Abstract: A barrier or dam to contain loose insulation from falling through an attic access hatch or scuttle opening is provided. Embodiments include four pieces that can be assembled together around the perimeter of hatches of varying sizes. Two of the pieces may be male pieces and two may be female pieces. Each piece may have a securing tab on its bottom end to attach each piece to joists that define the hatch opening. A kit comprising the barrier pieces may be utilized by homeowners, contractors or insulation installers for quick and easy installation of the containment dam.

Abstract: A cover for closing an access opening that leads to an infrequently used space within a building, such as an attic, provides thermal and acoustic insulation at the access opening. The cover may be in one or two portions, including a closure alone or a closure and a frame having an aperture that can be closed by engagement between the closure and the frame. When the cover is used alone it engages a frame or a wall circumscribing the access opening. The cover is sized and shaped to close a hatch, a stairwell, the opening at one end of a stairway, or an opening in a generally vertical wall that is not necessarily associated with a stairway. The closure and frame are each made of one or more components.

Abstract: This device for closing an opening includes a frame (4) that delimits a pass-through access opening (10) suitable for receiving a cover (6) and which includes a frame hinge knuckle (18). The frame hinge knuckle (18) includes a hinge surface (38) and a pass-through hinge knuckle opening (40). The frame (4) has an exterior side and an interior side. The device also includes an inserted plug (52) positioned in a recess (50) of the frame hinge knuckle (18) located on the inner side of the hinge surface (38) and which makes the inner side of the frame hinge knuckle (18) appreciably sealed off from the outside.

Abstract: An integrally formed riser pan member for use as a modular component within an access passageway for an on-site waste disposal system, such as a septic tank, to receivably retain a secondary cover member within, the riser pan member including a cylindrical body having an upper portion having a vertical wall member adapted to receive another modular passageway component thereon, and a lower portion which includes an integral pan portion to seatably receive a secondary cover member. The riser pan member further includes an annular ring between the upper and lower portions. The riser pan member can be employed as a lowermost, a highermost, or as an intermediate component in, for example, an access passageway formed of multiple stackable riser members. In addition, the riser pan member may be formed integrally with a stackable riser member.

Abstract: A cover for a utility trench includes upper and lower surfaces enclosing a hollow cavity, which is subdivided by multiple, transverse channels recessed into an extending transversely across the lower surface. The channels form fused engagements or “kiss offs” with the upper surface, which increase the transverse rigidity of the cover for enhanced load-bearing capacity spanning across the opening formed by the trench. The hollow construction of the cover, which can comprise a suitable plastic, tends to minimize its weight A pair of flanges extend along respective sides of the cover and are bolted to the trench sidewall top edges in overlying relation. A pair of shoulders are formed inside the flanges and are adapted to extend into the trench with the cover positioned thereover. A method of manufacturing a utility trench cover includes rotary molding a hollow cover with kiss offs.

Abstract: A riser formed from a plurality of curved cylindrical segments with vertical side edges having mating vertically tapered projections and slots brought into interlocking engagement to pull confronting surfaces together as the tapered elements become increasingly mechanically engaged. The segments are assembled by a sliding engagement of the protruding mating element of one segment into the vertically tapered slot of an adjacent segment. When sufficient segments are joined together horizontally to complete a ring except for a last adjacent pair of vertical side edges, the ring is warped to align the protruding mating element of the last adjacent pair of vertical side edges with an opposite end of the adjacent tapered slot. Thus aligned, the final protruding mating element and tapered slot are then slipped together while un-warping the joined segments forming the remainder of the ring until the top and bottom ends of all the segments are aligned.

Abstract: A cover grating for a drainage channel or a similarly hollow body which can be installed in the ground is presented, wherein the cover grating is produced in a single piece and more particularly from a sheet metal strip, comprising at least two longitudinal webs extending on the underside of the cover grating and inlet slots formed in the cover grating between these longitudinal webs and comprising transverse webs resulting from the slot forming operation and extending on the lower side of the cover grating wherein the transverse webs are provided at each of their end regions with at least one receiving projection which at least partially engages in to a respective complementarily formed receiving slot in the longitudinal web.

