kunimoto engineering (1995) limited - hope · kunimoto engineering (1995) limited have been...

KUNIMOTO ENGINEERING (1995) LIMITEDConsulting Structural EngineersSuite 201 - 8678 Greenall AvenueBurnaby, British Columbia V5B 4G9Ph: 604.298.5950 Fax: 604.677.5950 Email: [email protected]

23 April 2015

Advantage Hope c/o Levelton Consultants Ltd.#110 - 34077 Gladys AvenueAbbotsford, B.C.

Attention: Ms. Stephanie Hooker

Re: Station House - 111 Old Hope-Princeton Highway, Hope, B.C.

Structural Review

1.0 Introduction:Kunimoto Engineering (1995) Limited have been retained by Levelton Consultants Ltd. as theirstructural consultant to perform a structural assessment of Station House (the building). Thepurpose of this report is to assess the existing condition of the building to allow the Hope Museumto relocate into the main floor of the building.

The scope of work for this review included a limited number of investigation openings to determinethe existing framing. Our review is based on a review of the visually accessible structural framingin the building. There may be hidden conditions covered by finishes that are not apparent from avisual review. The content of this review reflects our opinion based on our observations.

A review of the site was conducted on Friday, April 10, 2015.

2.0 Building Description:

2.1 General:This building was originally a single storey, wood frame station house with a small upper floor. Wewere informed that the building is approximately 100 years old. In the 1980s, the station house wasrelocated to its present location. A new foundation, retaining walls and wood frame basement wallswere constructed. The station house was placed on top of the new basement resulting in a twostorey (with small upper floor), wood framed, building.

Kunimoto Engineering (1995) Limited of 11Station House - 111 Old Hope-Princeton Highway, Hope, B.C. April 23, 2015

2.2 Station House (Current main floor):

The station house is a divided into three sections. At the east side of the main floor, there is akitchen and washroom area. The centre portion has lunch counter seating and stairs to the upperfloor. The west side of the main floor has the vaulted ceiling over the dining room.

2.2.1. Kitchen/washroom area:On the east side of the main floor has the kitchen and washrooms. The roof over the main floor isframed with sloped 2x8 rafters at 16 inches on centre, spanning to the north and south of a centre,east-west ridge in the roof. The horizontal north-south ceiling joists (collar ties) are a mix of 2x6and 2x10 joists spanning across the building. For framing, see “Flat Ceiling” area on Drawing S-3. The ceiling joists also function as a collar tie or tension tie which connects the ends of the roofrafters across the width of the building (See Detail 2 on Drawing S-6). At every fourth sloped rafter,2x4 diagonal web framing was added between the sloped rafter and the ceiling joist. (See Detail2 on Drawing S-6) This appears to be an attempt to construct a roof truss every 4 feet. See photos#1 and #2. Unfortunately, the web framing was not correctly designed nor constructed to functionas a truss therefore we have ignored this framing in our analysis.

1. Roof framing above kitchen. 2. Roof framing above kitchen.

2.2.2. Centre portion:The centre portion of the building has a small upper floor above the main floor. The upper floor was constructed with 2x10 floor joists spanning in the east-west direction. Four rows of built-up2x10 drop beams were installed in the north-south direction to support the east-west floor joists. Each row of drop beams spanned from the north and south exterior walls to a built-up post near thecentre of the building. For framing, see “Upper Floor” area on Drawing S-3.

The roof above the upper floor was constructed with 2x6 sloped roof rafters spanning from the north


and south exterior walls to a centre ridge. A collar tie, or tension tie was located approximately halfway up the span of the sloped rafter. (See Section A on Drawing S-4). For framing, see “UpperRoof Framing Plan” on Drawing S-4. See photo #3. At the two main windows at the north andsouth sides of the upper floor, dormers were constructed in the roof at each window. See photo#4.

The ceiling of the upper floor was attached to the underside of the sloped rafters at the north andsouth sides of the room, and the underside of the horizontal collar ties above the centre of theroom. The perimeter walls of the upper floor were all constructed with 2x4 studs at 16 inches oncentre.

3. Upper floor roof framing exposed. 4. Dormer at upper floor roof.

The overhang on the north and south sides of the upper floor roof were framed with either 2x4 or1x4 outriggers nailed onto the side of the existing 2x6 sloped rafters. The outriggers were notinstalled with sufficient back span (or enough lap) onto the side of the sloped rafters. This conditionis not a life safety issue therefore it may be addressed from the exterior side at a later date. However, if the ceiling is being removed to install the additional sloped roof rafter, it would be mucheasier to install the outriggers if there is access from the interior. We have indicated this repair tobe a separate price from the other items shown on the drawing. See Section A on Drawing S-4.

