Explore the 1/3 Running Bond Pattern + Designs


Explore the 1/3 Running Bond Pattern + Designs

This particular association of rectangular models is characterised by every unit being offset by one-third of its size in relation to the row under. This creates a visually dynamic format the place the vertical joints don’t align, leading to a staggered look. Think about a wall the place every brick course is shifted horizontally by a 3rd of a brick’s size in comparison with the course under it. This shift is constantly maintained all through the development.

The format described provides enhanced structural integrity in comparison with patterns with vertically aligned joints. The overlapping distribution of weight reduces the potential for steady cracking. Traditionally, this offset association has been favored for its mix of aesthetic enchantment and purposeful reliability, notably in masonry development the place each visible curiosity and strong development are desired. The slight offset additionally contributes to a extra environment friendly use of supplies because it minimizes waste throughout set up.

The dialogue will now shift to particular functions of this format in varied development eventualities, inspecting the sensible issues for its implementation, and exploring different bonding strategies that could be appropriate for various venture necessities and aesthetic preferences.

1. Structural Integrity

The association described offers inherent power, born from its deliberate offset. Think about a towering brick facade, uncovered to the weather for many years. Its resistance to the relentless forces of nature is not merely the sum of its particular person parts, however a product of how they work together. The staggered joints disrupt steady vertical strains of weak point. This break in alignment distributes stress, stopping cracks from touring unimpeded throughout the construction. It is a refined but highly effective protection mechanism, turning potential vulnerabilities into factors of resilience. The bond resists not by brute drive, however by strategic redirection.

Think about the historic metropolis partitions of York. Constructed utilizing ideas mirroring this offset technique, sections have withstood centuries of siege, climate, and the final passage of time. The effectiveness resides within the minimization of aligned joints. The identical could be seen in lots of home constructions. Every unit shares the load with its neighbors, forming a community of mutual assist. This interlocking sample creates a cohesive unit the place forces are dissipated slightly than concentrated.

The result’s an development the place a small change in design yields disproportionately massive positive aspects in sturdiness. This association stands as a testomony to the understanding that sensible development is not all the time in regards to the strongest supplies, however about probably the most clever association of supplies. The bonds enduring enchantment lies in its capability to meld visible enchantment with elementary ideas of structural stability, demonstrating that type and performance can certainly coexist in a harmonious relationship.

2. Visible Rhythm

The precise association of rectangular models offers extra than simply structural profit; it introduces a charming visible cadence. It’s a rhythm born not of music, however of geometry and the interaction of sunshine and shadow, and its affect extends far past mere aesthetics, shaping our notion of house and type. The predictability, paired with an interesting offset, establishes this visible tempo.

  • The Dance of Offset

    The one-third offset disrupts the monotony of straight strains, making a dynamic interaction of horizontal and subtly implied vertical actions. This deliberate asymmetry attracts the attention throughout the floor, stopping it from settling right into a static gaze. Think about a brick facade bathed within the afternoon solar; the shadows forged by every unit amplify the staggered association, enhancing the sense of depth and motion. This factor injects a refined vitality into what might in any other case be a static aircraft.

  • The Weight of Repetition

    The repeated motif of the offset creates a way of order and predictability, grounding the visible expertise. Whereas the offset introduces dynamism, the constant repetition of this offset reinforces a way of stability and management. This steadiness between shock and expectation is a key factor in its enduring enchantment. Think about the lengthy, low partitions present in rural landscapes; the constant sample anchors the construction inside its surroundings, creating a way of belonging and permanence.

  • The Language of Mild and Shadow

    The staggered joints will not be mere strains, however lively contributors in a perpetual dance of sunshine and shadow. As daylight strikes throughout the floor, the offset edges create refined gradations, highlighting the three-dimensional nature of the sample. This interaction provides depth and texture, reworking a flat floor right into a dynamic panorama. The shifting patterns of sunshine and shadow underscore the underlying geometry, revealing the clever design.

  • The Echo of Custom

    This association carries with it the load of historical past. For hundreds of years, craftspeople have employed this and comparable layouts, embedding inside it a way of custom and craftsmanship. When this format is used, it evokes a way of connection to previous generations, a reminder of the enduring ideas of fine design and stable development. From historic Roman aqueducts to modern structure, the echo of this sample resonates by way of time.