Abstract: A cover for closing an access opening that leads to an infrequently used space within a building, such as an attic, provides thermal and acoustic insulation at the access opening. The cover may be in one or two portions, including a closure alone or a closure and a frame having an aperture that can be closed by engagement between the closure and the frame. When the cover is used alone it engages a frame or a wall circumscribing the access opening. The cover is sized and shaped to close a stairwell, or the opening at one end of a stairway, or an opening in a generally vertical wall that is not necessarily associated with a stairway. The closure and frame are each made of one or more components.

Abstract: A manhole cover includes a support having an upper surface and a peripherally-extending portion. An outer insulating member is disposed over the entire upper surface of the support, and the support comprises a first material and the outer insulating member comprises a second material different from the first material. The peripherally-extending portion of the support is positionable over the lip of the manhole ring. The outer insulating member is positionable between the upper surface of the support and the upper surface of the rim of the manhole ring when the manhole cover is received in the manhole ring. In one aspect, the support comprises cross-members defining a grate having passageways through the support. In another aspect, the support comprises metal, and the outer insulating member comprises a composite of resin, reinforcement fibers, and stone aggregate. In another aspect, screen inserts are disposed in a plurality of passageways in the outer insulating member.

Abstract: A one-piece, unitary manhole cover has dual lifting ports that drain through the outer circumferential edge of the cover. A lifting channel runs from the interior of the upper face out to the outer circumferential edge. A lifting bar spans the lifting channel and defines an ergo lifting port and a pry bar lifting port. Both the ergo lifting port and the pry bar lifting port drain through the outer circumference of the manhole cover.

Abstract: A log staircase is disclosed along with a method of producing components for the log staircase. The log staircase includes an elongated stringer capable of angularly extending from a lower level to an upper level. The stringer has an outer circumference with a notch formed therein. A protuberance extends upward from the notch. The log staircase also includes a tread having a semicircular periphery with a flat surface. An opening is formed in the semicircular periphery of the tread. The opening is designed to mate with the protuberance to retain the flat surface crossways to the stringer. The method includes cutting a number notches and protuberances in each of a pair of stringers, and cutting a pair of openings in a predetermined number of treads which are capable of mating with the protuberances to retain each of the treads crossways to the pair of stringers.

Abstract: A manhole cover having an integrated locking system that is self-locking and easy to open. The device includes a cover plate adapted to rest on a manhole cover support surface of a manhole frame so as to be substantially flush with a top portion of the manhole frame and a surrounding surface in which the manhole frame is situated. An anchor on the cover plate is adapted to engage the manhole frame at a first location in a manner that resists lifting of the cover plate proximate to the first location. A locking member on the cover plate is movable between a locked position and an unlocked position. In the locked position, the locking member is adapted to engage the manhole frame at a second location in a manner that resists lifting of the cover plate proximate to the second location. In the unlocked position, the locking member is disengaged from the manhole frame.

Abstract: A stop mechanism advantageously combined with a manhole cover includes a holder body having a passage which slidably receives a stop member able to be cammed in and out upon advance or retraction of a threaded drive member having an enlarged tip engaged with a down sloping channel formed in the stop member. Upper sides of the channel engage the tip upon reversal of the drive member to cam the stop member back into the holder body. The stop member when extends prevents removal of the cover from being blown completely free of the manhole vault structure in the event of an explosion.

Abstract: The present invention discloses a multi-purpose adjustable quick expandable installment which can be quickly and finely adjusted and ascend or descend freely, by a snap design which adjusts ascending or descending with a slope principle, based on a mechanical principle that a force is constant if acting on a same area and an opposite force compensates with the force. Through a structure which follows the law of action and reaction to compensate with a sliding force which occurs naturally, a stable movement without moving accidentally is formed, so as to increase safety in adjustment of ascending and descending. Therefore, an adjustable expandable installment which is provided with multi-purposes and is able to quickly and freely ascend, descend or expand is provided.

Abstract: A window well for use by a person to escape through a window formed in a basement wall including a generally U-shaped body member having upper and lower ends and inner and outer ends. The open upper end of the body member has a spacer and a removable lid mounted thereon. The body member is comprised of a composite material such as fiberglass.

Abstract: An insulating construction. The construction is formed from a blank construction having a square or rectangular central portion and a side section attached to each side of the central portion. Two wing sections are attached to each of two opposing side sections. The wing sections are attachable to an adjacent side section free of a wing section. Then the blank construction is folded in a three dimensional configuration, it supported by a rod construction.

