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Like partitions and ceilings, the way two spaces are connected is a fundamental component of interior design and architecture. This spatial connection can be made with clear openings in the barrier between the two spaces and with doors and glazing. Both barriers and the openings in them are important for their own reasons; barriers separate and openings reconnect.
The way this connection is made is important for two reasons. Of course, the connection must allow the passage of people, goods, vision, and light while providing for physical separation needed for privacy, fire separation, acoustics, and security. On a more fundamental level, the connection either makes the separation complete or it unifies the various spaces and celebrates the passage between one and another. Openings make otherwise disconnected rooms and spaces into a complete design composition.
Unfortunately, in contemporary construction openings have been mostly reduced to functional necessities. Openings are often just punched holes. Doors are simply used to let people and goods get from one room to another while providing the fundamental requirements of fire separation, security, and privacy. Only in some instances, such as residential front doors and store entrances, do designers utilize the full design potential of door openings as a creative design element. Likewise, glazing is often not used to its full potential, simply being a way to provide basic views and admit daylight.
While a simple approach to providing openings in much of interior construction is of ten justified based on function and cost, the interior designer should recognize the value of the design of openings to contribute to the overall design intent of the project. Passage, views, and light are all important aspects of the human experience of space. This expanded vision of opening design can be realized while satisfying functional needs and specific constraints.
This section discusses some ideas the interior designer can use to develop design concepts for clear openings as well as door and glazed openings and gives some guidelines to begin detailing. Refer to Section 5 for other ideas on vertical barriers that allow some degree of opening between spaces.
Viewed individually, all types of openings can be designed in hundreds, if not thousands, of ways. When combined, as they often are, the number of possibilities increases significantly.
For openings, the basic components are size, shape, and trim. For both door and glazed openings, the basic components are the material and opening con figuration, the frame, and their relationship with the surrounding construction.
Openings are clear areas within an otherwise solid barrier. They may extend to the floor to allow people to walk through or they may be above floor level to allow vision, sound penetration, light, or the transfer of objects. They are sized to meet the requirements of the project and may be con figured in hundreds of different ways with a variety of trim styles.
Opening design is limited only by the designer's imagination. --- shows just a few of the possibilities.
Openings can frame views, direct movement, and modulate the connection between two spaces. They can be used singly or grouped. Openings can be placed in pairs, creating a vestibule or intermediary space to serve as a transition from one type of space to another that can heighten the experience of passage.
The interior designer can meet functional requirements and make a strong spatial connection with doors through their size, material, hardware, method of operation, and relationship to the surrounding partition, as well with the doorframe's configuration, material, size, and finish.
Doors can also direct movement, control views, and maintain privacy when partially open by their placement and direction of swing.
--- Openings (a) basic shapes (b) variations and trims (c) celebrated openings.
One of the simplest ways to give a door and entrance emphasis is with door size and a material. Most door types can be made larger than a standard 3-ft (900 mm) width and a 7-ft or 8-ft height 2100 mm or 2440 mm). This can usually be done without a significant increase in cost. The designer can vary the material by using a different base material or simply a different veneer. E.g., any number of distinctive laminates can be specified instead of a standard wood veneer finish. Alternately, a stainless steel or bronze door can be used instead of a simple painted hollow metal door. Which approach is used depends on the effect desired and limitations on cost and code requirements. However, even with the constraints of egress requirements and budget restrictions, the interior designer can use size and material options to create distinctive openings.
As with door material, available hardware offers the designer a wide choice of effects.
The type, shape, and finish of handles, locksets, hinges and other hardware can be varied in hundreds of ways. E.g., brightly finished, surface-mounted hardware can emphasize the traditional connection of movable door attached to fixed construction. Conversely, using door pivots and concealing closers instead of hinges and surface-mounted closers can deemphasize the hardware, if that is the desired effect.
In addition to size, material, and hardware, the way a door operates creates a particular type of experience of entrance and passage. --- illustrates some of the many ways doors can be con figured based on their method of operation. E.g., a pair of doors pivoted at the midpoints of the doors, creates a unique entry, entirely different from a simple side-swinging door. Of course, code-mandated egress requirements and ease of use may preclude using some of them in certain circumstances.
