Attachment 3 Structural Evaluation Report Linnincott Cottage.pdf

STRUCTURAL EVALUATION REPORT

LIPPINCOTT COTTAGE, JOHNSTOWN FLOOD

NATIONAL MEMORIAL

ST. MICHAEL, PA

PREPARED FOR:

National Park Service

US Department of the Interior

Historic Preservation Training Center

Contract No. P14PC00248

Order No. 140P2118F0350

December 23, 2016 Final Comprehensive Structural Evaluation Report

March 14, 2019

PREPARED BY:

NATIONAL PARK SERVICE

HISTORIC PRESERVATION TRAINING CENTER

STRUCTURAL EVALUATION REPORT

LIPPINCOTT COTTAGE

ST. MICHAEL, PA

I

TABLE OF CONTENTS

PAGE

REFERENCES .............................................................................................................................................. II

ABBREVIATIONS ........................................................................................................................................ II

1 EXECUTIVE SUMMARY

2 PROJECT DESCRIPTION

3 TASK SCOPE OF WORK

4 BACKGROUND

5 METHODOLOGY

6 COTTAGE DESCRIPTION

7 ASSUMPTIONS

8 BASEMENT DEFICIENCIES

9 FIRST FLOOR DEFICIENCIES

10 SECOND FLOOR DEFICIENCIES

11 THIRD FLOOR DEFICIENCIES

12 SUMMARY

APPENDICES

STRUCTURAL EVALUATION REPORT

II

REFERENCES

1. National Park Service Scope of Work for Architect & Engineer Service, Contract

P14PC00248, Order No. 140P2118F0350, Pre-Design Services for Lippincott Cottage, Johnstown National Memorial, Western Pennsylvania Parks, St. Michael, Pennsylvania, August 29, 2018

2. Historic Structures Report (HSR), South Fork Fishing & Hunting Club, Clubhouse, Brown Cottage, Moorhead Cottage, and Clubhouse Annex, Landmarks Design Associates, Architects, December 1993

3. Landmarks Design Associates Architects Drawings, November 30, 1992 o 21, Existing Conditions for the Moorhead Cottage, Basement Plan o 22, Existing Conditions for the Moorhead Cottage, First Floor Plan o 23, Existing Conditions for the Moorhead Cottage, Second Floor Plan o 24, Existing Conditions for the Moorhead Cottage, Third Floor Plan

4. Report of Asbestos Survey for Lippincott Cottage, Cottage Lane, St. Michael, Pennsylvania, Intertek Professional Service Industries Inc., May 30, 2018

ABBREVIATIONS

ASCE – American Society of Civil Engineers

B – Basement

Btwn - Between

E – Exterior

F – First Floor

Fb – Extreme Fiber stress in Bending

Fv – Extreme Fiber stress in Shear

HSR – Historic Structure Report

Incl. - Included

LVL – Laminated Veneer Lumber psf – pounds per square foot

S – Second Floor

T – Third Floor w/ - With

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1 EXECUTIVE SUMMARY 1

This report has been prepared in fulfillment of National Park Services Contract P14PC00248, 2 Order No. 140P2118F0350. 3

The cottage was constructed in 1885-1887 and is one of the original sixteen cottages built along 4 Lake Conemaugh by members of the South Fork Fishing and Hunting Club. Its owner, Jesse H. 5 Lippincott (1842-1894), was a wealthy businessman, investor, and stockholder who made his 6 fortune by founding the Rochester Tumbler Company, which was one of the largest glasswork 7 manufacturers in the world. Lippincott was also a director of several banks and one of the 8 original stockholders of the Bell Telephone Company. 9

After the Johnstown flood of 1889, Lippincott abandoned the lakeside cottage and sold it in 10 1910. It was subsequently purchased and resold a number of times It was last occupied in 11 1986. At that time, it was purchased by the National Trust for Historic Preservation, and in 2008 12 it was transferred to the National Park Service. 13

The cottage is currently in disrepair. The primary structural concerns are failure of the 14 foundation walls and decay of wooden components due to rainwater infiltration. The Historic 15 Structures Report indicates that the cottage was originally built without a perimeter foundation, 16 although chimneys and some piers support major loads. Some perimeter walls with foundations 17 have been built over time to control settlement. The National Park Service has implemented 18 emergency stabilization measures to secure the foundation, but an integrated repair has not 19 been implemented. 20

A site investigation was performed during October 9-10, 2018. The site investigation consisted 21 of structural inspection of accessible areas of the cottage by visual methods. Structural framing 22 was inspected in unfinished locations, and areas where plaster or flooring had been removed. 23 In general, areas covered with intact plaster or flooring was not inspected, with the exception of 24 two locations. In the following two locations, small holes were cut into intact plaster to enable 25 inspection of structural framing behind: 26

In the main staircase landing between the first and second floors, a small hole was cut to 27 enable inspection of the framing supporting the staircase landing 28

In Room 204, a small hole was cut in the ceiling plaster to enable inspection of the floor 29 framing, to assist in determination of the cause of the floor sagging in Room 304. 30

Observations and recommendations provided in this report are based on available 31 documentation plus observations made during the site visit. The scope of this report focuses on 32 structural adequacy of the cottage and repairs necessary to restore the cottage to safe and 33 useful condition. Neither strictly architectural concerns, nor mechanical, electrical, plumbing or 34 HVAC concerns are within the structural scope. 35

