Interior TRANSITIONS--STRUCTURAL

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INTRODUCTION

A sense of structure is basic to a person's perception of the environment. People live in a world of gravity, compression, tension, bending, twisting, and impact. Even without knowledge of the technical aspects of structural design, people have a sense of building elements responding to these basic structural forces. E.g., people have an inherent sense of whether a column looks like it’s adequate to support a beam or if a sign looks too heavy for the wires supporting it.

Every experience in architecture and interior design is judged, consciously or unconsciously, within the context of these structural forces. The result is conformation of structural forces being stable or a visual dissonance when what is visible runs counter to a person's nor mal experience and expectations. In most cases, the structural forces are perceived in terms of a structural transition from one component to another, such as a beam resting on a column. In this section structural transition refers to the connection of one element to another, whether the connection is a real, supportive link or whether the connection is simply a visual suggestion of a structural connection.

Of course, by law, interior designers cannot design the actual structure of a building or major structural elements. However, in the broadest sense, even the simplest interior detail has a structural component. E.g., a countertop spanning an open area must support its own weight and any weight placed on it without bending or breaking. Interior designers are involved in structure-related design in the following ways:

  • _ By covering the real structure of the building with finishes, either to emphasize the structure or conceal it
  • _ By creating presumed structure with, E.g., false beams and columns
  • _ By detailing building elements governed by prescriptive codes in seismic zones
  • _ By designing and detailing suspended elements that are not otherwise governed by building codes
  • _ By detailing and specifying the anchorage of wall-mounted items
  • _ By detailing architectural woodwork where minor forces are present
  • _ By detailing other miscellaneous interior elements such as low partitions, openings, or panel supports, that have a real or presumed structural component

The ability to create structural expression provides the interior designer with a powerful tool to enhance design concepts, shape experience, and solve detailing problems. The designer can decide whether to express and celebrate structure, articulate an opposition to it, or to design independently of it. The designer can create a sense of stability, provoke dissonance, create interest, suggest wonder, or completely conceal structure. Any approach is not necessarily better than another; the interior designer must simply determine which structural expression best meets the design goals of the project.

Structure can also suggest and de fine spatial volume. Historically, structure has been the prime determinant of spatial character and has largely been lost as a design tool in much of current architecture and interior design. E.g., the huge columns, vaulted ceilings, and massive walls of the great cathedrals are the main form givers of those interior spaces, not the detailed painting and carving on their surfaces. Contrast that approach with most any contemporary interior where flat ceilings, plain walls and nondescript openings give little clues as to what actually supports the spatial enclosure. If desired, the interior designer can articulate the structure of a building as a starting point for de fining space and speci fic use areas.

This section discusses the conceptual ways to make transitions between major building elements as well as smaller building components. These transitions can be categorized into three broad areas: columns, beams, and suspended elements. Section 4 discussed some of the basic structural methods of detailing connections, while suggestions for speci fic structural connections have been given in various other sections.

COLUMNS

Columns are one of the most common architectural structural elements that remain visible in interior design. They may appear freestanding in the middle of a room or may prominently extend out from an otherwise flat wall. Other structural building elements, such as beams, joists, and bearing walls, are generally concealed by other architectural or interior construction finishes. The interior designer may choose to minimize the appearance of columns within a space by applying a finish with the smallest possible dimensions while still retaining any required fire-resistive coatings or by hiding them within partition construction. In other instances, the designer may elect to emphasize the column by enlarging the dimensions of the finish or by changing the shape of the finish covering.

Regardless of the final size and con figuration of the column itself, the design and de tailing of the transition between the column and the ceiling, floor, or beam are important considerations in expressing the designer's approach to structure.

Column-to-Ceiling Transitions

The method by which a column supports a ceiling or a beam is a basic design archetype.

Most fundamentally, a beam rests directly on a column. The beam, in turn, supports other secondary beams or the ceiling. All people intuitively understand this fundamental structural principle and use it to assess other structural conditions that they experience. However, in interior design most conditions present the intersection of a column with the ceiling directly, without an intermediate beam.