The design of the surrounding construction can affect the overall impression of the entry as much as the door opening itself. The method by which a door is placed within a partition can greatly affect the sense of entrance and passage, including those design elements and principles of form, scale, balance, harmony, focus, contrast, variety, and proportion. --- diagrams some of the many ways a door can be con figured in relationship to the partitions, floor, and ceiling. Most of the options shown can be constructed without a significant increase in cost or without compromising function, code requirements, or accessibility. In some cases, such as a recessed doorway, the placement of the door even helps satisfy other needs, such as preventing swing into the required path of egress travel.
A simple punched opening in a partition depends on the door and frame alone to provide any design emphasis. Recessed openings create a separate area for the doors, while addressing the problem of door swing into a path of travel. Recesses can be made any width or depth and can be combined with glazing to develop an entrance with varying degrees of transparency as required by the design intent of the project. Recesses must provide for maneuvering clearances as required for accessibility.
Doors can also be coordinated with overhead construction, whether that is a simple piece of cornice trim or a separate canopy below the height of the adjacent ceilings. See (e)-(h). Floor finishes can also be designed with door openings to emphasize the transition from one space into another as long as the transition is detailed to avoid any tripping hazard or accessibility problem. See (i). Doorways also provide an appropriate place to make a change in direction of movement or to mark a transition space between two different spaces.
Lastly, the interior designer can use frames to create a design feature of doors as well as to solve practical problems of connection to the adjacent partition, protection, and finish.
Frames can vary in their size, material, finish, and color. They can be complementary with the door or contrast with it. Frames can be underplayed or emphasized. Some of the many approaches to frames are diagrammed. Some of these concepts can also be used to frame clear openings.
--- Types of door operation (d) revolving (h) center pivot (e) sliding or pocket (b) double acting (c) balanced (a) hinged or pivot (g) bifold (f) bipass
--- Doors with surrounding construction (a) punched (b) recessed (d) recessed curved (c) recessed angled (e) cornice trim (f) portal (g) change in height (h) canopy over (l) alcove (j) 90° change in direction (k) 45° change in direction (i) floor emphasis
--- Frame concepts (e) transom (h) portal (b) standard (d) head emphasis (a) none (i) splayed wall (f) wide (g) ornate (c) shaped
Glazed openings provide the interior designer with a multitude of design options to modulate the visual connection between two spaces. Glazing can be used to affect the sense of enclosure, direct views, and allow daylight deep into buildings while satisfying functional requirements of security, acoustic control, and fire separation. Glazing can even become a design feature in itself with the use of art or etched glass, or any of the many new glazing products available.
While Section 5 discusses the use of glazing for entire translucent barriers, this section focuses on the use of glazing for smaller openings within a partition.
As with doors, the interior designer can use glazing material, shape, placement, framing, and the relationship of the glazing to the surrounding construction to make the desired connection between two spaces. ---- lists many of the types of glazing available. Refer to ---- for a listing of some of the many specialty glazing material manufacturers.
--- illustrates some of the many window opening shape and placement concepts the designer can employ. Some can be used for both views and daylight penetration, while some, such as a high or low strip of glass, can allow some daylight penetration while maintaining privacy. Frames can be con figured the same way as described in the previous section and shown.
Because glazing is also commonly used both in doors and adjacent to doors, the interior designer can combine solid partitions, doors, and glazing in a nearly unlimited number of ways to develop the precise type of connection required for any programmatic need. --- shows some of the basic conceptual ways to use glass in and adjacent to doors.
--- Glass Types: Type / Description
- --- Types of glazed openings punched unit slot privacy floor level above built-ins holes band shapes window box curved grid scaled random division full height corner
--- Door relationship to glazing (e) transom (g) full sidelite (i) side window (f) standard sidelite (h) flanked sidelites (b) half glass (c) narrow lite (d) full glass (j) continuous glass (k) glass door in solid partition (a) vision lite
In many cases, the transparency of an interior glazed opening must be adjustable to meet the need for privacy or adjustment of light transmission, either to control glare or to temporarily darken a room. This can be done with a variety of window coverings, including vertical blinds, horizontal blinds, shades, draperies, solid sliding covers, and electrochromic glazing. These coveringsmay be side closing, top closing, or bottom closing. Some, such as solid sliding covers, offer only two states, open or opaque, while others, such as vertical blinds can provide a range of closure and translucency or be completely pulled out of the opening. Window coverings can be surface mounted so that they are visible when open or the construction surrounding the glazing may be detailed to provide pockets to conceal the coverings. Methods of window covering are discussed in more detail later in this section.