These sides, taken collectively, reveal how this association of models achieves visible distinction by way of a fastidiously orchestrated steadiness of dynamism and order, gentle and shadow, custom and innovation. It’s a sample that engages the attention, soothes the thoughts, and connects us to a wealthy historical past of design and development.

3. Materials Effectivity

The bond described is not merely an aesthetic selection; it embodies a philosophy of resourcefulness. Its very design inherently minimizes waste, an important consideration in any development endeavor. The format’s genius lies in its capability to make the most of customary unit sizes with minimal chopping. It’s an acknowledgement that each fragment of fabric represents embodied vitality, labor, and environmental affect. To squander is to ignore these investments.

Think about the development of a protracted backyard wall. Utilizing different patterns would necessitate frequent chopping of parts to take care of alignment at corners or edges. These partial items typically turn out to be unusable, relegated to the scrap pile. Conversely, the constant one-third offset permits the strategic use of partial models, typically generated from unavoidable breakage, alongside the wall’s size. These fragments discover goal, turning into integral to the construction’s stability and visible enchantment. The affect extends past mere price financial savings. Decreased waste interprets to fewer sources extracted from the earth, diminished transportation wants, and decreased landfill burden. The affect of minimized waste is compounded when utilized to bigger initiatives. Multiplied throughout huge developments, the cumulative environmental advantages turn out to be important. A single selection in bonding sample resonates far past the development website, touching the surroundings, financial system, and social accountability.

The bond thus represents greater than mere aesthetics or structural integrity. It’s a dedication to sustainability, a recognition that the accountable use of sources is integral to creating enduring and environmentally sound constructions. It serves as a refined reminder that design selections, seemingly minor, can have profound and lasting penalties. This strategy to materials utilization showcases a timeless precept: environment friendly design not solely saves prices but in addition honors the planet.

4. Joint alignment

Inside the craft of masonry, joint alignment occupies a place of vital significance, dictating each the structural integrity and visible concord of the completed work. When contemplating the precise association the place rectangular models are offset by one-third of their size, the strategic manipulation of joint placement turns into a central theme. The deviations from steady vertical seams turn out to be a design characteristic, not an anomaly.

  • Disrupted Verticality: A Load-Bearing Technique

    The hallmark of the described format is its deliberate disruption of vertical joint continuity. This deviation serves as a foundational factor for distributing hundreds extra successfully. Think about a wall uncovered to substantial lateral forces, resembling wind or soil stress. Steady vertical joints act as strains of weak point, liable to cracking and eventual failure. By offsetting every course by a 3rd of a unit’s size, the load path is compelled to traverse throughout a number of models, successfully distributing stress. The person parts perform as an interconnected system, not as remoted components.

  • Horizontal Emphasis: Visible and Structural Implications

    The one-third offset locations a powerful emphasis on the horizontal aircraft. Visually, this creates a way of size and continuity, drawing the attention throughout the floor. Structurally, it interprets to elevated resistance to horizontal shear forces. Think about a protracted, low backyard wall constructed with this format; the horizontal strains visually anchor the construction to the panorama, whereas the overlapping parts resist forces that would in any other case trigger the wall to buckle or collapse. The horizontal planes create a stabilizing counterpoint to the vertical forces.

  • The Interaction of Stretcher and Header: Bond Energy Enhanced

    Whereas the standard operating bond typically entails alternating programs of stretchers (models laid lengthwise) and headers (models laid with their ends uncovered), the format in focus sometimes employs solely stretchers. Nevertheless, the one-third offset simulates among the interlocking advantages of a header course. The overlapping sample successfully “ties” the wall collectively, stopping particular person models from shifting independently. This enhances the general bond power of the construction. Every part turns into built-in inside the bigger entire.

  • Accuracy and Precision: The Craftsman’s Mandate

    The visible and structural benefits of the described format are predicated on exact execution. Even minor deviations in joint alignment can compromise the supposed results. The craftsman should preserve meticulous management over spacing and leveling to make sure the integrity of the sample. The constant offset depends on the cautious placements. The extent of precision reinforces the sturdiness of the construction.

In conclusion, joint alignment is just not merely a technical element inside the format described; it’s a elementary design precept that dictates its aesthetic and structural character. The deliberate disruption of vertical joints, the emphasis on horizontal continuity, and the interaction of stretchers all contribute to a singular and compelling strategy to masonry development. The craftsman’s adherence to accuracy and precision ensures that the format features as supposed, delivering each visible enchantment and lasting structural efficiency.