From a strictly design standpoint, it’s sometimes dif ficult to design and detail an elegant column to ceiling transition because in much of contemporary construction the ceiling is a suspended acoustical ceiling whose grid may or may not be coordinated with the building structural grid or the functional layout of partitions is completely independent of the building's structure. However, when possible, the interior designer can consider some of the following approaches to structural expression. The first four suggest the column is actually supporting the ceiling, the ceiling being dependent on the column. The second group of four indicate that the ceiling is clearly independent from the interior column and, thus, the building structure itself.

--- Dependent column-to-ceiling transitions (a) none (b) enlarged (d) flared (c) capital The simplest type of column-to-ceiling transition is to have none at all. This is common because of its low cost and quick and easy installation. When a suspended acoustical ceiling is used, a ceiling angle may be the only construction visible at the junction of the two elements.

An enlarged column is a simple transition, acknowledging the meeting of column and ceiling without elaborate construction.

A capital is a major design feature between the column and the ceiling. The capital can be simple, as shown here, or more decorative. Traditionally, a capital was used to create a broader bearing area. It’s best used when coordinated with the type and layout of the ceiling.

A flared capital appears to spread the weight from above and gives a sense of stability. As with other dependent column transitions, the location of the ceiling grid should be coordinated with the size and shape of the capital where it touches the ceiling.

NO TRANSITION

The most common method of making the transition between a column and a ceiling is no transition at all. This is the simplest and least costly and is one way to minimize the appearance and signi ficance of the structure, if that is the designer's intent. If no fire-resistive coating is required, the structural column may even be left exposed to minimize the size of the column. This approach is the most tenuous in suggesting that the column is supporting the ceiling.

If a gypsum wallboard ceiling is used, the transition with a gypsum wallboard column will appear as a simple inside corner. The intersection with a suspended acoustical ceiling will only be interrupted with a simple ceiling angle. It appears like any other wall or penetration of the ceiling.

ENLARGED

The classic method of making a transition from column to ceiling is with a capital or other transition device or to have the column support a beam, which, in turn, supports the ceiling.

If the column appears to support the ceiling directly, as is typical with interior construction, the transition may be made with a simple enlargement of the column. This is a slightly more elegant solution to the transition detail. It gives a suggestion of a traditional approach to column design but without elaborate construction or cost. It can be as simple as an extra layer of gypsum wallboard or plain wood trim. The trim is usually identical to other trim or crown molding used against the partitions.

CAPITAL

A transition with a capital uses a distinct and fairly large element between the top of the shaft of the column and the ceiling. It’s the classical method of construction with the capital providing a larger bearing surface for two beams joining at the column than the column could provide alone. Intuitively, people see the capital collecting the weight of the structure above and placing it on the column.

Capitals can be designed in a wide variety of configurations, from the simple column cap to ornate classical capitals. Of course, the detailing of the capital should be coordinated with the type and style of the ceiling and with the overall design concept of the space in which it’s used. --- two variations of how to detail capitals with metal framing.

FLARED

A flared capital is one of many variations that can be used. Flared capitals make the obvious transition from the size and shape of the column shaft to the size of the upper portion of the capital. Flared columns can easily be detailed by using metal framing.

-- Framed column capital option A--new option B--existing structural column and fireproofing existing column cover suspended acoustical ceiling brace as required new column cover--dimension as designed framing suspended from structure above optional trim

--- Independent column-to-ceiling transitions: (b) bypass (a) reveal (c) separated (d) column to wall

A bypass installation distinctly separates the suspended ceiling from the column, which appears to extend untouched to the structure above. The distance between the column and the edge of the ceiling trim can be set at whatever value the designer wants.

A separated column visually disconnects the column from the ceiling. Although the actual structural part of the column extends to the beam above, when viewed at eye level, the effect is that there is no connection between the column and the ceiling.

In this design, the column is enlarged to appear to be a thick partition or bearing wall. Portions not occupied by the actual column can be used for storage or other uses.

A reveal transition may be created by using a simple W-trim supporting acoustical tile or with a deeper and wider reveal created by framing an opening around the column with trim accessories or gypsum wallboard.

