Eidem Farm Brooklyn Park, MN

Transcription

1 Eidem Farm Brooklyn Park, MN East Farm House Structural Condition Assessment Prepared By P O R T L A N D A V E N U E S O U T H, S U I T E M I N N E A P O L I S, M I N N E S O T A P H O N E : F A X : Project Number August 13, 2015

2 August 13, 2015 Mary Pat Black City of Brooklyn Park Recreation & Parks Department th Avenue North Brooklyn Park, MN Re: Historic Eidem Farm Eats Farm House Structural Condition Assessment CDG Project Dear Mary Pat, We have completed the Structural Condition Assessment for this project as proposed. This report summarizes our evaluation procedures along with our observations, conclusions regarding probable causes of the structural deterioration, and recommendations for repairs. The services performed in evaluating the house structure and in preparing this report have been in accordance with the level of skill and care normally used for this type of project. The conclusions and recommendations discussed in this report are our best professional opinions based on our knowledge of current design and repair of this type of building. No warranties are expressed or implied. It has been a pleasure to perform this service for you. If you have any questions, or if we can be of further assistance, please feel free to call. Very truly yours, Collaborative Design Group Craig Milkert Principal I hereby certify that this plan, specification or report was prepared by me or under my direct supervision, and that I am a duly Licensed Engineer under the laws of the State of Minnesota. Date 8/13/2015 Craig Milkert, PE License #18360

3 TABLE OF CONTENTS EXECUTIVE SUMMARY... 1 INTRODUCTION... 2 SCOPE OF REPORT... 2 Review of Documents... 2 Discussion with City Staff... 2 Observations... 2 DISCUSSION AND CONCLUSIONS Discussion Recommendations... 13

4 EXECUTIVE SUMMARY This summary is intended to provide a brief overview of our study. The entire report must be read to understand the full content of our observations and recommendations. This study focused on the structural condition of the East Farm House foundation. Based on our visual observations, the house foundation can be considered to be in average structural condition overall. It is obvious that some movement and deterioration has occurred over the course of more than 120 years; however, this movement does not appear to be currently detrimental to the structural integrity of the house. The 2001 Historic Structures Report indicates that some cracking and movement of the foundation was evident in 2001, likely due to unstable or sinking footings. The lack of significant cracking of the basement walls and 1 st level interior walls seems to indicate that the foundation movement is currently insignificant. Much of the original foundation has been replaced with cast in place concrete or CMU. The foundation under the north portion of the house appears to be the original limestone. This foundation under the north wall appears to be out of plumb and may not be fully supporting the floor and wall above. Because there are no significant signs of movement of the wall structure above, the foundation is not likely to be in eminent danger of failure. However, continued movement of this foundation could cause movement and cracking in the structure above. The only structural foundation condition that should be addressed is the movement of the north foundation wall. Although the movement appears to be minor, and may not be ongoing, further movement could create a condition of inadequate support for the floor and wall above. We recommend that this repair be completed within the next 2-3 years. Ongoing observations should be made no less than annually to monitor movement and stability. 1

5 INTRODUCTION The Eidem East Farm House is a two story building with a partial basement. The house was reported to have been constructed in the late 1890 s. The wood frame house has had significant restoration work completed to bring it to its current condition. The purpose of this study is to address the structural condition of the foundation of the house, and to assess whether there is ongoing settlement and need for remediation. SCOPE OF REPORT Review of Documents The Historic Structures Report dated January 2001 prepared by The 106 Group was reviewed. This report provided a thorough history of the property. The story and a half portion of the house was reported to have been built in 1890, with the two story addition constructed in the The foundation is constructed with a variety of materials, including limestone, brick, concrete block, and is covered on the exterior with a concrete skim coat. Vertical cracking is reported on the northeast corner of the house which may be a result of sinking footings. Other cracks were reported on the west and south sides of the house. The porch foundations had unstable or sinking footings that were evident due to the separation of the concrete floor from the house. The wood frame walls are balloon framed. Although the framing was not exposed for observation, there was no interior or exterior evidence that the framing was in poor condition. Discussion with City Staff The City staff responsible for maintaining the property reported that significant restoration work has occurred since the 2001 Historic Structures Report was completed. The house is currently being rented, which imposes certain requirements from the City for safety certification. Observations A site visit was performed on June 26, 2015 to observe the structural condition of the building. The following rating system was used in assessing the condition of the building components: Good: The building component is new, with no apparent defects. Average: The building component is able to perform its originally intended function in its current condition. Any defects are minor and do not affect the performance of the building component. Poor: The building component is unable to perform its originally intended function in its current condition. The component has major defects, but is repairable. 2

6 Unacceptable: The building component is unable to perform its originally intended function in its current condition, and cannot be economically repaired. Replacement of the building component is required. Visual observations of the building are recorded below. 1. South elevation of the house. The porch on the south and east sides of the house was an obvious addition. 3