Abstract: An attic access apparatus comprises an access frame with sidewalls extending upward from a flange member and configured to extend upward into an attic opening between structural members forming the attic opening. A recessed groove along inner surfaces of the sidewalls is configured such that fastening screws can be located in the groove. A trim flange extends outward from the sidewall to cover fasteners used to fasten the ceiling to the bottom of the structural members, and a support flange extends inward from the sidewalls to form a support flange. An insulated lid drops into the access opening formed by the inner surfaces of the sidewalls and rests on the support flange, and a seal member provides a seal between the lid and the access frame to prevent air movement between the lid and access frame.

Abstract: A plaster collar assembly having a first ring, a second ring secured to the first ring, and a mechanism arranged at an outer periphery of at least one of the rings for axially displacing the first and second rings during rotation of the secured rings relative to each other.

Abstract: A security key tool for unlocking and locking a manhole security device that secures a manhole access opening. The security key tool includes a longitudinal body portion and a handle portion. A security key at a first end of the longitudinal portion is adapted to engage a security lock on the security device for actuating a locking mechanism on the security device to an unlocked position. A slidable member may be used to help engage the security key to the security lock or to protect the security key. A latch release tool at a second end of the longitudinal portion is adapted to release a latch on the manhole security device for actuating the locking mechanism to a locked position. Optionally, the latch release tool may be disposed on a tool head that also includes a lifting tool adapted to engage and lift the security device away from a manhole frame after the security device is unlocked.

Abstract: The invention relates to a device and method for sealing a manhole structure. A band with a relatively rigid angled corner engages the upper margin of a manhole structure. Adhesives may also be used with the band to enhance the seal with the manhole structure.

Abstract: A method of sealing an attic access opening; a first step for which involves providing an attic access opening with a peripheral interior sidewall. A second step involves providing an insulated attic access cover, which consists of a first panel having a peripheral edge and a second panel having a peripheral edge. A flexible web connects the peripheral edge of the first panel with the peripheral edge of the second panel, and defines an insulation cavity between the first panel and the second panel filled with compressible insulation. A third step involves positioning the insulated attic access cover within an attic access opening and moving the first panel and the second panel toward each other to compress the insulation in the insulation cavity and cause the insulation to bulge outwardly to engage the peripheral interior sidewall of the attic access opening.

Abstract: An adapter for a tank, having a bottom with one or more adhesive-receiving channels formed therein, an inner wall, structure for supporting a riser component on the adapter, and wall reinforcement structure. The adapter is particularly suited to providing pre-cast concrete tank lids with structural, interengaging support for a column of stackable riser components to form a passageway to facilitate access to the tank from a higher elevation.

Abstract: A watertight manhole insert and tether locking apparatus and method of use designed to prevent unauthorized entry into a sanitary sewer or other closed drainage system through a manhole closed by a manhole cover. The manhole insert is located beneath the manhole cover and is connected to the manhole by a tether apparatus in the manhole to prevent water entry into the manhole, theft of the manhole insert and to deny access to the manhole. The manhole insert includes a pan-shaped insert body having pressure-relief valve and a lift strap and a side wall fitted with a top rim for engaging a shoulder shaped in the manhole, to support the manhole insert in the manhole.

Abstract: A window well for use by a person to escape through a window formed in a basement wall including a generally U-shaped body member having upper and lower ends and inner and outer ends. The open upper end of the body member has a spacer and a removable lid mounted thereon. The body member is comprised of a composite material such as fiberglass. A stair structure is positioned adjacent the inner surface of the front wall of the body member and is also comprised of a composite material.

Abstract: A manhole system that includes a manhole cover and a frame with at least one locking device for maintaining the manhole cover in place on the frame. The locking device is selectively movable between locked and unlocked positions to selectively engage the cover to hold the cover in place on the frame. The locking device may be rotatable between “locked” and “unlocked” positions about an axis perpendicular to the plane of the cover. The locking device may includes a plurality of cam locks that engage the outer circumferential edge of the cover and are configured to increasingly clamp down the cover against the frame with increasing rotation from “unlocked” position to “locked” position. A plurality of locks can be arranged around frame to engage the cover at different locations.