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REVEAL

The second broad group of column-to-ceiling transitions includes those that clearly and obviously treat the ceiling as a separate, distinct interior finish from the architectural structure of the building. A reveal provides a subtle separation between the column and the ceiling.

With a reveal, it appears that the column is penetrating the ceiling. It’s one of the most honest expressions in contemporary construction because, in most cases, columns really don’t support the ceiling. The ceiling is a separate and arti ficial plane, and the interior finish is separate from the architecture. Reveals can be constructed easily with the same gypsum wallboard trim discussed. Larger reveals can be detailed by using ceiling trim held away from the column by a few inches.

BYPASS

To very clearly separate the column from the ceiling a bypass detail can be developed. With this detail, there is a large gap between the column and the edge of the suspended ceiling. The ceiling appears to float independently from the column and if the gap is large enough the building structure and mechanical services may be visible. Because the edge of the ceiling suspension system is visible some type of trim should be used.

SEPARATED

A separated column appears to stop short of the ceiling line. To make this effect work the finish covering must be signi ficantly larger than the actual structural column, which may be dif ficult if the column is concrete or steel with applied fire-resistive coating.

The column cover must extend out from the actual column enough so that the sightline from most areas of the space prevents the actual column from being visible. To enhance this effect, the actual, smaller column that extends through the ceiling can be finished with a mirror to reflect the surrounding ceiling surface.

COLUMN INTO BEARING WALL

A column can also be designed and detailed to be independent from the ceiling by transforming it into something other than a column. As diagrammed, the column can be enlarged into what appears to be a thick partition. The final finish can be simply gypsum wallboard or any finish material that is consistent with the overall design concept of the space.

To make more ef ficient use of the space, the portion of the enlarged partition that does not actually contain the column can be used for shelving or other functional needs.

Column-to-Floor Transitions

As with a column-to-ceiling transition, the intersection between the base of a column and the floor can be understated, emphasized as a normal structural condition, or the two elements can be clearly differentiated. However, unlike the top of a column, any additional construction at the floor line requires additional floor space and may present a tripping hazard if it exceeds the thickness of standard wall base. As with column-to-ceiling transitions the column at the base can appear to be dependent on the floor or independent from it.

NONE

The column can terminate directly on the floor, with no base or only the standard base used elsewhere in the room applied to the column. This is the easiest and least costly approach that requires the least amount of floor space and that minimizes the appearance of the column. This is the simplest type of dependent transition.

ENLARGED BASE

The second type of dependent column-to- floor transition is an enlarged base. As with columns supporting the ceiling or a beam, the most stable-looking transition is a column resting on a base larger than the column. Structurally and traditionally, this was a way to spread the weight of the column load over a larger area of the floor. Even though this is not actually the case in most instances in contemporary construction, the visual effect is the same. People perceive this type of transition as being inherently stable. The size of the base can be as large and complex as desired.

FLOOR MATERIAL CHANGE

As diagrammed the base condition can be emphasized by using a large base as well as by changing flooring materials around the base. This provides additional highlighting of the intersection without using additional floor space or creating a tripping hazard. The floor material around the column can be extended as far as the designer wants or, in large spaces, it can run continuously from one column to the next, suggesting the actual structural grid of the building.

--- Dependent column-to- floor transitions: (b) enlarged base (a) none (c) floor material change

An enlarged base appears as the most stable and normal as this is the traditional way to treat columns so the weight appears to be spread out on the supporting floor. An enlarged base may be a simply applied wood trim or broader, built-up sections of wood, stone, or other materials.

A distinct floor material placed around the column base calls attention to the transition without requiring any special base detailing and without presenting a tripping hazard, assuming the two floor materials are flush.

To deemphasize the column at the base, the designer may choose to provide no base at all or just a minimal base as used elsewhere in the room. This is the easiest and least costly approach and requires no elaborate detailing.

--- Independent column-to- floor transitions (b) bypass (a) floating (c) surround A bypass column distinctly separates the interior floor from the structural elements of the building. If the gap is large enough it can present a tripping hazard unless a rail or toe guard is provided.

When a significant portion of the column is surrounded by other construction, the column is less noticeable and appears to be part of the other construction. This concept can be combined with the "column-to-wall" concept to completely conceal the column.

