• Spiral staircase

The staircase is designed in the form of a spiral.

• Partially screw

When straight sections of a staircase alternate with turning sections, simply put, the entry can be straight, then two or three steps with a turn, then straight again and again a turning section, etc.

• Straight

Made from a single straight element, without turns.

In this way, the stairs can pass over windows, doors, and arches.
And if all the steps and turns are calculated correctly, then climbing up and down it will be not only convenient, but also as safe as possible.

It's all about precise design; if the calculations are incorrect, a number of inconveniences can arise later. For example, with a fan-shaped staircase, a mistake is when the narrow part emerges like a fan from a single point. It should be done smoothly, not from a single point, with the riser in the narrow part extending deep under the top step. The standard tread width on the wide side is 3-4 cm, and on the narrow side, 7-8 cm, since most of it extends into the fan. This prevents the toe from slipping.
All fan-shaped steps in a turn are designed so that the middle is slightly wider than the steps on the flight. Typically, a straight step is 30 cm, a turning step is 38 cm, and the middle is 40 cm.
If a staircase has a turn, the design is always as follows: the bottom of the stringer rests on the floor, and the top rests against the wall. The next stringer rests on the top of the previous one at an angle, and the next stringer, in turn, rests on and supports the previous one. This distributes all the loads evenly. The treads fit into the stringer, into their grooves, in turn overlapping the joint and further strengthening the connections. A riser, usually double, on turning steps increases strength. I agree, this isn't easy; it requires skill. Many small details are unnoticeable to the naked eye, but they are precisely what allows you to walk up and down stairs with confidence.

Handrail.

It's made to fit the hand, with the height of the posts, balusters, and handrail angle adjusted to ensure a comfortable grip—lower on curves, slightly higher on turns. An imperceptible difference of 3-5 cm ensures reliability and convenience.
The handrail itself with balusters plays an important role, creating not only safety, but also an additional angle of rigidity for the entire structure.
Therefore, a high-quality assembled and calculated staircase does not require any pillars.
It can be floating, without any supports, without seeming flimsy and unreliable.

Generally, wooden stairs are made without any screws or metal ties. All joints are carpentry, with the balusters mortised into the tenon in the stringer eye. A properly fitted joint, taking into account the pith of the wood, will never split or crack.
The steps on the flight are sawn at the right places using a dovetail joint, so the staircase is tightly pulled together, without any gaps, and even without glue, it is very strong and does not creak.
But of course, I glue everything thoroughly. I've been using Stolyar PVA glue for many years; the quality is excellent.
The wooden staircase is self-sufficient; it rests on the floor. The top edge does not need to be secured to the ceiling.

If the house is made of timber or rounded logs, settling of a few centimeters is always possible, especially when the house is new, so the top is not secured to avoid putting unnecessary stress on the staircase structure. This also applies to brick houses.
Wood "breathes" a few millimeters in cold, damp, and summer conditions. In rare cases, anchor bolts are necessary, but this requires careful consideration.

In my wooden staircases, I carefully consider every element. You can always add more formality and character, expand the space, or visually increase the ceiling height. For example, if the staircase has a turn or landing, simply widen the entry by about 10-15 centimeters, and then gradually reduce the subsequent steps by 3-5 centimeters until they reach a straight flight. This creates the illusion of increased space and ceiling height.
And the entire structure of the staircase as a whole does not seem bulky, does not oppress, but rather “invites” you to climb up it.
You can also decorate your staircase with wood carvings featuring beautiful elements; this gives it an additional, individual look or can be used as a visual "lightening" technique.
Decorations in the form of metal inserts are also used: gold, silver, bronze, ornaments and patterns.
But I believe that a properly made staircase looks good on its own and does not always require the addition of exquisite decorations; the shape and dimensions of the staircase itself are already beautiful.

ABOUT STAIR LIGHTING AND SAFETY.

People often ask about backlighting. It's a controversial issue. To illuminate steps in the dark, backlighting is installed under the stair nosing. LED strip lights are best for this. Bulbs on the sides or elsewhere look impressive, but are often useless, blinding the eyes with their light. This becomes clear when all the lights are off and you're walking up and down the stairs at night. Installing lower-power backlighting is also ineffective—you'll only see the bulbs, not the steps you're walking on.