Tips to tell Concrete Buildings
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The document provides guidance on estimating the number of pre-1980 hazardous concrete buildings in California. It outlines collecting data on total buildings, concrete buildings, and pre-1980 buildings in specific jurisdictions. The volunteer surveyed Alameda using maps, library research, and walking tours to identify 126 verified pre-1980 concrete buildings, with 24 uncertain buildings. Additional effort could reduce uncertainties but was not required for the survey.
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Tips to tell Concrete Buildings
- 1. Dave McCormick Concrete Coalition Toolkit
- 2. What Are We Looking For? Number of hazardous concrete buildings in California. 1. 2. 3. Estimate number of pre-1980 concrete buildings in specific jurisdictions. ◦ Capture buildings constructed with 1973 UBC or earlier Extrapolate to estimate number in state. Perform studies to determine which are most hazardous. (PEER) Category Number Total Number of Buildings A Total Number of Concrete Buildings B Pre-1980 Buildings C Pre-1980 Concrete Buildings D
- 4. Concrete Building Types Count Data City Buildings X County Buildings Optional – Other Databases Available1 X State Buildings X Post Offices X County and State Courthouses X Federal Office Buildings and Courthouses X Hospitals Regulated by OSHPD X Utility-Owned Bldgs. Including Substations X X Grade K-12 Public Schools UC and CSU X Community Colleges X 1 volunteers must indicate if they counted these building types Do Not Count Data
- 5. Concrete Building Types Count Data Prisons X Special Districts including Pump Stations and Buildings at Treatment Plants X Churches X Port Buildings X Regional, County, and city Parks Optional – Other Databases Available1 X 1 volunteers must indicate if they counted these building types Do Not Count Data
- 6. Concrete Building Types Count Data Concrete Frame with Masonry Infill X 1-Story Cast-in Place Concrete with wood Roof (including walls with pilasters) X Concrete Shear Wall with Steel Gravity Frame X Mixed Construction2 Do Not Count Data X Wood-frame residential on Conc. Podium Optional – Other Databases Available1 X Tilt-ups X Dual System with Concrete Shear Wall3 X X Parking Garages Buildings Whose Concrete Elements are Limited to Fire Walls Between Sections X Buildings Whose Concrete Elements are Limited to Basement or Retaining Walls X Includes horizontal additions of concrete as well as buildings with concrete lateral load systems in one direction only. 2 Do not need to make exceptional efforts to verify whether a building has a dual system or not, but if you know, don’t count it 3
- 7. Concrete Building Types Count Data Retrofitted Buildings4 X Buildings in Areas Scheduled for Redevelopment X Building-like Nonbuilding Structures5 Do Not Count Data X Abandoned Buildings Optional – Other Databases Available1 X X Nonbuilding-like Nonbuilding Structures6 Concrete Structures Supported on Piers or Wharfs over Water X Buildings used for storage – No Occupancy X 4 Obtain approximate retrofit date is possible. 5 Includes campanile, substation and pumping stations. 6 Includes silos, tanks, bridges, canopies, covered walkways and monuments. Do not include concrete block buildings without concrete walls.