A floating column appears not to be attached to the floor. If the actual structural portion of the column is large, the covering must be sufficiently large to conceal the real column when viewed at normal eye level.

--- Finish column-to-beam transitions (b) simple intersection (a) simple one way (c) capital (d) intermediate material A simple intersecting beam and column transition is typically used for columns in the middle of a space that supports structural beams that are enclosed with gypsum wallboard finish. In large spaces, this creates an interesting pattern of low beams and ceiling spaces that define the structural bays of the building.

A capital used on top of a column that, in turn, supports a beam is a classical way of post-and-beam construction.

It can be used with simple wallboard finishes or with false structures of wood or other materials that the interior designer may create. Normally, the capital is approximately the same width as the column.

An intermediate material may be used much like a capital but it may have a different size and shape and be constructed of a different material, at the designer's discretion. It generally is only effective if the column and beam are of materials that are normally associated with structural materials, such as wood.

Simple beam to column connections are made by resting the beam directly on the top of the column. This approach can be used with typical structural materials, such as wood, or it can be created with gypsum wallboard to create one smooth surface.

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FLOATING COLUMN

A floating column is one type of independent column-to- floor transition that visually separates the structure from the interior finish of the space. Because the actual structural column must continue to and through the floor, an additional thickness of finish material must be detailed that stops short of the finish floor line. This can be as simple as using a base reveal or by furring out from the original finish covering to extend the finish several inches out from the actual column. One way this can be done is with a J-runner. Whichever way this concept is detailed, it’s most effective when the actual column cannot be seen at normal eye level and it so the column truly looks like it does not touch the floor.

BYPASS

As with a bypass column-to-ceiling transition, a floor bypass distinctly separates the interior finish from the structure of the building. Although this can be an effective way to create an independent column-to- floor transition, it can present a tripping hazard if the reveal is too large. Some of the ways to create a bypass column at the floor line are the same as the partition condition.

SURROUND

A column surround uses the column as a position to create additional construction so that the column no longer appears as a structural support but as a functional element within the space.

The surround can take on the appearance of a thick partition or be surrounded by storage or other usable construction.

Column-to-Beam Transitions

While a column-to-ceiling transition is the most common in interior design, there are three situations where the intersection of a column and a beam is visible or suggested. In the first instance, the structural column and beam may be exposed as part of the architecture of the building. The interior designer can elect to leave them exposed as part of the interior design or cover them. In the second instance, finish materials, such as gypsum wallboard, cover the actual structural column and beam, but the covering follows the same general line as the structure. E.g., a furred-out covering below the ceiling line indicates that there is an actual structural beam dropped below the ceiling. In the third case, the designer may create an arti ficial column-to-beam connection, either as a one-time instance in the space or to repeat an existing architectural connection.

There are several different conceptual approaches to finish column-to-beam transitions.

These are shown diagrammatically. In all these examples, gypsum wallboard construction is used.

SIMPLE ONE-WAY CONNECTION

In the one-way connection the actual structure of the building is covered with some type of finish material, most often gypsum wallboard on metal framing.. The depth and width of the beam covering depends on the size of the structural element and, if the beam or column is steel, any fire-resistive coating that was applied during construction of the building. This type of detail minimizes the effect of the structure as much as is possible and is the least costly to create.

Quite often, the finish covering may have been applied as part of the base building construction and the interior designer may choose to keep what is there, change the shape or finish, or make the covering larger. In any case, any fire-resistive coating must not be disturbed or removed. Some architectural details incorporate the gypsum wallboard covering as the fire-resistant covering. In this situation, it should not be removed or disturbed, but additional construction can be built around it. Of course, if the columns or beams are concrete no additional fire-resistive coating will be present. The interior designer should review the architectural plans of the building or consult with the architect or building of ficial if it’s unclear what the column or beam material is or how it’s fireproofed.