2.2.3. Dining Room (vaulted ceiling area):The west side of the building at the main floor dining hall has a vaulted ceiling at the roof above themain floor dining room. The roof framing consists of 2x8 sloped rafters at 16 inches on centre,spanning north and south of a centre ridge in the roof. It appears that the vaulted ceiling was notpart of the original building construction. It was a renovation that involved removing the originalceiling joists, and installing new 2x6 sloped ceiling joists (to vault the ceiling) below the roof rafters. The slope of the vaulted ceiling appears to be approximately half of the slope of the roof rafters. The ceiling joists were spaced at 32 inches on centre and supported half way up the slope, from


the roof rafters with 2-2x6s and hung from the ridge with 2-2x6s. (See detail 1 on drawing S-6). See photos #5 and #6.

5. Vaulted ceiling above dining room. 6. Roof framing above vaulted ceiling.

The west wall of the dining room was the original exterior wall of the building. An addition wasconstructed onto the west side of the original building, below the roof overhang. We were informedthat this addition was going to be removed. Therefore, we did not review the framing of thisaddition.

7. West elevation. 8. View from southwest.

Addition to beremoved

Addition to beremoved


2.3. Roof Overhang:Around the perimeter of the roof above the main floor, an overhang was framed to extend the roofslope, beyond the exterior wall. The overhang was constructed with 2x6 sloped roof raftersprojecting outward from the wall of the building. The sloped rafters were supported by a 2-2x10drop beam near the edge of the roof overhang. Wood brackets were installed between 8' and 14'apart around the perimeter of the building to support the 2-2x10 drop beam. (See detail 4 ondrawing S-5).

2.4. Main floor framing:The main floor framing consists of 1 ½" thick plank decking installed over 2x12 floor joists at 16"on centre. The floor joists span from the north and south exterior walls of the building and aresupported by an 8x12 drop beam near the centre of the building. The 8x12 drop beam wassupported by a row of 6" diameter steel columns spaced at approximately 14 feet apart. To connectthe 8x12 beam to the top of the steel column, a piece of steel channel was installed on theunderside of the 8x12 drop beam. A vertical bolt was welded to the steel channel and extendeddown approximately 4" to a steel plate on top of the steel column. See “Existing beam to columnconnection” on Detail 2 on Drawing S-5.

The basement level which was constructed in the 1980s, consists of a concrete retaining walls atthe west, south and east sides of the basement. With the main floor at grade level on the southside of the building, the retaining wall on the south side of the building is retaining soil for the fullheight of the wall. At the east and west retaining walls, the soil slopes down to the north. The northwall of the basement is above grade. This wall appears to be framed with 2x6 studs at 16 incheson centre.

We had the contractor dig down at the north side of the basement wall to determine the depth ofthe footing. The north wall of the building appears to be an eight inch thick concrete wall extendingapproximately 7 feet below grade. We were informed by the engineer that designed the 1980sretaining wall, that the foundation on the north side of the building is deep because the area to thenorth of the building was built-up with soil brought in to raise the level of the site.


3.0 Review:Using the snow and live load requirements in the current building code, we calculated the loadingrequirements on the building based on a Part 9 building used as a museum. We did not includeany lateral (wind or seismic) analysis of this building based on the comments from the buildingofficial (Ms. Dawn Gillingham) on the Kerkhoff Engineering Report dated December 11, 2014. Wefound the following areas in the building where modifications are needed to satisfy the currentgravity load (snow and live load) building code requirements.

1. Roof over upper floor: The upper floor roof shown on drawing S-4, requires an additional2x6 sloped rafter to be installed onto the side of the existing collar tie. Where the new 2x6,the existing collar tie, and the existing 2x6 sloped rafter all intersect, this connection mustbe strengthened with screws which pass through all three members. See Section A onDrawing S-4.

2. Upper floor framing: The existing 2x10 floor joists supporting the upper floor are adequate. However, the built-up drop beams spanning in the north-south direction are over stressed. On Drawing S-3, we have indicated the number of additional 2x10s that must be added tostrengthen the existing drop beam. Additional studs supporting the additional 2x10s bothat the centre post, and at the exterior walls, must be installed.

