool deck structure associated with the Central City Condominiums located in Atlanta, Georgia. Walter P Moore has no direct knowledge of, and offers no warranty regarding the condition of concealed construction or subsurface conditions beyond what was revealed in our review. Any comments regarding concealed construction or subsurface conditions are our professional opinion, based on engineering experience and judgment, and derived in accordance with current standard of care and professional practice. Various other non-structural, cosmetic and structural damage unrelated to this evaluation may have been observed throughout the structure, some of which are discussed in general in this report. However, a detailed inventory of all cosmetic, nonstructural and structural damage was beyond the scope of our evaluation. Comments in this report are not intended to be comprehensive but are representative of observed conditions. In this study, we did not include review of the design, review of concealed conditions, or detailed analysis to verify adequacy of the structure to carry the imposed loads and to check conformance to the applicable codes. Repair recommendations discussed herein are conceptual and will require additional engineering design for implementation. We have made every effort to reasonably present the various areas of concern identified during our site visits. If there are perceived omissions or misstatements in this report regarding the observations

9 Page 9 of 9 made, we ask that they be brought to our attention as soon as possible so that we have the opportunity to fully address them in a timely manner. This report has been prepared on behalf of, and for the exclusive use of, Community Management Associates in regards to distress in the pool deck structure associated with the Central City Condominiums in Atlanta, Georgia. This report and the findings contained herein shall not, in whole or in part, be disseminated or conveyed to any other party or used or relied upon by any other party, in whole or in part, without our prior written consent. We very much appreciate this opportunity to provide these services to you. Please do not hesitate to contact us if we can further assist you with the follow-up evaluation and development of repair documents for the distress conditions described in the following report. Sincerely, WALTER P. MOORE AND ASSOCIATES, INC. Joshua Caron Associate Diagnostics Group Sunil Puri, P.E. Principal Diagnostics Group

10 APPENDIX A PHOTOGRAPHS

11 Page A-1 of A-12 Photo 1. Overall view of the Central City Condominiums pool deck. Photo 2. Separation between pool coping and adjacent slab.

12 Page A-2 of A-12 Photo 3. Separation up to 3/8 inch on south side of the pool basin. Photo 4. Separation up to 1/8 inch on east side of the pool basin.

13 Page A-3 of A-12 Photo 5. Separation between the basin wall and pool coping. Photo 6. Separation up to 1/4 inch on the north side of the pool basin.

14 Page A-4 of A-12 Photo 7. Separation up to 1/8 inch on the east and west side of the pool basin. Photo 8. Cracking in the basin wall.

15 Page A-5 of A-12 Photo 9. Horizontal cracking up to inch in the basin wall. Photo 10. Typical pool deck floor slab cracking perpendicular to the trench drain.

16 Page A-6 of A-12 Photo 11. Typical pool deck floor slab cracking at basin corners. Photo 12. Typical pool coping tile cracking on the north and west side of the basin.

17 Page A-7 of A-12 Photo 13. Typical deteriorated pool deck coating. Photo 14. Previously repaired area of pool deck slab.

18 Page A-8 of A-12 Photo 15. Evidence of water infiltration on crawl space wall. Photo 16. Evidence of corrosion and section loss in steel angle and metal deck bearing end.

19 Page A-9 of A-12 Photo 17. Evidence of corrosion on metal deck soffit. Photo 18. Typical standing water in crawl space beneath pool deck.

20 Page A-10 of A-12 Photo 19. Typical deteriorated coating in crawl space. Photo 20. Typical weep holes in vertical face of slab depression beneath the pool basin.

21 Page A-11 of A-12 Photo 21. Clogged weep hole. Photo 22. Horizontal cracking on vertical face of the slab depression.

22 Page A-12 of A-12 Photo 23. Typical slab soffit cracking. Photo 24. PT anchor pockets visible from the exterior of the garage.