Because openings serve many purposes, which can sometimes con flict with each other, the interior designer should have a clear understanding of what functions an opening must satisfy.
Clear openings, doors, and glazed openings generally provide one or more of the following functions:
Connecting two spaces while de fining each Framing views Directing movement Controlling physical passage Providing variable visual privacy Controlling sound transmission
Providing security Providing fire and smoke resistance Providing for the control of light Allowing for the use of daylighting Providing radiation shielding Providing for the passage of goods Allowing views to the outside Serving as a design feature Only by understanding the specific functions an opening must perform can the de signer select the best combination of opening type, size, con figuration, material, frame, and connection to the surrounding construction and develop appropriate details.
To the extent possible, door and glazed openings and the materials used to create them should contribute to the overall sustainability of the design. Refer to the sidebar for suggestions on how sustainability issues can be addressed through the design and detailing of openings.
Sustainability Issues Related to Openings Sustainability issues related to openings include the following:
_ Specify doors, trim, glazing materials, and frames that use as much recycled content as possible.
_ Specify and detail door openings such that the frame and door can be relocated or reused.
_ Use glazing as much as practical to maximize daylight and views to the outside. This includes line of sight between 30 in. (762 mm) and 90 in. (2286 mm) above the floor and a direct line of sight from a point 42 in. (1067 mm) above the floor to perimeter vision glazing.
_ Consider using regional materials to the maximum extent possible.
_ Select window coverings for exterior windows to minimize heat gain, while allowing daylight and views. Consider the type of window glass used in a building constructed within the last five to ten years may have glazing that has the required properties.
Consider using automated window shade control based on daylight conditions.
_ Specify window coverings with recycled content and that don’t adversely affect indoor air quality.
For clear opening connections between two spaces there are very few constraints limiting how the interior designer creates the connection. The existing ceiling height may be the only factor limiting the overall con figuration and scale. Because interior opening are non-load-bearing, there usually is no limitation on the width of the opening; most can be detailed with metal or wood stud framing to span the opening. When wide openings are present, standard metal or wood headers can be used or that portion over the opening can be suspended from the structure above. When additional loads are present, framing can be reinforced with structural steel supports as required by the detail.
For doors, constraints most often include the levelness of the floor, cost, and the code requirements for egress and fire resistance. Accessibility requirements dictate minimum clear opening width, hardware types, opening force, and limits on threshold height, as well as maneuvering space adjacent to the door.
For glazed openings, constraints include code-mandated fire resistance (if any), acoustic requirements, and potential building movement when very large sections of glazing are used.
Fortunately, fire-resistive-rated glazing is available for nearly all situations, in both doors and interior windows. Acoustic requirements can be addressed through the use of laminated glass and spaced glazing. These are discussed in the later section in this section on methods.
For clear openings, there is little coordination required with other buildings elements or details. The designer should consider the size, shape, and height of openings relative to the desired amount of connection or separation between two spaces. Further, the designer should consider the position of the opening relative to furniture placement, views, and the number of people moving through the opening or the size of objects being moved through the opening.
Door opening design must be coordinated with the type of partition in which the door is located; different partition types and thicknesses may require different types of frames and frame anchorages. Door swings must be coordinated with sight lines, furniture location, and the required direction of travel as well as the clear space required to remain unobstructed in an egress path. Provide sufficient maneuvering space at the strike side of a door for accessibility.
Generally, 12 in. (305 mm) is required on the push side of a door and a minimum of 18 in. (455 mm) is required on the pull side. Door locations should be positioned in a room to maintain good circulation and provide room for furniture placement.
Glazing must be coordinated with the amount and direction of views needed, both between adjacent spaces and with views to the outside. This also relates to the amount of glazing required to maximize daylighting. Lighting must also be placed relative to glass to avoid unwanted r eflections. Detail coordination includes provisions for window covering pockets, allowances for building movement, and safety glazing requirements.