5. Set up Complexity

The act of laying brick, stone, or tile is a craft steeped in custom, but tempered by the realities of contemporary development. Whereas the described association provides compelling aesthetic and structural benefits, it introduces particular challenges to the set up course of. These complexities, although manageable with correct planning and talent, demand a nuanced understanding of the craft.

  • The Phantasm of Simplicity: Sustaining Alignment Throughout Programs

    At first look, the staggered look of this setup would possibly counsel a better set up in comparison with completely aligned patterns. Nevertheless, the constant one-third offset necessitates cautious consideration to element. Every unit have to be exactly positioned relative to the course under, requiring fixed measurement and adjustment. The absence of steady vertical joints, whereas structurally useful, removes a visible information that simplifies the alignment course of in different patterns. The result’s a refined rigidity between the obvious simplicity of the design and the rigorous calls for of its execution.

  • The Curse of the Nook: Mitigating Cumulative Error

    Corners characterize a vital juncture in any masonry venture. The one-third offset can amplify the challenges of attaining a clear, correct nook. Even slight deviations in unit placement accumulate over successive programs, resulting in noticeable misalignment and aesthetic imperfections. Skilled masons typically make use of specialised strategies, resembling “racking again” or the strategic use of nook blocks, to mitigate these cumulative errors. The nook turns into a microcosm of the general set up course of, demanding precision and foresight.

  • The Dance of the Minimize: Precision Chopping for Edges and Infill

    Whereas the association minimizes waste, it inevitably requires exact cuts to suit models alongside edges, round openings, and in tight areas. The one-third offset necessitates that these cuts be correct and constant, as even minor variations can disrupt the visible rhythm of the sample. The power to execute clear, exact cuts turns into an important talent for masons working with this format. A poorly executed lower stands out, drawing undesirable consideration and undermining the general high quality of the work.

  • The Significance of the Bond: Guaranteeing Adhesion and Stability

    The effectiveness of this setup depends on correct bonding between models. Mortar joints have to be totally stuffed and correctly compacted to make sure that every unit is securely anchored. Gaps or voids within the mortar can compromise the structural integrity of the sample, doubtlessly resulting in cracking or displacement. The act of laying parts turns into extra than simply stacking materials; it’s the making a cohesive, load-bearing system.

The association of rectangular models requires a mastery of elementary abilities, a deep understanding of fabric properties, and an unwavering dedication to accuracy. Whereas its aesthetic and structural advantages are plain, the set up course of calls for respect and a focus. This cautious effort transforms uncooked supplies into one thing of lasting worth and sweetness.

6. Historic Precedent

The association of rectangular models, shifted by a 3rd of their size with every successive course, isn’t any trendy invention. Its roots delve deep into the annals of development historical past, a testomony to its enduring practicality and aesthetic enchantment. To grasp this format is to embark on a journey by way of centuries of architectural evolution, tracing its presence in constructions which have weathered the relentless exams of time and human endeavor. Its longevity is just not unintended; it’s born from a mix of structural effectivity, materials financial system, and visible concord that resonated with builders throughout cultures and eras.

Think about the traditional brickwork of Roman aqueducts. Whereas not all the time an ideal execution, the spirit of staggered joints, aimed toward distributing load and stopping catastrophic failure alongside steady vertical strains, is undeniably current. These enduring feats of engineering, many nonetheless standing millennia later, showcase the foundational ideas upon which the format rests. Transfer ahead to the medieval interval, and one finds examples within the sturdy partitions of castles and cathedrals. Brick and stone, laid in comparable overlapping patterns, supplied each defensive power and visible curiosity. The one-third offset, or shut variations, allowed for the creation of visually interesting surfaces with out compromising structural integrity, a vital consideration in an age the place sources had been restricted and development experience was paramount. Even in colonial America, this format discovered favor within the development of houses and public buildings. The straightforward, repeating sample supplied an economical and dependable methodology for creating stable, weather-resistant partitions. The desire wasn’t merely stylistic; it was pushed by sensible issues born from a necessity for sturdy constructions that would stand up to the cruel components of a brand new world.