On December 11, 2018, Alpha met with NPS personnel to discuss the condition of the cottage 37 and NPS’s preferences in repair options. The Repair Options sections and Cost to Repair 38

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March 14, 2019 Page 2 of 68 tables presented in this report indicate NPS’s preferred repair method and their associated 1 costs, along with alternative costs. 2

The site investigation identified a number of overall conclusions, listed below: 3

Construction of the cottage on piers, rather than with continuous foundations under load-4 bearing walls leaves the cottage foundations vulnerable to damage due to lateral forces 5 (wind and seismic). Piecemeal repairs of foundation structures over time have not been 6 successful in correcting foundation problems. A redesign of the foundation is required to 7 achieve a lasting structure. 8

Visual inspection of the building wooden framing identified several areas where framing 9 has deteriorated. The deterioration is due to rot and decay primarily due to rainwater 10 leakage through the roof. Some decay of basement structures appears to be the result 11 of excessive humidity in the basement, but the high basement humidity is primarily due 12 to rainwater infiltration as well. 13

Wooden members that have been protected from moisture are in generally good 14 condition despite their age. 15

There are a few cases where framing design in the cottage differs from modern 16 conventional construction. In most cases, redesign of atypical framing is not warranted. 17 Except for cases where decay has occurred due to moisture or foundation settlement 18 has occurred, the wooden framing remains in good condition despite its age. In cases 19 where large areas need to be replaced, reconstruction should be made following a 20 modern design approach. In areas where only a few members require replacement, it is 21 acceptable to replace members in kind or with a more modern equivalent section. In 22 cases where atypical design appears to be failing (i.e. framing beneath the roof turret), 23 or where design may not meet future loading (i.e. hanging staircase landings), redesign 24 should be considered. 25

Significant structural repairs are necessary to make the cottage safe for continued use. 26 The required structural repairs are primarily associated with the cottage foundation and 27 structural components that have decayed due to moisture. In addition to the structural 28 repairs, architectural repairs (roofing, flooring, wall finishing, and asbestos abatement 29 work) and Mechanical, Electrical, and Plumbing (MEP) repairs (including HVAC) will be 30 required to utilize the cottage for routine use. These architectural and MEP repairs are 31 also necessary to halt rainwater intrusion that has caused the existing structural decay. 32

Once structural, architectural, and MEP repairs have been made, the cottage can be 33 used as a historic attraction, NPS office, or other use. 34

The May 2018 asbestos survey report is included as an appendix for reference. The asbestos 35 survey report was not prepared by Alpha nor under Alpha’s direction; therefore, we cannot 36 attest or confirm its results or completeness. 37

Sketches found in the appendices were created based on drawing provided by NPS. 38

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2 PROJECT DESCRIPTION 1

The historic Lippincott Cottage requires stabilization and repair. In order to develop project 2 funding requests, a Comprehensive Structural Evaluation Report is required to serve as 3 guidance in preparing future construction documents for the repair. 4

3 TASK SCOPE OF WORK 5

The “Project”, Structural Evaluation Report for Lippincott Cottage, will provide Pre-Design 6 structural engineering services in preparation for the stabilization of Lippincott Cottage. Work 7 includes site survey and assessment, identification of structural deficiencies, presentation of 8 repair alternatives, and recommendations for repair. Additionally, provide cost estimates for 9 each repair alternative. The final Comprehensive Structural Evaluation Report will encompass: 10

1. Documentation of Existing Structural conditions, 11

2. Presentation of Repair Alternatives, 12

3. Class C Cost Estimates, 13

4. Documentation of NPS-Preferred Repair, and 14

5. Documentation of NPS-Preferred Construction Methods. 15

4 BACKGROUND 16

The Lippincott Cottage (previously referred to as the Moorhead Cottage) is a large, three-story, 17 wood framed structure in the Queen Anne style with seventeen (17) rooms. The cottage was 18 constructed in 1887. It is one of 16 cottages built along Lake Conemaugh and associated with 19 the South Fork Fishing and Hunting Club. The club and lake provided a refuge for wealthy 20 Pittsburgh residents until May 31, 1889. On this date, the lake overflowed and breaking the 21 dam, sent massive amounts of water down the Conemaugh Valley into Johnstown, PA, creating 22 the famous Johnstown Flood. 23

In 2006, the National Park Service Historic Preservation Training Center’s (HPTC’s) Carpentry 24 Section completed the “Emergency Stabilization of the 1889 Clubhouse and Moorhead Cottage, 25 Johnstown Flood NM” project. 26

In 2011 the Western Pennsylvania Parks (WEPA) created PMIS Project #171820 27 “Rehabilitate/Repair Roof & Porch of Lippincott Cottage” and in 2018 the project was funded. 28 The scope of the project is to replace the structure’s roof and rebuild the front porch, however, it 29 was determined that it would not be safe to perform this work without first addressing structural 30 and hazardous material issues. In May 2018, the building received a full asbestos survey. 31

5 METHODOLOGY 32

The Project is subdivided into six (6) tasks: 33

1. Task One – Kick-Off Meeting, Field Investigation and Site Survey 34

2. Task Two – Preliminary Draft Comprehensive Structural Evaluation Report 35

3. Task Three – Draft Comprehensive Structural Evaluation Report 36

4. Task Four - Preferred Treatment Alternatives & Preferred Construction Methods Meeting 37

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5. Task Five – Preliminary Final Comprehensive Structural Evaluation Report 1