SIMPLE INTERSECTION

A variation of the one-way beam-to-column connection is the simple intersection in which a structural beam is framed into a girder on top of a column. All the structural elements are covered with gypsum wallboard. In large spaces, this type of simple transition can be used to express the structure as well as to create distinct spatial volumes within each structural bay. As a variation on the simple intersection, an enlarged capital may be used to give a sense of support between the column and the beams. The finish column covering may be smaller or larger than the width of the beam covering, at the discretion of the interior designer.

CAPITAL

Using a capital to distribute the weight from the beams to the column is a classic method of construction and can be suggested by simply enlarging the wallboard framing above the shaft of the column. Painting or other finish materials can further enhance the effect.

INTERMEDIATE MATERIAL

An intermediate material used between the top of the column and the beam enclosure may be used to emphasize the structural transition and make it a more important detail. The intermediate material can be as simple as a different paint color or finish, or it may actually be a different material, such as wood trim or stone veneer around the column.

It can be as simple or elaborate as the designer feels necessary to coordinate with the design concept of the space.

There are several different conceptual approaches to architectural column-to-beam transitions; that is, those that look like a true structural connection rather than just being a finish covering. The beams can bear on top of the column, on brackets or ledgers, or other types of connectors can support the beams as the column appears to continue upward.

--- Architectural column-to-beam transitions: (b) ledger (a) bracket (c) straddle (d) connector A ledger is attached to the column to provide support for the beam. For false beams and columns, the ledger may be designed in any configuration and any size. For wood construction the ledger is generally wood but may also be a steel angle or other type of connector.

A pair of column members can straddle the beam as shown here or two horizontal members may straddle a single column. Bolts or other fasteners are used to connect the beam and column.

Connector transitions make a design feature of the joint between the beam and column. Steel plates or other types of metal connectors may be used and the fasteners and plates may even be sized larger than would normally be required for strictly structural reasons to bring them into scale with the structural elements and the space in which they are used.

A bracket appears to support or brace the connection between the beam and the column. Brackets can be designed in a variety of ways and may or may not include visible fasteners, such as bolts or screws.

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BRACKET

A bracket, sometimes called a knee brace, projects out from the column to support or brace the beam. Brackets can be detailed in a wide variety of con figurations, two of which are shown. Brackets emphasize the connection between the column and beam to highlight the structural aspects of the construction. If two columns are close together the brackets can also give a strong sense of division between the spaces on either side of the beam. Brackets can simply be a wallboard shape or the designer can detail them with wood, metal, or other materials as simply or elaborately as required to suit the design concept of the space.

LEDGER

In structural terms, a ledger is relatively small construction element attached to the column that supports a beam framing into the column instead of resting on top of it. Sometimes also called a corbel, a ledger can take on any con figuration, from a simple rectangular block of wood to ornately carved woodwork.

STRADDLE

A straddle connection is one in which either two vertical members are placed on either side of the beam or one or two horizontal members are supported by a single column. In either case, the members are connected with nails, screws, pegs, or bolts to transfer the loads from the beam to the column. The beams and column are typically wood in this type of joint. This type of transition provides an interesting detail and emphasizes the structural nature of the connection. For a nonstructural, false connection that the interior designer may be detailing, the actual fasteners are not critical. However, in most cases, this type of joint expresses the structure the best when bolts are used.

CONNECTOR

A connector is a metal fabrication used with bolts or other fasteners to hold two or more structural components together and transfer loads. Generally, connectors are used for wood-members. E.g., a steel plate fastened between the column and the beam gives a stronger sense of structure than just showing the beam resting on the column. Connectors come in a wide variety of shapes, sizes, and con figurations.

Of course, for the false structure the interior designer may be detailing, the actual size and con figuration is not critical, so the designer may develop any type of detail that looks appropriate. In addition to the simple connection shown connectors are useful for making joints when several elements, such as wood beams and columns, intersect at odd angles.

BEAMS

Beams are major structural elements but are typically concealed in both commercial and residential construction. When they are exposed, they are usually designed as a major architectural feature of the building, and the interior designer may want to leave them exposed to respect the architectural design.

In some cases, structural beams encroach into the interior space and require an area to be furred down to conceal them and any fire-resistive coating material applied to them.

This is especially true where the floor-to- floor dimension is small and the distance from the suspended ceiling and the floor above is not suf ficient to conceal all the structural members.