Abstract: A quick, field installed sump cover system for below ground sumps includes a support ring, a seal between the ring and sump upper lip, preferably two compression brackets each having two spaced regions extending under riser parts, at least one elongated member coupled between the support ring and compression brackets for selectively applying tension forces therebetween causing the bracket regions to engage the riser parts and the support ring to compresses the sealing member to form liquid-tight seal with the sump lip. The sump top can be closed by a dome-cover removably coupled to the support ring. The elongated members can include chain-like members with tensioning devices that, in field installations, can accommodate various sump sizes.

Abstract: A flexible attic access cover positionable for attachment to the framework of an attic access opening of an attic access door for the purpose of reducing heat transfer between the attic and conditioned portion of a building or house.

Abstract: A manhole security device for securing a manhole access opening includes a circular barrier adapted to rest on a manhole cover support flange of a manhole frame. Locking members on the barrier are movable between a locked position in which the locking members are adapted to engage the manhole frame and an unlocked position in which the locking members are not adapted to engage the manhole frame. A biasing mechanism on the barrier is adapted to bias each locking member to its locked position. A rotatable locking mechanism on the barrier engages the locking members and has a locking rotational position wherein the locking members are in the locked position and an unlocking rotational position wherein the locking members are in the unlocked position. The locking mechanism has a security lock adapted to receive a security key that applies a rotational torque to the locking mechanism.

Abstract: A manhole cover assembly including a frame defining an opening and a cover sized to engage the opening. A lift pin is retained by the frame, defining a first axis, and includes a bearing portion, and a top end connected to the cover. The lift pin is free to slide axially along the first axis. A spiral cam is retained to the frame by a torque shaft including an upper and lower end, defining a second axis offset from the first axis. The spiral cam includes a cam surface in selective engagement with the bearing portion of the lift pin so that rotation of the torque shaft about the second axis causes rotation of the spiral cam about the second axis and displacement of the lift pin along the first axis.

Abstract: An insulating cover for an attic or other opening is provided which mounts on top of a stair frame or framed opening or the like without the necessity of attic flooring, characterized by economical construction, economical shipping, ease of assembly, ease of installation above the opening, and a footprint substantially similar to the frame of the folding stair or the empty opening. The present invention further provides an insulating cover that is rugged enough for continued use yet light enough and supported in such as way as to have an ease of opening, staying open and closing as the consumer needs. In a further embodiment, the invention components may be substantially flat packed for ease of shipping and handling. In a further embodiment, the invention provides a multifunction insulating cover that may be fitted with a ventilation means, such as a louver or powered fan to enable ventilation through the framed opening even though the attic cover would be closed.

Abstract: An egress system for an interior space such as an attic covered by roof decking. In one embodiment, the egress system comprises a steel frame adapted for installation within an opening formed in the roof decking between two adjacent roof joists. A hatch panel is releasably secured within the opening defined by the frame by means of a plurality of removable pins. In accordance with one aspect of the invention, an upper surface of the hatch panel is substantially flush with the upper surface of the roof decking, allowing for the uniform application of roofing material, such as composition shingles, overtop the roof decking and the hatch panel, thereby concealing the presence of the egress system beneath the roofing material. Deployment of the egress system is accomplished with the use of a cutting implement inserted from the underside of the egress system inside the interior space into a gap maintained around the periphery of the hatch panel when secured within said frame.

Abstract: Covers for attic trap doors and pull down attic stairs or ladders are described each of which is formed of an insulating material. The covers are structured to effectively seal a ceiling access opening. In some embodiments, a closure member constructed of insulating material is cooperatively and frictionally received within a frame formed of the same material to form an airtight seal therebetween.

Abstract: An attic access apparatus comprises an access frame with sidewalls extending upward from a flange member and configured to extend upward into an attic opening between structural members forming the attic opening. A recessed groove along inner surfaces of the sidewalls is configured such that fastening screws can be located in the groove. A trim flange extends outward from the sidewall to cover fasteners used to fasten the ceiling to the bottom of the structural members, and a support flange extends inward from the sidewalls to form a support flange. An insulated lid drops into the access opening formed by the inner surfaces of the sidewalls and rests on the support flange, and a seal member provides a seal between the lid and the access frame to prevent air movement between the lid and access frame.