6. Task Six – Final Comprehensive Structural Evaluation Report 2

There are many locations where finishes are damaged; thus, allowing for inspection of structural 3 framing. The assessment of the structure conformed to the guidelines and methodology 4 presented in The American Society of Civil Engineers, Guideline for Structural Condition 5 Assessment of Existing Buildings, ASCE 11-99. 6

6 COTTAGE DESCRIPTION 7

The cottage has both hipped and gabled roofs, dormers, an octagonal tower, and porches on 8 both the first and second floors. The cottage is constructed on a steep slope on block piers. 9 Concrete and glass block infill walls have been constructed between the piers. The structure 10 has wood shiplap and new aluminum siding and an asphalt shingle roof. 11

The cottage is wood-frame construction above the basement level. Except for the lack of 12 continuous foundations beneath all load-bearing components, the construction is similar to 13 conventional residential structures built today. There are two (2) main interior bearing lines from 14 basement to roof which support typical wood framing. 15

The main staircase overhangs with landings that are supported vertically at only three corners. 16 In typical construction, landings are supported by walls or columns at all four corners. Landings 17 for a “hanging” staircase, (i.e. one which is open beneath), can be constructed without vertical 18 supports at one or two corners, but this normally requires structural members cantilevered 19 through walls to provide vertical support for the landing. The landings for the hanging staircases 20 at Lippincott Cottage do not utilize cantilevered members, yet are supported vertically at only 21 three corners. With this construction, horizontal members of the landing are connected to 22 diagonal stringer members by nailed connections which must support flexure. This type of 23 construction is less strong compared to cantilevered landings. This may be a concern if the 24 building is opened to the public, where multiple persons may be on the stair flights 25 simultaneously. Unless steel columns are inserted into the walls, it is not possible to reframe 26 the staircase landings using cantilevered support. Adding a vertical column beneath the 27 unsupported corner of the landings would detract from the architectural style of the staircase. 28 Additional rigidity and strength could be achieved by installing steel connectors or wooden 29 blocking at existing staircase joints. 30

In addition to the construction of main staircase, the historic structures report indicates a 31 structural deficiency along Bearing Line No. 2 for the first floor, which is directly above the 32 decayed timber beam (Condition B11 in this report). The HSR indicates a live load capacity of 33 only 10 psf along Bearing Line No. 2. The basis for this conclusion is unclear. No “softness” 34 was detected by walking on the first floor above Bearing Line No. 2. However, during the 35 current evaluation, the basement beam along Bearing Line No. 2 was observed to be 36 strengthened using LVL members because the original beam was badly decayed. The ends of 37 the newer LVL members were also decayed at the exterior wall, as a result of moisture. By 38 appearance, if the original Bearing Line No. 2 beam had not been decayed, it would have 39

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March 14, 2019 Page 5 of 68 provided adequate support for higher live loads than the 10 psf mentioned in the HSR. 1 Therefore, it is concluded that the low live load capacity mentioned in the HSR is due to the 2 decay of the original basement beam. Strengthening the original beam with the LVLs improved 3 the condition, but now that the LVLs are decaying, additional repairs are required. 4

Except for the staircase and Bearing Line No. 2, the HSR indicates live load capacities ranging 5 from 40 to 100 psf in finished areas. HSR live load estimations do not consider decayed 6 members identified in this report, but it indicates relatively sound timber framing was used in 7 original construction. 8

It is concluded that for the most part, after decayed members are replaced in kind or with 9 equivalent alternatives, the strength of the cottage framing will be adequate to sustain expected 10 loads should the cottage be opened for public tours, or alternative use. As indicated previously, 11 strengthening the main staircase should be performed before public access is permitted. 12

7 ASSUMPTIONS 13

The following assumptions have been made during the evaluation: 14

1. Framing size, spacing, and condition in concealed locations is similar to the framing in 15 exposed locations. 16

2. Based on the Structural Engineer’s Report by Pennoni and Associates included in the 17 Historic Structures Report, wood framing is assumed to be eastern hemlock with 18 minimum allowable stresses of: 19

1. extreme fibers in bending, Fb = 1000 psi 20

2. horizontal shear, Fv = 70 psi 21

3. the live load requirements per ASCE 7-10 for stairs and corridors in office 22 buildings is 100 psf. This exceeds the 40 psf requirement specified for one and 23 two-family residential dwellings. 24

4. Since it is not anticipated that facility rooms will be used for public assembly, a 25 live load of 50 psf is considered appropriate. The 50 psf live load is based on 26 office use, which exceeds the 40 psf live load requirement for one and two-family 27 residential dwellings. Partitions loads are not included for historic structures 28 since new work cannot be added due to the historic nature of the facility. 29 Partition loads should be based on actual partitions installed at the time of repair. 30

8 BASEMENT DEFICIENCIES 31

Walls 32

The basement is unfinished, and the basement is not currently functional as a living space. It 33 houses an old furnace and some oil tanks and provides paths for HVAC ducting to the rest of 34 the cottage. The primary concern in the basement is the condition of the masonry walls that 35 support wooden construction of the first floor and above. Many basement walls are cracked, 36 and some are not vertically plumb. Some walls have been built without a proper foundation, 37

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March 14, 2019 Page 6 of 68 and it can be assumed that settlement of these unfounded walls contribute to uneven settlement 1 of the cottage as a whole. 2

