PA Building Codes Illustrated: Building Heights & Areas

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CH 5
Kara Biczykowski
Flashcards by Kara Biczykowski, updated more than 1 year ago
Kara Biczykowski
Created by Kara Biczykowski about 3 years ago
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1) economics & utility gen. dictate that bldgs be built using the least: 2) the 1st design choice impacting allowable heights & areas is: 3) the 2nd design choice impacts: 1) costly & complicated type of const. that will meet the criteria set in the code 2) design of a given occ. must provide enough area to contain the known uses 3) speculative bldgs built for economic gain like office/retail to max allowable height & area using the most economical const. type
1) to address the question of max. the economically viable bldg size, designers must use: 2) ultimately the goal is to achieve the max (___) w/ min (___) in const. mat.'s while still meeting/exceeding: 1) an iterative process; must make assumptions of const. type & analyze relative cots & return for const. types before the owner can decide 2) max area w/ min investment / code-mandated req.'s to protect public health, safety, & welfare
1) code is based on a set of basic criteria that are then modified by mitigating factors to allow: 1) increases or trade-offs btwn heights, areas, const. types, fire protection, life safety systems
BLDG HEIGHTS & AREAS SUMMARY 1) designer typ knows the occ. classification 2) program area is typ set by program needs or by budget 3) const. type will typ be determined during schematic design 4) regarding fire extinguishing systems, code req.'s for fire sprinkler systems must be determined at this time 5) since most bldgs have a mix of incidental & accessory occ. &/or a mix of occ. classifications, provisions of 508 must be carefully examined
DEFINITIONS 1) definitions have very specific code-related criteria that may be different from: 2) ex- height limitations for bldgs in planning & zoning reg.'s: 3) never apply bldg code criteria to: 1) the colloquial meanings of the terms 2) don't necessarily use the same criteria or definitions for determining heights 3) planning issues, or vice versa
1) bldg area is usually considered to exclude the: 2) gross bldg area is typ calc. to: 3) the most conservative way to calc. bldg area is by: 1) thickness of the exterior walls, based on language describing gross floor area 2) the exterior side of the exterior walls 3) measuring from outside face of wall to outside face of wall, generating the most bldg area that should never be challenged by the AHJ
1) basement, grade plane, & bldg height are correlated & based on: 2) "bldg heights" are measured to: 3) "story" is defined as: 1) relationship of bldg parts blw/abv grade plane as it is defined 2) the avg height of the highest roof, allowing for pitched roofs, varying parapet heights, rooftop equip enclosure 3) occupiable or usable space located inside the bldg contained by a floor blw & a plane (next story/roof) abv
DEFINITIONS 1) vent shafts (+ shaft wall thickness) & courts are excluded from Bldg Area 2) areas included w/in the horiz. projection of a floor or roof abv even if not enclosed by surrounding walls -ex roof overhangs can matter in area calcs 3) "basement" is defined by what it is not - "a story, but one that's not a story abv grade plane" 4) ^if finished surface of the floor abv the lower level is more than 6ft abv grade plane or more than 12ft abv grade at any pt, then level is considered to be "a story abv grade plane"
DEFINITIONS 1) the story height for the topmost floor takes into acct the vol. of the upper floor, but not projections abv roof: 1a) to the top of sloping roof rafters 1b) to the top of ceiling joists *parapets are excluded from height definition but not pitched rafters 2) "story height" is measured as vert. distance from top of one finished floor to next successive finished floor = "story abv grade plane" if entirety abv grade plane 3) "grade plane" is a ref. plane rep. the avg grade levels along the exterior walls of bldg
DEFINITIONS 1) for sloping sites, grade plane is based on lowest pts w/in the area btwn the bldg & the lot line, or btwn the bldg & a pt 6ft from bldg, whichever is smaller 2) "bldg height" is the vert. distance from the grade plane to the avg height of the highest roof surface 3) "mezzanine" is an intermediate floor level & is limited to 1/3 of the space containing them or it will be considered a story 3a) when mezzanine & equip platforms are co-located, no more than 2/3 of the area of the space is allowed 3b) mezzanines aren't considered a story & don't contribute to the floor area
1) per 503.1.1 what types of spaces are exempt from the height & bldg area limitations per 504 & 506 & why? 2) Type 1 bldgs permitted to be of unlimited height & area don't req.: 1) low-hazard, high-bay spaces like mills or foundries b/c special-process req.'s & little occ. loads & public access is recognized 2) mitigations for unlimited-area bldg imposed on other const. types (except some group-H occ.)
