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Domestic Building Regulations Explained

A domestic staircase is defined as “A stair intended to be used for one dwelling” i.e. a stair case that is used within a house or flat.

The building regulations with regards to domestic staircases are laid out within “section K” of the the building regulations, and are referred to as a “Private stair”

Section K can be downloaded by clicking here

Please note the below information is only applicable for England, Wales and Northern Island, Scotland has separate building regulations.

This is also our interpretation based on the most commonly asked questions, to be absolutely sure we would recommend checking with your building inspector


Key Points:

1) Rise, going and angle
2) Kite winders
3) Width(s)
4) Headroom
5) Landings
6) Handrails & balustrades
7) Nosings
8) Obstacles
9) Open Riser stairs
10) Space saver stairs


 1) Rise, going and angle;

The following rules must be met:

  • The individual rise must be between 150mm and 220mm
  • The individual going must be between 220mm and 300mm
  • The Pitch of the stair cannot be greater than 42 degrees

Note that the ind. going doesn’t include the nosing overhang.

Because of the pitch being restricted to 42°, the minimum individual going depends on the individual rise.

The table to the right shows the minimum ind. going based on the ind rise for a 42 degree pitch.

The individual rise is the total rise divided by number of risers.


So for example;

A staircase has a 2600mm total floor height,

The individual rise, can be no more than 220mm so,
the minimum number of risers would be 12, which is 217mm (2600/12 = 216.6)
the maximum number of risers would be 17, which is 153mm (2600/17 = 152.9)

As such, we would normally use 12 risers on this staircase, because that’s the minimum number of risers, which will in turn result in the lowest amount of floor space being taken up by the staircase.

However, with a individual rise of 217mm, if we used the minimum individual going which would be 220mm, the pitch would be 44.6°, which is too steep for the maximum 42° pitch.

As such, with a individual rise of 217mm we must use a individual going of 242mm, and with a individual rise of 217mm and a individual going of 242mm, we would get a pitch of 41.8°, which means the pitch would comply to domestic building regulations.


Other Restrictions:

All risers must be equal on a flight of stairs, for example, you cannot have some risers at 200mm and some at 205mm.
However, on a staircase with a landing, each flight may have a different individual rises.

Twice the individual rise plus the going (2R +G) must be between 550mm and 700mm, however, this only causes a problem in extreme scenarios.

Ind. Rise Minimum Ind. Going for 42° pitch
198 mm 220 mm
199 mm 220 mm
200 mm 223 mm
201 mm 224 mm
202 mm 225 mm
203 mm 226 mm
204 mm 227 mm
205 mm 228 mm
206 mm 229 mm
207 mm 230 mm
208 mm 232 mm
209 mm 233 mm
210 mm 234 mm
211 mm 235 mm
212 mm 236 mm
213 mm 237 mm
214 mm 238 mm
215 mm 239 mm
216 mm 240 mm
217 mm 242 mm
218 mm 243 mm
219 mm 244 mm
220 mm 245 mm

2) Kite Winders;

Kite winders are a useful tool to minimise the space taken up by a staircase with a turn,
There are certain rules that must be adhered to when using kite winders,

A stair with kite winders will normally have a mixture of straight treads and winder treads, as shown in the digram below:



To measure the individual going of the winder treads, this is done by measuring the arc around the tread which is created from the centre of the lower flight to the centre of the upper flight, this is the blue line as shown on the diagram above.


Each winder individual going must meet the following criteria;

- The winder treads must all be equal to or greater than the straight treads
the going of all winder treads must be equal



In the example to the left, the straight treads are all 242mm,
as such, we have designed the kite winder to also have treads of 242mm measured around the arc.

If they were less than 242mm then they would not comply to building regulations, however it is okay for the individual going of the winder treads to be more than 242mm as long as they are all equal.

This applies regardless of the number of kite winders within the winder box.
The implication of this is that:
- 3 kite winder box - on a narrow staircase, the kite winder may take up significantly more space than the width of the flight, as the narrower the stair, the closer the centre line is to the narrower end of the tread.
4 kite winder box - take up significantly more space than 3 kite winder box


The problem with two kite winder boxes:

The rule for all treads says that, “Twice the individual rise plus the going (2R +G) must be between 550mm and 700mm” as outlined in section 1 above.

This can cause a problem with two kite winder boxes,
if you look at the example two kite winder box to the right,
this is a typical two kite winder box, based on.
2600mm total rise (12 equal risers @ 217mm)
242mm straight treads which give a pitch of 42°

The winder treads are both equal and greater than the straight treads so they meet building regulations, however, they’re very large, if we apply the following rule;

“Twice the individual rise plus the going (2R +G) must be between 550mm and 700mm”

It works out as (2x217 +344) = 778mm
This is greater than the 700mm maximum stipulated by the building regulations, this means that the 2 kite winder in this example would not comply to building regulations, however a different two kite winder may well comply.


