STAIR FRAMING
W A L L M A X X , Copyright 2009 All Rights Reserved
I N C
CONCEPTUAL*OVERVIEW Stairs'are'a'triangle.''They'have'RISE,'RUN,'and'DIAGONAL'components. The'total'vertical'distance'is'the'total'RISE'you'will'travel. The'total'horizontal'distance'is'the'total'RUN'you'will'travel. The'diagonal'distance'is'the'hypotenuse'of'the'triangle'and'when'constructed'is'typically'called'a'STRINGER.
CODES Educate'yourself'with'all'applicable'building'codes'in'your'area'for'the'construcFon'of'stairs.
'hLp://www.stairways.org/pdf/2006%20Stair%20IRC
A'good'visual'reference'of'the'2006'IRC'code'for'stairs'can'be'found'at:
%20SCREEN.pdf
Read'through'the'enFre'thing'for'familiarizaFon.
TERMINOLOGY* STRINGER
Stri
S
er g n tri
nge r
The'diagonal'structural'component'of'the'stairs'that'is' typically'cut'from'2'x'12’s'or'LVL'(Laminated'Veneer' Lumber)material. Most'codes'require'no'more'than'1/8”'variaFon'per'riser' and'no'more'than'3/8”'total'cumulaFve'variaFon'over'the' enFre'stringer.
The'above'IRC'code'images'are'from'the'PDF'file'created'by''The'Stairway'Manufacturer’s'AssociaFon
TERMINOLOGY (CONTINUED)
STRINGER When'selecFng'material'to'use'for'your'stringers,'it'is'imperaFve'to'choose'the'most'structurally'sound'and' straight.''Using'knoLed'up'2'x'12’s'is'asking'for'a'structural'failure.''' Many'people'insist'on'not'over'cu_ng'when'fabricaFng'the'stringers.''My'method'of'stair'manufacturing' makes'this'argument'moot*.
*'Proper'word'selecFon'/'spelling'corrected'by'Tinstaa'on'ContractorTalk.com
TERMINOLOGY (CONTINUED)
Riser'Code
Tread'Code
TERMINOLOGY (CONTINUED)
RISER The'single'unit'of'rise'per'step.'' This' is' determined' by' dividing' the' total' rise' height' by' the' number' of' steps.' ' This' value' typically' falls' nearest'to'7'5/8”'but'is'in'a'range'from'6'¾”'per'riser'to'7'¾”'per'riser.
Here' is' a'40'year' old' set' of'stairs.' 'The'stringers' were' cut' from' 2x10' material,' which' doesn’t' leave'much'strength.
TERMINOLOGY (CONTINUED)
TREAD The'single'unit'of'run'per'step.'' This'is'usually'given'in'the'plans,'by'the'designer.''This'value'typically'is'between'10”'and'11”. In'some' cases,' treads'have'been'made' less'than'10”'and' are' difficult'to'safely' transit'and' are'no' longer' allowed'by'code.
Here' is'the' same' 40' year' old' stringers' in' a'remodel.' ' When' walking' on' them' it'felt' like' you' were'going'to'fall'down'the'stairs.
TERMINOLOGY (CONTINUED)
FIRE'BLOCK Solid'draft'stopping'is'typically'required'in'the'stud'bays'of'all'the'walls'that'are'part'of'the'stairwell.'' Their'length'is'determined'in'the'CM'calculator'as'follows: Stud'bay'width'[RUN]'stair'pitch[PITCH]'press'[DIAG] They'are'then'cut'long'to'short'(I'used'joblsite'shortlhand'='L2S)'using'the'stair'pitch'in'degrees.
g in
ck lo e %B
%Blo cki ng
Fir
Fire
TERMINOLOGY (CONTINUED)
THRUST'PLATE Is' a' 2x4' plate' that' is' fastened' securely' to' the' lower' floor' system' that' is' to' resist' the' horizontal' “sliding”' pressure'that'is'exerted'by'the'stringers.''It'helps'to'“locklin”'the'stringers.
Thrust'Plate
Thrust'Plate'notch'outs
TERMINOLOGY (CONTINUED)
SPACING'LEDGER Is'a'2x4'or'someFmes'a'1x4'that'is'sandwiched'in'between'the'stringer'and'the'wall. It'allows'for'the'drywall'and'a'skirt'board''to'be'easily'installed,'leaving'a'¼”'final'gap'on'each'side'of'the'treads. It'is'best'to'glue'and'nail'this'to'the'wall'first,'then'glue'and'nail'your'wall'stringers'to'this'ledger. This'ledger'should'follow'the'boLom'edge'of'the'stringer'as'well'as'the'fire'blocks.