3. Roof over dining room (vaulted ceiling): We reviewed the conditions at the vaultedceiling. It appears that the vaulted ceiling was constructed during a renovation of the roofframing where the horizontal ceiling joists (collar ties) were removed in order to constructthe vaulted ceiling. The horizontal ceiling joists (collar ties) are tension members whichresist the horizontal thrust created by the sloped roof rafters. When the ties were removed,the horizontal thrust of the sloped roof rafters, caused the top of the exterior walls to deflectoutward.

In some locations, we measured the top of the wallto be leaning outward at the top by three inches. See photo #9. This condition must be repaired. There are two options to repair this condition.

9. Line of laser level is at bottom of wall.


Option A: The vaulted ceiling can remain with a new, drop beam installed below the ridge of thevaulted ceiling.

1. The sloped roof rafters would need to be supported at the centre of the roof (underthe ridge) with a new drop beam under the vaulted ceiling. Additional framing willneed to be installed into the attic above the vaulted ceiling, in order to transfer theload of each roof rafter down to the new drop beam.

2. The displacement at the top of the exterior walls would need to be repaired. The topof the walls will need to be pushed back to return the wall to vertical. As the wallsare pushed back to vertical, the new drop beam will likely need to be installed withtemporary shoring jacks under the beam. The drop beam will need to be raised(jacked up) as the exterior walls are pushed back.

3. Since it is too far to span a new drop beam for the full length of the vaulted ceiling,we have indicated a new, interior post to be installed to reduce the span of the newdrop beam. We have located the post, near a post in the basement to reduce theimpact of the additional load, on the drop beam under the main floor framing.

We have assumed that the owners wished to retain the vaulted ceiling so our drawings haveindicated this repair. See Drawing S-3.

Option B: The vaulted ceiling could be removed and the original flat ceiling can be reinstated. 1. New, horizontal ceiling joists (collar ties) would need to be installed. 2. The ceiling joists would not be able to span the full width of the building therefore,

a line of east-west beams and posts would be required near the centre of thebuilding to support the ceiling joists.

3. The displacement at the top of the exterior walls would need to be repaired. The topof the walls will need to be pushed back to return the wall to vertical.

In our opinion, this repair would be more expensive than the repair in Option A, therefore we didnot show this repair option on our drawings.

4. Roof over kitchen and washroom: We analyzed the roof framing above this area of thebuilding and found it will require some minor modifications. We have assumed that theexisting partition walls at the kitchen and washrooms will remain. These walls help supportthe ceiling joists to prevent them from sagging.

Some of the existing ceiling joists are not continuous across the width of the building. Inthese locations, an additional 2x6 collar tie is required to provide a continuous tie across the building, from sloped rafter to sloped rafter. At each location where the existing or newcollar tie, laps onto the side of the sloped rafter, additional screws are required to strengthenthis connection. See Detail 2 on Drawing S-6.

5. Roof overhang and wall brackets: The roof overhang outside of the exterior walls, was


supported at the building wall with brackets spaced around the perimeter of the building. See photos #10 and #11.

10. Wall brackets on north and east walls. 11. Wall brackets on south elevation.

12. Connection of horiz. member to 13. Connection of knee brace to vertical member. horizontal member

The brackets were constructed with a vertical 4x6 which was fastened to the building wall and ahorizontal 4x6 which was supported with a knee brace. See photos #12 and #13. Each bracketwas intended to support the 2-2x10 beam near the edge of the roof. See photo #13. The verticalload from the 2-2x10 beam pushes down on the end of the bracket. The horizontal member at thetop of the bracket is carrying a tension load and is trying to pull away from the vertical member. Thediagonal knee brace is a compression member to counteract the tension force from the horizontalmember and the vertical force from the 2-2x10 beam. In some areas, we found that the horizontalmember is starting to pull out from the vertical member. See photo #12. It appears that a squarehole was cut into the vertical member and the end of the horizontal member was cut down to asquare shape to slide into the square hole in the vertical member. We did not find any fasteners to

Wall brackets

2-2x10 Beam

Vertical 4x6 Knee brace

Horizontal 4x6


connect these two members.

The brackets create a torsional load (bending) and shear force (vertical force) on the wall, thereforethere needs to be structural framing in the wall to resist these forces. We opened a small hole onthe interior side of the wall behind the bracket and found the bracket was bolted to a horizontalmember, spanning between 2x4 studs. We calculated the load supported by the bracket and foundthe following:

1. The 2x4 studs in the wall behind the bracket are over stressed due to the torsionalforces created by the bracket. We recommend a solid wood 6x6 post be installedinto the wall to span from the floor to the roof. At the corners, a 4x6 post can beused since the amount of load on the corner brackets is less.