Inside tread dimension:

The building regulations also stipulate on kite winders that the tread should be 50mm minimum tread width at the narrow end, on the digram to the left, you can see that tread 4 is 112.78mm at the narrow end, and tread 6 is 90.22mm at the narrow end which would satisfy building regulations.

3) Width;

There is no minimum width stipulated for a domestic staircase within part K of the building regulations.

However, it is generally accepted that on a main staircase, going up to the first floor serving multiple rooms should be no less than 800mm, however, we would recommend 850mm to 950mm as this allows more space to get things up the stairs.

For loft conversions, the generally accepted minimum width is 600mm, however between 700mm and 750mm is recommended.

On staircases with a turn, it’s acceptable to have each flight a different width, like on the example to the right.

For a staircase with a kite winder, if the stairs are more than 1000mm wide then please contact us.

4) Headroom;

Headroom at all points going up a staircase:

Headroom is one of the most common problems with staircases, the building regulations state that you must have two meters headroom at all points when walking up the staircase from the pitch line.

The pitch line is a line that is drawn across the front of all of the treads, as indicated by the blue line in the diagram to the left.

It is a common misconception that headroom is measured from the top of the tread, however the building regulations stipulate that headroom must be measured from the pitch line of the staircase.

Note; Where there are real difficulties with headroom when converting existing spaces such as lofts, some building control officers may be lenient, but it is always best to check before installing your staircase.

Also note;

We’re also able to offer drawings for your staircase and calculate headroom for you before you order it to avoid problems after they’re installed.

Reduced headroom for loft conversions with sloping ceilings:

Where there is not enough headroom to achieve two meters headroom as shown in the previous section, it is acceptable where there is a sloping ceiling to have 1800mm headroom at shoulder height so long as there is 1900mm headroom at the centre of the staircase, as illustrated in the diagram to the right.

However, this is only applicable for loft conversions.

5) Landings;

A landing can either be:
Where the staircase changes direction, a flat platform.
Part of the floor, the area at the bottom or top of the stairs.

The building regulations state that, the width and length of a landing which constitutes part of the floor area must be at least equal to the smallest width of the narrowest flight of the staircase.

So, in the example above, because the width of the staircase is 750mm, the space at the top and bottom of the stairs must be a minimum of 750mm as well.


6) Handrails & Balustrades;

Correct Height Of Handrail:

The building regulations that apply to domestic stairs state that, the position of the top of the handrail should be between 900mm and 1000mm from the pitch line or floor.


Height handrail is required:

The building regulations state that, handrail must be provided at the sides of flights where there is a drop of more than 600mm.

This means that, on most staircases, the maximum number of steps you can have without a handrail is two, an example of this would be as shown to the left.

From this point on, handrail must be provided on any part of the staircase which is open to prevent people from falling.


Gap between spindles:

The building regulations state that, a 100mm sphere should not be able to pass through any opening in the balustrade, as such, the maximum gap between the spindles should not be any greater than 99mm, as shown on the diagram to the right.

Please Note; with turned spindles, this should apply to the smallest part of the spindle, so on a run of spindles, with turned spindles you would need more spindles than you would with square or stop chamfered spindles.

Horizontal Rails:

The building regulations forbid the use of what are commonly referred to as ranch rails, this was a popular style of balustrade and is often favored due to being cheap and easy to install, although they’re not directly forbidden, the building regulations state that in a building where children under five years of age have access, then guarding that can be climbed must not be used, an example of this is shown below;

7) Nosings;

Nosing is the area of the tread that overhangs the riser, as shown in the diagram to the right.

On a domestic staircase with closed risers, there is no minimum or maximum overlap for the nosing overhang, however we would recommend 20mm.

It is also possible to make stairs with no nosing overlap for a domestic staircase (unless it’s open riser)

8) Obstacles;

The building regulations stipulate that there must be 400mm from the door, or swing of the door to the bottom of the stairs.
The diagrams below illustrate this.

9) Open riser stairs;

The building regulations stipulate that a 100mm sphere should not be able to fit through the staircase at any point.
This means that, generally open riser staircases cannot have fully open risers. The solution to this is to either use a partial riser in timber, or a chrome riser bar to ensure that there is no more than 100mm gap anywhere. The diagram to the right shows an example of a mini open riser staircase.

Also, on an open riser straight the treads must overhang by at least 16mm

Below are example of a mini open riser stair and a stair with metal bars that conform to building regulations.


10) Space saver stairs;

In a situation where it’s not possible to fit a standard stair in, it is possible to use a space saver staircase.
These are also known as ‘loft stairs’ or ‘alternating tread stair’.

However, the building regulations state that these may only be used if serving a single room, for example, a loft conversion with a single bedroom.

It’s worth noting that most building inspectors do not like them and you should only use them as a last resort.

The building regulations state that space savers need to have a rise of no more than 220mm and a going of no less than 220mm on the long side of the tread the 42° pitch rule does not apply because of this.

It’s also worth noting that, on a space saver stair handrail or wall handrail must be installed both sides of the staircase.


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