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Stairs. Objectives. Be able to calculate size needed for a staircase Apply staircase calculation to own stairs Identify types of staircase designs Gain knowledge of general size information. Stairway .
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Objectives • Be able to calculate size needed for a staircase • Apply staircase calculation to own stairs • Identify types of staircase designs • Gain knowledge of general size information
Stairway • Series of steps with or without landings or platforms which is installed between two or more floors of a building • Provides easy access to various levels • All styles of homes have stairs except ________? Ranch Design
Main stairs vs. service stairs • Main stairs • Generally prefabricated parts and are of a much better quality than the service stairs • Typically made from hardwoods (oak, maple, birch) • Service stairs • Typically constructed on site of Douglas fir or pine (construction lumber)
Seven types of stairs • Straight run • L stairs • Double-L stairs • U stairs • Winder stairs • Spiral stairs • (Circular stairs)
Straight run stairs • No turns • Not as expensive as other types to construct • Require a longer open space
L stairs • One landing at some point along the flight of steps • “long L” • Used when there is not enough space for straight run
Double L stairs • Two 90 degree turns along the flight • Typically not used in residential construction • Expensive and break up the floor plan
U stairs • Wide or narrow U • Two flights of steps parallel to each other • Landing between the two flights of steps
Winder stairs • Pie shaped steps • Width of the triangular/pie shaped steps? • Sufficient at midpoint • Not as safe as other stairs
Spiral stairs • Gaining in popularity • Used where little space is available • Most are made from steel and welded together • Not very safe
Circular stairs • Custom made • Trapezoid shaped steps • Large homes. Probably too big for your two-story houses
Terminology • Open Stairs-stairs that have no wall on one or both sides • Enclosed stairs-have a wall on both sides (“housed” or “box” stairs)
Terminology • Landing-floor area at either end of stairs and possibly in between
Terminology • Rail (handrail)- Designed to be grasped by the hand. They are supported by posts or fixed directly to a wall. • Baluster- Vertical member that supports the handrail.
Terminology • Newel-main posts of the handrail at the top, bottom or points in between where stairs change directions
Handrail Newel
Terminology • Stringer (string’ er)- structural member that supports the treads and risers • Two are usually sufficient. But if width exceeds 3 feet, a third stringer is needed Plain stinger Housed/closed stringer
Plain Stringers • Made from fir • Risers and treads nailed directly to the stringer • Service stairs, main stairs if they are carpeted • Sturdy • Squeaky and do not have a finished appearance • Risers are 1in and treads are typically 2in
Housed Stringers • Made from finished lumber • Generally precut or preassembled • Stringer is routed to hold the treads and risers • Wedges are driven in to hold in place • Glued and nailed in place
Terminology • Nosing-rounded projection of the tread that extends past the riser
Terminology • Tread- horizontal member of each step. Usually 1 ¼” thick. Either 10½”(most popular) or 11½” deep • Run-the distance from the face of one riser to the face of the next • Total Run-total horizontal length of the stairs 10-1/2” 10-1/2”
Terminology • Riser-vertical face of a step. Usually ¾” thick, between 7” and 7 5/8” high • Rise-distance from the top of one tread to the same position on the next tread • Total Rise-total floor-to-floor height 7” – 7 5/8” 7” – 7 5/8” 7” – 7 5/8”
Terminology • Headroom-shortest clear vertical distance between the nosing on the treads and the ceiling (6’-8” minimum) 6’-8” min.
Rules • Stairs should be minimum 3’-0” wide (traffic circulation rule) • The slope of the stairs (rise-run ratio) should be between 30 and 35 deg • The sum of two risers and one tread should equal approximately 25 in • The product of the riser height multiplied by the tread width should equal appox. 75in • The sum of one riser and one tread should be 17-18 inches
Procedures Example Problem: • What is your Ceiling Height of your first floor? (Standard ceiling height: 8’ - 12’) _________ Add together:finished floor to finished ceiling (Ceiling Ht.) ________thickness of ceiling material (drywall) .5”width of floor joists (2” x 10”) 9.5”thickness of subfloor (.5” plywood) .5”thickness of finished floor .75” Total Rise = ________ 10’-0” Ceiling Height 10’-0” 10’-11 ¼ ”
Procedures • Convert Total Rise from feet to inches. [ _________ x 12 ] + _________ = __________ • Divide Total Rise (inches) by 7” (min. riser height) to find the total number of risers for your stairs. _________ 7 = __________ 131.25” 10 11 ¼ # of feet leftover inches Total Rise (inches) 131.25” 18.75 # of Risers Total Rise (inches)
Procedures • If your Total Riser # is a decimal, plug the whole number into the equation below, WITHOUT the decimal part: • Example: If the Total Riser # is 22.18, plug in 22 _________ _________ = __________ • The numbers below would allow you to draw elevations How many Risers do your stairs have? ________ What is the Height of Each Riser? ________ 131.25” 18 7.29” Total Rise inches # of Risers (w/out decimal) Height of Each Riser (inches) 18 7.29”
Procedures • Calculate Total Run _________ x [_________ - 1] = __________ • Convert Total Rise and Total Run back into Inches. _________ 12 = __________ (For Elevations) _________ 12 = __________ (For Floor Plans) 10.5” 18 178.5” Tread Depth # of Risers Total Run ***THERE IS ALWAYS ONE LESS TREAD THAN RISER 131.25” approx. 10’-11” Total Rise (in) Total Rise (ft/in) approx. 14’-10” 178.5” Total Run (in) Total Run (ft/in)