No steel reinforcement was observed in basement walls. Steel reinforcement was not used in 3 common practice during original construction, lightweight horizontal (wire ladder) and vertical 4 (rebar) reinforcement has typically been used in masonry walls since the late 1980’s. The lack 5 of steel reinforcement in basement walls contributes to the cracking and tilting. Most original 6 walls are composed of solid blocks, and it is not possible to incorporate vertical reinforcement 7 into such walls. Since the cottage is an ASCE-7 Seismic Risk Category B structure, 8 unreinforced masonry walls are permissible by current code, provided the unreinforced walls 9 have been designed to sustain design wind and seismic forces. The tilting and cracking of both 10 original and new walls indicates that the walls were not designed to sustain required lateral 11 loads. 12

Some basement walls are of CMU construction and are clearly not original. These repairs have 13 evidently been built to replace failed original walls or fill in between original piers. It is not clear 14 when these replacement walls were installed. Some of these new walls are cracked. The 15 cracking of new walls is evidence that the building continues to shift and settle despite repair 16 efforts. 17

As indicated above, the primary concern within the basement is the continued settlement of 18 masonry walls, resulting in cracking and tilting of the walls. Evidently, the walls were built to fill 19 in gaps between the original piers to enclose the basement. As such, the walls were not built to 20 sustain vertical or lateral building loads. However, due to settling and shifting of the piers, some 21 of the building load began resting on some walls, causing them to fail. This shifting and 22 settlement has evidently been occurring for some time, as jacks and shoring have been installed 23 to control the shifting. The date this shoring was installed is not clear, but it has clearly been in 24 place for a significant duration prior to this visit. 25

Uniform settling of the cottage by a small amount is normally not a problem. However, it 26 appears that settling of the cottage is non-uniform. In Room 304, it appears that the majority of 27 the room has settled more than the area adjacent to the chimney. Flooring secured at the 28 chimney is higher than elsewhere in the room. 29

Since the basement walls are unreinforced masonry, they cannot be expected to sustain 30 significant load eccentricity; the loads they carry must be centered directly above them. Walls 31 with inadequate or no foundations are also susceptible to settling and shifting. 32

As indicated above, the fact that the masonry walls were never designed to sustain expected 33 lateral loads (wind, seismic, and static thrust loads), is likely contributing to basement wall 34 cracking and displacement. The observed tilting and shear cracking of masonry walls is nearly 35 always the result of either lateral loads or inadequate foundation. Decay of wooden 36 components on the first floor and above may also result in uneven load distribution on the 37 basement walls, contributing to cracking. 38

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Moisture 2

Of secondary concern is that basement moisture has resulted in the decay of numerous wooden 3 members. Although the degree of decay is pronounced in places, the structure remains solid in 4 places without sagging or collapsing. One exception is that decay of the wooden basement 5 staircase has rendered it unsafe for use. The failure mode for decay of wooden members is 6 fairly clear – moisture, either from rainwater intrusion or high humidity, has promoted wood 7 decay. 8

8.1 Overview 9

ID Basement Deficiency Name Room Location

B1 Inadequate or No Foundation B01, B05, B08

B2 Basement Wall Shifting/Tilting B01, B02, B04, B05

B3 Basement Wall Cracked B01, B05

B4 No Bond Beam B01, B05, B08

B5 Hole in Foundation Wall B04

B6 Joist Decayed B04, B05, B08

B7 Header Decayed B01

B8 Sill or Plate Decayed B04, B08

B9 Joist Cut/Notched B01

B10 Wooden Stair 100% Decayed B04

B11 Beam Decayed B01

8.2 Description 11

The basement is composed of unreinforced masonry wall construction. Original and older 12 masonry is solid block and brick. There have been some repairs made with hollow-core 13 concrete masonry units. Some of the original walls have been constructed directly on earth, 14 with no foundation. Some other older walls have been built on foundations of rough stone. 15 New concrete foundations were constructed for new CMU replacement walls. 16

Framing above the basement is rough-sawn lumber. Typical joists in the basement ceiling are 17 nominally 2”x8” or 2”x10”, but the actual dimensions of these joists varied from nominal. 18

Dimensions of 2¼”x8” and 23/8”x10¼”. 19

The following photographs illustrate structural deficiencies identified in the basement. 20

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1. B1 – Inadequate or No Foundation 1 Several masonry walls in the basement have 2 been constructed directly on soil without a 3 proper foundation. Masonry walls require a 4 foundation formed of concrete or similar 5 material to distribute loads and reduce flexural 6 stresses in the masonry. Masonry walls 7 without adequate foundations should be 8 expected to shift and crack. The upper photo 9 at right shows the south wall or Room B05 and 10 the lower photo shows an external wall in 11 Room B01. Both of these walls are load-12 bearing. Neither wall at right has experienced 13 excessive cracking, but foundations are 14 necessary to prevent future degradation of the 15 walls. 16

The photograph at right shows a section of 28 older masonry foundation below a newer 29 Concrete Masonry Unit (CMU) wall. The older 30 masonry foundation is bulging inward due to 31 soil pressure from the outside. Instability of 32 the foundation jeopardizes the integrity of the 33 new wall. 34

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2. B2 – Basement Wall Shifting/Tilting 1

Some basement walls are shifting or are not 2 vertically plumb. This is caused by the lack 3 of an adequate foundation. The photo at 4 right shows the exterior of the north face of a 5 wall for Room B05. 6