In other cases, the interior designer may want to express the location of beams and possibly add false beams to enhance the sense of the building's structure or to use the implied structural elements to de fine space.

There are three basic conditions that the interior designer must consider when designing the transition of beams to other building elements: between a beam and a partition, between a beam and the ceiling, and between a beam and another beam. These can be combined with the beam-to-column transitions discussed in the previous section to develop an overall design concept related to structural transitions.

As with other structural transitions, how the designer treats beams depends on the de signer's overall philosophy of structure: whether to treat the interiors as completely independent from the architectural structure of the building, to emphasize the structure, or to minimize the appearance of the structure when it’s an unavoidable feature.

--- Beam-to-partition transitions: (b) corbel (a) none (c) engaged (d) freestanding.

A corbel provides a visible means of support for the beam framing into it. The corbel may be made simply from wallboard or it can be wood or some other material. The corbel can appear to be supported by a vertical member by applying another finish to the partition or by installing a thin layer of finish that extends to the floor as shown here.

An engaged column provides a simple post-and-beam connection that most people recognize as being structurally stable. The engaged column can be gypsum wallboard if the beam is enclosed in wallboard or it can be wood or some other material. A corbel may also be used to emphasize the structural nature of the transition.

A freestanding beam-to-partition transition appears as if the beam and the column don’t touch the partition at all. This may be constructed by actually holding the false structural members away from the partition or by using a simple wallboard reveal so it appears that the partition runs past the column and beam.

The simplest transition is one in which the beam runs directly into the partition. The beam may be a wallboard covering or it may be any other material with the wallboard finished around it. This is the least accurate expression of structure because there appears to be nothing supporting the beam.

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Beam-to-Partition Transitions

NONE

The simplest transition is none at all. In this case, the structural beam or the finish covering simply disappears into the partition. As with other types of structural transitions, this approach minimizes the appearance of the beam and may even appear as an enclosure for ductwork or other mechanical equipment. If the structural beam is exposed, the designer may choose to cover it with gypsum wallboard or some other finish to disguise its appearance.

CORBEL

A corbel is a small projection from a wall designed to support a structural member. Traditionally, corbels were stone members projecting from stone walls to support stone arches but the concept can also be used for any material. --- shows one approach to creating a corbel. They can be constructed of gypsum wallboard on metal framing or by using a more traditional structural material such as wood or stone. However, wood or stone on a simple wallboard partition may look out of character, so the designer may want to use the same material as the corbel and extend it down the partition.

ENGAGED COLUMN

An engaged column is a column that is attached to a wall. In commercial design, it typically appears as a gypsum wallboard covering over an actual column, but an arti ficial one may be created simply by furring out from the partition. Using an engaged column to make the transition to an enclosed beam is a more honest representation of a structural connection and can create a visual interest along a partition, particularly a long one that would otherwise be uninterrupted. An engaged column may be combined with a corbel to create an even stronger sense of structure. While an engaged column emphasizes the structure, it requires very little floor space and generally does not interfere with the functional use of the space. If the beam is deep and the corbel relatively large, this approach is good for creating a strong de finition of space on either side of the beam.

FREESTANDING COLUMN

A freestanding column visually separates the structure from the interior partition. The partition may be placed well away from the column so that there is actually open space behind the column or the partition can be constructed with a small reveal to make it appear that the column is freestanding. The column may either be covered with gypsum wallboard or wood or other materials can be used. Freestanding columns require more floor area to create and may interfere with furniture placement or other functional uses, but they do give a strong sense of structure to the space.

Beam-to-Ceiling Transitions

Beam-to-ceiling transitions occur when the interior designer is responsible for both the ceiling design and the treatment of any exposed beams. However, if the intent of the building architect was to leave the roof or ceiling structure exposed, the interior designer may elect to keep it exposed or just provide intermittent suspended ceiling elements.

This section discusses some of the alternate ways to design and detail the connection between a beam and the ceiling plane.

STANDARD ENCLOSURE

In most cases, in both commercial and residential construction, beams that drop below the finished ceiling are enclosed in gypsum wallboard or wood concealing the actual structural beam. Metal or wood framing is suspended from the structure above to provide the base for the application of wallboard and finish.

