STAIRWAY Building cde infrmatin fr ne- r twfamily dwellings and twnhmes. Building Safety Department 400 2 nd Street Suth St. Clud, MN 56301 Phne 320-255-7239 Fax: 320-650-3397 www.ci.stclud.mn.us Stairway Illuminatin (R303.7) All stairways need t be illuminated, including landings and treads. Interir stairways shall be prvided with an artificial light surce lcated in the immediate vicinity f each landing. Exceptin: an artificial light surce is nt required at the tp and bttm landing if a light surce is prvided directly ver each stairway sectin. Cntrl f the light surce shall be lcated at each flr level where the stairway has six r mre risers. Exterir stairways shall be prvided with an artificial light surce lcated in the immediate vicinity f the tp landing. Exterir stairways prviding access t a basement frm utside shall be prvided with an artificial light surce lcated in the immediate vicinity f the bttm landing. Cntrl f the light surce shall be lcated inside the dwelling unit. Stairways shall have a minimum 6-8 headrm measured vertically frm the slped line adjining the tread nsing r frm the flr surface f the landing r platfrm. Exceptin: existing basement stairways shall have a minimum headrm f 6-4 measured vertically frm the slped line adjining the tread nsing r frm the flr surface f the landing r platfrm. Where the nsing f treads at the side f a flight extend under the edge f a flr pening thrugh which the stair passes, the flr pening shall be allwed t prject hrizntally int the required headrm a maximum f 4¾. Headrm (R311.7.2 & R305.2.2) Width (R311.7.1.2) Stairways shall have a minimum width f 36 at all pints abve the permitted handrail height (34 t 38 ) t belw the required headrm height (6-8 /6-4 ). Stairways with a handrail installed n ne side f the stairway shall have a minimum width f 31½ at and belw the handrail Stairways with a handrail installed n bth sides f the stairway shall have a minimum width f 27 at and belw the handrail Page 1 f 5
The maximum riser height is 7¾. The riser is measured vertically between the leading edges f the adjacent treads. The greatest riser height cannt exceed the smallest by mre than 3/8. If risers are nt vertical the slpe frm the underside f the nsing f the tread abve shall be an angle nt mre than 30-degrees frm the vertical. Open risers are nly allwed as lng as the pening between the treads des nt allw a 4 diameter sphere thrugh. The minimum tread depth is 10. The tread is measured hrizntally between the vertical planes f the fremst prjectin f adjacent treads and at a right angle t the tread s leading edge. The greatest tread depth cannt exceed the smallest by mre than 3/8. Treads shall have a maximum slpe f ne-unit vertical in 48-units hrizntal (2% slpe). All stairs with clsed risers shall have nsing nt less than ¾ but nt mre than 1¼. Exceptin: nsing is nt required n stairs with a tread depth f 11 r greater. The radius f the curvature at the nsing shall be n greater than 9/16. The greatest nsing prject cannt exceed the smallest by mre than 3/8 between tw stries, including flrs and landings. Beveling f nsing shall nt exceed ½. Risers (R311.7.5.1) Treads (R311.7.5.2, R311.7.7 & R507.3) Nsing (R311.7.5.3) Landings (R311.7.6, R311.7.7 & R312.1.1) A landing is required at the tp and bttm f each stairway. A landing is nt required at the tp f an interir flight f stairs prvided a dr des nt swing ver the stairs. The width (perpendicular t the directin f travel) f the landing shall nt be less than the width f the stairway it is serving. The depth (in the directin f travel) f the landing shall nt be less than 36. Landings shall have a maximum slpe f ne-unit vertical in 48-units hrizntal (2% slpe). Guards shall be prvided fr landings that are mre than 30 abve grade. See the guard sectin f this handut fr guard requirements. Vertical Rise (R311.7.3) A flight f stairs shall nt have a vertical rise greater than 12 between flr levels r landings. Page 2 f 5
Special Stairways (R311.7.5.2.1, R311.7.10.1, & R311.7.10.2) Special stairways shall fllw all previus requirements f the cde with the fllwing exceptins: Winder stairways. Treads at winder stairways shall have a minimum depth f 10 at a pint measured 12 alng the nsing edge frm the side where the treads are narrwer. The largest tread depth shall nt exceed the smallest winder tread by mre than 3/8. Treads shall have a minimum depth f 6 at any pint within the clear width f the stairs. Winder treads can be used in the same flight f stairs as rectangular treads. Tread depths within the winder prtin f the flight f stairs d nt need t be within 3/8 tread depth f the rectangular prtin. Spiral Stairways. Minimum 26 clear width at and belw the handrail. Minimum 7 ½ tread depth. Measured at 12 frm the narrwer edge. All tread depths must be identical. Maximum 9 ½ riser Minimum 6-6 headrm. Bulkhead enclsure stairways. Stairways serving bulkhead enclsures d nt need t meet any f the previus stairway r landing requirements as lng as they meet ALL