1) 503.1 allows 1 or more "fire walls" to divide a : 2) 503.1.2 states that multiple bldgs on a single site may be considered as: 3) for a group of bldgs to be considered as a single bldg, group must meet: 4) areas btwn open to sky don't count to: 5) walls facing btwn space don't have to conform to: 1) single structure into a number of "separate" bldgs 2) separate bldgs w/ assumption of imaginary line btwn them, or a single bldg for determining bldg areas 3) aggregate area must not exceed the single bldg area of the most restrictive occ., & means of egress must also be met 4) area, but do if covered 5)exterior fire separation
1) "NS" are bldgs not equipped throughout with an: 2) "S" are bldgs equipped throughout with: 3) "S1" are bldgs a max of one story abv grade plane with: 4) "SM" are bldgs 2 or more stories abv grade plane equipped with: 5) "S13R" are bldgs in group-R occ. 4 stories in height in bldgs not exceeding 60 ft & equipped throughout with: 1) automatic sprinkler system 2-4) an auto sprinkler system installed via 903.3.1.1 (NFPA 13) 5) an auto sprinkler system installed via 903.3.1.2 (NFPA 13R)
1) w/in const. Types I - V, "A" & "B" mean: 2) the intersection of occ. group & const. type = 3) gen. the higher the level of fire & life safety = 1a) "A" = const. that is "protected" w/ increased fire-resistance -typ means bldgs w/ higher allowable heights & areas than B 1b) "B" = const. not provided w/ fire-resistance protection 2) allowable bldg height & area per 502 3) the larger & taller a bldg can be
1) heights are expressed in 2 ways, first is height in ft abv grade plane which is tied to: 2) the 2nd height listed in stories is tied to: 3) why are 2 types of height listed? 1) fire-resistance 2) occupancy 3) to avoid having high floor-to-floor heights btwn stories that could generate a bldg complying w/ allowable stories but exceeding height limit in ft abv grade plane
MEZZANINES 1) max allowable area of occupied space: 2) mezzanine areas are excluded from: 3) mezzanine areas aren't excluded from: 4) Type I & II bldgs housing special industrial occ. get a mezzanine bonus of: 5) Type I & II bldgs w/ sprinklers/voice/alarm systems may have a mezzanine bonus of: 1) 1/3 of the area 2) overall bldg area & total floor area calc 3) the overall "fire area" (code def. ch2) 4) 2/3 of the room floor area 5) up to 1/2 the area of the room floor area
MEZZANINES 1) mezzanines must be of habitable height: 2) enclosed portions of a room aren't included when: 3) mezzanines are req.'d to have: 1) 7ft clear at mezzanine level & blw 2) determining the size of the room in which a mezzanine is located 3) means of egress & where common path of travel or occ. load exceeds limits (table 1006.2.1) then 2 means of egress req.'d
1) in table 506.2 for allowable bldg areas "NS" non-sprinklered values are used for: 2) what is "frontage" 3) in order to receive area increases every bldg must: 4) when a bldg has more than 25% of perimeter opening onto a public way or open space 20ft wide: 1) area-increase calcs even for sprinklered bldgs 2) how much open space adjoins the bldg 3) adjoin or have access to a public way 4) bldg's area may increase based on added extents
FRONTAGE EQUATION (5-5) If = (F/P-0.25) W/30 If -(area increase due to frontage) F -bldg perimeter frontage on public way/ o.s. min 20ft width P -total perimeter of entire bldg W -width of public way/ o.s. Note - W/30 cannot exceed "1" except only may be up to "2" when the bldg meets all criteria of 507 except for compliance w/ the 60ft public way or yard req.