If the designer wants to emphasize the structure of the building, additional false beams of gypsum wallboard, wood, or other materials may also be used. The enclosures and false beams can be detailed larger than actually required to conceal the structural beams to further emphasize the structural framework.

--- Beam-to-ceiling transitions: (b) suggested (a) standard (c) trimmed (d) structural ceiling A smaller gypsum wallboard enclosure can be used when the actual structural beam only extends slightly past the ceiling or when the designer wants to indicate where the structural grid is but needs to maximize headroom.

A trimmed beam transition uses some type of molding or intermediate material between the vertical portion of the beam and the horizontal plane of the ceiling. This is one of the traditional methods of finishing the beam and can create a distinct coffered ceiling when beams frame four sides of a space. This diagram shows a simple block trim on one side and a more ornate wood molding on the other side.

The simplest way to make a beam-to-ceiling transition is to use a simple gypsum wallboard enclosure regardless of what type of ceiling is used. To highlight the structure for additional interest, an additional step of wallboard framing can be applied, as indicated here with the dashed lines.

Planking or other fill material can be used between beams in a very traditional way to give a strong sense that one material supports the other.

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SUGGESTED ENCLOSURE

A suggested indication of structure may occur when the actual structural beam drops below the finished ceiling by only a small amount or when the designer wants to just give an indication of the structure but is limited in the distance the enclosure can be dropped below the ceiling. As with standard enclosures, the beam can be indicated with simple wallboard framing, or wood or other materials may be applied directly to the ceiling or attached to framing above the ceiling.

TRIMMED

A trimmed beam transition is a more traditional way to treat the transition between a beam and the actual ceiling. In this detail some type of additional material is placed at the intersection of the beam and the column. As diagrammed, the material may be as simple as an additional wallboard step or as elaborate as complex as wood cornice molding.

This design looks best when the ceiling is gypsum wallboard or other type of decorative ceiling other than an exposed grid acoustical ceiling. In large spaces where there are several structural bays, this design concept creates a strong coffered ceiling with a rhythm reflecting the structure of the building.

--- Beam-to-beam transitions (b) connector (a) hidden (c) hanger (d) direct bearing.

A connector is typically used with wood beams and makes a very clear statement of how one beam is supporting another. It may be part of the original architecture of the building or the interior designer may create a series of false beams and connectors.

A hanger is a simple way to frame a beam into a girder.

It’s primarily a functional connection used in wood framing but can be replicated in interior construction.

As with using connectors, this is a way to maximize headroom.

Direct bearing is the classic method of supporting beams on top of girders and gives a clear indication of how one part of the structure is supported by another.

A hidden beam transition conceals any indication of the actual structural connection or even the type of beams that are connected. Instead, they are hidden with a gypsum wallboard covering. However, this type of transition can create a strong sense of the location of the structure.

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STRUCTURAL CEILING

A structural ceiling is one in which the intermediate fill between beams is exposed. In residential construction, it could be exposed wood decking, and in commercial construction it may be just a replication of decking or other finish material. This design approach emphasizes structure the most if the fill material is resting on beams, which, in turn, is resting on girders (as discussed in the next section), which are resting on exposed columns.

Beam-to-Beam Transitions

For interior design, beam-to-beam transitions are limited because of the limited ceiling height generally encountered in either commercial or residential construction. If the original building architect designed a high-ceiling space with the intent of leaving the structure exposed, the interior designer may want to keep the structural expression as it is. In other cases, the interior designer can consider the following structural concepts.

HIDDEN

A hidden beam-to-beam transition is one in which the actual structural beams are concealed with a finish material, commonly gypsum wallboard, and only give a suggestion of the structure. In some cases, only one enclosure may contain a real structural beam and the designer may add other intersecting enclosures to indicate where other structure is located or simply to create smaller structural bays. The bottom of the intersecting beams can be flush with the main beam or made smaller. As with beam-to-ceiling enclosures, the construction is detailed using gypsum wallboard on metal or wood framing.

