OUTLET BOX VAPOUR SEAL

COUPE-VAPEUR DE BOITE DE PRISE DE COURANT

English Abstract

A resilient sealing membrane for an electrical
outlet box is open with side and bottom walls. The side
walls extend outwardly to be clamped by the cover plate
against the drywall or snub over the outlet box edge to be
clamped against the edge by the cover plate, The sealing
membrane may be located inside or outside the outlet box and,
whether inside or outside, may be a physically separate
member or a coating on the outlet box.

Claims

The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. The combination of a sealing membrane and an electrical
outlet box, and a cover plate, which electrical outlet box has side
and bottom walls and outer edges on said outlet box side walls, said
sealing membrane being formed of flexible, compressible, resilient,
fire resistant and , at expected operating temperatures, non-toxic,
material and having side and bottom walls,
said sealing membrane having bottom and side walls
being dimensioned and shaped to be placed inside and overlie the
side and bottom walls of said box,
an edge flange on said membrane adapted to extend
outwardly from the outer extremity of said membrane side walls,
over said outlet box side wall edges, and adapted to be clamped
against said edges by an outlet box cover plate,
wherein said edge flange is dimensioned to include
a surrounding portion adapted to extend over drywall which surrounds
an aperture for said box,
said surrounding portion being of substantially uniform
thickness sufficient to be clamped against said drywall by said
outlet box cover plate.
2. The combination as claimed in claim 1 wherein said
membrane is provided separately from said box.
3. The combination as claimed in claim 1 wherein said
cover plate generally defines a flat plane and has a downwardly
curved peripheral edge substantially uniform about its periphery,
wherein said cover plate is dimensioned so that said
peripheral edge may contact said drywall when installed,
wherein said surrounding portion of said membrane is
thick enough to be compressed against said drywall with said cover









plate installed and thin enough to allow said cover plate edges to
contact said drywall.
4. The combination as claimed in claim 2 wherein said
cover plate generally defines a flat plane and has a downwardly
curved peripheral edge substantially uniform about its periphery,
wherein said cover plate is dimensioned so that said
peripheral edge may contact said drywall when installed,
wherein said surrounding portion of said membrane is
thick enough to be compressed against said drywall with said cover
plate installed and thin enough to allow said cover plate edges to
contact said drywall.
5. A method of installing an outlet box, comprising :
providing an electrical outlet box,
which electrical outlet box has side and bottom walls
and outer edges on said outlet box side walls; and providing a
sealing membrane, separate from said box, said sealing membrane being
formed of flexible, compressible, resilient, fire resistant and at
expected operating temperatures, non-toxic, material and having side
and bottom walls,
said sealing membrane being dimensioned and shaped
to be placed inside and overlie the side and bottom walls of said
box,
an edge flange on said membrane adapted to extend
outwardly from the outer extremity of said membrane side walls,
over said outlet box side wall edges, and adapted to be clamped
against said edges by an outlet cover plate,
wherein said edge flange is dimensioned to include a
surrounding portion adapted to extend over drywall which surrounds
an aperture for said box,









said surrounding portion being of substantially uniform
thickness sufficient to be clamped against said drywall by an
outlet box cover plate,
forming an aperture in the membrane,
passing power wires, through said aperture,
installing the membrane in the outlet box,
connecting the power wires to a receptacle,
attaching the receptacle to the outlet box, and
applying cover plate to seal the surrounding portion of
said edge flange against drywall surrounding said box.
6. The method as claimed in claim 5 wherein said cover plate
has downturned peripheral edges outwardly of said surrounding
portion, and said cover plate is applied to compress said surrounding
portion until said peripheral edges contact said drywall.
7. A sealing membrane for use with an electrical outlet box,
which electrical outlet box has side and bottom walls and outer
edges on said outlet box side walls, said sealing membrane being
formed of flexible, compressible, resilient, fire resistant and,
at expected operating temperatures, non-toxic material and having
side and bottom walls, said side walls defining an outer extremity,
said sealing membrane being dimensioned and shaped to be
placed inside and overlie the side and bottom walls of said box,
an edge flange extending to an outer periphery on said
membrane extending outwardly from the outer extremity of said
membrane side walls, and adapted to extend over said outlet box
side wall edges, to be clamped against said edges by an outlet box
cover plate,
wherein the outer periphery of said edge flange has a