2. The tension load in the horizontal 4x6 requires hardware or fasteners to transfer thehorizontal load, to the 6x6 post in the wall. We recommend a steel strap be installedto connect the horizontal member to the 6x6 post. The strap may be painted blackor another colour as recommended by the museum.

3. The vertical 4x6 must be bolted to the new 6x6 post to transfer the shear force in thebracket, to the new post.

4. The 2-2x10 beam near the edge of the roof that spans between the brackets is overstressed. An additional 2x10 must be added to the beam.

All of the above recommendations are shown in Details 4 through 7 on Drawing S-5.

6. Main floor framing:Based on a museum use for this floor, we calculated the capacity of the existing floor framing. Theplank decking and 2x12 floor joists are adequate. However, the row of 8x12 beams that are nearthe centre of the building are over stressed. The existing 8x12 beam would have to be replacedwith a 7"x14" Parallam beam.

Also, the current connection at the top of the steelcolumn to the 8x12 beam must be repaired. The8x12 beam bears on a piece of steel channel. Thesteel channel has a single vertical bolt at the centreof the channel that extends down to a steel plateon top of the steel column. All of the verticalsupport for the beam is provided by the single,vertical bolt. See photo #14.

14. Steel column connection to 8x12 beam.

8x12 Beam

Steel channel

Bolt

Steel Column


The new Parallam beam will require a new connection between the top of the steel post and thenew Parallam beam. This would eliminate the existing connection at the top of the steel column. We have shown the new connection for the Parallam to the existing steel column in Detail 2 onDrawing S-5.

4.0 Specific questions:

1. Can the upper floor be demolished so that the current upper floor roof can be made into ahigh, vaulted ceiling above the main floor?

Currently, the upper floor acts as a diaphragm. A diaphragm is essentially a horizontalbeam which transfers horizontal load (wind and seismic loads) to vertical elements such asexterior and interior walls. In this case, the upper floor is providing lateral support for theexterior walls. See section A on drawing S-4. The studs at the exterior walls are notcontinuous through the upper floor. The top of the main floor studs, terminate at the upperfloor, and the bottom of the upper floor studs also terminate at the upper floor. If the upperfloor is removed, the exterior walls would have a joint at the upper floor where there studswould not be supported. Therefore, the upper floor cannot be removed.

The stairs to the second floor can be removed and replaced with a ladder access. Theupper floor would then be used for storage only.

2. Can a balcony be constructed on the north (rear) side of the building?

We analyzed the strength of the existing foundation under the north wall of the building and a balcony can be attached to the north side of the building. We have assumed that thebalcony framing would be attached to the north wall of the building, and have beams, postsand footings at the north edge of the balcony. Based on the remaining additional capacityin the existing footing under the north wall of the building, we estimate that a 12 foot widebalcony could be constructed. The new footings for the north edge of the balcony wouldhave to be excavated down to native, undisturbed soil. Since much of soil was fill broughtin to build up the site and based on the depth of the footing of the building, these footingswould likely have to be excavated down, several feet. A geotechnical engineer would haveto be consulted to determine when adequate bearing soil is reached. We have based ourestimate on a light, wood framed balcony without heavy finishes such as concrete paversetc.


3. Can concrete topping be installed on the main floor?

We checked the capacity of the main floor joists and found that a 1 ½" thick concretetopping would be too heavy to install on the joists without either adding additional joists, oradditional drop beams, columns and footings in the basement.

4. Can the new display cases, currently stored at the visitor centre, be installed on the mainfloor?

We documented and measured the new display cases and calculated the weight of eachcase. The cases can be installed anywhere on the main floor provided the items displayedin the case do not weigh more than 400lbs for the display case that is 4'x4' in plan, and800lbs for the display case that is 4'x8' in plan.

The display cases currently have a leg that is a 1 ½" square steel tube. The steel tube legmay dent the wood floor. Also, since the display cases are tall and heavy, they must beanchored to the floor to resist tipping over or sliding during a seismic event. Werecommend that an approximately 6"x6"x3/8" thick steel plate be welded to the bottom ofeach tube to:a. Spread the weight of the display case over a larger footprint area to prevent the leg

from denting the floor.b. Provide holes in the plate to anchor the display case to the floor.A structural engineer should be retained to design the correct size of base plate andanchors. The design of the base plate and anchorage to the main floor will depend on theweight of the case plus the contents.

Please contact us if you have any questions regarding this report.

Reported by: Dan Kunimoto, P.Eng. Reviewed by: Joselito Manrique, P.Eng

Enclosures: Drawings S-1 through S-6 dated April 23, 2015.

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