The historic precedent of this association serves as a strong reminder that sound design ideas will not be certain by time or expertise. The enduring recognition of this sample is as a result of its worth is constant throughout eras. It has constantly supplied a steadiness of structural soundness, materials effectivity, and visible enchantment. By understanding this historic context, trendy builders and designers can recognize the inherent knowledge embedded inside the sample, leveraging its confirmed benefits to create constructions which are each purposeful and aesthetically pleasing. The continued use of this format connects us to a protracted lineage of craftspeople who understood the significance of constructing nicely, constructing effectively, and constructing to final. The echoes of the previous resonate in each brick, each stone, each fastidiously aligned unit.

7. Design Adaptability

Design adaptability, within the context of masonry, speaks to the capability of a specific bonding sample to combine seamlessly with numerous architectural kinds and purposeful necessities. The described association, with its constant one-third offset, possesses a stunning diploma of this inherent flexibility, a chameleon-like capability to enrich each the stark minimalism of contemporary designs and the ornate prospers of historic constructions. This isn’t merely a matter of aesthetics; it’s a testomony to the underlying ideas of proportion and visible steadiness that govern profitable architectural compositions. Think about a recent loft conversion, the place uncovered brickwork serves as a textural counterpoint to smooth metal and glass. The constant rhythm of the offset association introduces a way of heat and visible curiosity with out overwhelming the minimalist aesthetic. The predictability within the setting offsets the smooth surrounding surfaces.

Conversely, think about the meticulous restoration of a Victorian-era townhouse. Right here, the bond in focus can seamlessly mix with the prevailing brickwork, preserving the constructing’s historic character whereas subtly reinforcing its structural integrity. The one-third offset, a typical characteristic in Victorian development, permits for the discreet integration of latest brickwork with the previous, making certain that the restored facade retains its authentic attraction and authenticity. This design association additionally provides sensible benefits by way of adapting to irregular constructing shapes or accommodating structural modifications. The power to simply modify the bond sample round home windows, doorways, or different openings permits for a seamless integration with the general design. This adaptability is especially useful in renovation initiatives, the place surprising challenges typically come up, requiring inventive options and a versatile strategy to development.

In essence, the design adaptability of the format stems from its inherent steadiness between order and dynamism, predictability and visible curiosity. It’s a sample that may be readily scaled and tailored to go well with a variety of architectural contexts. The understanding of its capabilities is vital for architects and builders in search of to create constructions which are each aesthetically pleasing and structurally sound. The selection is just not merely stylistic, however a elementary determination that shapes the character and longevity of the constructed surroundings.

8. Waste discount

Within the realm of development, the place supplies are painstakingly quarried, processed, and transported, waste discount is just not merely an financial consideration; it’s an moral crucial. This idea positive aspects specific resonance when inspecting the precise bond, the place rectangular models are constantly offset by one-third of their size. The intentionality of this format fosters materials effectivity, reworking what may be thought of scrap into integral parts of the construction.

  • The Strategic Salvage of Offcuts

    In contrast to bonding patterns that demand completely uniform models, the aforementioned setup capitalizes on the inherent geometry of its design. Think about a bricklayer going through the inevitable actuality of damaged bricks on a worksite. As an alternative of consigning these fragments to a landfill, the one-third offset permits them to be strategically integrated into the wall. These offcuts, sometimes deemed unusable in different patterns, turn out to be useful infill, sustaining the visible rhythm and structural integrity of the development. This deliberate salvage minimizes materials waste, decreasing each environmental affect and venture prices.

  • Minimizing the Want for Specialised Models

    Sure architectural designs necessitate specialised brick or stone models to accommodate corners, openings, or ornamental options. The manufacturing of those customized parts typically entails important waste, as producers should create molds and processes tailor-made to particular dimensions. The constant one-third offset, nonetheless, mitigates the necessity for such specialization. The inherent flexibility of the sample permits for the mixing of normal models, minimizing the demand for customized items and thereby decreasing general materials wastage. The construction can retain a streamlined, visually constant sample.

  • Optimizing Mortar Utilization

    Whereas the main target typically stays on the stable parts of a wall, mortar performs a vital position in its structural stability and longevity. Extreme mortar utilization contributes to each materials waste and elevated prices. The exact, repeating nature of the setting permits for optimized mortar utility. Expert masons can effectively apply mortar, minimizing extra and making certain a constant bond between models. This discount in mortar utilization additional contributes to the general purpose of waste discount.