Abstract: An enhanced security manhole cover is disclosed, comprising a frame, outer cover, inner cover, crossbar, saddle, eyebolt, and padlock. The inner cover, which closes the lower opening in a manhole, includes a detent in the top surface for receiving the eyebolt. The crossbar is positioned above the inner cover and engages the walls of the frame. The crossbar includes a threaded hole that aligns with the detent. The saddle, an upside down U-shaped member, is positioned over the crossbar and includes a slot for the eyebolt to partially extend through. The saddle may include a shoulder on the base, to protect the eyebolt. The eyebolt passes partially through the saddle and crossbar and threads into the bore. The shackle of the padlock passes through holes in the upright of the U-shaped saddle below the crossbar, locking the saddle in place. The upper cover closes the top of the frame.

Abstract: An adjustable manhole cover frame assembly for mounting on a manhole basin upper section (12) has an outer ring (22) and an inner ring (20) engaging the outer ring by screw threads and supporting the manhole cover (10). The lower annular surface of the frame assembly rests on a convexly curved surface (36C) of a metallic adapter (36), which in turn rests on the generally flat surface (12A) of the manhole basin upper section (12); this allows the orientation of the frame assembly to be adjusted. Also, the frame assembly itself may have parts which allow its upper part to be adjusted for slope when the lower part of the frame assembly has been fixed. Another feature is a hinge mechanism (16) having a hinge arm (74) connecting two pivots (72,76), and having interlocking means (18) which prevent the hinge side of the cover from being raised when the cover is closed.

Abstract: An insulated cover for attic openings is provided which is adapted for pivotal mounting to the portion of the building surrounding the attic opening. The insulated cover includes cover structure for positioning in spanning relationship across the opening, a pivotal mount for enabling the cover to pivot from a spanning position enclosing the opening, to an access-permitting position, and a magnetic coupler including a plurality of magnetic pairs for releasably holding the cover structure in position. The cover structure includes a recess for receiving a pullcord of the like, and a receiver adapted to couple with a rod for controlled pivoting of the cover structure and release of the magnetic connection between the magnetic pairs.

Abstract: A plaster collar assembly having a first ring, a second ring secured to the first ring, and a mechanism arranged at an outer periphery of at least one of the rings for axially displacing the first and second rings during rotation of the secured rings relative to each other.

Abstract: Provided herein are covers useful for covering the open end of an access conduit that may contain fluid control equipment. A cover according to the invention comprises a disc-shaped base portion having a top surface and a bottom surface, with a plurality of risers attached to its bottom surface. There is a contact shoe associated with each of the risers, and the contact shoes have a curvature and are disposed sufficiently on the bottom surface of the base portion so as to exert an outward mechanical force against the inner wall of a conduit that is capped by a cover according to the invention, when such cover is in its installed position, thus providing a secure, yet conveniently removable access cover/conduit assembly.

Abstract: A window well assembly includes U-shaped walls that have smooth interior and corrugated exterior surfaces, and are formed from polyvinyl material. The walls have coextensive ribs juxtaposed along an exterior surface thereof that are compressible. Each wall has an end wall with an opening formed therein, allowing the ribs to compress and expand. The openings are spaced at opposed ends of selected ribs. A mechanism is included for stacking the walls wherein a top edge of one wall receives a bottom edge of another wall. Ladders are seated against the interior surfaces of the walls. A mechanism is included for snapping the ladders onto the wall interior surface. A safety grill is mounted on top of the second wall, having an outer edge extending along a top edge of the second wall, for prohibiting the user from stepping into a cavity defined between the walls and the foundation window wall.

Abstract: Provided herein are covers useful for covering the open end of an access conduit that may contain fluid control equipment. In one embodiment, a cover according to the invention comprises a disc-shaped base portion having a top surface and a bottom surface, with a plurality of groups of stability tangs attached to its bottom surface. A cover as provided herein is readily adaptable to fit a large number of conduit boxes, valve boxes and the like which are presently in common use.

Abstract: This road manhole comprises a frame (4) which delimits an opening (6) and which is provided with an internal collar (8) which extends radially inwards, a cover (10) which comprises a blocking web (12) and a cylindrical skirt (14) which complements the internal collar (8), the blocking web and the skirt defining a concave corner (16), and a main gasket (18) which is arranged on the internal collar (8) and which is interposed in the closed state between the cover (10) and the frame (4). The road manhole (2) comprises an auxiliary gasket (20) which is in contact, at least in the closed state, with the concave corner (16).