7 2. East elevation of the house. Note the lack of gutters and downspouts along the roof edge. 3. North elevation of the house. 4

8 4. North portion of the west elevation of the house. A gutter and downspout has been installed din this area. 5. West elevation of the house. The white pipe shown is the discharge for the sump pump in the basement. 5

9 6. The original foundation of the house is constructed with limestone. Cement parging has been used to cover the exposed portions of the foundation walls. 7. Portions of the foundation walls have been replaced with concrete masonry units (CMU). Some cracking is evident in the foundation walls on all sides of the house. 6

10 8. The cracking in the foundation has been present for some time, as paint is evident on the inside edges of the cracks. 9. The cracking in the foundation has been present for some time, as paint is evident on the inside edges of the cracks. 7

11 10. The foundation wall on the north side of the house appears to be out of plumb, and leaning towards the north. 11. The wood sill that is bearing on the north foundation wall appears to be in average condition, but is not bearing fully on the stone foundation. 8

12 12. Cracks in the foundation are as large as ¾. The larger cracks are located under the porch on the south side of the house. 13. A basement is located under the middle of the two story portion of the house, as well as under the one and one half story portion. There is no basement under the north portion of the house, and access to the crawl space was not available. The original foundation walls were constructed with limestone, and are in average condition. 9

13 14. Some of the foundation walls were replaced with CMU, and are in average condition. 15. Some of the basement walls have been replaced with cast in place concrete, and are in average condition. 10

14 16. Some evidence of water seepage into the basement is present. 17. A sump pump has been installed due to the evident water seepage. 11

15 18. The walls on the 1 st level of the house appear to be in average condition, with only minor cracking evident. Non-Destructive Testing Thermal imaging testing was proposed as a possible test to be performed on this building. The intent of the testing was to investigate the locations of possible water intrusion. Thermal imaging is a technique used to measure the difference in temperatures in adjacent building materials. This difference in temperatures can be from a variety of reasons, including breaches in thermal insulation, or moisture within the building assembly. A wet building material will have a different thermal mass that a dry material, and will therefore show up as a different temperature in the thermal image. Thermal imaging was not performed as a part of this investigation because there was no indication that the water intrusion in the basement is causing deterioration to the foundation. DISCUSSION AND CONCLUSIONS Discussion This study focused on the structural condition of the foundation of the East Farm House. Based on the visual observations described above, the foundation can be considered to be in average structural condition overall. It is obvious that some movement and deterioration has occurred over the course of more than 120 years; however, this movement does not appear to be currently detrimental to the structural integrity of the house. 12

16 The 2001 Historic Structures Report indicates that some cracking and movement of the foundation was evident in 2001, likely due to unstable or sinking footings. The lack of significant cracking of the basement walls and 1 st level interior walls seems to indicate that the foundation movement is currently insignificant. Much of the original foundation has been replaced with cast in place concrete or CMU. The foundation under the north portion of the house appears to be the original limestone. This foundation under the north wall appears to be out of plumb and may not be fully supporting the floor and wall above. Because there are no significant signs of movement of the wall structure above, the foundation is not likely to be in eminent danger of failure. However, continued movement of this foundation could cause movement and cracking in the structure above. Movement in foundations typically occurs due to consolidation of the supporting soils, or from frost heave. Consolidation is due to compression from applied loads, or re-arrangement of the soil particles due to water or vibrations. It is not likely that applied loads are continuing to cause consolidation after all of these years. It is also not likely that the cracking is due to frost heave, as the soils are reported to be granular (which do not retain water and are frost resistant) on this site. The City staff has indicated that there were significant vibrations caused during the recent construction of the school across the road to the north. It is very possible that these large vibrations have caused the granular soils native to this area to consolidate at the north foundation wall, causing continued movement of the foundation. Another cause of the soil consolidation and settlement could be poor site drainage and excessive water collecting in the area due to lack of gutters and downspouts. The cracking of the foundation wall on all sides of the building does not appear to be causing any structural instability at this time. Future or continued movement of the north foundation wall may cause some gradual structural instability. Recommendations The only structural foundation condition that should be addressed is the movement of the north foundation wall. Although the movement appears to be minor, and may not be ongoing, further movement could create a condition of inadequate support for the floor and wall above. The recommended repair is to excavate the soils to expose the wall, and reconstruct the stone foundation wall in a plumb condition. The wall should be constructed tight to the underside of the wood sill, and support the entire width of the sill. A metal flashing or membrane should be installed on the underside of the wood sill prior to the installation of the mortar to prevent moisture transfer to the wood. The wall can be re-constructed in short lengths (approximately 4 ) so that temporary supports for the floor and wall above will not be required. We recommend that this repair be completed within the next 2-3 years. Ongoing observations should be made no less than annually to monitor movement and stability. Improvements to the grade to promote drainage away from the house and the installation of gutters and downspouts will help to prevent further soil consolidation. 13