FRONTAGE EQUATION (5-4) Weighted Avg (W) = (L1 x W1 + L2 x W2 + LxWx...) / F Ln -length of exterior perimeter wall Wn -width of o.s. at wall Ln F -bldg perimeter w/ Wn>/= 20ft Note - W is measured perp. from bldg face to nearest property line - where W is > 30ft, use 30ft in calcs - length of side not included in "F" total perimeter when Wn (width of o.s.) less than 20ft
AREA FACTOR INCREASE B/C OF FRONTAGE EQUATION (5-1) Aa -allowable area (sf) At - tabular allowable area factor (NS, S1, S13R as applicable w/ table 506.2) NS - tabular allowable area factor from 506.2 for nonsprinklered bldgs (regardless if bldg is sprinklered) If - area factor increase due to frontage (%) as calc w/ 506.3 (equations 5-4 & 5-5) 1) begin w/ equation 5-5: If = (F/P-0.25) W/30 2) equation 5-1 for single occ., one-story bldgs: Aa = At + (NS x If)
AREA FACTOR INCREASE B/C OF FRONTAGE EQUATION (5-2) Aa / At / NS / If all remain the same definitions from equation 5-1 -Sa - actual number of stories abv grade plane (not to exceed 3 for nonsprinklered bldgs & not 4 for sprinklered group-R blgs w/13R sprinkler system) 1) begin w/ equation 5-5: If = (F/P-0.25) W/30 equation 5-2 for multistory bldgs w/ a single occ. group Aa = At + (NS x If) x Sa
BLDG HEIGHT AREA & CALC PROCEDURE 1) read charging language at 503.1 -some exceptions apply -determine the height & area of the proposed bldg & if multiple bldgs on a single lot are to be treated as a single bldg or as multiple bldgs w/ assumed lines btwn -ea. portion of a bldg separated by fire walls shall be considered to be a separate bldg
BLDG HEIGHT AREA & CALC PROCEDURE 2) read charging language at 504.1 -some exceptions apply - the height (ft) & # of stories of a bldg shall be determined based on the type of const., occ. classification, & if there is an auto sprinkler system installed throughout the bldg
BLDG HEIGHT AREA & CALC PROCEDURE 3) read charging language at 504.1-504.3 & determine allowable bldg height in ft using table 504.3 -some exceptions apply 4) read 504.4 & determine allowable bldg height in stories using table 504.4
BLDG HEIGHT AREA & CALC PROCEDURE 5) read 506.1 through 506.2.3 & determine the values req.'d for determining max bldg floor area in equation 5-2 (if needed go to 506.3) - determine what frontage increases area available for proposed bldg based on its location on property 6) read 506.3 through 506.3.3 & determine applicable allowable area frontage increase from equations 5-2/3 -determine if weighted avg's are necessary for frontages per equation 5-4 (typ when variation along perimeter of bldg) or if basic frontage increase formulas can be used per equation 5-5
BLDG HEIGHT AREA & CALC PROCEDURE 7) using values obtained in step 5 & 6, determine max bldg floor area using equation 5-2, 5-3, or 5-4 -insert values from equations 5-4 & 5-5 into equations 5-1 (single story single occ.), 5-2 (single story multi occ.), or 5-3 (multistory multi occ.) depending on bldg configuration 8) determine max allowable area per story for the bldg using equation 5-2, 5-3, or 5-4 -multiply allowable area by number of stories based on allowable increases for unsprinklered or sprinklered bldgs
UNLIMITED AREA BLDGS -507 allows bldgs of other than Type I const. to be of unlimited area when certain conditions are met, these exceptions overlay the height, story, & area tables 1) other occ. than those listed in the allowances for unlimited area bldgs is ok if the occ. meets the criteria for "accessory" occ. per 508.2 - ex - an A-2 restaurant in a retail space 2) open space may be measured using the entire width of a public way to meet the 60ft criteria
UNLIMITED AREA BLDGS 3) for certain bldgs the req.'d 60ft yard may be reduced to 40ft for not more than 75% of bldg perimeter if the exterior wall facing the reduced open space & openings have a min fire-resistance rating of 3hrs 4) as opposed to measurements for fire separation distance, this "yard" open space is primarily for fire dept access & is to be measured "in all directions" (even at a corner's radius) when determining compliance
MIXED USE & OCCUPANCY 1-3) this section address more than 1 occ. in a single bldg: *note areas complying w/ live/work spaces or separation from hazardous occ. don't apply 1) accessory occupancies 2) nonseparated occupancies 3) separated occupancies
ACCESSORY OCCUPANCIES 1) still to be classified by their uses in ch3 2) areas don't req. separation from primary occ. if criteria of 508.2.3 is met (if it's a distinctly different use & doesn't occupy more than 10% of floor area of story in which it is located) 3) allowable bldg area & height is to be based on the main occ. 4) separations req.'d for uses incidental to main occ. per 509, group-H-2/3/4/5 to be separated, dwelling & sleeping units in I-1, R-1/2/3 occ. to be separate from ea. other & from adj occ.