--- Types of Doorframes (c) standard wood frame (b) standard aluminum frame (a) standard hollow metal frame (d) wood frame without trim varies wood stop shim and wood blocking base below casing trim, size and shape may vary drywall reveal edge trim dimension frame 1/4" (6) wider than partition to account for flared edges of wallboard edge trim double-rabbeted hollow metal frame gypsum wallboard 1 1/2" or 2" (38 or 51) typ. double metal stud with stud anchor metal stud aluminum frame profiles vary 1 1/2" (38) typ. varies
--- Standard doorframe and hinge settings jamb door 1-15/16" (49.2) for 1-3/4" door 1-9/16" (39.7) for 1-3/8" door frame clearance:
1/8" (3.2) clearance for hinge barrel or use wider hinge inset: 1/8" (3.2) hinge backset:
1/4" (6.4) frame clearance: 1/16" (1.6) casing trim
There are innumerable ways to detail clear openings, doors, and glazed openings shown conceptually in ----. Some of the possible ways to develop openings in barriers were discussed in Section 5 and shown in ---. Standard frame details can be used to develop many of these. This section provides some starting points for developing opening details.
Most doors can be detailed with one of the three standard frame materials, shown in (a), (b), and (c), or with a minor mod ification of one of these. E.g., (d) shows a wood framed door without a casing trim. Single- or double-rabbeted steel frames are available in a number of depths and face con figurations. Aluminum frames are available in a number of shapes, sizes, and finishes. Wood frames can be mod ified by varying the size and shape of the casing trim and by varying the size and con figuration of the stop.
However, when custom wood frames are detailed the designer should use industry standard dimensions for the placement of hinges and positioning of the door within the frame. These are shown. Maintaining standard dimensions simpl ifies detailing and minimizes the cost and difficulty of building the detail.
When fire-rated doors are required the necessary fire rating of the door depends on the use and the fire rating of the partition in which the door is located. Part of ---- summarizes these requirements. E.g., in a 1-hour-rated corridor partition in a non-sprinklered building, a 20-minute-rated door is necessary, while in a 1-hour- rated occupancy separation partition, a 3/4-hour-rated door is required.
--- Types of glass frames (c) standard wood frame (b) standard aluminum frame (a) standard hollow metal frame (d) single-rabbeted wood frame 1/4" (6) shim space opening as required base below trim as required glass metal stud aluminum frame 1 1/2" (38) typ. varies wood stop shim and wood or metal studs base below casing trim double-rabbeted hollow metal frame gypsum wallboard 1 1/2" or 2" (38 or 51) typ. double metal stud with stud anchor profiles vary.
STANDARD GLAZED OPENINGS
Standard glazed openings using float, tempered, laminated, or nearly any type of decorative glass can be set in standard wood or metal frames. These standard frames can be mod ified in many ways to create details consistent with the design intent and specific needs of the project. When detailing glazed openings, certain dimensions should be maintained to hold the glass in place.
Hollow metal frames can be single or double rabbeted with face frames from 1 in. (25 mm) wide, although 2 in. (52 mm) is standard. Custom hollow metal frames can be ordered within the limitations of the presses used to form the frames. Aluminum frames can also be ordered in a wide variety of sizes, profiles, and finishes.
If the design intent is to minimize the appearance of the glazed opening, the designer can use frameless glazing, which makes the glass seems to float within the opening. The details can be con figured to make the finish materials appear to continue uninterrupted from one side of the glass to the other. (a) shows one method of detailing the sill and head of a full-height piece of glass. This detail shows the necessary glass framing recessed completely into the structure. Jamb framing can be completely eliminated with the edge of the glass held away from the wall a fraction of an inch. The gap can be left open or sealed with silicone sealant. If more than one panel of glass is required, the edges are butted together, and the joint either left open or filled with silicone sealant if sound control is required. Silicone sealant can be either clear or black, but clear sealant can show bubbles and may be more visually objectionable than black. The recommended joint width based on glass thickness.
The thickness of the glass used depends on the size of the opening and the rigidity required. Interior glazed partitions must meet seismic requirements of 10 psf (0.48 kPa). The IBC also requires that when two adjacent panels of glass are unsupported (butt jointed with no sealant) the differential d eflection cannot be greater than the thickness of the glass when a force of 50 lb per ft (730 N/m) is applied horizontally to one panel 42 in. (1067 mm) above the walking surface. ---2 gives the recommended glass thicknesses based on the two conditions of full-height glass panels that have open or sealed joints. Glass thickness should be ver ified with the glass installer and local codes.
When full-glass doors are used with frameless glazing, the door can extend to the ceiling.
The door may have a continuous bottom fitting to hold the pivot and lock as shown (j) or simply have a fitting at one corner to hold the pivot, as shown (k).
Details must accommodate the floor pivot or floor closer and anchorage for the top pivot and a door stop. One way of doing this is shown. If the concrete floor is not thick enough to accommodate a floor closer, overhead closers can be used, but they are more difficult to anchor.
