Soaring stairs

Per­haps this rep­re­sen­ta­tive of the fam­i­ly of inter­floor stairs is the most spec­tac­u­lar. Some­times it seems that its steps are float­ing in the air. But this is only an illu­sion, in fact, in front of you is a care­ful­ly thought-out engi­neer­ing design.

The tra­di­tion­al wood­en stair­case on bow­strings or stringers, with its mas­sive pil­lars, oblig­a­tory ris­ers, chis­eled balus­ters and wide handrails, cre­ates a feel­ing of solid­i­ty, but at the same time blocks the light flow and lim­its the field of view. In oth­er words, it requires a lot of free space. Mod­ern inte­ri­or styles do not tol­er­ate such extrav­a­gance: designs should be light and trans­par­ent, lines sim­ple and fast.

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1. The main sup­port of this unusu­al stair­case can­tilever brack­ets, aux­il­iary sup­port ceil­ing ties. The design has retained its visu­al light­ness, despite the fact that its steps are quite mas­sive, and thanks to the handrail and the rope fence, it is very con­ve­nient and safe to move along it.
2–4. The can­tilever prin­ci­ple is wide­ly used in the man­u­fac­ture of spi­ral stair­cas­es. The node of their attach­ment to the pole can be made so that the step does not need any addi­tion­al sup­port. The pil­lar will have to be made more mas­sive, but nei­ther a bow­string nor a stringer will be required.

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5. Usu­al­ly the steps are strung on a cen­tral pole, installed at a dis­tance between the ceil­ings, and pinched with the help of spac­er bush­ings.
6. Bolts and minia­ture wall brack­ets are used to stiff­en the struc­ture.
7, 8. The lam­i­nat­ed tem­pered glass rail­ing (7) has a sig­nif­i­cant mass, so it is almost nev­er sup­port­ed on steps, but is attached to ceil­ings. Such rail­ings can become addi­tion­al sup­port for the march, and steel brack­ets attached to the wall (8) take on the main load.

ATresponse to the requests of design­ers, new types of stairs appeared can­tilever, sus­pend­ed (on strands), bolt, spinal (on the cen­tral stringer) and com­bined. Prob­a­bly, the dream of fans of min­i­mal­ism and high-tech style is ful­ly embod­ied by con­sole mod­els, in which there are no unnec­es­sary details. only steps, and attached to the sup­port (wall, pil­lar, col­umn) with only one end, while the sec­ond freely “floats” in the air. They try to make the fenc­ing of such stairs as less notice­able as pos­si­ble, and in rad­i­cal ver­sions they do with­out rail­ings at all. But still it should be not­ed that such extremes are rare and are designed more for demon­stra­tion than for prac­ti­cal appli­ca­tion. And the can­tilever steps them­selves in their pure form are rarely seen usu­al­ly this mount is com­bined with oth­er sup­port nodes.

As a rule, can­tilever stairs are not sold ready-made, they are made accord­ing to the size of a par­tic­u­lar room and tak­ing into account the require­ments of the own­er of the house. When ful­fill­ing such orders, Euro­pean com­pa­nies take one of their cat­a­log mod­els as a basis and use fac­to­ry com­po­nents, mak­ing a min­i­mum of changes to the design (due to this, their prod­ucts are of con­sis­tent­ly high qual­i­ty). Domes­tic firms pro­duce most­ly piece goods.

AT looking for a foothold

Build a can­tilever stair­case dif­fi­cult and labo­ri­ous task. Its foun­da­tion must be laid at the stage of erect­ing the walls of the build­ing (or, at least, before the start of inte­ri­or dec­o­ra­tion), because each step must with­stand a load of at least 150 kgf applied to its hang­ing, that is, unsup­port­ed end (and this is in addi­tion rail­ing weights!). Such high strength can be achieved in dif­fer­ent ways.

Step ter­mi­na­tion. Dur­ing the con­struc­tion of the wall, the ends of the steps are embed­ded in it for a length of at least 200mm (with a max­i­mum march width of 800mm). This is fea­si­ble only if the mason­ry is made of bricks or suf­fi­cient­ly heavy (for exam­ple, sol­id expand­ed clay con­crete) blocks, and it is nec­es­sary that each step be pressed down by at least ten rows of mason­ry. When using porous ceram­ic and hol­low clay­dite-con­crete blocks, as well as slot­ted bricks, the embed­ment depth must be increased to 300–400mm, which does not always allow the thick­ness of the wall to be made. Dur­ing the con­struc­tion of aer­at­ed con­crete, it will be nec­es­sary to strength­en the place of embed­ding each step with embed­ded ele­ments of heavy con­crete. Steps are also not suit­able for every­one, but only made of very hard and elas­tic mate­ri­als, such as rein­forced con­crete. How­ev­er, they are quite easy to dec­o­rate with wood over­lays, lam­i­nat­ed pan­els, nat­ur­al or arti­fi­cial stone. BUTyou can leave the steps in their orig­i­nal form - you can’t find any­thing bet­ter for a loft-style inte­ri­or.

