ARNOLD AND

O’SHERIDAN INC

CONSULTING ENGINEERS

 

September 24, 1998

 

Mr. Mike Bailey

150 Shaw Street

Lansing, IA 52151

 

RE:       OLD STONE SCHOOL

Lansing, Iowa

A&O Project No. 98287

 

Dear Mike:

 

On September 16, 1998, I visited the school to assess the structural condition of the north exterior wall. The wall contains the main entry door and five windows.

 

Building Construction

The building was originally constructed in the 1860's. It is unknown if the area in question was original construction or a later addition. The building is wood framed and supported by bearing walls. The exterior walls are surfaced with cut limestone. The inside surface of the walls was covered with wood sheathing. It is suspected that uncut limestone is used as the back up material for the cut limestone facing.

 

Building Condition

Observations were made best as possible without removal of existing building materials. Observation of the inner masonry layer of the exterior wall was not possible because of the wood facing. Evaluation of the foundation was made through a crawl space entry in the east wall. The excavated area encompasses only the east half of the central portion of the building. The foundation under the north wall was thus not observable.

 

The foundation system is stone masonry. The masonry widens at the base to create a footing at roughly four feet below grade. The mortar has been largely leached from this wall as is typical of foundations of this type and age. The continued stability of the foundation relies on its thickness and mass as it is no longer bonded together.

 

The outer face of the exterior walls are parged below window level with what appears to be three layers. The purging resurfaces what is expected to be a deteriorated outer face of stonc. The deterioration is typically caused by moisture absorption and freeze thaw cycling. The moisture would come from absorption from adjacent soil (rising damp) and from the splash of roof water coming over plugged or leaking roof gutters. Disconnected gutters have caused undermining of the sidewalks and steps and they now direct surface water back toward the building. This then

 

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Mr. Mike Bailey

Re: Old Stone School                                                                                                                                                              Page 2

 

contributes to the continuing face deterioration of the stone. The foundation is also affected as

the water deteriorates the mortar bonding the stones together.

 

We understand that no heat has been provided to the building since 1973. This lack of heat raises the interior moisture levels causing obvious damage to the wood floors. A more subtle deterioration occurs in the exterior walls. The interior moisture tends to migrate through the wall. With cooler weather, this moisture freezes inside the wall and causes the facing of the limestone blocks to spall off.

 

Window and door units set in the walls are placed without flashing and caulks that are common today. The original builders relied on mortar at the perimeter of openings and close tight fits to keep water from entering the wall. In this building, wooden lintels were used at window and door heads. As the wood tends to change dimension responding to varying humidity, the perimeter joints tend to open. This aliows moisture to enter the wall. If water gets deep enough into the wall, entire stones can be pushed out as its happening adjacent to the front door.

 

Problems Particular to the North Wall and Their Solution

 

Repair Item 1 - bulge in stone wall adjacent to entry door

The repair for this situation would involve removing stones from the wall starting on the outside surface. Stones would be removed until a solid wall section was encountered. This conceivably could involve repair of the entire wall thickness. Stones would be removed from the wall and relayed using mortar compatible with the original. Stones would be reused as much as possible with broken ones obviously requiring replacement. The wall would be rebuilt from roughly midheight of the window on down.

 

Repair Item 2 - bowed wall at secondfloor level

A second and unrelated problem is the bowing outward of this wall. At the horizontal stone band at what would be the second floor level, outward movement is noted. Evidence of the movement is easily seen at the stair run inside the wall where a gap has opened adjacent to the stair treads. Additional observations include vertical cracks on the outside face of wall extending from window head to sill. A horizontal string line pulled at the second floor on the outer face of the wall shows this lateral movement beginning at east and west window jambs. Movement outward is estimated at 2-2½".

 

Two wall anchors (large bolts with serpentine washers) are present above the first floor windows. They have, however, been cut though and serve no function anymore. These anchors suggest that a section of floor may have been removed to place the stairs.

 

The cause of wall movement is attributed to:

a)      The number of openings in the wall

b)      Lack of a floor system at second level to laterally stabilize the wall

c)      General reduction in wall strength due to water entry and associated deterioration of mortar

 

Mr. Mike Bailey

Re: Old Stone School                                                                                                                                                              Page 3

 

Two options are conceived for repair of this wall. The first and cheapest is to stabilize the wall

in its present position. To accomplish this, we would propose placement of a steel member horizontally behind the wall at roughly the second floor level. The steel section would be full width of the building and probably be placed through an opening cut completely through the east or west wall. The wall would then be tied into this beam and regain its lateral stability. This option is relatively inexpensive but has certain drawbacks:

 

1)      Intrusion of steel beam into the stair run. Stair width versus existing requirements would have to be verified.

2)      Disruption of wood interior by the steel beam. This would require trim work to conceal the beams presence.

3)      This solution stabilizes the wall but does not bring it back into its original position.

 

The second repair option then would be to rebuild the area of the wall where the bowing is occurring. This would involve full thickness rebuild of the wall to return it to its original position. It is felt that the steel beam would again be added under this repair scenario to insure long term stability.

 

Repair Item 3

As previously noted the base of this wall is also deteriorated. Again this is a result of surface water intrusion. Our repair solutions for this would involve:

a)      Proper gutters at the roof. Proper direction of down spouts to move roof water away from the building.

b)      Removal of concrete sidewalk and concrete step units at two doors. These elements are presently cracked and directing water back to the foundation.

c)      Excavation of the north (front) wall to expose the foundation from the outside.

d)      Rebuilding of wall as required from its base. This may involve full or partial thickness replacement. Facing stones would be replaced to give an as new appearance.

e)      Installation of full thickness flashing, if possible, to limit rising damp.

f)        Installation of vents in the front wall (if appearance acceptable) to ventilate the crawl space. .

g)      Replacement of concrete walks and stairs with proper drainage away from the building.

 

Cost Estimate

The estimate is essentially directed at the north wall. It assumes work done by a larger restoration contractor paying prevailing wages. The costs are in 1998 dollars. It would be noted that a significant contingency would need to be carried to handle unknown situations.

 

1) Repair Item 1. Repair wall adjacent to door - an area of a

     proximately 2 feet x 4 feet                                                                                              $ 1,400

 

_Mr. Mike Bailey

Re: Old Stone School                                                                                                                                                              Page 4

 

2) Repair Item 2.

      a) Stabilize wall in place. Includes placement of steel

           beam and attachment to wall, also repair to wood

           sneathing on inside surface.                                                                     $7,000

      b) Option to above - rebuild wall to eliminate bow.

           Stabilize with steel beam as noted above.                                                $20,000          

 

3) Repair Item 3

      a) On north wall and around comer on east side to first

           door. Remove and replace concrete steps at two doors.

           Remove and replace sidewalk in local area. Rebuild

           wall below window all along north side and east side

           around corner to door. Rebuild outer wythe of wall

           down to footing. Gutters and downspouts are not

           included in this cost.                                                                               $16,000

 

I trust this report is helpful in your efforts to stabilize this building. It was a pleasure to travel to Lansing again. Please call me if you have any questions.

 

Sincerely,

 

Arnold and O’sheridan, Inc.

Consulting Engineers

 

Robert B. Corey, P.E.

Senior Structural Project Engineer

 

RBC/kkm