MIXED OCCUPANCIES 1) nonseparated occ. - the entire bldg is regulated according to the most restrictive of the height, area, & fire-protection req.'s for ea. of the multiple occ. 2) separated occ. - may req. that an occ. separation w/ a fire-resistance rating per table 508.4 be provided btwn occ. 3) exception to nonseparated occ is for H-2/3/4/5, I-1, R-1/2/3 dwelling & sleeping units all to be separated from ea. other & adj occ.
SEPARATED OCC. EXAMPLE 1) A-2 occ. allowable: 50ft / 2 stories / 11,500sf floor area per story 2) A-2 occ proposed: ,50ft / on 1st floor / 3,000sf floor area 3) M occ. allowable: 50ft / 3 stories / 14,000sf floor area per story 4) M occ. proposed: <50ft / 3 stories / 10,000sf floor area SEPARATED OCC. CALCULATIONS EX (A-2 actual area/allowable area) + (M actual area/allowable area) < 1.00 = (3,000sf/11,500sf) + (10,000sf/14,000sf) = 0.26 + 0.71 = 0.98 < 1.00 = OK! *note - A-2 occ. can't be abv 2nd floor since A-2 occ. can only be 2 stories & is to be completely separated w/ 2hr fire barrier per 707 & 712 horiz. assemblies
INCIDENTAL USES 1) when the bldg occ. contains 1 or more incidental uses, areas are considered part of the main occ. but require fire-resistance rated separations (*this req. not applicable to dwelling units) 2) refer to table 509 for list of incidental uses 2) incidental uses listed in Table 509 include those that carry inherent risk of fire like boilers, furnace rooms, etc. 3) per 707 & 711 fire barriers should extend from floor to underside of fire-resistance-rated floor/ceiling/roof
INCIDENTAL USES 1) an auto fire-extinguishing system may be substituted for the fire-rated separation (still must resist smoke passage), per 509 it only needs to be provided in the incidental use room 2) even though 509.4.2.1 only req.'s the sprinkler system w/in incidental area, this limited system won't qualify a bldg for things like area increases granted for provision of a sprinkler system throughout the bldg -ex *don't confuse table 508.4 of occ. separations w/ incidental use 509
COMMON INCIDENTAL USES 1) furnace room w/ equip of 400,00BTUH input / boiler room w/ equip >15psi & 10hp / refrigerant machinery room = 1hr separation or auto sprinkler system 2) incinerator room = 2hr w/ auto sprinkler system 3) paint shops not H occ. & in occ. other than F = 2hr or 1hr w/ auto sprinkler 4) labs not H occ. in groups E, I-2, ambulatory care = 1hr or auto sprinkler (group E) / 1hr w/ sprinklers (I-2 & ambulatory care) 5) laundry rooms >100sf = 1hr or auto sprinkler (I-2 laundry) 6) storage rooms > 100sf in ambulatory or I-2 occ. = 1hr w/ or w/out sprinklers
SPECIAL PROVISIONS - MIXED OCC./USE -per 510.2, when all of the following conditions are met, exceptions are allowed from restrictions in tables 504.3-4, 506.2 1) max bldg height in ft is per 504.3 & measured from grade plane for bldg having the smaller allowable height 2) allowed uses abv horiz. assembly: assembly occ. w/ <300 ppl & groups B, M, R, S occ. 3) items like shafts & stairs enclosures through horiz. assembly don't have <2hr fire resistance rating w/ opening protectives per 716.5 (can have 1hr shaft abv if lower portion is 3hrs)
