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HomeMy WebLinkAboutEngineer's Field Observations 12.31.2014KURTZ & ASSOCIATES. INC. 5012 County Road 154 Glenwood Springs, CO 81601 STRUCTURAL CONSULTANTS Phone & Fax (970) 945 6305 FIELD OBSERVATION REPORT To; Nicholas Pisto 29 Goldfield Court Parachute, Co. 81635 Date: Dec. 31, 2014 Re: 109 Mosher, Travelers Highlands Industrial Park, Garfield County, CO. Brian Kurtz, P.E. of Kurtz & Associates, Inc. performed a structural inspection of the noted building on Dec. 31, 2014. The noted building has suffered differential foundation settlement. The building measures, in plan, 64'-0" north -to -south by 30'-0" east -to -west. The exterior wall height of each building = 16'-0". The exterior walls are constructed of 8'-0" wide by 16'-0" high precast concrete wall panels. The roofs are framed with pre - manufactured wood roof trusses spaced at 24" on center, spanning 30'-0" east -to -west. The perimeter foundations were not exposed to view. Based upon previous observations which I have made of similar buildings in the Travelers Highland Subdivision, it can be concluded that the structure is founded upon a perimeter foundation system which is constructed of continuous concrete foundation walls (grade walls) and footings. Note that all of the building's loads (The building weight or dead load and the roof snow load) are supported on the perimeter foundation walls and footings. There are no interior supports. Given the height of the building, and the rigidity of the concrete wall panels, one is able to view differential movements of the walls. Note that some of the exterior wall panels have window openings and man -door openings which were formed into the pre- cast panels. The subject building has three (3) locations where the precast panel was omitted to accommodate a garage door opening:. 1, There is a 12'-0" wide by 14'-0" high garage door opening centered on the south end of the building. 2. There is a 14'-0" section of framed wall centered on the north end of the building (This framing perhaps in -fills a garage door opening). 3. There is a I2'-0" wide by 14'-0" high garage door opening on the east side of the building. The interior concrete slab -on -grade floor at 109 Mosher displays differential settlement. I utilized a surveyor's self leveling level to establish differential slab displacement. The slab is divided with a series of construction joints. Joints running east- (2) to -west across the building are spaced at 16'-0" on center. There are two (2) north -to - south joints dividing the slab in that direction into three (3) sections. The center section of slab is 12'-0" wide, and the east and west sections are 9'-0" wide. The high point of the slab is the northwest building corner. The low point of the slab is S'-0" south of the northeast building corner. The low point is 12" lower than the high point. The difference in slab height along the 64'-0" long east wall is 4". 'Mc difference in slab height along the west wall is 8.1/2". It is very likely that the perimeter foundation has suffered differential foundation settlement, and that the edges of the interior slab on grade have been pulled down with the perimeter foundation. The differential foundation settlement is being caused by the weight of the building and intermittent, excessive ground moisture. The natural, on sight, soils are fine grained silts and clays which are prone to settlement when wetted excessively. The building's weight is also a significant factor contributing to the differential settlements. Note that the building weight, including the foundation (concrete footing and grade wall), the 16'-0" high pre -cast wall panels, and the wood framed roof equals approximately 1300 PLF. The two (2) garage door openings and the framed section of wall on the north side of the building are much more flexible than the pre -cast wall panels. Consequently, much of the differential foundation movement is reflected in the noted door openings and framed section of wall: the door openings and the doors are out of square. The differential movements have caused the exterior wall panels to wrack. The panels along the west wall display a separation at the vertical panel joints (At 8'-O" on center) and some amount of cracking of the panels. Along the east, north and south walls the panels do not display significant cracking. Along these three (3) walls the differential movements are absorbed in the 12'-0" wide garage door openings. RECOMMENDATIONS It is my professional opinion that the building, at this time, is in acceptable structural condition, and is not in danger of sudden collapse. Consequently, temporary shoring is not recommended at this time. The building owner, as part of his building maintenance program should, at the northeast section of the building, examine the precast wall panel to foundation wall connection. He may wish to consider jacking the precast wall panel up off of the foundation in this area: i.e. extending from the northeast building corner, the 8'-0" long panel at the north wall and the 8'-O" long panel at the east wall. He should verify that continuous bearing of the panel is being maintained at the top of the foundation wall and that there is no visible cracking or distress of the precast concrete where the panels are (3) bolted to the foundation wall. In this same portion of the building the roof truss to wall panel connection at the top of the wall panels should be examined to verify that the trusses are in good condition and that the truss to wall connection is in good condition. At present, the surface drainage conditions are contributing to excessive ground moisture adjacent to the building. The present and natural site drainage is down to the south towards the Colorado River. Finish grades on the north side of the building and on the east side of the building near the northeast corner are such that surface water tends to pond in close proximity to the building. The installation of drainage system which directs surface and subsurface water away from the foundation represents a proven method of mitigating future differential foundation settlements. In the case of the subject building, a subgrade drainage system along the north side of the building and along the north end of the east side of the building could, as part of a building maintenance program, be installed to intercept and divert surface and near surface water. The drainage system should include an impervious membrane and a perforated drain pipe with a gravel and filter fabric surround. The drain pipe should extend well away from the foundation and carry the excess water to a drywell via a solid walled pipe. Continuous roof gutters are installed on the east and west sides of the building. Each gutter runs to a downspout at the south end of the building, and each downspout deposits roof runoff within 18" of the building foundation. The downspouts should be extended so as to deposit roof runoff as far from the building foundation as is practicable. In that the south wall has settled differentially relative to much of the building, you may also wish to consider a concrete apron slab along the south wall to divert surface moisture away from the building. If you have any further questions, feel free to call. Kurtz & Associates, Inc. Brian J. Kurtz, P.E.