Stair drawing – check list.
The stages that are required to achieve the staircase and handrail to be designed without constantly redrawing the stairs are listed below, this is a quick guide with a brief explanation of the different stages.
The stair drawing is best done before rooms etc. are added to the floor space, thus allowing for the landings to be set at a suitable position without having to shoehorn the staircase into the space that is left.
1. Determine the space.
Example details: The space I am going to allow for includes the room for two passing flights with a well set between.
This will include length, width and height that each flight will be restrained too.
Example details.
Plan area:
L 2560 _ W 2215 _ FFL – FFL 3045
L 8′ 4 3/4″ _ W 7′ 3 1/4″ _ FFL – FFL 9′ 11 7/8″
2. Determine the layout.
This may to an extent be dictated by the floor plans and space that you have to work with.
Example details: I am going to use a straight flight with 180º turn.
This layout has the diminishing flyers before the winders, The advantage of this is: the change of pitch and direction are divorced, giving a constant pitch through the turn. this makes the flow much nicer and production of the parts using tangent handrailing a lot easier.
3. Determine Rise and going.
The rise is a fixed dimension from finished floor level to finished floor level.
From this you can calculate the minimum going that may be used.
In the U.K. this is a maximum pitch of 42º. Therefore by trigonomatry you can calculate the minimum going.
Total rise ÷ Tan of max pitch.
Tan 42º = .9004
Total rise ÷ .9004 = min Going.
Once you have this you can increase the going if so desired to create a more comfortable pitch.
In this example we have a total rise between Finished Floor Levels of 3045mm Therefore 3045 ÷ .9004 = 3381.8mm
Hence the minimum chord length through the centreline of the treads must be equal or greater than 3381.8mm.
4. Draw the proposed plan view.
The proposed plan view can be drawn using the handrail centre line as the edge of the stairs.
The reason for this is: when we do the stretchout to confirm the handrail flow, this is the centreline of the handrail, It is this centre line that will control how the handrail flows. Therefore the edge of the stairs will be calculated from the handrail centre line and the size the handrail support, whether it be spindles, metal balusters or glass.
Read more about the centre line.
N.B.
The ideal space between handrail centrelines on level turns e.g. landings and half space landings is:
For same pitch in turn as flight through turn = half a going.
For coming to level in the centre of the turn = a full going.
5. Draw the stretch-outs.
Probably one of the most important yet much missed operations of drawing the stairs, this will highlight most problems in manufacturing the stairs before you pick up the first stick of timber to machine.
The stretch out will confirm the handrail flow and spindle spacing around the winders, winder positions, the transtions onto landings etc.
This is achieved by opening the staircase out into a 2D view, some times refered to as the development, from this you can get all the pitches flowing into each other through all the flights.
Read more about the stretch out and how it may be used to confirm handrail flow or set the riser postions.
6. Choose the handrail support .
Whether spindles, glass, metal or a parapet wall you will need to have the offset from handrail centre line to stringer face before the next stage is carried out.
This may be done a stage or two later but is best resolved at this stage, it will have to be done at this stage if using spindles or balusters of any sort.
In this example I am going to use 35mm turned spindles.
With this in mind I can draw the spindles into the plan view.
Further reading.
Find out how to get the stringer face postion.
View our selection of pre-drawn spindles, they come with 2D outlines and 3D models to drop into your cad/modeling package.
7. Draw the stringer faces and nosings.
The final detail to check is that the nosings do not interfere with the spindles.
Now you have the riser positions and spindles drawn in, you can add the stringer face then the nosing offset from the riser position, to give the nosing line, extend the nosing line till it meets the stringer face.
On traditional staircases the nosing projection is the same as the tread thickness.
The two standard sizes of tread thickness are:
Ex 1 1/4″ or 1 1/8″ – 29mm par
Ex 1 1/2″ or 1 3/8″ – 35mm par
In this example I will use 29mm nosings.
8. Stringer to skirting transition.
Consider the wall stringer to landing skirting transition, how these two interact may change the position of the stringer away from the structural wall or how thick the plaster may have to be for the stringers to flow into the skirting.
9. Draw Alignment grid.
Although not part of the staircase drawing this is a usefull aid both during the drawing stage and the fitting stage. With a grid drawn out any part of the drawing that you may work on separatly especialy if creating 3D models, can be easily dropped back into place .
This will also give a position to fit the staircase to on site and allow any deviation from the grid to be set out on site for when flights do not set directly over each other.
The grid can be set at each FFL, this also confirms during the drawing stage that the flights have been drawn to the correct height.
I will normally lock the grid layer once set; so as to avoid accidental movement during drawing.
The grid may be drawn before you start the first flight or before you start on the second flight; so you keep the plans correctly aligned while working up or down through the flights.
These are the basic steps, from here on it is a matter of adding the elevation.
The same principal is used for round landings, the landing area is considered a tread and should be treated as such, being drawn in with its fascia rather than risers.