The photo at right shows shoring and bracing 12 in Room B04 that has been constructed to 13 control further shifting of basement walls. 14

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3. B3 – Basement Wall Cracked 1

Many cracks have been observed in the 2 basement walls. Most cracks occur through 3 mortar joints, but as seen at right, some continue 4 through masonry units. 5

For purposes of this report, linear cracks within 6 construction joints are not considered structural 7 deficiencies, unless relative shifting has occurred 8 between adjacent structural elements (Type B2). 9

4. B4 – No Bond Beam 20

Modern design practice for hollow-core 21 masonry construction is for a bond beam to 22 be installed at the upper-most block course 23 in a wall. Bond beams are also placed in 24 locations beneath concentrated loads on the 25 wall, i.e. beneath a beam. A bond beam 26 typically consists of masonry units with open 27 ends that allow placement of horizontal steel 28 reinforcement over the entire length of the 29 beam. The reinforcement is held in place 30 with grout. The bond beam distributes 31 concentrated loads and minimizes wall 32 cracks, which often initiate at the top of the wall. No bond beams were observed in basement 33 walls. Bond beams would not be expected in original construction where solid masonry blocks 34 are used, but they are expected in more recent construction, such as that shown in the photo at 35 right. Arrows in the photo show locations where masonry blocks should be grouted solid and 36 reinforced for a minimum of one full course. 37

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5. B5 – Hole in Foundation Wall 1

The photo at right shows a hole in the 2 foundation wall. The hole appears to have 3 been created intentionally as a penetration, 4 but it is no longer being used. 5

6. B6 – Joist Decayed 11

Many joists in the basement are decaying. 12 Decay is associated with the presence of 13 moisture. In some locations, moisture may 14 be seeping down through holes in walls or 15 floor. The upper photograph shows a 16 location where joist ends at an exterior wall 17 have been decayed due to exposure to 18 seeping moisture. 19

The lower photograph shows a different 22 decay mechanism. The decay shown in the 23 lower photo is likely the result of poor 24 ventilation and lack of HVAC in the cottage 25 basement. Near record annual rainfall has 26 occurred in the area the year prior to site 27 inspection, resulting in high humidity and 28 condensation in the basement. 29

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7. B7 - Header Decayed 1

Wood headers are also susceptible to decay 2 for the same reasons as joists. The header 3 at right is in Room B01. 4

8. B8 -Sill Plate Decayed 12

The photograph at right is viewed from the 13 first floor, looking down the stairs into the 14 basement. The flat horizontal member to 15 the left of the stair is the sill plate beneath 16 the studs of the first floor. The sill plate and 17 studs are for an external wall, and both are 18 severely decayed as the result of moisture. 19

Header Decay

Joist Decay

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9. B9 – Joist Cut/Notched 1

Severe notches have been cut into joists 2 supporting the first floor at the staircase. 3 Without reinforcement, notches greater than 4 1/6 of the joist height are prohibited, notches 5 longer than 1/3 of the joist height are 6 prohibited, and notches extending into the 7 middle third of the joist span are prohibited. 8 The notch in the joist at right is located in 9 Room B01, and was for a back basement 10 stair, which has been removed. 11

10. B10 – Wooden Stair 100% Decayed 14

The staircase between the basement and the 15 first floor is completely decayed due to 16 moisture. The wall to the right of the stair is 17 an exterior wall which has extensive decay. 18 Moisture penetrating the wall has drained 19 onto the staircase, causing it also to decay. 20

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11. B11 - Beam Decayed 1

The composite beam extending east/west in 2 Room B01 is severely decayed at the west 3 end. The original beam was a 6”x10” built-4 up sawn member that has since been 5 reinforced by two 2”x12” LVL members. 6 The end of the built-up sawn member are 7 visible in the lower photograph. The LVL 8 members were attached to the sides of the 9 built-up beam. As shown at right, the LVL 10 members are decaying severely. The 11 original member is probably also decayed, 12 necessitating reinforcement by the LVLs. 13

As shown in the lower photograph, the 15 original beam extends through the exterior 16 CMU wall, exposing the end of the beam to 17 moisture from the outside. 18

8.3 Repair Alternatives 24

The following repair strategies have been proposed for each of the identified structural 25 deficiencies. 26

1. B1 – Inadequate or No Foundation 27

All modern construction methods require a solid foundation to support and distribute bearing 28 loads to the soil below. Inadequate foundations can result in high soil bearing loads and failure 29 of the underlying soil. Common practice at the time of the Lippincott Cottage construction was 30 to use rough stone foundations cemented with mortar. Modern construction utilized either plain 31 or reinforced concrete foundations. The need for reinforcement is determined based on the 32 presence and magnitude of concentrated loads and the tensile capacity of the foundation 33 material. 34

Decayed LVL Nailed to Original Built-up Beam

Ends of Sawn Members of Original Beam

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Repair Options 1

Option A -The lack of foundations is one of several inadequacies of the cottage foundation 2 walls. One repair technique that covers the range of deficiencies is to jack up wooden portions 3 of the cottage as required to remove load from the existing walls and foundations. The existing 4 walls and foundations are demolished and replaced with new foundation walls on new concrete 5 foundations. A continuous foundation would be constructed of reinforced concrete, and 6 foundation walls could be constructed of either modern CMU blocks or solid masonry units 7 similar to that used in original construction depending on the location. Steel reinforcement 8 would be used as required within the new CMU walls. 9

