Hanson Regional Park Farm House Preservation 23862

STRUCTURAL CONCEPTS, INC.

STRUCTURAL ENGINEERING INVESTIGATIONS

BUILDING INSPECTIONS

132 W. Piccadilly St. | Winchester, VA 22601 | (540) 667-6174 | fax (540) 722-4748 | WWW.SCI-ENGR.COM

June 19, 2012 SCI Job No. 2012.030

Hanson Regional Park Farm House Preservation

23862 Evergreen Mills Road Leesburg, Virginia

Structural Investigation

INTRODUCTION The purpose of this document is to give a general description of the building site, general description of the building and structural framing systems including; load requirements, soil conditions, foundations, gravity load bearing systems, lateral bracing systems, exterior wall framing, the existing condition of the building, repairs required for mothballing and other mothballing requirements. A current photograph of the building can be seen at right. The owner plans to mothball the building for a period of time before a renovation. Recommendations for temporary shoring of the building to prevent a collapse during the mothball period as well as the existing structural condition will be discussed. Sketches SK1, SK2, SK3 and SK4 are attached to show the existing framing conditions and the locations of the temporary shoring for the mothball period and SSK5 to SSK8 are supplemental details and notes for the installation of the shoring. Representatives of Structural Concepts, Inc. visited the building site and performed a visual evaluation of the building and the elements of the building structure which were accessible for visual observation without demolition of existing building finishes on May 15, 2012 and again on June 1, 2012.

BUILDING SITE DESCRIPTION The building site is located on the western side of the property located to the east of Evergreen Mills Road in Leesburg, Virginia. The front of the building is facing west towards Evergreen Mills Road. The site has a relatively flat slope and it appears that standing water near the building is possible. The grade of the site should be

Hanson Regional Park Farm House Preservation June 19, 2012

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investigated and adjusted as required to drain water away from the building. The weather was relatively dry at the time of the site visit.

GENERAL BUILDING DESCRIPTION The building is a two story wood framed structure that was originally constructed in the early 1870’s and appears to have had one or two later additions (see right). The sunroom is an addition that was constructed with modern construction techniques and is not historically significant. The kitchen appears as if it could have been an addition that was added soon after the home was constructed. The construction style and materials used in the kitchen are consistent with the main sections of the home. A tight crawl space where the first floor joists are placed very close to grade level is typical below the building. There is an excavated cellar area below part of the living room and the hallway and the sunroom addition is on a slab on grade. The main support of the building is provided by exterior and interior wood stud bearing walls and interior wood beams. The interior bearing walls and beams are located near the center of the building parallel to the main roof ridge. All of the interior bearing walls are supported by a wood beam in the first or second floor framing. The exterior walls are supported on a mortared stacked stone foundation wall.

LOAD REQUIREMENTS This building was constructed in an era where there limited or nonexistent building codes. For the purposes of this report the available load capacity of the building framing will be compared to the required load capacity of The International Building Code 2009 (IBC), which is the current code governing new construction in Virginia. IBC applies a uniform floor loading to an area of a building depending on the particular use of the area. The building is not currently occupied but, has always been used as a residence in the past. IBC requires a live load capacity of 40 pounds per square foot (psf) for residential occupancy. The projected use of the building in the future has not been determined but the building will be used as something other than a residence. Office space and public areas are required to have a floor live load capacity that typically ranges from 50psf to 100psf. The loading used for the existing framing and the


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additional shoring during the mothball period will be 20psf which is typically the live load required for construction loading. IBC requires the snow loading applied to the roof framing to be based on a ground snow load of 25psf. A majority of the floor and roof framing do not have the capacity to support the code required residential loading (40psf) and the code required snow loading. Many areas will also require temporary shoring to support the 20psf construction loading while the building is mothballed. Significant reinforcing of the floor and roof framing will be required when the building is restored. The size and extent of the reinforcement will depend on the IBC required floor live load capacity based on the proposed use of the building. IBC requires buildings to have adequate lateral load resisting capacity to support wind and seismic loads. A loading that results from a wind speed of 90mph is required by IBC for the current building use and location. Seismic loading of wood framed structures does not typically govern the lateral resistance design for buildings of this type and size in this area. The International Existing Building Code (IEBC) governs the design when existing buildings are altered. When there are minor alterations with no change in use of the building only the affected localized areas of the building are required to comply with IBC. When there are major repairs along with a change of use the gravity and lateral load resisting systems of the entire building are required by IEBC to comply with IBC.