----Frameless glazed opening partition silicone sealant metal or wood support- brace to structure above as required 3/4" x 3/4" (19 x 19) channel carpet and pad or other floor finish as scheduled aluminum angle; proprietary ceiling glazing track is also available ceiling angle edge of wall beyond glass (a) head and sill section (b) jamb
--- All glass interior entrance door threshold floor closer wood or aluminum head section-brace to structure suspended acoustical ceiling angle stop with bumper pivot 1/2" (13 mm) or 3/4" (19 mm) tempered glass door
---- Opening Protective Requirements for Interior Partitions (Dimensions and Sizes Are for Wired Glass Only) Doors-Limiting Dimensions for fire-Protection Glazing or Wired Glass Window Glazing-Cannot Exceed 25% of the Area of the Common Wall between Rooms
FIRE-RATED GLAZED OPENINGS
When the building code allows the use of glazing in a fire-rated partition, the glazing (in conjunction with the frame as a total assembly) must also have a fire rating, which is con firmed by standard fire tests of the glazed assembly. The required fire rating of the glazed assembly depends on the use and fire rating of the partition in which the glazing is located. ----- summarizes these requirements for window glazing as well as glazing in doors. The maximum glazed sizes given in this table are for wired glass. Fire-resistance-rated glazing may be used in larger sizes, which vary with each manufacturer.
Historically, wired glass was the only type of glazing that was acceptable for use in fire-rated doors and for windows in fire-rated partitions. Wired glass has traditionally had a 45-minute rating and was allowed in hazardous locations, such as a door or a sidelite next to a door, even though it’s not considered safety glazing. New developments in glazing products now make it possible to replace traditional wired glass with other products that meet both fire rating and safety glazing requirements. These new products also have fire-resistance ratings greater than 45 minutes.
The IBC now does not allow the use of wired glass in hazardous locations as described in the next section of this section. The IBC does allow the use of two types of glazing that can be used in fire-resistance-rated partitions: fire-protection-rated glazing and fire-resistance-rated glazing.
Fire-protection-rated glazing is 1/4 in. (6 mm) thick wired glass in steel frames, or other types of glazing that meet the requirements of NFPA 252, Standard Methods for Fire Tests of Door Assemblies, or NFPA 257, Standard for Fire Test for Window and Glass Block Assemblies.
Such glazing must have a 45-minute rating and is limited to 1-hour-rated fire partitions or fire barriers when the fire barrier is used to separate occupancies or to separate incidental accessory occupancies. The amount of such glazing is limited to 25% of the area of the common wall within any room using the glazing. This limitation applies to partitions separating two rooms as well as to a partition separating a room and a corridor. Individual lites of fire-protection-rated glazing cannot exceed 1296 in. 2 (0.84 m2 ) in area, and any one dimension cannot be more than 54 in. (1372). The IBC still accepts 1/4 in. (25 mm) wired glass (if not in a hazardous location) as meeting the requirements for a 45-minute rating without specific testing, but other glazing must meet the NFPA 252 or 257 test requirements for a 45-minute rating.
Fire-resistance-rated glazing is glass or other glazing material that has been tested as part of a fire-resistance-rated wall assembly according to ASTM E119, Fire Tests of Building Construction and Materials. This glazing de finition allows the use of special fire-rated glazing that can have fire-resistive ratings of up to 2 hours.
There are four types of fire-resistance-rated glazing. The first is a clear ceramic that has a higher impact resistance than wire glass and a low expansion coefficient. It’s available with a 1-hour rating in sizes up to 1296 in.^2 (0.84 m^2 ) and with a 3-hour rating in sizes up to 100 in.^2 (0.0645 m^2 ). Although some forms of ceramic glass don’t meet safety glazing requirements, there are laminated assemblies that are rated up to 2 hours and are impact safety rated.
The second type is a special, tempered fire-protective glass. It’s rated at a maximum of 30 minutes because it cannot pass the hose-stream test, but it does meet the impact safety standards of both ANSI Z97.1, Safety Glazing Materials Used in Buildings-Safety Performance Specifications and Methods of Test, and 16 CFR 1201, Safety Standard for Architectural Glazing Materials.