Attach­ment of brack­ets. ATwall to a depth of 250–300mm embed sec­tions of a pro­file pipe up to 1m, leav­ing out­lets equal to approx­i­mate­ly 2/3 of the step length. At the same time, the require­ments for the wall are not reduced at all, but the steps can be made of engi­neered sol­id wood, as well as mate­ri­als based on wood com­pos­ite (chip­board, MDF). The fact is that in this design they cease to be self-sup­port­ing, but rely on steel brack­ets. Met­al parts, as a rule, are hid­den in grooves or holes milled (drilled) in steps. It should be not­ed that for the imple­men­ta­tion of projects with pinched and walled-in con­soles, only lead­ing con­struc­tion com­pa­nies should be con­tact­ed, and archi­tec­tur­al super­vi­sion is a pre­req­ui­site for suc­cess.

Anchor fas­ten­ing. The method is applic­a­ble after the com­ple­tion of the main con­struc­tion, but will require weld­ed brack­ets with sup­port plat­forms. Each such ele­ment is fixed to the wall with four or more anchor bolts with a length of at least 150mm and diam­e­ter from 10mm. The require­ments for the mate­r­i­al of the enclos­ing struc­ture in this case are very strict: nei­ther the porous block nor the slot­ted brick will hold the anchors (or, in order to reduce the pull-out force, the sup­port plat­forms will have to be much larg­er).

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9. Cre­at­ing more and more orig­i­nal archi­tec­tur­al forms is becom­ing a great way for man­u­fac­tur­ing com­pa­nies to demon­strate the skill of their engi­neers.
10–12. High-tech style cor­re­sponds to prod­ucts made of alu­minum, glass and plain lam­i­nat­ed pan­els (10, 12). Sol­id wood steps with chrome handrails empha­size the eclec­tic inte­ri­or (11).

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13, 14. When mak­ing a cus­tom-made fence, you can give free rein to your imag­i­na­tion, for exam­ple, dec­o­rate poles and balus­ters with inserts made of cop­per, brass, bronze or cut glass. It is only impor­tant not to over­load the sup­port­ing nodes and not to vio­late the styl­is­tic uni­ty of the inte­ri­or.
15. Glass steps always require bolt sup­port as they only allow short wall brack­ets.
16. Only the most expe­ri­enced spe­cial­ists under­take the design and con­struc­tion of rein­forced con­crete stairs.

Don’t depend on the walls

If the wall does not have the nec­es­sary strength, this is a seri­ous obsta­cle to the con­struc­tion of a can­tilever stair­case. But still man­age­able. Let us describe the method of fas­ten­ing steps, which can be imple­ment­ed in almost any build­ing before the start of fin­ish­ing work. Its essence is the use of a pow­er­ful weld­ed met­al frame from a chan­nel or a pro­file pipe. The design is made up to the ceil­ing, for the entire length of the march, placed close to the wall and tied to the upper and low­er ceil­ings. Toracks are weld­ed (or bolt­ed) can­tilever sup­ports for steps. The frame is then hid­den with dry­wall sheath­ing or light­weight block mason­ry.

The most dif­fi­cult type of can­tilever stair­case with brack­ets weld­ed (screwed) to a sin­gle steel bow­string, which is attached to the ceil­ings by means of pow­er­ful sup­port plat­forms and anchors. So that the bow­string does not twist under load, it must itself be a com­plex weld­ed truss with lon­gi­tu­di­nal, trans­verse and diag­o­nal stiff­en­ers (like a tow­er crane boom). Andnev­er­the­less, even a well-thought-out and well-made con­sole (except for a wall-mount­ed one) does not allow you to com­plete­ly get rid of the unsteadi­ness of the steps. First of all, the stair­case should be safe and com­fort­able, and what kind of com­fort can we talk about if you feel deflec­tions and back­lash­es at every step? We have to look for ways to strength­en the struc­ture.

AT console help

The task of engi­neers is to cre­ate a not too notice­able, but suf­fi­cient­ly reli­able sup­port for the sec­ond end of the steps. For exam­ple, you can rigid­ly con­nect all the treads to each oth­er with the help of bolts and thus trans­fer the load to the floors. Bolts are called hid­den bolts used in con­junc­tion with spac­ers. ATIn the case of a can­tilever struc­ture, each pair of steps is con­nect­ed with just one such bolt (and not two, as in a typ­i­cal bolt), locat­ed at the post­ed edge. Since the main load is tak­en by the wall mount, the bolts can be made minia­ture and dis­guised as the details of the fence or hid­den inside the ris­ers. FROMon the oth­er hand, the use of bolts makes it pos­si­ble to sig­nif­i­cant­ly sim­pli­fy and reduce the brack­ets: a pair of rods with a diam­e­ter of 30–40 is enough for each stepmm and length 400–600mm embed­ded in the wall at 80–160mm.

Fas­ten­ing steps to the ceil­ing with strands is no more dif­fi­cult than a bolt con­nec­tion. It is only nec­es­sary to pur­chase stain­less steel cables with a thick­ness of 8–10mm and install screw hooks, allow­ing you to select the slack of the strands, lan­yards. Hang­ing lad­ders look even more airy than bolt lad­ders.

The edi­to­r­i­al staff thanks the com­pa­nies “White Maple”, “SM Square”, Euroscala, UNION
for help in prepar­ing the mate­r­i­al.

• Source: Ideas for Your Home Magazine#180

Mate­r­i­al pre­pared

Vladimir Grig­oriev