- 9. Strategy “Walk” the City (bike ride actually) ◦ Focus in commercial districts and where larger buildings are located Used knowledge of City Alternate approach would be to use Google Contact Building Official and ask for help ◦ Assessor data ◦ Zoning map ◦ Sanborn maps Visit library Re-walk part of the City Review Sanborn maps again Walk small part of the City one more time
- 10. Walk the City “Walk” the City ◦ Use knowledge of the City to: Identify the buildings already known to be concrete Look in likely locations like commercial districts ◦ Record data on form that would provide more than information currently required by the Coalition including photograph ◦ Troublesome areas: No access to some military installations Some buildings are conglomerations of building types Modified buildings Supplies – – – – – Map Clip board Camera Previous lists Panniers
- 11. Envisioned Survey Form Address Number Torsional? Frame of or Shear Stories Wall Photo Other 1 Main 2 Yes, corner building Frame with masonry infill 1, 2 Adjacent wood frame buildings with no gap at property lines 2 3rd St 2 No Shear wall 3, 4 See what appears to be wall anchors at roof 66 Oak 1 Yes, open front ? 5, 6 It looks like concrete, should verify 53 Elm 3 No Frame 7, 8 Looks like first floor is soft story, much greater floor height
- 12. Data Sheet Used No. of Stories 1 Irregularities Open front Occupancy Commercial Adjacency One side Condition No deterioration observed Comments Verified concrete Brick veneer Parapet bracing 1538 Webster/Alameda Pizza +
- 13. Tricks to Identify Concrete Buildings Walk behind the building – fewer architectural finishes ◦ Look for form boards Look inside Look for elevated floor/cripple wall – probably wood ◦ Vents Knock on wall Differentiate from tiltups Look for retrofit
- 14. 1546 Park Concrete in the back Looks like brick in front
- 15. 1328 Park Concrete in the back
- 16. Tilt-ups Look for joints or pliasters
- 17. Contact Building Official Building officials generally have excellent information about their jurisdictions ◦ Could ask him/her to estimate number of concrete buildings ◦ Ask which areas are post-1980 construction ◦ Where would older concrete buildings like be found? Mr. Greg McFann was very helpful ◦ Had member of his staff access the Assessor data Total number of buildings in Alameda 18,868 Total number of pre-1980 buildings Alameda – 12,674 ◦ Provided zoning map that helped identify residential districts that can be eliminated ◦ Provided access to Sanborn Maps
- 19. Zoning Map Skip one family residential – few in other residential areas
- 20. Area 5 20
- 21. Sanborn Maps • Used by the insurance industry and updated until about mid-1980s in Alameda. SERENDIPTY! • Able to get through the book in about 4 hours with assistance of Marguerite Bello, S.E. • Issues: Some buildings uncertain, require field verification. Some buildings may have been torn down but Building Official said that is a rare occurrence. Large portion of the City – Naval Air Station – not covered by Sanborn Maps.
- 22. Sanborn Map
- 23. Sanborn Maps – Note Taking
- 24. What if Sanborn Maps Had Been Older? Need to find an approach for estimating the number of concrete buildings not included on Sanborn maps that were constructed prior to 1980. ◦ ◦ ◦ ◦ Use of historic aerial photos Building department records Guidance from building official Judgment/Estimates
- 25. Library Search Lots of historic buildings listed in studies. ◦ Attempting to get buildings qualified for National Historic Building Register Lots of studies authored by Woody Minor – Architect Discovered lots of interesting things about Alameda unrelated to the study.
- 26. Library Search Walking Tour of Alameda’s Historic Downtown & Civic Center District. 1977 Unreinforced Masonry Buildings Survey. 1980. Woodruff Minor California Department of Parks and Recreation – Historic Resources Inventory. Webster Street Commercial Area. Survey of Pre-1945 Commercial Buildings, City of Alameda. Woodruff Minor. Historic Commercial Buildings of Alameda. 1993. Woodruff Minor. A Guide for Historical Research in Alameda. The Alameda Architectural/History Survey. Woodruff Minor. 1979. Alameda: The Island City. 1941.