The third type consists of two or three layers of tempered glass with a clear polymer gel between them. Under normal conditions, the glass is transparent, but when subjected to fire, the gel foams and turns opaque, thus retarding the passage of heat. This product is available with 30-, 60-, 90-, and 120-minute ratings, depending on the thickness and number of glass panes used as well as how the product is tested by each manufacturer. There are restrictions on the maximum size of lites and the type of permitted framing. This glazing may be used in partitions that must have a rating higher than one hour, although the glazing must have the same rating as the partition in which it’s used. There are no limitations on the total area of glass, but there are limitations on the size of individual framed units. These limitations vary with each manufacturer.
The fourth type of glazing is glass block. However, not all glass block is rated. The glass block must have been specifically tested for use in fire-rated openings and approved by the local authority having jurisdiction.
In all cases, the type and detailing of the frame is critical to the rating of the glazed assembly. Frames must be of the type required by the manufacturer of the glazing material and approved with the ASTM E119 test. Typically, framing is larger than for standard window glass. --- shows one type of frame.
--- Typical fire-resistance-rated glazing detail 3/8" (10) shim space opening as required within limits set by manufacturer some manufacturers may not require end of wall to be wrapped with wallboard base below nonrated elastomeric joint sealant fastener as required by manufacturer and substrate fire-resistant-rated glazing fire-rated glazing tape as required by manufacturer rated partition frame size and configuration varies fire-safing insulation as supplied by manufacturer bottom framing may be raised on rated wall to provide room for finish base material 3/8" (10) varies 2-3/4" to 3-1/8" (70 to 79) varies 1-15/16" to 4-3/4" (49 to 121) (a) vertical section (b) jamb section.
SAFETY GLAZED OPENINGS
The IBC requires safety glazing in hazardous locations. Hazardous locations are those subject to human impact such as glass in doors, shower and bath enclosures, and certain locations in walls. The typical places where safety glazing is and is not required according to the IBC are shown. The exact requirements are given in the Code of Federal Regulations,16 CFR Part 1201. The IBC also allows glazing materials to comply with ANSI Z97.1 in all applications other than storm doors, entrance-exit doors, sliding patio doors, closet doors, or in doors and enclosures for hot tubs, bathtubs, saunas, whirlpools, and showers. Technically, safety glazing is any product that passes one of these two tests for the specific applications allowed. Practically, safety glazing is tempered or laminated glass, although plastic glazing would also qualify if it met the requirements of the tests.
Details for safety glazing must hold the glass in place and are typically the same as for standard glazing If a crash bar is used in place of safety glazing as diagrammed, it must be able to withstand a horizontal load of 50 lb per ft (730 N/m).
---Safety glazing locations YES; NO less than 24" (610) greater than 24" (610) greater than 18" (457) less than 60" (1524) less than 36" (914) any glass door must be tempered 34"-38" (864-965) 1-1/2" (38) min. less than 9 ft (0.84m ) 2 crash bar must be able to withstand horizontal load of 50 lb./ft. (730 N/m) NO = safety glazing is not required YES = safety glazing is required.
--- Recessed blind pocket aluminum angles ceiling angle edge of wall beyond glass depth as required by stacking height width as required by mounting bracket and service access additional bracing as required by size and weight of blinds metal studs braced with kickers heavy-gauge sheet metal enclosure; attach to studs with sheet metal screws
ACOUSTIC CONTROL GLAZED OPENINGS
When a partition with a glazed opening must minimize sound transmission, special details must be used. A single thickness of glass provides only limited sound transmission loss. E.g., a 1/4 in (6 mm) thick sheet of float glass only provides an STC rating of about 29 dB. When higher STC ratings are required, a combination of detailing strategies must be used.
Refer to Section 3 for a discussion of methods of controlling sound transmission for both doors and glazed openings. ---- shows one detail for a glazed opening with acoustical control.
In most situations, interior glazed openings are intended to remain uncovered to allow views and daylight to penetrate interior spaces. However, in some cases, the opening must be temporarily closed off for privacy or light control. Blinds and shades can be surface mounted to the ceiling or the wall as with any window covering, but this requires stacking space and the covering is always visible. The designer can detail side pockets recessed into the wall space for vertical blinds or drapes. Horizontal blinds can be recessed into a pocket that is recessed above the ceiling. ---- shows one way of doing this for a full-height glazed opening.
Alternately, electrochromic glazing can be used. Electrochromic glazing is a general term for a type of glazing that changes, when electric current is applied, from either a dark tint or an opaque milky white to clear. When the current is on, the glass is transparent; when the current is turned off, the glass darkens or turns white (depending on its type).