f the fllwing: They prvide access frm the utside grade level t the basement; The maximum height frm the basement finished flr t the grade adjacent t the stairway des nt exceed 8 ; and The grade level pening t the stairway is cvered by a bulkhead enclsure with hinged drs r ther apprved means. Guards (R312) Guards are required n pen sides f flrs, stairs, ramps, and landings that are lcated mre than 30, measured vertically, abve the flr r grund belw. Guards, when required, shall be a minimum f 36 in height measured vertically abve the adjacent walking surface, adjacent fixed seating, r the line cnnecting the leading edges f the treads. Guards at stairways shall be a minimum 34 in height measured vertically frm a line cnnecting the leading edges f the treads. Guards, when required, shall nt have penings which allw passage f a 4 diameter sphere. Exceptins: The triangular penings at the pen side f stairs, frmed by the riser, tread, and bttm rail f a guard, shall nt allw the passage f a 6 diameter sphere. Guards at stairways shall nt allw the passage f a 4 3/8 diameter sphere. Guards shall be built t withstand a single, cncentrated lad f 200 punds, applied in any directin, at any pint alng the tp. In-fill cmpnents, balusters and panel fillers shall be built t withstand a hrizntally applied lad f 50 punds n an area equal t 1 square ft. Page 3 f 5
Handrails are required n at least ne side f stairways having fur r mre risers. Handrails are a minimum 34 and maximum 38 in height, measured vertically frm the slped plane adjining the tread nsing, r the finished surface f a ramp. Exceptins: The use f a vlute, turnut r starting easing shall be allwed ver the lwest tread. When handrail fittings r bendings are used t prvide cntinuus transitin between flights, transitins at winder treads, the transitin frm handrail t guardrail, r used at the start f a flight, the handrail height at the fittings r bendings shall be permitted t exceed the maximum Handrails shall be cntinuus fr the full length f the stairs, frm a pint directly abve the tp riser f the flight t a pint directly abve the lwest riser f the flight. Exceptins: Handrails can be interrupted by a newel pst at a turn. The use f a vlute, turnut, starting easing r starting newel shall be allwed ver the lwest tread. Handrails shall be returned r shall terminate in newel psts r safety terminals. Handrails (R311.7.8) Handrails shall be ne f the fllwing types r prved equivalent graspability. Type I: Handrails with a circular crss sectin shall have an utside diameter f at least 1¼ and nt greater than 2. If the handrail is nt circular, it shall have a perimeter dimensin f at least 4 and nt greater than 6¼ with a maximum crss sectin dimensin f 2¼. Edges shall have a minimum radius f 0.01. Type II: Handrails with a perimeter greater than 6½ shall have a graspable finger recess area n bth sides f the prfile. The finger recess shall begin within a distance f ¾ measured vertically frm the tallest prtin f the prfile and achieve depth f at least 5/16 within 7/8 belw the widest prtin f the prfile. This required depth shall cntinue fr at least 3/8 t a level that is nt less than 1¾ belw the tallest prtin f the prfile. The minimum width f the handrail abve the recess shall be 1¼ t a maximum 2¾. Edges shall have a minimum radius f 0.01. Handrails shall be built t withstand a single, cncentrated lad f 200 punds, applied in any directin, at any pint alng the tp. In-fill cmpnents, balusters and panel fillers shall be built t withstand a hrizntally applied lad f 50 punds n an area equal t 1 square ft. Page 4 f 5
Ramps (R311.8 & R312.1.1) Ramps shall have a maximum slpe f 1-unit vertical t 12-units hrizntal (8.3% slpe). Ramps can have up t a slpe f ne-unit vertical t 8-units hrizntal (12.5% slpe) where it is technically infeasible t cmply with ne-unit vertical t 12-units hrizntal because f site cnstraints. A minimum 3 by 3 landing shall be prvided in the fllwing lcatins: At the tp and bttm f ramps. Where drs pen nt ramps. Where ramps change directin. Handrails shall be prvided n at least ne side f all ramps exceeding a slpe f ne-unit vertical t 12-units hrizntal. See the handrail sectin f this handut fr handrail requirements. Guards shall be prvided n ramps and landings that are mre than 30 abve grade. See the guard sectin f this handut fr guard requirements. Wd/Plastic Cmpsite Materials (R311.5.4, R311.7.8.4, & R507.3) Wd/plastic cmpsite materials shall bear a label indicating the required perfrmance levels and demnstrating cmpliance with the prvisins f ASTM D 7032. When using wd/plastic cmpsite materials as stair treads verify the prduct has been apprved fr use as a stair tread, and verify spacing f stair stringers. (Fr the purpse f this handut: = ft/feet; = inch(es)) The infrmatin in this handut is just an verview. See the 2015 Minnesta Residential Cde fr cmplete infrmatin. The cde is available t view nline at: http://cdes.iccsafe.rg/app/bk/tc/2015/minnesta/residential/index.html Page 5 f 5