- 27. Sample Data from Library Reference Building Name Historic Building Name Current Address # Address Street Reinf. Conc. Age Stories Structure Type Comments Gibson, William W., Machine Shop/Neptune Bowl Fred's Wrench-house 647 Buena Vista Ave Yes 1938, 1939 1 Two rectangular shapes built separately into one RC walls with corrugated metal roof building Alameda Printing Company Schroeder-Dent, Inc. 741 Buena Vista Ave Yes 1933, 19641965 1 RC with gable roof. Neptune Court Neptune Court 600 Central Ave 1925-1926 4 Wood frame Safeway Store/New Island Market Thrifty Jr. Drug Store 704-710 Central Ave Yes 1941, 1955 1 Marina Court Marina Court 726-736 Central Ave Browning, Henry, Garage None 650 Naval Air Lockers/Courtesy Cleaners Divers Exchange Luben Bros. West End Livery Stable Hay Barn Tony's Body & Fender Works Britt's Hotel/Encinal Hotel/Pioneer Hotel/Croll's Croll's or Croll Building Black, Henry and Catherine, Rental House None Addition in back in 1964-1965 to house equipment RC, probably with wood roof 1955 is CMU 2-story residential addition 1918, 1923 Wood frame Group of 10 buildings of mixed use Haight 1916 Wood frame 649 Pacific Ave 1941 1 651 Pacific Ave 1893 1&2 1423-A Wood frame 1 story garage and 2 story barn Wood frame 1879, 1907, 1908, 19781982 Webster Street/ Central 1400-1410/705 Ave BrIck Multiple phases. Webster Street 1895 1 Wood frame 1878-1879, 1907-1908 Probst, Louis and Maria, Building Santos Liquors 1425-1431 Webster Street 2 Wood frame Stelling, Martin, Building None 1432-1436 Webster Street Yes 1941 1 RC and brick walls Original plus addition Lucky Store No. 9 Grand Auto Store 1440 Webster Street Yes 1941, 1969 1 RC Gutted by fire in 1967. Garage bay and fenestration added at that time. Alameda/Savings Bank/American Trust Co./Wells Fargo Bank Trans Pacific National Bank 1442 Webster Street Yes 1917, 1946 Brick, RC Original brick, 1-story east addition RC Stelling, Martin, and Scales, Dixie Building None 1443-1453A Webster Street Yes 1941 1 RC Piers with brick infill Alameda Dairy Co. Tillies 1500 Webster Street Yes 1916, 1940 1 Wood frame and concrete Concrete storage room added in rear
- 28. Building List Developed list of buildings by combining ◦ List from initial walkthrough ◦ List from Sanborn Map ◦ Lists from library research. Number of locations where there were conflicts ◦ 10-15% of buildings Did some verification with Google maps
- 29. Re-walk the City Sanborn maps identified a large number of buildings I did not observe during initial walkthrough ◦ ◦ ◦ ◦ Some turned out to be demolished Some were inaccurately identified by maps Some were correctly identified – I missed them in walkthrough Some were behind other buildings, often small garage type structures for residences or canopies for multi-unit residences My initial walkthrough seems to have included 85% of final total. ◦ Probably good enough.
- 30. Revisit Sanborn Maps After re-walking there were still a number of structures where my walkthrough disagreed with the Sanborn maps, but there was some uncertainty due to limited access. ◦ Made one more visit to the City to look at the Sanborn maps. I noticed some things during the second review of the maps that I had missed the first time. I made one more trip to a few buildings to come to a final conclusion.
- 31. Added Up My Buildings There are a number of buildings that I did not count because: ◦ They were unoccupied storage buildings ◦ They are wood warehouses separated into sections by concrete firewalls ◦ They are podium structures with concrete block shear walls Southshore Center buildings extensive remodel – best estimate is 6 additional pre-1980 concrete buildings. Ended up with 24 pre-1980 buildings not sure about.
- 32. Summary of Alameda Data Number Final Count Total Number of Buildings Total Number of Concrete Buildings Pre-1980 Buildings Pre-1980 Concrete Buildings Tilt-up Buildings Schools with Concrete Buildings Chipman Alameda High Encinal High ….. 18,868 138 + k(24) 12,674 126 verified + k (24) (24 uncertain) 68 (not included above) Note: this is all we are asking be done. Lists and photographs are extra efforts that are appreciated but not necessary. If you count schools, etc. Identify them in your list.
- 33. Summary Initial walkthrough identified about 85% of total buildings Relying on Sanborn Maps alone would not have been relatively accurate. ◦ Error: inaccurate structure type assignment Large military presence resulted in areas where Sanborn Maps did not address. ◦ Identification of building age primarily based on judgment Many of buildings counted are obviously not high seismic risks. ◦ One-story, lots of shear walls. ◦ Not your job to figure out now.
- 34. Summary Older buildings of mixed construction due additions are problematic. ◦ Counted buildings with significant concrete portions. It is quite possible that a number of podium type residential structures were missed (parking under wood frame residential structures). Add photo
- 35. Summary Southshore – main shopping, was constructed in 1950s, added onto and recently remodeled. ◦ The construction type is uncertain. ◦ Had to assume number of old concrete buildings. ◦ Theoretically if they are high risks they may have been retrofitted. ◦ Data should be available at City Hall
- 36. Summary Walking into a number of structures could decrease the uncertainty in the number of structures. Included count of tilt-up buildings for completeness ◦ Problems with addresses changing in newer buildings constructed in the 1980s. Concrete schools and hospitals were observed and noted but not counted.
Editor's Notes
- Tilt-ups – known deficiencies, different ordinance