INTRODUCTION TO CONSTRUCTION TYPES Code Consultant:Steven R. Winkel, FAIA, PE The Preview Group, Inc. Contractor: Scott Smith James E. Roberts-Obayashi Corp. Architect:Anne Torney WRT | Solomon E.T.C. Presenters:

INTRODUCTION TO CONSTRUCTION TYPES For Infill Multi-Family Housing 1. The five basic construction types (as defined by the Building Code)  Mid-rise vs. high-rise  Options for 5 stories of housing over non-residential base 2. Typical configurations for San Francisco housing 3. Relative costs for different construction types 4. Case studies …and why they’re not important …and why it’s not that simple …and why there’s no such thing

IIIIIIIVV 1. The Five Basic Construction Types Wood: Heavy Timber Any material Fire-Resistive: Concrete or Steel MostLeast Any Material with Fire Resistive Exterior Walls; Interior Any Material Fire Resistance Allowable Area Allowable Height Allowable # of Stories Cost per Square Foot Rarely used for new construction

© John Wiley & Sons, from Building Code Illustrated

© John Wiley & Sons, adapted from Building Code Illustrated Showing allowable building heights (with and without sprinklers) number of stories (with sprinklers) and proportionate floor areas per story)

TYPICAL CONFIGURATIONS TYPE V Fulton Grove

TYPICAL CONFIGURATIONS TYPE V Del Carlo Court

Fine Arts Building TYPE V over TYPE I PODIUM TYPICAL CONFIGURATIONS

8 TH AND HOWARD David Baker and Partners TYPE V over TYPE I PODIUM TYPICAL CONFIGURATIONS

101 San Fernando TYPE II or Type III over TYPE I PODIUM TYPICAL CONFIGURATIONS

Broadway Family Apartments Type I Midrise TYPICAL CONFIGURATIONS

PLAZA APARTMENTS LMS/ Paulett Taggart Architects Type I Midrise TYPICAL CONFIGURATIONS

International Hotel Herman Coliver Locus Architecture Type I High-rise TYPICAL CONFIGURATIONS

RELATIVE CONSTRUCTION COSTS – Based on Construction Type + metal + fire safety features + fire-treated lumber framing at exterior walls + metal deck w/ concrete topping + concrete frame CONSTRUCTION TYPE RELATIVE COST / SF WHY RESIDENTIAL FLOORS GARAGE/UNFINISHE D T.I. SPACE HIGH-RISE (concrete)1.30 GARAGE ON GRADE (single level) 0.50 GARAGE BELOW GRADE0.60 METAL (plywood deck)1.07 TYPE I: GARAGE ON GRADE (multi-level) 0.40most efficient + shoring, waterproofing METAL (plywood deck)1.04 # OF RES. STORIES TYPE V:WOOD1.004 MAX TYPE III: *WOOD1.035 MAX TYPE II:METAL (metal deck)1.105 MAX TYPE I:MID-RISE (concrete)1.258 MAX UNLIMITED + 1% per floor over 9 * Man lift and possibly tower crane needed for buildings over 60’. Cost per square foot varies. Relative costs courtesy of Scott Smith of the James E. Roberts-Obayashi Corporation

WHY YOU SHOULD IGNORE THE PREVIOUS SLIDE Relative construction costs are driven by type of construction AND… Site:Shape, size, topography, soils, fire finishing & construction access, zoning Unit Type:Flats (double or single loaded), townhomes, studios, family units, stacking, repetition Ownership vs. Rental Circulation Ratio of skin to interior area Size of project Parking:Yes or no, configuration, efficiency Foundation Systems Mechanical, Electrical and Plumbing Systems Finishes Et cetera…

CASE STUDY: MID-RISE vs HIGH RISE Mid-rise High-rise (403) Floor level (not “height”) at less than 75’ feet above lowest Fire Dept. access Sprinklers required for R Occupancy No elevator lobbies in sprinklered < high-rise No command center ≥ 4 stories, elevator on emergency power (generator) or provide horizontal exit for accessible means of egress (1007) Fire alarm No smoke control Typ. stair shaft enclosures, 2 hour > 4 stories No standby power Communication required for accessible means of egress No rescue air Defined as floor level at more than 75’ above lowest Fire Dept. access Sprinklers required Elevator lobbies Fire command center Elevator on standby power = generator, in 2 hour rated room Voice/alarm Smoke control Smoke proof enclosure Standby power for fire command, fire pump (if any) Stairway communication Rescue air replenishment system in SF

WHY 75’ FOR A MID-RISE? © John Wiley & Sons, from Building Code Illustrated

CASE STUDY: MID-RISE VS. HIGH-RISE Costs per S.F. increase… But costs per unit may decrease. S.F. RELATIVE COST/UNIT OPTIONUNIT S RELATIVE COST/ S.F. RELATIV E COST 8-STORY MID-RISE 66 8 & 13-STORY HIGH-RISE 13-STORY HIGH-RISE , , , $121,875 $176,800 $199,120 $1,846 $1,768 $1,508

CASE STUDY: FIVE FLOORS OF HOUSING

SANSOME & BROADWAY

CASE STUDY: FIVE FLOORS OF HOUSING over NON- RESIDENTIAL BASE SANSOME & BROADWAY

CASE STUDY: FIVE FLOORS OF HOUSING - OPTIONS OPTION TOTAL # STORI ES # OF UNITS RELATIVE COSTS A 5 stories Type II metal over 1 story Type I podium 5 stories Type III metal over 1 story Type I podium B C 5 stories Type III wood over 1 story Type I podium D 4 stories Type III wood over 1 story Type III concrete over 1 story Type I podium 650 CONSTRUCTABILI TY NOTES Most?? Least?? Fire-resistive construction throughout, including metal deck floors with Levelrock topping Could have plywood decking at floors 2-hour exterior walls w/ fire-treated lumber; dense lowest wood level, which can create utility coordination issues Avoids dense lowest wood level & associated mech. & elect. coordination issues Option D appeared to be the option with the least cost for this particular project, but the answer will vary from project to project.