% NG CI
A SP DG LE ER
TERMINOLOGY (CONTINUED)
ANCHOR'LEDGER Some' architects' draw' /' require' that' the' top' of' the' stringer' be' notched' in' a' way' to' rest' on' a' horizontally' installed'2x4'ledger.
ANCHOR LEDGER
TERMINOLOGY (CONTINUED)
PRESSURE'BLOCK This'is'the'way'to'add'shear'nailing'prior' to'the'introducFon'of'metal'fasteners.'' Install'the'first'wall'side'stringer.'' Cut'a'2x8'or'2x10'block'the'length'of'the' space'between'the'first'and'second' stringer. Glue'and'nail'it'up'tight'to'the'first' stringer,'at'the'top'of'the'stairs'(into'the' header). When'installing'the'second'stringer,'glue,' toe'and'face'nail'it'into'the'header'and'the' pressure'block. In'this'photo,'the'plans'called'for'a' Simpson'A35'clip'to'be'installed'from' stringer'to'header'first,'thus'the'gap' between'the'pressure'block'and'the' stringer.
PRESSURE BLOCK
PLANS Study'the'(engineer'and'city/county'approved)'set'of'plans'for'your'project. Look'for'section'views'of'the'stairs;'finished'floor'to'floor'heights;'joist'and'sublflooring'types. A'common'mistake'made'by'architects'and'designers'is'that'they'don’t'draw'the'project'to'the'size'using' the'proper'material'sizes.''For'example,'an'architect'will'draw'a'section'view'of'a'wall'and'call'out'the' height'of'the'wall'to'be'8’.''Actually,'that'wall'will'be'the'total'height'of'the'thickness'of'3'plates'(3'x'1'½”)' plus'a'stud,'in'our'region'(7’l8'5/8”)'for'a'total'of'8’l1'1/8”.''That'1'1/8”'difference'means'that'you'can’t' prelcut'your'project'from'using'the' architect'plans'alone. Ensure'that'the'stairwell'(the'hole' framed'in'the'floor'system)'is'in'the' correct'locaFon'and'is'the'correct'size. Determine'if'the'treads'are'going'to'be' real'hardwood,'syntheFc'wood,'or'OSB' or'2x’s'treads'with'carpet'on'top.
GATHER*GIVEN*DATA Begin'by'gathering'all'the'perFnent'data'required'to'calculate'the'proper'dimensions'to'fabricate' your'stairs. Make'a'list'of'this'data'to'compare'to'the'stair'secFon'view'in'the'plans,'as'a'double'check'of'your' work'as'well'as'the'architect’s.''The'numbers'should'agree. You'will'need'3'things'at'a'minimum'to'determine'stairs: F2F'HT'–'that'is,'the'Finished'Floor'to'Finished'Floor'height'or'Floor'2'Floor'height. The'number'of'total'risers'required.''(A'riser'being'the'verFcal'porFon'of'an'individual'step). The'required'tread'length.''(A'tread'being'the'horizontal'porFon'of'an'individual'step).
In'some'instances,'you'will'need'to'calculate'the'tread'length'based'on'the'stairwell'run,'divided'by' the'total'number'of'treads. I'use'a'scienFfic'calculator'that'I'have'wriLen'small'RPN'rouFnes'for.''To'keep'it'easy'for'me,'I'wrote'the'input'and'output'of'the' lengths'in'an'array'format'of'[FEET]''[INCHES]''[SIXTEENTHS]'or'FIS.''6’l10'¼”'would'be'6l10l4.''In'this'presentaFon'many'of'the' lengths'are'in'this'format.''This'should'look'familiar'to'anyone'who'handles'trusses.
FLOOR*2*FLOOR In'most'stairs'that'are'to'be'built'inside'a' home,'it'can'be' safely' assumed' that' the' lower' floor' system' is' level' for' the' enFre'length'of'the'new'stair'run.''Always'verify. Take'your'tape'measure'and'determine'the'plumb'distance' from'the'top'of'the'subfloor'on'the'lower'level'to'the'top'of' the'subfloor'on'the'upper'level. Typically' on' any' non' interior' stair' applicaFon,' the' lower' level' (ground' or' landing)' will' be' sloped' and' ' not' exactly' level.' ' In' this' case' you' will' need' to' measure' the' plumb' height' from' the' top' of' the' stairs' where' they' meet' at' the' upper'level,'to'the'boLom'of'the'stairs'where'the'stringers' make'contact'with'the'lower'level.'