SPECIAL PROVISIONS - MIXED OCC./USE 4) bldgs are separated by a horiz. assembly having a min 3 hr fire rating 5) ^ bldg blw 3hr can now be more than 1 story abv grade plane 6) limitations for # of stories is determined for ea. bldg, so "bldg" abv horiz. fire assembly count begins here 7) bldg blw horiz. assembly is sprinklered per 903.3.1.1 8) bldg blw horiz. assembly is of Type 1-A const. 9) basements blw grade plane are allowed in the Type 1 portion of bldg 10) allowed uses blw the horiz. assembly include any occ. other than group-H
GROUP S-2 Enclosed Pkg Garage w/ S-2 Open Pkg Garage Abv 1) all pkg garages are S-2, so no need to be separated, 510.3 allows an open garage to be built over an enclosed garage while treating the transition btwn as a new ground plane when fire-resistance req.'s are met 2) b/c allowable areas differ, sum of ratios of actual areas divided by allowable areas shall be < 1 3) height & # of tiers at open garage is per table 406.5.4 (begins abv enclosed) 4) openings btwn open & enclosed garages only need protecting at exit openings
GROUP S-2 Enclosed Pkg Garage w/ S-2 Open Pkg Garage Abv 5) enclosed garage may only be 1 story abv grade & must be Type I or II const. & be = to fire-resistance req.'s for group S-2 open garages 6) enclosed garage is only used for private vehicles, may have office, waiting rooms, toilets = 1,000sf total, mech equip rms, but no repairs
PKG BLW GROUP R 1) when S-2 pkg garage (open/ or enclosed) at 1 story abv grade, w/ entrance at grade, Type I const., blw group-R occ., the # of stories used to determine min const. type is to be measured from floor abv pkg area 2) pkg to be max 1 story abv grade plane 3) floor assembly btwn pkg garage & group-R occ. is determined by const. type req.'s for pkg garage & is to have fire-resistance rating as an occ. separation
SPECIAL PROVISIONS GROUP R-1 & 2 1) of type III-A const. may increase to 75ft & 6 stories when 1st floor const. abv basement has 3hr fire rating & floor area is sub-D by 2hr fire walls into areas not more than 3,000sf 2) of Type II-A const. may increase to 100ft & 9 stories when: 2a) the 1st floor const. has fire rating of 1-1/2hrs 2b) the bldg is separated from any other bldg on same lot & from property lines no less than 50ft 2c) exits are enclosed by 2hr fire walls
Open P-garages blw Groups A, I, B, M, R 1) the height & area of open pkg garage is regulated by 406.5 2) the height & area of group A, I, B, M, R occ. are regulated by 503 3) the height in stories & feet must be measured from the grade plane for the entire group of stacked uses Group S-2 Open P-garage abv Group B, M 1) height of S-2 open pkg garage doesn't exceed limits of 406.5, the height in ft & stories to be measured from the grade plane, including the bldg blw the horiz. assembly
Group S-2 Open P-garage abv Group B, M 2) exits serving the pkg garage must be separated by 2hr fire barries & discharge directly to street or public way 3) the occ. abv the horiz. assembly is limited to a group S-2 open pkg garage 4) height blw horiz. separation doesn't exceed limits set forth in 503 5) the bldgs must be separated w/ a horiz. assembly having a min 2hr fire rating 6) occ. blw horiz. separation limited to groups B & M 7) bldg blw horiz. assembly is Type I or II const., but not less than type req.'d for group S-2 open pkg garage abv
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