  • Extending the Lifespan By way of Structural Integrity

    Waste discount extends past the development section. Buildings constructed with a powerful and environment friendly bond are much less liable to cracking, displacement, or different types of deterioration. The inherent power of the format interprets to an extended lifespan for the constructing. By minimizing the necessity for repairs or replacements, the format contributes to the long-term discount of waste related to development and demolition actions. The emphasis is shifted in the direction of creating sturdy, lasting constructions.

The narrative of waste discount, due to this fact, is interwoven with the very essence of this setting. Its intentionality in the direction of materials effectivity transforms what may be thought of scrap into integral components. By optimizing useful resource utilization all through the development course of and lengthening the lifespan of the construction, the one-third offset stands as a testomony to the potential for sustainable constructing practices, echoing the enduring worth of considerate design and accountable craftsmanship.

Regularly Requested Questions

These questions characterize a compilation of the commonest inquiries encountered when discussing the format described. They function a information by way of the intricacies and nuances of this enduring sample, revealing its inherent strengths and addressing lingering misconceptions.

Query 1: Is the one-third offset really stronger than a normal operating bond, or is it merely an aesthetic desire?

The assertion of elevated power is just not merely an ornamental flourish; it stems from the basic ideas of load distribution. Think about two partitions, equivalent in supplies and development, but differing solely of their bonding sample. In the usual operating bond, steady vertical joints present a direct path for cracks to propagate. The staggered joints within the offset association disrupt this pathway, forcing stresses to navigate a extra circuitous route. This refined shift in load distribution enhances the wall’s resistance to cracking and deformation. The structural benefit is demonstrable, born from the deliberate manipulation of joint alignment.

Query 2: Does this format translate to important price financial savings on large-scale initiatives, or is the fabric effectivity negligible?

The cumulative affect of fabric financial savings could be substantial, particularly when utilized to massive initiatives. Think about a sprawling housing improvement, the place numerous bricks are required to assemble the outside partitions. The power to include damaged or partial models into the offset format, slightly than discarding them as waste, can yield important price reductions. The minimization of specialised cuts and the optimization of mortar utilization additional contribute to those financial savings. Whereas the person financial savings per unit could appear small, they mixture over the whole lot of the venture, leading to tangible financial advantages. It is the facility of incremental effectivity.

Query 3: Is the set up course of considerably extra complicated, requiring specialised coaching for masons?

Whereas the association calls for precision and a focus to element, it doesn’t essentially require specialised coaching past the core competencies of a talented mason. The important thing lies in sustaining correct alignment and constant spacing all through the development course of. Skilled masons readily adapt to the refined nuances of the sample, using strategies to mitigate cumulative errors and guarantee a clear, skilled end. The requirement is just not experience, however diligence and a dedication to high quality craftsmanship.

Query 4: Does this format restrict design flexibility, or can it’s tailored to varied architectural kinds?

The enduring recognition of this sample stems, partly, from its exceptional design adaptability. As evidenced by its presence in constructions spanning centuries and architectural actions, the format can seamlessly combine with numerous aesthetic sensibilities. From the country attraction of colonial-era houses to the smooth strains of contemporary lofts, the offset sample provides a timeless enchantment that transcends stylistic boundaries. The flexibility permits for nuanced adaptation.

Query 5: Are there particular sorts of supplies for which that is notably well-suited?

The format is inherently versatile, accommodating a variety of supplies from conventional clay bricks to pure stone and even concrete blocks. The important thing consideration is the constant dimension and form of the person models. So long as the models preserve uniform dimensions, the one-third offset could be successfully utilized, whatever the materials composition. The adaptability of the sample extends to a wide range of development supplies.

Query 6: Does upkeep or restore of a wall constructed with the described format current distinctive challenges?

The upkeep and restore of partitions follows comparable ideas as different bonding patterns, however some consideration must be accounted. The one-third offset simplifies the method of changing particular person models, because the staggered joints present simpler entry and scale back the chance of disturbing adjoining parts. The secret’s to match the prevailing supplies and preserve the constant one-third offset when putting in substitute models, making certain a seamless integration with the unique development. The refined variation makes restore much less intrusive.

