1.Staircases and Ramps.Today I wish to talk about movement between different horizontal levels within a building.

Depending on the nature of the building this is done traditionally in one of three ways

1. Ladders 4. Hoists (in some obscure Greek Monasteries)

2. Stairs

3. Ramps.

With the advent of taller buildings, mechanical means of travelling from one level to another have been developed and these fall into two main categories

1. Elevators.2. Escalators.

Even if these last two categories are used alternative ways of moving from floor to floor must

be provided in case of breakdown or Fire.

Lifts cannot be used for obvious reasons if there is a fire.

Except in Hopi Indian settlements Ladders are used solely for maintenance or in some instances fire escapes so we will deal today simply with stairs and ramps.

With the consequences of serious injury being far greater when travelling vertically to that

Posed, by travelling horizontally you can imagine that fairly strict regulations are applied to

the design and construction of Staircases and ramps.

These are detailed in various British standards and distilled and contained in a legal document called the Building regulations.

The Building regulations fall under the Health and safety acts and apply to all aspects of the majority of building works undertaken in this country today, so you had better become used to finding your way around them. The actual regulation is often simple such as; a thing must be safe, fortunately there are approved documents that if adhered too, will lead to the item in question being deemed safe.

The section dealing with staircases and ramps is Approved document K. This sets out various design criteria that must be met to design a safe means of moving from one level to another.

We will deal with the basic rules and criteria laid down in the regulations but you will be advised to read through the document your selves, which is not too arduous as it is only some 20 pages long.

Normally we would not burden you with the minutiae of detailed regulation at this stage of your education but as it is impossible to design a stair or ramp without knowledge of the basic rules you will have to become familiar with them. The legal part of the act says simply that;

“ stairs ladders and ramps shall be so designed, constructed and installed as to be safe for people moving between different levels in or about a building.”

The rest of section K goes on to define how this rather vague sounding statement can be achieved.

You will need to provide Stairs ramps or ladders when ever a difference in level occurs of 600mm or more.

Public staircases have a stricter requirement than do private domestic staircases this is to take account of peoples unfamiliarity with the stair and the greater numbers using them. Access or inspection stairs will have lesser requirements for the opposite reasons.

Before we go on I wish to explain the terminology used with staircases

1. Rise2. Going3. Tread4. Nose5. Pitch 6. Pitch line7. Headroom8. String9. Flight10. Landing11. Handrail12. Guarding13. Newel post

Private stairs can have a rise of between 155mm and 220mm

with a going between 223mm and 300mm

Public stairs can have a rise of between 135mm and 180mm with a going between 280mm and 340mm

Other stairs can have a rise of between 150mm and 190mm with a going between 250mm and 320mm

Private stairs max rise 220 min going 220Public stairs max rise 180 min going 280Other stairs max rise 190 min going 250

The maximum pitch of a private stair is 42 degreesThe maximum pitch of a public stair is 33 degreesThe maximum pitch of an other stair is 37 degrees

All risers must be equal in a flight as must be the goings.

The normal relationship between the rise and the going is given by the equation 2R+G=550mm-700mm so anywhere within that range should be acceptable, as long as it doesn’t contravene any of the above.

With open risers an overlap of minimum 16mm must be maintained. If however children below the age of 5years can use the stair no opening that a 100mm sphere can pass through should be left.

A minimum headroom of 2000mm should be available.

The maximum number of steps in any one flight should be 16

If a stair has more than 36 steps in total then a change of direction should be made of at least 30 degrees

Landings must be provided at the top and the bottom of the flight and should be –at least as long as the stair is wide.

A landing can be part of a room as long as it is left unobstructed.

Doors can open out onto a landing but not within 400mm of the first or last nosing.

These are the basic rules for straight flight stairs.

Now how do we go about using all this information to start designing a stair ?

First decide weather your stair is in the Public, private or Other category.

Then find the scope of riser dims that would be acceptable within that category.

Find the exact distance between the top and bottom of your stair.

Divide this distance into equal parts within the permissible riser dims.

So let’s say the stair is a public one the above would mean our riser must be between 135 and 180mm.

If our floor to floor height was say 3,000m this would mean we have between 22 risers at minimum rise and 17 risers at maximum rise a variation of 5 risers (4 treads) If we opted for say 17 risers (to give us 16 steps and two even flights of 8 treads) That would give us a rise of 176.5mm. This below the maximum rise of 180mm so OK.There is always one less going than riser.

Next we need to see what size going we will need.We know that 2x R+G = 550mm-700mm so lets see what solving this would give us

2x 176.5 = 353mm This means our going mathematically can be between 197mm and 347mm (min 550-353= 197 and max 700-353=347) the minimum going is legally however 280mm so our going must be between 280 and 347mm

Space available often dictates the plan size of the going if you opted for a going of 300mm (above the minimum allowed) then the overall length of your stair would be 8x 300= 2.4m plus two landings (top and bottom) if the stairs were 1100mm wide this would add 2.2m to 2.4m = 4.6m.

If the space available was only 4.5m for example, you would have to divide the remaining length less the landings by 8 = 4,5m-2.2m=2.3m 2.3m/8 =287,5mm This is still within your permissible going arrived at above and would fit the plan space available. A check could be tan © = 176,5/287,5 this gives an angle of 31,5 degrees so is good as it is less than 33 degrees (max pitch for public stairs).

For Tapered treads the above rules apply but the dims are measured in the middle of the tread for stairs less than 1000mm wide (ie domestic) and at 270mm from each side of the tread if greater than 1000mm for both stairs goings should measure 50mm minimum at their smallest end and should be uniform. The 2R+G=550mm-700mm remains the same!

If tapered and straight treads are used together the tapered going must not be less than the straight going.

No minimum width of stairs are stated but attention should be given to provisions required by means of escape in case of fire and invalid access. If public stairs are over 1800mm wide they should be subdivided with a handrail

Handrails

These must be provided to at least one side if the stair is less than 1000mm and to both sides if wider.

The height of the hand rail should be between 900mm and 1000mm measured from the pitch line or the floorFlights and handrails should be guarded from the sides when there is a drop of more than 600mm in dwellings or when there are more than two rises in other conditionsIf children under 5 can have access to the stair the 100mm sphere rule again applies to the guarding.

RampsThe steepest slope of a ramp should be not greater than 1: 12 all other provisions regarding handrails headroom landings etc are the same as for stairs. However if the ramp is the sole access for the disabled the landing provision should conform to part M of the building regulations which states that;

Ramps at 1:20 = max going = 10m and max rise = 500mm.Ramp length for 3m rise =68m Ramps at 1:15 = max going = 5m and max rise = 333mm Ramp length for 3m rise =56m Ramps at 1:12 = max going = 2m and max rise = 166mm Ramp length for 3m rise =54m

ProtectionProtection from falling must be provided to all stairs ramps balconies and roofs that have access as well as light wells as with stairs this is needed for any change of level above 600mm

The height of the protection should be ;

Private,

stairs, ramps and landings……………….. 900mm

external balconies and roofs……………1100mm

Public,

For hand rails to stairs and ramps………900mm

Everything else…………………………1100mm

Barriers for cars are…………………….375mm

But on a ramp are……………………….610mm

These are the basic rules for designing both ramps and stair cases and if you keep to these rules your staircases will be safe.