Abstract: Covers for mounting onto upper edges of drainage channels or similar surface water drainage arrangements are well known, which are mounted onto the drainage channel by means of fixing devices. To simplify construction, storage and assembly it is proposed that the cover include a frame to which fixing means are attached and which includes devices for the retention and fixing of surface elements. The surface elements may be formed in various ways.

Abstract: A controllably releasable security locking arrangement for a manhole cover allows a manhole cover to be locked into position but allows the manhole cover to rise up in stages upon development of upward forces in an explosion to vent gases developed by the explosion. A lock body mounts a latch slide which has an outer end and which can be extended to prevent removal of the manhole cover. When a shear pin fails the lock body pivots down, to a limited extent, and a secondary shear pin can also be included allowing the cover to be blown completely free upon development of pressures of a great magnitude. A slotted skirt directs venting gas flow so as to retard the inflow of free air and attenuate the explosion.

Abstract: A lightweight manhole cover assembly includes a cover and a base, with the cover including an inner surface having a plurality of ribs extending therefrom. The base includes an inner surface having a plurality of receptacles extending therefrom. The receptacles of the base have a layout that corresponds to the ribs of the cover, such that the ribs are adapted to be inserted into the receptacles.

Abstract: A structural panel, such as an appliance door, includes first and second frame members each having inner and outer peripheral edges with the inner peripheral edges each defining an opening. At least one of the frames is constructed from synthetic polymeric/copolymeric material. A glass panel has an outer peripheral edge in sandwiched relationship with at least one annular member inner peripheral edge thereby closing the opening thereof, and the two frames are secured together. A second glass panel can be associated with the other frame to close the opening therein, and the glass panels can be in spaced parallel relationship to each other. Alternatively, one of the glass panels can be of a concavo/convex relationship, particularly when the structural panel is a washing machine door.

Abstract: A method for manufacturing, transporting and installing on a building site a prefabricated structure made of reinforced concrete for the replacement of a structure such as a manhole, access chamber, access vault, junction box or other, which is buried in the ground and is part of an underground network such as a sewer, aqueduct, gas, electrical distribution, telecommunications, cable television and the like. In this method, concrete is poured in factory against the external surfaces of an integrated removable handling system, which is used as top part of a mold for manufacturing the prefabricated structure. The handling system is fixed to the prefabricated structure in a removable manner. The handling system remains in place during the subsequent steps of unmoulding, transporting and installing the prefabricated structure to the building site. Finally, once the installation is completed, the handling system is removed from the structure.

Abstract: This invention is a device permitting a plug or a cover to lock in a detachable manner onto a frame. In accordance with the invention, the metal washer (9), interposed between the screw head (4) and the mounting surface (7) formed at the bottom of the housing (5) of the cover (2), includes two radial wings diametrically opposite (9a) working together with internal parts (13) of the housing (5) butting and preventing a rotation of the washer (9) during tightening of the fastening screw (3). The invention has applications for public roadways.

Abstract: A casting riser pan for defining an access opening in a cast concrete structure, serving as a cast for a cover for closing the access opening, and serving as a seat for the cover. The casting riser pan includes an orientation element for orienting the cover in case of out of round distortion of the casting riser pan and the concrete cover, an inner wall and an outer wall for increased radial strength, and a continuous securement element for attaching the casting riser pan to a casting mold for simultaneously casting the concrete structure and the cover.

Abstract: Security System for Sewer, Aqueduct, Telephone and Energy System Manhole Caps or Covers including an electromechanical cover (1), on the surface of which is placed an electromagnetic crane (2) that has a handle (3), and that has an emitting coil (4), a battery (5), an electronic card (6) and a control panel (7); inside a waterproof space at least partially enclosed by the electromechanical cover (1) are placed a receiving coil (8), electronic card (12) and two motors (9) that move a pin (10) that has bellows (11), and that are connected to an electronic card (12). The system operates by the emitting coil (4) transferring electromagnetic energy to the receiving coil (8), and at the same time sending an exclusive binary code.

Abstract: A thermal insulating cover is presented. The cover includes a top, a plurality of sides extending from the top and a wide base perimeter extending from the plurality of sides. The device may be formed as a unitary piece, or may be provided in two or more sections which are easily assembled together. A piece of foam, acting as a gasket may be affixed to the base perimeter.