Option B - Each basement wall without a foundation is demolished. In its place, a new concrete 10 foundation and new basement wall is constructed. The demolition and construction is done in 11 four foot sections to minimize the need for shoring. Walls with inadequate foundations will be 12 strengthened by widening the existing foundations. Unlike Option A, Option B only constructs or 13 modifies foundations where existing foundations are failing or where they do not exist. New 14 foundation walls are built only where existing walls are failing 15

Option C - For basement walls without foundations, hand excavation is performed beneath each 16 wall, and the excavation filled with non-shrink concrete. The walls can be repaired or rebuilt as 17 required above the foundation. Walls with inadequate foundations will be strengthened by 18 widening the existing foundations. 19

Option Discussion 20

Option A replaces all building foundations except for the chimneys. No evidence that the 21 chimneys have settled was observed. This integrated approach provides the greatest certainty 22 for a lasting repair. It allows the walls to be waterproofed on the exterior of the building. It is the 23 most consistent and costly repair. As can be observed, some relatively modern basement wall 24 repairs are failing. Option A eliminates the concern that piecemeal repairs may be less 25 effective. In addition, the floor discontinuity in Room 304 provides evidence that the cottage has 26 settled unevenly, with the perimeter walls settling more than the chimney. In that location, 27 headers for floor joists have been attached to the chimney structure. It was not possible to view 28 whether floor framing has been attached to chimneys in other locations, but it is reasonable to 29 expect so based on the floor construction in Room 304. Jacking up the wooden portion of the 30 house provides an opportunity to level the structure and better align floors with masonry 31 chimneys. This option provides the most reliable solution that addresses all foundation 32 problems. 33

Option B replaces basement walls which do not have foundations. Intact walls with minor 34 cracking will still need to be repaired. Like Option A, it provides an opportunity to rebuild 35 basement walls with a more consistent type of masonry, but since not all walls will be rebuilt, 36 inconsistencies in wall materials will remain. This option does not allow leveling or exterior 37 waterproofing as noted above in Option A. Waterproofing would need to done on the interior of 38 the structure, which is generally less-effective than when done from the outside. 39

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Option C provides the minimum-cost solution, but it is also the least reliable. There is a greater 1 potential for wall settlement if the foundation is placed beneath an existing wall. Existing walls 2 still need to be repaired. This option does not allow leveling as noted above in Option A. 3 Waterproofing would need to done on the interior of the structure. 4

Preferred B1 Option 5

Option A: NPS noted that the cost of the comprehensive foundation repair is comparable to the 6 other repairs, and also that past piecemeal repair efforts have been ineffective in resolving 7 foundation issues. 8

2. B2 – Basement Wall Shifting or Tilting 9

Repair Options 10

Option A for B2 is identical to Option A for B1. Rebuilding new basement walls enables the 11 walls to be centered directly beneath load bearing walls and other load-bearing structures. 12

Option B consists of rebuilding tilted and shifted basement walls. It may be possible to realign 13 the new walls to some degree to achieve better alignment with neighboring structures, but 14 realignment will be limited by the location of the existing foundations. It will be possible to 15 rebuild the new walls with masonry that better matches historic or aesthetically-pleasing types. 16

Option C consists of jacking tilted or shifted basement walls back into place and cementing 17 them back into position. Typically, the walls can be repositioned into place without jacking up 18 the wooden structure above. This alternative will be the lowest cost, but also provides the least 19 likelihood of a lasting repair. 20

Option Discussion 21

As indicated above, Option A will have the highest-cost, but it provides the best likelihood of a 22 lasting and aesthetically-pleasing repair. 23

Option B provides an intermediate solution, but it may provide a reasonable repair strategy. 24 One concern is that some tilted walls are of concrete masonry unit construction, which means 25 they are rebuilt walls themselves, so that there is a potential that new walls, like the current 26 walls, will tilt. 27

Option C provides the least costly alternative. It is not recommended. Most of the tilted walls 28 should be load-bearing, but because of the manner in which they were constructed, or because 29 they have settled or shifted, they carry no load. Cementing the existing wall sections into a 30 vertical position does not provide assurance that load is well-founded or that the walls will not 31 return to a tilted position. 32

Preferred B2 Option 33

N/A: Selection of Option B1A covers necessary repairs for Deficiency B2. 34

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3. B3 – Basement Wall Cracked 1

Repair Options 2

Option A is identical to Option A of B1. Replacement of the basement walls will resolve the 3 problem. 4

Option B involves removal of select masonry units and recementing units in place. Where 5 possible, only a few blocks near the crack will need to be removed and reset. In cases with 6 large and multiple cracks, sections of walls will need to be removed and reset. If existing 7 masonry blocks are intact, they can be reused. However, some are already cracked and others 8 will likely be broken during the removal process, so some new blocks will need to be installed. 9

Option C involves filling wall cracks with an epoxy based or similar repair material. This low-10 cost option will provide waterproofing and weatherproofing. 11

Option Discussion 12

Option A provides the most reliable and aesthetically pleasing solution. 13

Option B provides an intermediate-level repair, but the repairs will be visible. An additional 14 concern is that it may not be possible to find replacement masonry blocks identical to the 15 existing blocks, making the repairs more apparent. Option B will provide a stronger repair 16 compared to Option C. 17