CONNECTOR

A connector transition uses a steel angle or type of metal fabrication to physically join one bean with another as shown. This connection is typically used with wood beams with bolts or other fasteners prominently exposed. A connector transition emphasizes the structural nature of the beams and can provide an interesting contrast with a finished ceiling. This type of structural connection may be part of the original architecture of the building or the interior designer can create a false grid of beams and girders using these types of connectors.

HANGER

A hanger is similar to a connector transition in that a metal fabrication is used to hang one wood beam from a wood girder to maximize height clearance. Girders are the primary structure, while beams are secondary members and frame into girders.

Depending on the type of hanger used, the fasteners may not be as prominent as those used with an angle connector. The fasteners are usually nails or screws.

DIRECT BEARING

A direct bearing transition is seldom encountered in interior construction unless it’s part of the original architectural design of the building. This is because it requires a signi ficant amount of space below the elevation of the ceiling or roof. Direct bearing is a fundamental structural archetype and the most honest expression of structure because people can see beams resting on girders.

SUSPENDED OBJECTS

For interior design projects, suspended objects may include things such as signs, lighting, specialty ceilings, display systems, panels, HVAC equipment, and piping. In many cases, the designer wants to minimize the appearance of the suspension system and may specify the thinnest wire and smallest connectors possible. In other instances, the designer may want to make the transition between the ceiling and the suspended object a design feature in itself. The suspended objects discussed here assume that the construction element is distinctly separated from the ceiling or structure above rather than being directly attached to it. To meet accessibility requirements no suspended object can be less than 80 in. (2030 mm) above the floor level.

The basic design concept determines the general approach to detailing the suspension system. Which method is finally selected also depends on the following factors:

  • _ Ceiling material and structure
  • _Weight of the suspended object
  • _ Rigidity required
  • _Material of the suspended object (what kind of fastener is possible)
  • _ Thickness of the suspended object
  • _ Requirements for electrical power, if any
  • _ Adjustability up and down, if any
  • _ Ability to change out the suspended object without changing the support
  • _ Ability to change the location of the suspended object

--- shows some of the possible conceptual approaches to detailing suspended objects. Some of the concepts shown can be used with either a thick or a thin suspension element, while some can only be used with a thick suspension element.

Thin Supports

Thin supports include cable, chain, double hooks, and rods. Cable is one of the simplest ways to hang most objects in the most unobtrusive way possible. It’s flexible and can accommodate flat or three-dimensional objects and both light and heavy weights by varying the cable size and attachment methods. With loop or hook attachments cable-supported objects can be repositioned easily.

A variety of connectors are available to attach cable to both the ceiling and the object being suspended. Alternately, thin, threaded rods can also be used. --- show three variations of this method assuming the wire is connected to the suspended object along the top of the object. --- show other variations when using thin cable or rods. Some of the basic connectors used with cable suspension. For light loads suspended from an acoustical ceiling T-bar clamps can be used with cable, hooks, or chains. Heavier loads can be supported with toggle bolts installed through the ceiling or with channels resting on the tops of the T-bars. Some of the various methods for attaching cable to signs and thicker suspended objects.

Clamps

As shown in, clamps provide an easy way to hang thin panels with a relatively small connection between the wire and clamp. However, the clamps and fasteners can be oversized if the designer wants to emphasize the structural connection. Additional cables can be added to support heavy loads. In addition to the methods shown illustrate two other methods for suspending panels with clamps.

---Suspended object transitions (d) connector emphasized (a) thin wire (g) multiple supports (j) single post (m) straddle (b) splayed in (k) plate, parallel (n) side support (f) chain (c) splayed out (i) thick (l) plate, perpendicular (o) bottom support (e) multiple elements (h) clamp

--- Suspension hardware: T-bar eye hooks with cable loop T-bar clips eye or hook with toggle bolt channel suspension with cable or rods clamp termination with hook support cable with ball termination cable with panel bolted to rail eye bolt on thick panel banner on cable suspended hook (a) ceiling attachments (b) suspended object attachments

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Thick Supports

Thick supports include round and square pipe as well as other tubular material. For heavy or large objects, thick suspension members give a greater sense of structure to the detail and create a significant architectural element.

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