SOIL CONDITIONS A geotechnical engineering study of the existing soils has not been prepared for this evaluation. None of the soil supporting the buildings stone foundations could be seen. Based on a visual observation of the stone foundations there are no signs of soil issues that could be detrimental to the support of the stone foundations.

FOUNDATIONS All of the building except for the second addition is supported on stacked stone foundation walls with mortared joints. The walls could be seen in the cellar and in a few areas around the perimeter of the building at the crawl space. The foundation walls that could be seen are in fair condition and appear to be adequately supporting the structure. A photo of the cellar stone foundation wall can be seen to the right.


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The foundations are currently suitable for the mothball period but will require some repair when the building is restored. These repairs would consist of re-pointing any damaged mortar joints and rebuilding a few areas where the stone has been removed or fallen away. There is one location in the cellar where the top of the wall has been removed to install piping (see right). Solid blocking will need to be installed to provide a bearing point for the joists where the wall section was removed (see SK1). When the building is restored the foundations of the building will be required to resist horizontal, upward and downward reactions from the lateral loading required by IBC. The stone foundations are not very well suited to resist the reactions caused by lateral loading and new foundations will need to be install that replace or supplement the existing foundations.

WOOD BEARING WALL FRAMING CONDITIONS Observation of the wall studs was obstructed by the interior and exterior finishes. The building did not show any signs of distress that could be caused by deteriorated or inadequate wall studs except for one area. Wall studs in this era were typically spaced at 16 to 24 inches apart and would extend the full height of the building from the foundation to the roof framing elevation. The wall at the north west corner of the building adjacent to the chimney is bowed outward and the stud wall and the chimney have pulled away from the second floor framing (see right and SK1&SK2). Since the second floor joists do not bear on this wall the bow could have been caused by inadequate connections of the wall studs to the floor framing. The chimney could also be pulling away from the wall due to settlement caused by poor soil conditions or deteriorating mortar joints in the chimney stone work. The stud wall and the chimney will need to be stabilized for the mothball period. The soil supporting the chimney and the condition of the chimney mortar joints will need to be investigated further. If the soil is inadequate the chimney will need to be stabilized with hydraulically driven piers. These piers are steel piers that are driven into the ground with hydraulic equipment until suitable soil is encountered then are attached to the base of the chimney. The existing stucco will need to be removed to inspect the chimney mortar joints and re-point any deteriorated mortar joints. Once settlement or deterioration of the chimney is repaired or determined not to be a problem the stud wall


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and the chimney will need to be stabilized by anchors to the second floor framing (see SK2 & SK5). A more permanent solution will need to be implemented when the building is restored that could possible involve demolition and re-construction of a new wall section and chimney. The upper section of the chimney is leaning and in poor condition and could possibly fall causing damage to the roof (see right). Prior to mothballing the upper section will need to be removed from above the roof level. The chimney opening will need to be capped to prevent water infiltration. The bottom of the wall studs are in close proximity of soil on the exterior and in the crawl space. This makes the walls susceptible to rot and insect damage. There is not currently any evidence there is deterioration of the wall studs. The existing wall studs are adequate to support the building for the mothball period. We recommend removing wall finishes along the lower portions of the wall prior to the renovation to inspect for any possible deterioration.

FIRST FLOOR FRAMING CONDITIONS The first floor joists are 6 to 8 inch diameter logs that are spaced approximately 24 inches apart (see right and SK1). In the main section of the building the joists span east to west and are supported by 7½”x6½” beams near the center line of the building and by the stone foundation walls. The beams spanning east to west are also supporting post and load bearing walls that support the framing from the floor levels above. There are also some additional 7½”x6½” beams spanning east to west below sections of the hallway walls that are not bearing on a foundation wall. The kitchen joists span north to south and are supported at each end on the stone foundation walls. There are many areas of the floor that are currently sagging and are most pronounced at the wall between bedroom #1 and #2. The first floor framing could be seen in the cellar and some of the framing above the crawl space could be seen. The framing that could be seen did not appear to be rotten but had minor damage on the outer layers from powder post beetles. This damage was not enough to significantly reduce the effective section area of the framing members. The crawl space was too shallow to enter for inspection and many of the first floor framing members could not be seen. There are areas where many of the members are in contact with the dirt floor of the crawl space (see right, next page). This makes the


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members more susceptible to rot and insect damage. Since these members could not be closely inspected their condition could not be determined. The first floor joists have the capacity to support the 20psf construction loading but will need to be reinforced for any loading over 20psf when the building is restored. The concealed joists over the crawl space areas may or may not be deteriorated. If some of these joists are in poor shape and continue to deteriorated while the building is mothballed it will not result in excessive damage or catastrophic failures to the building. It will most likely result in increases sagging of the first floor level. The concealed joist can remain in their current condition and will not require any bracing until the building is restored. The beams near the center line of the home are overstressed when loaded with 20psf and will need to be temporarily reinforced. New beams, posts and foundations will need to be added in the locations shown on SK1.