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downwardly extending rim dimensioned to extend over the edges and
then a short distance along the outer side of the box.
8. The sealing membrane as claimed in claim 7 wherein said
membrane is provided separately from said box.
9. A membrane for use with an electrical outlet box, which
outlet box has side and bottom walls and outer edges on said
outlet box side walls,
said sealing membrane being formed of flexible,
compressible, resilient, fire resistant and, at expected temperatures,
non-toxic, material and having side and bottom walls,
and dimensioned and shaped to receive therein said
outlet box,
an edge flange on said membrane adapted to extend inwardly
from the outer extremity of said side walls over said box side wall
edges and to be clamped there against by an outlet box cover plate.
10. Membrane as claimed in claim 9 wherein said membrane is
provided separately from said box.
11. In combination, an electrical outlet box having side and
bottom walls and outer edges on said outlet box side walls,
a flexible compressible resilient coating layer on the
side and bottom walls, said layer being formed of material which
is fire resistant and non-toxic at expected temperatures.
12. A combination as claimed in claim 11 wherein said coating
is on the inside of said box.
13. A combination as claimed in claim 11 wherein said coating
is on the outside of said box.
14. A combination as claimed in claim 12 wherein said layer
extends over the outside edge of the box and is dimensioned to be


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clamped by a cover plate against said outside edge.
15. A combination as claimed in claim 13 wherein said layer
extends over the inside edge of said box and is dimensioned to be
clamped by a cover plate against said outside edge.




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Description

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This invention relates to sealing membranes for use in
combination with an outlet box to inhibit air flow through and
about the box at the internal wall (usually drywall) between the
habitable or usable area of the : house office or factory or the
like; and the space between the drywall and the exterior wall.
An outlet box is the metal or plastic box which is usually
mounted on a 2"x4" and which mounts a receptacle in the form of a
socket, switch or the like for connection to the building electrical
supply. A cover plate is attached to the receptacle or box to cover
the opening of the box and cover the receptacle except for the
receptacle interface, e.g. the toggle switchlfemale socket etc. The
^over plate extends outwardly beyond the box to contact the drywall
about the outlet opening.
It is an object of the invention to provide a membrane
impé-rvious to air flow having side and bottom walls and designed to
be received inside the outlet box or to surround the outlet box to
inhibit the flow of air therethrough or therearound. The membrane
also tends to seal to electrical leads passing therethrough to prevent
rlow of air through the lead apertures.
The membrane useful with the invention will be resilient
and compressible, (in most cases it will be between 1/8" and 3/16"
thick), it will have to be fire resistant in most jurisdictions and
should be non-toxic over the expected temperature range.
In one aspect of the invention the membrane is manufactured
as a separate body for assembly to the inside of the box for use.
For such use, the membrane, although compressible and flexible, is
formed to retain its own shape when unstressed. Such separately
manufactured membrane is designed primarily for retrofitting in
existing installatio~s although it may also be used in new instal-
lations.

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The outlet box will (other than for the membrane), be
of conventional construction with a number of optional 'punch-outs'
or weakened areas for admission of the electrical leads at selected
locations. A coated membrane layer will cover such optional
punch-outs or weakened areas to be pierced at the selected location
by the electrician. The membrane, after piercing, being resilient,
will tend to seal to the electrical leads reducing air flow through
the aperture.
(Regardless of the orientation of the box in use, the
box wall facing the opening is called the 'bottom wall' and the
surrounding box walls (whether the box is round, rectangular or of
another shape) are referred to as side walls.)
With the separately manufactured membrane, for use inside
the box, it will be noted that this arrangement will be the most
convenient for retrofitting. The separately extending membrane is
provided with an outwardly extending flange extending over the
outside edges of the box for clamping between the drywall and the
receptacle cover plate; or with an outwardly, extending 'snub' over
the outside edges of the box for clamping between the cover plate
and such outside edges. What is called a 'snub' herein is a short
extension of the membrane wall which is shaped to extend over the
outside edges of the box wall and back along the box wall a short
distance along the side wall of the box opposite to the main body
of the membrane. Thus the portion of snub may be clamped, for
sealing, between the outside edges of the box and the receptacle
cover plate. An aperture must be made in the membrane to allow
passage of the two live wires although the ground connection will
usually be made between the bottom wall of the box and the bottom