F2F'HEIGHT
FLOOR*2*FLOOR (CONTINUED)
Take' the' informaFon' gathered' from' the' plans' concerning' the' type' of' stair' treads,' along'with'the'thickness'sizes'of'the'types'of' finished' floor' coverings' for' the' lower' and' upper'level'floor'systems'and'do'some'math. Take'the'total'F2F'distance'and'subtract'the' height'of'the'finished'materials'on'the'lower' floor' (i.e.' Fle' or' hardwoods)' and' add' the' height'of'the'finished'materials'on'the'upper' floor'(i.e.'Fle'or'hardwoods)' This'gives'you'the'true'FINAL'Finished'Floor' to'Finished'Floor'Height.''F2F. Ge_ng'the'F2F'is'criFcal'to'creaFng'code' compliant'stairs.'' In'mulFlfloor'applicaFons'care'must'be' taken'to'fully'know'what'is'happening'to' each'finished'floor'level'and'landings.''Ouen' light'weight'gyplcrete'and/or'other'floor' coaFngs'are'scheduled'to'be'applied'auer' the'stairs'are'completed.''It'may'be'helpful' to'CAD'out'what'you'will'be'building'to' ensure'that'you'have'considered'everything.
FLOOR*2*FLOOR (CONTINUED)
RISER*COUNT The'riser'count'should'be'on'the'stair'detail'or'can'be'counted'visually'on'the'secFon'view.'' If'no'riser'count'is'given,'take'the'F2F'and'divide'it'by'7'5/8”.''Take'the'result'and'round'it'up'to'the'next'whole' number.''This'is'the'riser'count.'' For'ADA'(American’s'with'DisabiliFes'Act'of'1990)'requirements,'the'riser'can'not'exceed'7”'so'make'sure'you'verify' before'you'proceed.
TREAD*LENGTH This'is'either'given'in'the'plans'or'determined'by'overall'stairwell'run'divided'by'treads. Some'people'build'stairs'with'the'top'riser'actually'being'the'header'in'the'floor'system. Others'build'the'top'step'to'be'flush'with'the'top'of'the'finished'floor.
DO*THE*MATH F2F'(Floor'to'Floor)'height'÷'Riser'Count'='Riser'Height For'this'exercise'we’ll'use'8’F11%¾”
Divide'F2F'by'7'5/8”'(to'quickly'verify'how'many'risers'“should”'be'in'this'set'of'stairs)'=''14.13115 Plan'calls'for'14'risers'so'this'agrees'with'the'check'we'just'did. Divide'F2F'by'14'=' 7%11/16”%%or 7.696428571'(for'use'in'the'Offset'command'in'AutoCAD)
DO*THE*MATH (ConFnued)
Riser'Ht.'[RISE]'''Tread'Length'[RUN]'''[DIAG]'Step'Diagonal The'enFre'consecuFve'step'diagonals'in'FIS'are: 1l0l10' 2l1l4' 3l1l14' 4l2l8' 5l3l2' 6l3l11' 7l4l5
8l4l15 9l5l9 10l6l3 11l6l13 12l7l7 13l8l1
DO*THE*MATH (ConFnued)
Other'relevant'data'is'the'elevaFon'of'the'top'of'each'tread.''This'is'good'if'a' playorm'is'to'be'built'at,'let’s'say,'tread'5. The'enFre'consecuFve'tread'elevaFons'in'FIS'are: 0l7l11' 1l3l6'
5l1l9 5l9l4
1l11l1'
6l4l15
2l6l13' 3l2l8'
7l0l11 7l8l6
3l10l3' 4l5l14'
8l4l1 8l11l12
DO*THE*MATH (ConFnued)
Finally'you'can'determine'the' following: Stair'slope Stringer'material'order'length Fire'Blocking'length'(Long'to'Short'L2S'of' the'slope'in'degrees'as'bevel'cuts)
STRINGER*LAYOUT First,' select' the' best' material' for' the' job.'' If'the'material'has'a'slight'crown,'I'lay'it'so' that'the'steps'will'be'cut'into'the'crownedl up'side.