SECOND FLOOR FRAMING CONDITIONS The second floor joists are 1¾”x6½” sawn lumber that is spaced approximately 24 inches apart (see SK2). In the main section of the building the joists span east to west and are supported by a 6”x10” beam over the living room and hall and a bearing wall between bedroom #1 and #2 and the exterior stud walls. The beam and bearing wall are near the center line of the building. The joist support beam spanning east to west also supports a load bearing wall that supports the framing from the attic level above. The second floor joists above the kitchen span north to south and are supported at each end on the exterior stud walls. There are many areas of the floor that are currently sagging. Most of the joists could not be seen during the site visit but, there is not any evidence of deterioration of the joists. The joists on the eastern side of the interior support line have the capacity to support the 20psf loading for the mothball period. The joists to the west of the interior support line and the 6”x10” beam over the living room do not have capacity to support the 20psf loading. A new beam and post line will need to be added on the western side of the building and the beam over the living room will need to be sistered with new members to resist the loading during the mothballed period (see SK2). None of the second floor framing will have the capacity to support the floor loading when the building is renovated and will need to be reinforced to support the loading for the intended use.


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ATTIC FLOOR AND ROOF FRAMING CONDITIONS The attic floor joists are 1¾”x6½” sawn lumber that is spaced approximately 24 inches apart (see SK3). In the main section of the building the joists span east to west and are supported by bearing walls below and the exterior stud walls. The bearing walls are near the center line of the building. There are many areas of the floor that are currently sagging. Most of the joists could not be seen during the site visit but, there is not any evidence of deterioration of the joists. A knee wall is located 5 feet from the east and west exterior walls that provides support to the roof rafters (see right). The knee wall transfers roof load from the rafters into the attic floor framing. The attic floor joists do not have the capacity to support the roof loading from the knee wall and the 20psf loading. A new beam and post line will need to be added below each of the knee walls for the mothballed period (see SK3). The main roof rafters are 4 inch diameter logs spaced 24 inches apart and have the capacity to support the code required snow loading (see SK4). The connection of the rafters to the attic floor joist provides stability to the roof by preventing the roof from flattening. The actual connection does not have the calculated capacity to resist the forces that could flatten the roof. The ridge line of the roof is flat and level which is an indication that the roof has performed in the past to resist snow loading. The roof should continue to perform during the mothballed period as it has in the past and stabilization of the roof is not required at this time. When the building is renovated the rafter to joist connection will need to be reinforced to comply with IBC. None of the attic floor framing will have the capacity to support the floor and roof loading when the building is renovated and will need to be reinforced to support the loading for the intended use. The roof over the kitchen is a lower roof and there is not an attic (see right). A wood stud knee wall extends approximately three feet over the second floor level. The rafters bear on the top of the knee wall. The knee wall supporting at the ends of the kitchen rafters provides little resistance to prevent the roof from flattening. The rafters (3 inch diameter logs spaced 24 inches apart) do not have the capacity to


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resist the IBC required snow loading. A new beam will need to be added to each side of the ridge as shown in SK3. Posts will then extend down to two beams that bear on the top of the existing knee wall. A less invasive repair that allows for better access to the space may be designed when the building is renovated. This area also had holes in the roof and water damage. Sister any damaged rafters with 4x4’s as noted in SK3.

PORCH AND SUNROOM FRAMING CONDITIONS The rafters and ceiling joists in the roof section of the porch are the same size and spacing to the main roof framing and span from north to south. There is a 2x6 beam on each end of the porch that supports the rafters and ceiling joists. The corner posts at the roof level support a majority of the roof load. The bearing ends of the rafters are rotten (see below right) and sagging can be seen in the rafters. The second floor porch level framing could not be seen but is assumed to span north to south and match the size and spacing of the ceiling joists above. Beams are likely located on each end of the porch to support the joists. The rafters and the joists of the porch framing do not have the capacity to support the IBC required snow loading and the 20psf floor loading. There is also a column missing at the north west corner of the porch. Three new shoring walls will need to be installed that extend the full height of the porch that bear on the existing stone slab area. Locate one wall at the ridge and one near each eave as shown in SK1 to SK4. A majority of the porch framing will need to be reinforced and/or replaced when the building is renovated. The sunroom wall and roof framing was concealed and could not be seen (sunroom photo to right). The roof framing is sagging which is a result of undersized or deteriorated framing. The framing could be braced for the mothball period but the long term plan is to demolish the sunroom. We recommend demolishing the sunroom at this time to avoid the additional shoring effort in the area that will eventually be demolished. After the sunroom is demolished patches to the siding may be required where the framing joins the main section of the home. The slab on grade at the first floor of the sunroom can remain. The cellar opening in the sunroom area will need to be covered and waterproofed.