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wall of the membrane.
The separately manufactured membrane for use outside the
box can also be used for retrofitting although it will be noted
that the box must be removed to allow installation of the membrane.
In such arrangement the membrane side walls are provided with an
outwardly extending flange for clamping between the receptacle
plate and the drywall. The outside membrane could also be provided
with an inwardly extending snub for clamping between the receptacle
plate and the outside edges of the box. With such an outside
membrane the three-wire lead is led through an aperture in the
membrane outside the box.
With the membrane coated on the inside of the box, the
ground connection will extend through the membrane layer for
connection to the ground lead. The membrane, coated on the inside
of the box is coated over the outside edge and back along the
outside of the box a short distance to form a snub. The snub
material is clamped between the box edges and the receptacle plate.
Such coated membrane could be provided with an outwardly extending
flange although this is likely to be uncommon. The electrical
leads are led through an aperture in the coating corresponding to
that in the box wall.
With the membrane coated on the outside of the box,
arrangements are similar to those described in the preceding
paragraph with two exceptions. Firstly the ground lead is exposed
in this alternative. Secondly the outside coated membrane is
snubbed over the outside edge of the box and a short distance
inwardly along the box side walls so that the snub portion may be
clamped between the edge and the plate.




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2057267

Either coated membrane design will most commonly be used
on new installations. With new installations there will usually
be a vapor barrier of plastic film. For best sealing results the
vapor barrier will be fastened over the snub, to be clamped between
the snub and the receptacle plate.
In drawings whlch illustrate a preferred embodiment of
the invention
Figure 1 shows an embodiment with a physically separate
membrane inside the box,
Figure lA shows a perspective view of a membrane and
outlet box before attachment,
Figure 2 shows an alternate of the invention in Figure 1,
Figure 2A shows a front view of the device of Figure 2
with a cover plate removed,
Figure 3 shows an embodiment of the invention with a
physically separate membrane outside of the box,
Figure 4 shows an embodiment of the invention with a
membrane coated on the inside of the box,
Figure 5 shows an embodiment of the invention with a
membrane coated on the outside of the box.
In Figure 1 and lA is shown a section of a conventional
outlet box 10 mounted on a 2" X 4" (not shown) in association with
an opening in drywall 12. The outlet box is provided with bottom
wall 14 and side walls 16. The outlet box is formed with mounting
tabs for attaching the receptacle and knock out or weakened areas
33 for insertion of the power leads.
(The front view of the outlet box in Figure 1 (and all
figures) will be similar to that shown in Figure 2A although the




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2057267
membrane is different in each of Figures 1,2,3,4,5.)
A flexible resilient membrane 17 is shaped to provide
side and bottom walls 18 and 20. The membrane side walls are
dimensioned to lie alongside and inside the side walls of the box.
The membrane bottom wall is placed so that the ground connection
22 can be made between it and the bottom wall of the box. The
outer extremities of the membrane side walls are formed into an
integral flange 24 to over-lie the outside edges of the box and
the drywall about the opening. The membrane 17 is separately
manufactured and physically separate from the outlet box and such
physically separate membrane is known as a 'boot'.
In installation, which typically will be a retrofit of
a previous installation, the cover plate 30 and receptacle 26
(shown only as a lined outline with mounting tabs 32) are removed
from the box. The ground connection is affected or left in place
if previously made. An aperture is formed with any suitable
implement in the 'boot' and the two power wires 28 passed there-
through and the boot is then set in place. The power wires 28 are
connected to the receptacle 26.
The receptacle 26 is not shown in detail but may assume
many forms, e.g. a switch, female socket etc., and the receptacle
is thus shown only as a rectangular outline and the connections of
the power wires are not shown. The receptacle 26 is, however,
provided with mounting tabs 32 which, as is conventional, are
bolted to registering mounting tabs 36 on the outlet box. The
installation bolts for attaching tabs 32 to tabs 36 will pass
through the flange 24 of the membrane boot. The cover plate 30 is
then bolted in place by its conventional attachment (not shown) to