STRINGER*LAYOUT (ConFnued)
Second,' lay' out' the' entire' stringer' with' marks' that'reflect'the'cumulative'step'diagonals.
STRINGER*LAYOUT (ConFnued)
Thirdly,' use' a' framing' square' with' brass' stair' gauges' set' to' the' calculated' riser' height' and'tread'length. The'hammer'is'in'place'of'a'hand'holding the'framing'square'in'place'for'the'photo'only.
STRINGER*LAYOUT (ConFnued)
The'framing'square'should'land'exactly'in'between'the'step'diagonal'marks. The'step'diagonal'marks'are'not'absolutely'necessary…and'I'have'built'many'stairs'with' just' a' framing' square,' but' they' are' nice' to' have' as' a' doublelcheck' for' overall' stringer' accuracy.
STRINGER*LAYOUT (ConFnued)
You'will'need'to'remove'the'thickness'of'a'tread'from'the'bottom'of'the'stringer'and' the'thickness'of'a'riser'from'the'top'/'back'of'the'stringer.
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STRINGER*LAYOUT (ConFnued)
Finally,'it'is'critical'to'ensure'that'at'least'the'minimum'amount'of'head'room'is' present'when'the'stairs'are'completed'and'the'well'is'covered'with'its'final'veneer' (drywall,'wood'liner,'etc.) 6’l8”'is'a'common'height'in'most'codes'and'localities.''Where'possible'try'to'make'this' height'more'like'7’l0”.''Every'bit'you'allow'for'makes'it'easier'for'the'future'home'
owners'to'move'their'furniture'up'your'stairs.
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STRINGER*CUTTING I'am'right'handed'so'I'layout'my'stringers'so'that'the'I'start'at'the'right'end'of'the'stringer'to'begin'my' cuts'and'move'left. First,'cut'all'of'the'tread'lines'from'right'to'left. Then'starting'from'the'left'end'of'the'stringer'and'moving'right,'cut'all'of'the'riser'lines,'ending'up'back' at'the'right'end'of'the'stringer. This'keeps'the'saw'alignment'to'the'stringer'the'same'for'each'cut.''
Here,'all'the'tread'lines'are'cut'first.'' You'can'layout'with'your'square'flipped'to'produce'the'risers'on'the'right.''It’s'not' important'which'way'you'want'to'cut.'' What'is'important'is'that'you'develop'a'sequence'in'your'work'that'improves'your' ability'to'make'the'most'precise'cuts'with'the'limited'amount'of'effort'and'Fme.
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STRINGER*CUTTING '(ConFnued)
If' I' were' to' rotate' the' saw' 90' degrees' for' every' cut' it' would'be'inefficient.' 'So'instead'I'found'the'“make'all'likel cuts'first”'method'of'fabricaFng'to'work'well. Also,'I'plunge'cut'most'of'my'cuts.' 'With'the'front'end'of' the' saw' deck' firmly' placed' and' aligned' on' the' stringer,' I' start' the' motor' with' the' back' end' of' the' saw' elevated.'' Then,'with'careful'aLenFon,'I'lower'the'saw'into'the'wood' without' sliding' the' saw' in' any' direcFon,' unFl' it' is' fully' seated'flat'on'the'stringer.''This'technique'makes'for'a'very' straight'iniFal'cut.
TREAD*/*RISER*CUTTING If'the'stairs'will'be'having'a'finished'¾”'skirt'board'installed'later,'measure'the'width'of' the'stairwell,'minus'the'thickness'of'the'spacer'ledgers'(typically'2x4s'each'–'so'3”).'' This'is'what'to'cut'the'risers'and'treads.
TOOLS The'tools'used'are'as'follows: A'framing'square. A'set'of'brass'stair'gauges. A'tape'measure. An'ink'pen. A'pencil. A'construcFon'speciďŹ c'or'programmable'scienFďŹ c'calculator. A'circular'saw.''(sidewinder'type'is'lighter'and'faster'than'a'worm'drive'type) A'hammer'and'some'hand'drive'loose'nails. A'large'barrel'glue'gun'and'glue'tubes. A'pneumaFc'nail'gun,'hose'and'compressor. A'screw'gun'or'cordless'impactor'and'screws'for'securing'the'treads.