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LATERAL LOAD SUPPORT Typically lateral support is provided to wood framed buildings by bracing the wall studs, floor and roof framing. Bracing of the walls is typically provided with sheathing attached to the exterior side of the studs or diagonal bracing notched into the interior side of the studs. Stiffness to the floor levels is typically provided by sheathing applied as a subfloor. The sheathing used on the walls, floors and roof framing is typically plywood panels or board sheathing installed diagonal in relation to the framing. In a few locations it appeared that the original siding was fastened directly to the wall studs and this is assumed to be typical of all the exterior walls. In some locations diagonal bracing notched into the interior side of the wall studs could be seen. The finished floor and the roof boards are attached directly to the floor and roof framing. There is not currently any panel or board sheathing attached to the wall, floor or roof framing. It is not likely that lateral force resisting systems were specifically design given the age of the building. Base on our past experience this type siding, finished floor and wall bracing attachment provides limited lateral support and is unlikely that the building has adequate lateral load resistance to support the code required wind loading. The International Existing Building Code (IEBC) governs elements of existing buildings. IEBC does not require the lateral support of an existing building to be upgraded to meet current codes unless there is a significant change in the use of the building or the building is damaged as a result of limited lateral resistance. IEBC does not require any repairs to the lateral resisting systems of the building for the mothball period since the use of the building has not yet changed and there is not any structural damage that appears to be a result of lateral loading. Evaluating and upgrading the buildings lateral support system to meet the lateral wind and seismic load requirements of IBC will be required when the building is restored due to the projected change in use of the building. Repairs to the building will be required to comply with IBC.

ADDITIONAL MOTHBALLING REQUIREMENTS There are additional requirement that must be satisfied to preserve the home during the mothball period as required by the National Park Service’s “Preservation Brief 31: Mothballing Historic Buildings, the Historic Fortification Preservation Handbook”. The handbook gives guidelines for mothballing a building relating to waterproofing, pests, housekeeping, security, utilities and ventilation. Each of these are briefly discussed below but, all the areas must comply with the recommendations in Preservation Brief 31. Additional considerations for mothballing in addition to the structural concerns are listed below:


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1. The exterior envelope of the building will need to free from any moisture penetration to the interior of the building. The roofing, siding, doors, windows and chimneys will all need to be water tight. It was not raining at the time of the site visit but most of these items appeared to be water tight except in areas where there is damage from a fallen tree. There is damage to the roof above the kitchen area and to the siding on the north side of the building. There was a puddle of water in the floor of the kitchen during the site visit. A roofer should consulted with to inspect and patch the roof and flashing where required, cap the chimney opening and inspect and repair the gutters as required. Rainwater flows into the cellar and the floor of the cellar was wet at the time of the visit. The cellar door and opening will need to be repaired to prevent water from entering the cellar. The cellar opening at the sunroom will also need to be capped and waterproofed.

2. The building will need to be free of rodents and damaging insects. There is evidence of past insect damage in the first floor framing and an exterminator should be contacted to prevent damage in the future. Two snakes were seen in the roof framing and snake skins were seen through out the building. The snakes and any other rodents living in or on the building will need to be removed.

3. All trash and debris will need to be removed from the interior of the building and

all the floors need to be swept. Any significant architectural elements that have become detached should be labeled and stored in a safe place.

4. A plan should be implemented to insure the security of the building such as

notifying the police and fire department that the building is mothballed, securing and locking all doors and windows and developing a plan to monitor the building and maintain the grounds.

5. Any utilities that will be shut off will need to be properly terminated and secured.

If the building will remain unheated all the pipes will need to be drained and glycol added. If the electricity will remain on all the wire will need to be in a safe condition.

6. All areas of the building will need to be ventilated including the cellar, crawl

space and attic. Typically the minimum air exchange required is one or two exchanges every hour in the winter and twice that in the summer. All interior doors shall remain open to allow air flow. A mechanical engineer/contractor should be consulted with for the installation of the required exhaust fans.

Documents

Hanson Regional Park Farm House Preservation 23862