In abstract, the insights gained from these often requested questions serve to light up the inherent strengths and handle widespread misconceptions related to the described format. The association presents a harmonious mix of structural integrity, materials effectivity, design adaptability, and ease of upkeep, solidifying its place as a timeless and versatile selection for masonry development.

The next part will look at the varied functions of this format throughout varied development initiatives, showcasing its sensible utility and enduring aesthetic enchantment.

Crafting Longevity

The whisper of expertise echoes by way of the brickwork, a testomony to selections made and classes realized. These will not be mere directions, however hard-won insights born from years of grappling with the refined nuances of the format in query. The next are strategies refined over time, shared with the solemn understanding that good development is just not a matter of velocity, however of tolerating high quality. These insights are to be thought of and thoughtfully utilized.

Tip 1: Floor the First Course with Unwavering Precision. The primary course is the inspiration upon which all else rests. Guarantee it’s completely degree and meticulously aligned. Any deviation at this stage will amplify exponentially with every subsequent course. Make use of a laser degree, not merely a spirit degree, to confirm absolute accuracy. Think about the primary course as setting the usual for the whole lot constructed above it.

Tip 2: The Mortar is Your Ally; Grasp Its Consistency. Mortar that’s too moist will sag, compromising the bond and creating unpleasant gaps. Mortar that’s too dry is not going to adhere correctly, resulting in weak point and potential failure. Search the consistency of stiff butter, simply workable but retaining its form. Experiment with small batches to seek out the right steadiness for the precise supplies and local weather.

Tip 3: Stagger with Intention, Not by Probability. The one-third offset is just not a suggestion, however a exact measurement. Use a devoted spacer, a easy wood jig, to make sure constant staggering throughout each course. Keep away from counting on guesswork; the visible rhythm of the sample is dependent upon unwavering uniformity. A slight lapse in consideration can detract from the aesthetic grace.

Tip 4: Respect the Corners; They Demand Vigilance. Corners are probably the most susceptible factors in any masonry construction. Interlock the models meticulously, making certain that every nook is correctly tied in. Apply additional mortar on the corners, making a stable, impenetrable bond. Corners not finished appropriately will result in structural compromise.

Tip 5: Embrace the Damaged; Combine, Do not Discard. The described sample is forgiving, permitting for the strategic incorporation of damaged or partial models. Don’t view these fragments as waste, however as alternatives. Rigorously choose and place these items, making certain that they contribute to the general structural integrity and visible steadiness. The conscious integration is a measure of true talent.

Tip 6: Remedy with Persistence; The Wall Will Thank You. The curing course of is simply as very important because the laying course of. Defend the freshly constructed wall from excessive temperatures and direct daylight, conserving it evenly moist to advertise correct hydration of the mortar. The wall’s sturdiness is dependent upon a sluggish, regular remedy, not a fast, compelled drying. A protracted sluggish remedy ensures a stronger bond.

These will not be shortcuts, however enduring ideas, earned by way of the relentless pursuit of high quality. Apply these classes with thoughtfulness, understanding that every brick laid, every joint stuffed, is a testomony to the enduring energy of cautious craftsmanship.

Having absorbed these insights, the dialogue now transitions to inspecting potential challenges, these unexpected obstacles that inevitably come up within the follow of masonry. These are to not be feared, however anticipated, ready for, and overcome with talent and resolve. This part will equip the reader with the understanding to navigate these potential pitfalls.

1/3 operating bond sample

The previous exploration has traced the contours of a easy but profound design, the place every rectangular unit, offset by a 3rd, tells a narrative of power, effectivity, and flexibility. From its historic roots in historic fortifications to its trendy functions in modern structure, this association demonstrates an everlasting enchantment. This layouts structural integrity is born of disrupted verticality, visible rhythm derived from the dance of offset, materials effectivity emerges by way of ingenious waste discount, all testomony to considerate development practices.

The legacy of the format is not only within the constructions it helps, however within the ideas it embodies. In a world typically pushed by fleeting traits, the enduring worth of the format is a continuing. The selection to make use of is a silent dedication to lasting design, materials consciousness, and structural prudence. Allow us to assemble with imaginative and prescient, understanding that even the smallest design selection, just like the strategic offset of a single brick, can contribute to one thing enduring. The format stands as a testomony to how the pursuit of sturdiness, conservation, and sweetness can form our world, one exactly positioned unit at a time.

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