Option C will be the lowest-cost option. While it will provide some degree of weatherproofing, 18 the repairs will be visible, and it is likely that cracking will reappear in the repair material after a 19 few years since the thickness of the repair material is generally not the full thickness of new 20 mortar joints. 21

Preferred B3 Option 22

N/A: Selection of Option B1A covers necessary repairs for Deficiency B3. 23

4. B4 – No Bond Beam 24

Even though several new masonry walls have been constructed for the cottage, none of them 25 employ bond beams. Typical bond beam construction is illustrated below. 26

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Bond Beam Construction 2

Repair Options 3

Option A is identical to Option A of B1. A bond beam or equivalent can be cast while rebuilding 4 the basement walls. 5

Option B rebuilds bond beams individually. This will also require jacking the wooden structure 6 above the basement wall. Rather than recasting bond beams in the traditional method, precast 7 bond beams (similar to precast lintels) can be installed. A typical precast Iintel is shown below. 8

Typical Precast Lintel 10

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(Lintel shown is 3 ¾ inches wide. Two parallel lintels would be used for a nominal 8-inch masonry wall). 1

Option C reinforces existing masonry courses rather than replacing them. Fiber reinforcement 2 can be applied to the interior and exterior surfaces of the walls. For walls formed of hollow 3 masonry units, cores of units will be filled with grout. 4

Option Discussion 5

Option A provides the most effective and lasting repair approach, but it may also be the most 6 costly. 7

Option B provides an intermediate cost repair approach. It will be equally effective as Option A 8 with regard to achieving adequate bond beam capacity, but it is not an integrated approach 9 capable of correcting the range of deficiencies that Option A achieves. One disadvantage with 10 this approach is that for some wall types, it will not be possible to match the bond beam 11 masonry with the masonry type used below. Precast bond beams typically have the surface 12 texture of smooth concrete or the more porous texture of CMU masonry. It will not be possible 13 to match this type of bond beam material to red brick or yellow brick used in some locations of 14 the cottage. 15

Option C provides an approach that increases the capacity of existing walls. While it does not 16 replace the upper masonry course, it is necessary to install fiber reinforcement on both the 17 inside and outside surfaces, so that the repairs will be visible from the outside. The figure below 18 shows typical FRP-reinforced beams. Fiber reinforcing can be very expensive, and the cost 19 may exceed Option A depending on the amount of fiber reinforcing necessary. 20

Typical Appearance of Beams Reinforced Using Fiber Reinforced Polymer 22

Preferred B4 Option 23

N/A: Selection of Option B1A covers necessary repairs for Deficiency B4. 24

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5. B5 – Hole in Foundation Wall 1

Repair Options 2

Option A for deficiency B1 will correct the observed condition by replacing the basement walls. 3

Option B is to patch the hole in the wall with masonry cement. 4

Option C is to add plywood to cover the hole. The observed condition has likely existed for a 5 significant time and is not considered to be a major impact on overall building capacity. The 6 plywood will keep out animals and weather. 7

Option Discussion 8

Option A effectively corrects all problems with the basement walls and foundations by replacing 9 them. 10

Option B provides a repair to the observed condition, but the repair will be noticeable from the 11 outside of the building. 12

Option C is the least expensive, but it will not last as long as Options A or B. 13

Preferred B5 Option 14

N/A: Selection of Option B1A covers necessary repairs for Deficiency B5. 15

6. B6 – Joist Decayed 17

Repair Options 18

Option A is to replace decayed joists in their entirety. Decay observed on many joists is limited 19 to one location. 20

Option B installs new joists (sister joists) parallel to existing joists. Existing joist is left in place. 21 The sister joist is the full length of the existing joist and can be installed in contact with the 22 existing decayed joist or offset by some distance. Decayed sections would be sprayed with 23 wood preservative. 24

Option C installs a new joist section of length required to supplement the decayed portion of 25 existing joists. As with Option B, decayed portions of lumber remain in place. The decayed 26 portions will be sprayed with preservative. 27

Option Discussion 28

Option A removes decayed joist material. In doing so, it minimizes the potential of future mold 29 and insect damage from moisture occurring in existing joists. By removing decayed joists, it 30 also reduces the dead weight load that must be carried by members supporting the joists. 31

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Option B does not remove existing decayed joists, but it installs new joists adjacent and 1 attached to decayed joists in order to carry the load. It saves the cost of removing decayed 2 lumber. While decay generally stops once wood becomes dry, preservative should be applied to 3 decayed sections to kill mold and provide better assurance that decay is arrested. Option B is 4 more comprehensive than Option C in that installers do not have a responsibility to determine 5 how much of the joist needs to be replaced. It increases the dead load by increasing the 6 number of joists. This repair can be limited by the amount of decay in the existing joist. A 7 member that is decayed to the point where it cannot support itself cannot be left in place. 8

Option C installs portions of new joists to the extent necessary to supplement decayed portions 9 of joists. New joist sections must be spliced onto sound portions of existing joists. This option 10 relies on visual inspection of the existing joist to determine the extent of damage. Hidden 11 damage may be missed during inspection and construction. In addition, the fact that new 12 material is being added to existing members increases dead load for the structure, but the 13 added weight is less than Option B. Also, the fact that decayed material is left within the 14 building increases future concerns related to mold and decay. This repair is limited by the 15 amount of decay in the existing joist. A member that is decayed to the point where it cannot 16 support itself cannot be left in place. This will be the lowest-cost option. Depending on the 17 extents of the damage, Option B may have to be used in some instances. This option may be 18 limited by the capacity of the fasteners to attach reinforcing to the existing member. 19

