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Home My WebLink About520 N Sherwood St - Special Inspections/Engineering - 08/03/2012180 I N C O R P O R A 7! D August 3, 2012 River Rock Commons 520 North Sherwood Fort Collins, Colorado 80521 Attention: Don Flick Building Maintenance Committee Subject: Structural Engineering Consultation Deck Guardrail Post Replacement River Rock Commons, 520 N. Sherwood CTLIT Project Number: FC05954.000-501 L1 Dear Mr. Flick, Per your request, we made a site visit to the site referenced above on Wednesday, August 1, 2012. The purpose of our visit was to observe existing conditions of a deteriorated deck guardrail post and recommend an appropriate structural repair. Observations The second story deck consists of 2x10 joists at 16" o.c. supported by a (2) 2x12 rim beam. The rim beam is supported by 8" dia. log columns. The existing columns are continuous from the grade up through the deck and extend 4'-0" above the joists. The columns also serve as posts for the guardrail system. During our site visit, we observed the column in question at its guard rail connection above the deck surface. We understand that it is your intent to remove and replace the damaged section of column. Discussion/Recommendations We recommend removing the top portion of the column, beginning at about 2 inches above the bottom of the rim beam, and replacing it with a new 8 inch diameter log post. The bottom of the post should be squared to 4"x4", minimum. Two Simpson DTT2Z-SDS2.5 connectors should be installed onto the existing 2x10 joist per the attached details to support the new rail post. The exposed end of the existing column should be protected with sealant and ice/water shield. Limitations Our scope of services in this project is limited to the post referenced above. This report is based upon our site observations, a review of the documents provided (if any), 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. Thank you for sel 0 TTHOMPSON for your engineering 41Vhen we can be of additional servi O�plege./ec r� t the undersigned. O RF.G� v: very truly yo r� O -�� •� TH 'ST�9 CTLITHOM SQL, IN,G465 X : Reviewed By: 35177 Rae Doner, P 'r� ,OAIAI. G Wayne Thomp �� Project Engineer Project Manager F' SS/ONA� F� 351 Linden Street I Suite 140 1 Fort Collins, Colorado 80524 Telephone:970-206-9455 Fax:970-206-9441 INSTALL NEW SOLID BLOCKING SO THAT BOLTS ARE CENTERED IN POST, 48" LONG, ATTACH WITH (20) 16d NAILS EXISTING 2x10 DECK JOIST NEW 2x10 BLOCKING, 45" LONG, ATTACH WITH (20) Ibd NAILS "A' NEW 8" DIA. POST, NOTCH TO MIN. 4x4 SQUARE BELOW DECKING �— NOTCH POST TO ACCOMMODATE DECKING B I I I BY / /— EXISTING (2) 2x12 RIM BEAM BEYOND n EXISTING DECKING EXISTING 2x10 JOISTS 19 16" O.G. (2) 51MP50N DTT2Z-SDS2.5 DECK POST CONNECTORS, INSTALL PER MFR. EXISTING 8" DIA. POST, CUT OFF TOP OF P05T AND APPLY SEALANT AND ICE 4 WATER SHIELD TO EXPOSED END ELEVATION VIEW NEW 8" DIA. POST, NOTCH TO MIN. 4x4 SQUARE BELOW DECKING EXISTING 2x12 RIM NEW SOLID BLOCKING, EXISTING l2) 2x12 RIM BEAM 48 LONG, ATTACH W/ 2 SQUARE (20) lbd NAILS WASHERS 2" SQUARE EXISTING � WASHER ,5QUA, NOTCH TO MIN. 4x44 SQUARE DECKING BELOW DECKING EXISTING 2xl0 o o o ° o DECK OIST - ° o I � o O o o O 48" MIN z REMOVE EXISTING (2) SIMPSON DTT2Z-SD525 BLOCKING DECK POST CONNECTORS, v INSTALL PER MFR. (2) SIMPSON DTT2Z-SDS2.5 DECK POST CONNECTORS, EXISTING (2) 2x12 RIM BEAM INSTALL PER MFR. REMOVE EXISTING RIM J015T FOR NEW SOLID BLOCKING ALL -THREAD INSTALLATION, NOTCH TO HIDE BOLTS EXISTING 2x10 DECK JOIST EXISTING 8" DIA. POST, CUT OFF SECTION B-B TOP OF POST AND APPLY SEALANT AND ICE 4 WATER SECTION A -A (PLAN VIEW) SHIELD TO EXPOSED END River Rock Commons 520 N. Sherwood Fort Collins EFSTRUCTURAL ENGINEERS CTL 1 THOMPSON INCORPORATED I P:970-206-9455 351 Linden Street, Suite 140 F:970-206-9441 Fort Collins, CO 80524 www.ctIthornpsor.corn DRAWN. SHEET RMD PROJECT f 1 FC05954.000 DATE. OF 08/03/12 SCALE, 1 1 /4,=l,-0" • • ii'Mot d Rh III i N c o Q a o a a r c o September 6, 2012 River Rock Commons 520 North Sherwood Fort Collins, Colorado 80521 Attention: Paul Hegland Building Maintenance Committee Subject: Structural Engineering Consultation Deck Guardrail Post Replacement River Rock Commons, 520 N. Sherwood CTLIT Project Number: FC05954.000-501 L2 Dear Mr. Hegland, We previously made a site visit to the location referenced above to observe existing conditions of a deteriorated deck guardrail post. Following the site visit, we presented you a letter and repair design for the post (letter dated August 3, 2012). Since then, you have reviewed additional posts and two have been identified as deteriorated. This letter is in regards to an alternative repair design for the two additional deck rail posts at the subject location. You have requested that the alternative repair not involve removing any portion of the existing log column. Discussion/Recommendations We recommend installing two Simpson MSTI straps at each deteriorated post. The straps should be installed on the front and back sides of each post (on the outside away from the deck, and on the inside facing the deck). Each strap should be attached with (13) SD#9x2-1/2" long screws on the portion above the deck surface and (13) Simpson SD#9x2-1/2" long screws on the portion below (a total of 52 screws per deck post). It is the contractor's responsibility to probe the wood and determine where competent wood is located and where the deteriorated section at the deck is located. The straps should be long enough so that the deteriorated area is bridged and that the screws can be installed into fully competent material. As an alternate, thicker steel may be utilized with the same number of screws. Limitations Our scope of services in this project is limited to the two additional deteriorated posts referenced above. This report is based upon our site observations, a review of the documents provided (if any), 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. Thank you for additional servi Very truly CTLITHO Rae Doner, Project Eng CTLITHOMPSON for your engineering needs. When we can be of fggtact the undersigned. 46465 qi&/[?, OO RFG� ` e • 'TH S% Reviewed By: y• Wayne Thomooff;PE Project Manag&Q0X •., 35177 //Z 351 Linden Street I Suite 140 1 Fort Collins, Colorado Telephone:970-206-9455 Fax:970-206-9441