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the receptacle. (Although unusual it is noted that the cover
plate 30 could equally well be bolted to the outlet box.)
However it is important to note that the thickness of
the membrane is selected so that it is clamped between the lower
side of the cover plate and the drywall 12, and also clamped
between the lower side of the cover plate and the outlet box
edges 19.
The membrane is preferably about 3/16~ thick and
resiliently compressible, flexible and impervious to air flow.
It must be fire resistent and non-toxic over the range of expected
temperatures. We prefer to use a membrane made from foamed
polyurethane with closed cells.
Figure 2 shows a membrane similar to that in Figure 1,
except that the Figure 1 flange is replaced with a snub 34 being
an extent of the membrane material over the outside edges and back
a short distance along the outside of the box walls. The snub 34
as shown in the front view, Figure 2A is formed to pass on each
side of the box mounting tabs 36. The installation is the same as
with the previous alternative.
The snub 34 of the membrane material is chosen to be
sufficiently thick to be compressed between the lower surface of
the cover plate 30 and the edges 19 of the outlet box. (Thus it
is within the scope of the invention to form the boot with only a
short flange extending outwardly over the box edges 19 for sealing,
that is, without the return outward portion on the outside of the
box.) However the 'snub' arrangement is preferred. If possible
the drywall will be cut so that the return portion of the snub is,
if possible, compressed by the near edges of the drywall.

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2057267
Figure 3 shows a membrane 37 dimensioned to fit about
the outside of outlet box. An outwardly extending flange 38 is
dimensioned permit clamping between the inside of the cover plate
30 and the outside of the drywall. The installation requires
removal of the outlet box, passing the three wire lead 40 through
an aperture formed in the membrane and re-installing the box. The
receptacle 26 and cover plate 30 are then installed, the latter
clamping the membrane to the drywall.
Figure 4 shows an otherwise conventional outlet box with
a membrane layer 44 of about 3/16~ coated on the inside box walls
and back on the outside a short distance to form snub 45. The
techniques for providing such coating are well known. The ground
mounting screw 42 must extend inwardly through the membrane for
connection. The inside coated box is installed by bringing the
three wire lead 40 through the box wall and a registering opening
in the formed by the installer at a selected box opening for the
purpose. With box, receptacle and cover plate 30 installed the
snub 45 will be clamped between the cover plate and the box l9
edge customarily the membrane coating will not be applied over the
tabs 36 so that tabs 32 contact or nearly contact tabs 36. In a
new installation the vapor seal film 46 conventionally mounted
rearwardly of the drywall is available to complete the seal. After
the box is installed and before the cover plate the vapor seal
film 46 is then led over the snubbed edges of the box to be clamped
in place by the cover plate.
Figure 5 shows an otherwise conventional outlet box with
a membrane layer 48 coated on the outside of the box and having a
snub 5G extending over the box outside edges l9 to extend a short

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20 57 267

distance inwardly along the side wall. The ground screw is exposed
for connection. The 1nstallation is the same as for the device of
Figure 4 the three wire lead 40 passing through the membrane at a
point aligned with the box opening selected by the installer. The
cover plate 30 clamps the vapor seal film 46 and the snub 50 against
the box edge 19 as in Figure 4.
With both alternatives of Figure 4 and 5 the snubs may
be replaced by a shorter length of the membrane coating extending
over the box edges only.
Thus the membrane in accord with the invention will seal
against air flow between the cover plate and the outlet box front
walls, and about the electrical leads passing through apertures
formed in the membranes for that purpose. In some embodiments the
membranes will seal between the cover plate and the front of the
drywall and, depending on the skill in cutting the drywall between
the outlet box and the edges of the drywall. It is true that in
each case the seal will not be perfect. This does not alter the
utility of the invention in reducing and inhibiting air flow
through and about the outlet box located in the wall defining the
habitable area of a building.




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Representative Drawing