INSTALLATION*SEQUENCING Select'the'best'material. Crown'and'place'them'on'a'set'of'saw'horses. Determine'all'relevant'calculated'data. Layout'a'single'stringer'using'an'ink'pen'or'whatever'writing'instrument'makes'the'narrowest'line' possible.''Fat'lines'can'lead'to'incremental'measurement'errors'creeping'into'your'work. Count'and'number'each'riser'to'ensure'that'you'have'the'correct'number.''
INSTALLATION*SEQUENCING (ConFnued)
If'you'are'unsure'of'your'work,'just'cut'the'top'and'bottom'of'your'stringer'and'“test'fit�'it'where'it'will'be'going. Ensure'that'you'have'proper'headroom. Finish'cutting'the'first'stringer'and'use'it'as'your'pattern. Flush'the'bottom'edge'of'the'pattern'stringer'with'the'bottom'edge'of'the'next'stringer'material'you'are'transferring'the'pattern'onto'and' tack'in'place'with'hand'nails.
INSTALLATION*SEQUENCING (ConFnued)
Cut'all'of'the'stringers. Trace'and'cut'two'2x4'wall'spacing' ledgers'by'using'the'bottom'edge'of' the'stringer'as'a'pattern. Trace'and'cut'two'2x6'ripped'to'5�' the'same'way'as'for'the'spacing' ledgers,'but'these'will'be'nailed'to' the'unsupported'center'stringers'for' additional'structural'support.
INSTALLATION*SEQUENCING (ConFnued)
Set'the'first'paLern'stringer'against'the'walls'at'the'proper'height' and'scribe'the'boLom'of'the'stringer'at'every'stud. Install'the'fire'blocking'inlbetween'each'stud'bay,'above'this'line. Apply' glue' at' every' stud' and' along' the' edge' of' the' fire' blocks,' above'this'scribed'line. Place'the'spacing'ledger'2x4'against'the'wall,'with'its'boLom'flush' to'the'scribed'line,'and'nail'it'to'each'stud'it'touches.
INSTALLATION*SEQUENCING (ConFnued)
Glue'the'face'of'the'spacing'ledger'and'place'a'stringer'next'to'it'at'the'proper'elevaFon'and'nail'it'to'the' spacing'ledger.
INSTALLATION*SEQUENCING (ConFnued)
Complete'the'installaFon'by'centering'the'middle'stringer…or'evenly'spacing'them'if'more'than'3'are'being' installed.
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INSTALLATION*SEQUENCING (ConFnued)
Install'any'midlspan'knee'walls,'if'applicable. Install'the'risers'ďŹ rst.'Raise'them'up'to'be'ush'with'the'tread'line'cut'of'the'stringer.'Use'plenty'of'glue. Install'the'treads.''Use'glue'on'the'risers'and'stringer. For'temporary'treads,'apply'no'glue.''Screw'them'in'place,'or'tack'them'with'nails'for'future'removal.
GLUE?**NAIL?**SCREW? For'carpet'covered'stairs,'I'glue'everything'prior'to' nailing'it. I'use'HDG'nails'primarily,'so'I'nail'everything'and' there'is'little'or'no'squeaking'ever. On' some' occasions' I' also'screw' the' treads' down' with' 3�'deck'screws'in'addition'to'glue'and'nails.
FIRE*BLOCKING Fire'blocks'can'be'installed'at'any'Fme'in'the'process,' however,'it'is'best'to'install'them'prior'to'the'spacing' ledger'so'that'glue'can'be'installed'along'all'woodltolwood' contact'surfaces.
MID<SPAN*SUPPORT If'the'space'under'the'stairs'is'to'used'as'a'sloped'closet,'this'allows'for'a' knee'wall'to'be'built'at'or'near'the'midlspan'and'greatly'increases'the' structural'strength'of'the'stairs.
Go*Build*It. It'pays'to'do'it'right'the'first'time. It'also'pays'to'set'yourself'apart'from'the'crowd. Many'contractors'are'competing'for'the'bottom'dollar'“Yugo”'customers.'' Rise'above'that. Be'good'enough'at'what'you'do'to'go'after'the'“Cadillac”'customers.
Credits The'Soundtrack Transformers'l'Steve'Jablonsky Mentors Too'many'to'list...suďŹ&#x192;ce'to'say,'great'tradesmen'in'Texas,' Tennessee,'Georgia,'Kentucky,'and'Washington'states. InspiraFon Seeking'perfecFon.