Preferred B6 Option: 20

B6C: NPS noted the need to minimize costs, and also the desire to maintain as much of the 21 original structure in its historic condition. Joist repairs in the basement will be visible, but the 22 public will be excluded from the basement area. It may be possible for NPS to make some of 23 the repairs themselves in order to reduce cost. 24

7. B7 – Header Decayed 25

Repair Options 26

Option A removes existing headers in their entirety and replaces them with new members. 27

Option B installs redundant headers (sisters) to existing headers without removing the existing 28 decayed members. 29

Option C reinforces portions of decayed headers as required to carry the load. Reinforcement 30 may consist of steel straps, corner braces, or other components necessary to reinforce decayed 31 members. Existing decayed members are left in place. 32

Option Discussion 33

Option A is the approach that best simulates the historic structure. Decayed portions of joists 34 are removed, minimizing the risk of future mold and insect damage. In addition, dead load is 35 minimized by removing existing decayed members. 36

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Option B installs new header components but does not remove existing decayed members. 1 This option ensures adequate capacity is achieved but allowing decayed members to remain in 2 place increases concerns with mold and increases dead weight. This repair can be limited by 3 the amount of decay in the existing member, since members that cannot support themselves 4 cannot be left in place. Also, in some cases, there will be insufficient clearance to install 5 redundant headers. 6

Option C provides ancillary reinforcement (generally steel or wood) that supplements existing 7 decayed members. Similar to Option B, Option C also poses concerns associated with leaving 8 decayed members in place and increased dead weight. In some locations, repairs associated 9 with the option will be visible and not visually pleasing, but it is expected that the basement will 10 remain unfinished, so the appearance may be considered acceptable. This repair is limited by 11 the amount of decay in the existing header, since the ancillary reinforcement must be securely 12 attached to sound portions of decayed members. Nonetheless, this repair option may be 13 simplest repair approach in cases where the extent of decay is not great. This option may also 14 be limited by the capacity of fasteners used to attach reinforcing to the existing member. 15

Preferred B7 Option: 16

B7C: NPS selected the least expensive option. Since the public will be excluded from the 17 basement area, the appearance of the repair is less important. 18

8. B8 – Sill Plate Decayed 19

Repair Options 20

Option A of deficiency B1 includes replacement of basement sill plates. Replacement of a sill 21 plate is a major repair, and generally requires jacking up associated joists. Modern practice 22 employs pressure-treated sill plates to minimize the risk of decay, but this practice did not exist 23 during original construction of the cottage. If this repair strategy is employed, all basement sill 24 plates for the cottage will be replaced with pressure-treated members. Another current practice 25 that was not employed during original construction is the use of anchor bolts to secure sill plates 26 to the basement walls. This repair option includes installation of anchor bolts (and bond beams) 27 to support the sill plates. 28

Option B replaces basement sill plates for the entire structure in sections. This Option requires 29 jacking up the joists that rest on the sill plates, but this can be done locally rather than by jacking 30 up the entire cottage as a whole. 31

Option C involves replacement of only those portions of sill plates that are decayed and portions 32 of sill plates beneath joists that require replacement. This may require some local jacking of the 33 structure. 34

Option Discussion 35

Option A for B8 is identical to Option A of deficiency B1. As indicated above, Option A resolves 36 a number of concerns in concert. All basement sill plates will be replaced with pressure-treated 37

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March 14, 2019 Page 23 of 68 members in conjunction with replacement of the basement walls. This is the most 1 comprehensive repair strategy. 2

Option B replaces decayed basement sill plates with new pressure-treated members. 3

Since Option C replaces only certain sections of sill plates with pressure-treated members, 4 there remains some concern that decay can continue in original members that have not been 5 pressure treated. Option C will be the least expensive option, since it does not replace all sill 6 plates as would be done in Options A and B. Options A and B are equally effective, but will 7 have a higher cost. Since Option A jacks the entire house off the foundation, this simplifies 8 replacement of the sill plates, which are otherwise difficult to replace. 9

Preferred B8 Option: 10

N/A: Repairs made in by Option B1A will cover repairs required by deficiency B8. 11

9. B9 – Joist Cut/Notched 12

Repair Options 13

Option A – The existing notches in basement joists are associated with a staircase that is no 14 longer in place. Option A replaces the notched joists with complete new joists without notches. 15

Option B installs supplemental joists (without notches) parallel to the existing members in order 16 to provide adequate capacity. If there is some reason why the notch must remain in place, it is 17 permissible to install a sufficient number of redundant notched joists so the stress in the 18 notched section is acceptable. 19

Option C involves installation of steel reinforcement sections in notched members that increase 20 their strength to the required capacity. 21

Option Discussion 22

Option A provides a complete and permanent solution to the condition. However, removal of 23 the notches may make overhead space inadequate if it is desired to replace the second 24 basement staircase. 25

Option B also provides a complete solution. The option saves the cost of removing existing 26 joists, so it would be less expensive compared to Option A. If redundant joists are also notched, 27 the option would not be visually objectionable, and it would permit the stairway to be reinstalled 28 if desired. 29

Option C provides a lower-cost repair that is less…