Commercial Interior Space Designing II

Commercial Interior Space Designing 4(1+3)

Lesson 8:Specialised Facilities for commercial buildings

Staircases

In The Commercial Sector, The Staircase Reflects The Prestige Of The Building. It Serves A Functional Purpose In A Building Layout, Providing Access From One Floor To Another, But It Can Also Add A Decorative Element To A Room Or Hallway. There Are Several Staircase Styles And Designs, Ranging From Simple And Elegant To Bold And Formal. In The Right Style, Staircase Can Become The Focal Point Of A Space Instead Of A Solely Utilitarian Structure. Staircases Can Be Made Of Many Materials, With Traditional Looks Relying Heavily On Wood, And More Modern Aesthetics Making Use Of Different Metals, Heavy-Gauge Wires Or Man-Made Materials.

Stair Climbing And Descent Are Quite Different From Walking. When Climbing Stairs, The Body Center Of Gravity Is Shifted Forward, The Leading Foot Is Placed On The Tread Above, And Both The Leading And Rear Legs Combine For The Push-Off To Lift The Rear Foot To The Next Tread Above. In Descent The Body Center Of Gravity Is Shifted Backward, The Lead Foot Is Placed On The Step Below, And The Rear Foot Lifted, Swung Forward And Placed On The Next Step Below. Most Accidents On Stairs Occur In The Down Direction, And These Accidents Are Usually More Severe Because Of The Greater Energy And Impact Of The Fall.

Falls On Stairs Account For Over 60% Of Slip, Trip And Fall Deaths In Buildings And Can Result Due To A Number Of Complex Interacting Factors. Despite This, There Are Minimal Safe Stair Design And Construction Principles Within Building Regulations; However The Following Environmental Factors When Evaluating Safe Egress On Stairways Include:

• The Visibility Of The Stairway
  
• Slip Resistance Of Stair Treads
  
• Provision Of Suitable Handrails
  
• Dimensional Geometry Of Stairs

Design Guidelines And Dimensions
Designing A Staircase Properly Requires A Safe And Appealing Design. Strict Rules Must Be Followed For Staircase Design To Ensure Safety And Beauty Coexist. Elements To Consider When Designing A Staircase Vary Slightly Depending On The Type Of Staircase. Whether To Build An Indoor Staircase --- Traditional, Circular Or Modern --- Or An Outdoor Set Of Stairs, The Design Process Is A Crucial Step In Creating The Best Staircase For Any Given Space. The Structure Needs To Sound, The Measurements Must Be Accurate, And The Installation Must Be Flawless.

• Stair Width Must Be Measured Accurately And Designed In Proportion For The Space. Stairways Have To Be At Least 44" If An Occupant Load Over 50.
• There Should Be At Least 80" Of Head Height Measured Off The Tread Nosing.
• The Riser Height Must Be Between 4" And 7" And The Treads Must Be At Least 11" Deep.
• If The Stairs Have Winders They Need To Be At Least 11" Deep When You're 12" In From The Narrow Edge And The Minimum Depth Must Be 10".
• The Landins Must Be At Least As Deep As The Stairs Are Wide (Up To 4'-0") And Can’t Go Up More Than 12′-0" Vertically Without A Landing. Where A Door Opens Into The Landing It Can't Project More Than 7" Into The Required Depth Of The Landing.
• Handrails Must Be Mounted Between 34" And 38" Above The Tread Nosings And Landings. Where They Are Circular They Need To Be 1.25″ To 2″ In Diameter. If The Handrail Isn't Circular It Needs To Have A Perimeter Between 4" And 6.25" With A Maximum Cross Section Of 2.25". The Handrail Needs To Be Mounted A Minimum Of 1.5" Off The Wall.
• Handrails In Ibc Buildings Need To Return To A Wall, A Guard Or The Walking Surface Or Continue To Another Handrail. The Ibc Requires That Your Handrail Extend 12" Past The Top Riser And One Tread Depth Past The Bottom Riser. It Important To Note That The Ada Will Require You To Go One Tread Depth Plus 12" Past The Bottom Riser So It Generally Overrides The Ibc.
• Handrails Need To Be On Both Sides Of The Stair And Can't Project More Than 4.5" Into The Stair Width On Each Side. On A Very Wide Stair, There Is Need To Space Intermediate Handrails No More Than 60" Apart.
• The Visibility Of Safe Stairs Is Critical To Ensure That A Person Can Prepare To Coordinate Their Gait During Stair Ascent And Decent. For People With ‘Normal' Vision This Relies On Visual Clues Such As Handrails, Depth Perception In Good Lighting Conditions And High Visibility Of Step Nosings. Poor Delineation Of The Step Edge May Confuse People Negotiating The Stairs, Particularly In Poor Lighting Conditions Thus Increasing The Risk Of A Miss Step.