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Home My WebLink About808 W PROSPECT RD - SPECIAL INSPECTIONS - 10/5/2016. I N C O■ P O■♦ T E■ October 5, 2016 Christian and Robin Bachelet Maxiimo Development Group 706 S. College Avenue Fort Collins, CO 80524 Subject- Review of Concrete Integrity of Existing Slab (/808 West Prospect Road, Fort Collins, Colorado Project Number: FC07161-501 L2 Dear Mr. and Mrs. Bachelet, In late December of 2015, CTLIThompson produced a letter report regarding the existing elevated concrete slab at the site referenced above (CTLIThompson project number FC07161-501 1-1, dated December 10, 2015). We have recently been requested to review the existing foundation walls and comment on their Integrity and ability to support the proposed structure Protect Background In 2008, the foundation and main floor composite slab for an apartment complex were constructed Shortly after these items were built, a lumber package for the proposed apartments was delivered, but never installed That lumber package was later removed and the concrete slab was left exposed to the elements, and remains exposed to the present date. The foundation system was also left partially exposed, although the presence of backfill and the elevated slab protected the foundation from most of the weather extremes. At this time, we understand that a revised set of building plans has been submitted to the City of Fort Collins for review and a building permit may be granted shortly. The building department has asked for confirmation that the existing foundation is sufficient for the proposed structure. Structural Background The existing foundation walls are generally 12" thick doubly reinforced concrete walls, with some thinner walls at partitions and window wells. We understand that the structural system for the proposed building will be the same as the structural system (loads and load paths) that was initially planned. Therefore, the design loads on the existing foundation walls have not changed and the only concern is to confirm that the foundation integrity has not been compromised since original construction. Site Assessment For the elevated concrete slab, cores were taken and tested in compression Those strengths were found to be well in excess of the design strength of 3500 psi. At the same time, rebound hammer tests were made on site to get a qualitative comparison to the core strength Those tests returned numbers in the upper 40's to low 50's On October 4, 2016, personnel from our office visited the site to assess the foundation walls. We 400 North Link Lane I Fort Collins, Colorado 80524 Telephone 970-206-9455 Fax 970-206-9441 used the rebound hammer again and got consistent results in the 40's and low 50's. Those correlate to 4500+ psi concrete for the in place concrete, while the original required design concrete strength was only 4000 psi. A visual observation of the complete inside face and top outside face of the foundation walls was performed as well. In general, there was some minor vertical cracking observed that is indicative of typical concrete shrinkage cracking. There are also some horizontal cracks located at cold joints in the original pour. Cold joints occur when a lower lift of concrete begins to set before an upper lift can be worked into the forms. Water staining was observed at the cracks where surface water drains from the main floor slab and down the walls. We did not observe diagonal cracking that would possibly indicate differential movement. There is notable concrete distress at one of the southwest building corners (see Figure 1), The damage appears to be weathered and rust has formed on some of the rebar, indicating that the distress occurred years ago. Figure 1: Damage at Southwest Corner of Foundation Although dampproofing is not a structural element, we did note that some portions of the foundation have not been dampproofed to an elevation above final grade (see Figure 2). Those areas should be addressed to improve long term performance of the foundation. 2 MAXIIMO DEVELOPMENT 808 WEST PROSPECT ROAD, FORT COLLINS, CO CTL I T PROJECT NO. FC07161-501 L2 Figure 2: North Side of Foundation; Missing Dampproofing in Background nions and Recommendatio Based on our observations and the results of our testing, the foundation has maintained its integrity and will still perform as intended. The minor cracking observed is typical and is not a concern since the reinforcing steel is design with the expectation of concrete cracking. Our opinion is based on the data and observations listed above. To recap, these include: • Consistently high results from rebound hammer and earlier correlation to slab core tests. • Relatively minor amount of cracking or weathering. • The fact that the slab and backfill protected the walls from weathering. • The fact that the mass of the concrete would have allowed it to cure even in colder temperatures. The damaged concrete at the southwest corner should be exposed, cleaned and repaired. We recommend using a patching mortar such as Sikatop 111 Plus, using Sika®Armatec®110 EpoCem to pretreat the exposed rebar. All products shall be applied / installed in accordance with all manufacturer's printed installation instructions. (Note: This repair does not need to be complete prior to new construction activities, but must be complete before a certificate of occupancy is awarded.) We also recommend repairing any damaged or missing dampproofing systems (dimpleboard and /or spray -on membrane). The footings beneath the walls were not visible at any location. Since they were also protected by the basement slab, the elevated slab, and backfill, we are also confident that their integrity has not been compromised. Therefore, they are also acceptable for use. Limitations This report is based upon our site observations and our experience with projects of this type. Unseen defects may exist which could affect the performance of the structure. We believe this investigation was conducted with the level of skill and care used by structural engineers practicing in this area at this time. No warranty, express or implied, is made. 3 MAXIIMO DEVELOPMENT 808 WEST PROSPECT ROAD, FORT COLLINS, CO CTL I T PROJECT NO. FC07161-501 Thank you for selecting CTLITHOMPSON for your engineering needs. When we can be of additional service, please contact our office Very truly yours, CTLITHOMPSON, INC. Wayne Thompson, PE, LEED AP Oct 5 2016 7.45 AM Project Manager 4 MAXIIMO DEVELOPMENT 808 WEST PROSPECT ROAD, FORT COLLINS. CO CTL I T PROJECT NO FC07787.507 L2 June 15, 2017 Mr Mike Gebo Chief Building Official City of Fort Collins Building Services Department 281 N College Ave Fort Collins, CO 80522 RE: Variance Request regarding us of two non -conforming shower sizes The Slab, 808_W. Prospect r/ Fort Collins, Colorado Project No.1520 Dear Mike The intent of this letter is to request a variance for the shower size in two(2) Type B adaptable units at 808 West Prospect where the total number of units is sixty(60), including two(2) Type A accessible and fifty eight (58) Type B adaptable The variance request is as follows and would apply to two(2) first floor studio apartments 1 We are requesting approval of two shower sizes total in two separate Type B adaptable units to be reduced to a 36"x36" outside dimension size During construction, it was discovered that the plumbing for these showers fell directly over previously existing beams and because of the clearances necessary within the bathroom, the framing for the shower yielded a rough opening of 37" wide x 38 %" deep Because a 36"x36" clear interior dimension shower required by code requires a 38 %" x 38 %" rough framing dimension, we are finding ourselves not able to meet the letter of the code by 1-1/2" in these two locations Please feel free to contact me if you have any questions or comments regarding this Variance Request and thank you for your consideration in this matter Sincerely, Bj/o�D alm2s i "19— Karen Szelei-Jackson, AIA cc Robin Bachelet