U.S. patent application number 09/918522 was filed with the patent office on 2003-02-06 for apparatus and method for extending the length of a vent pipe above the elevation of a building roof.
Invention is credited to Menzies, Samuel John.
Application Number | 20030024185 09/918522 |
Document ID | / |
Family ID | 25440513 |
Filed Date | 2003-02-06 |
United States Patent
Application |
20030024185 |
Kind Code |
A1 |
Menzies, Samuel John |
February 6, 2003 |
Apparatus and method for extending the length of a vent pipe above
the elevation of a building roof
Abstract
Apparatus and a method for extending the length of a vent pipe
for a predetermined distance above the elevation of a building roof
includes an elongated extension pipe connectable with the vent
pipe, a flashing attachable to the roof while fitted as a sleeve
over the extension pipe, and a vent cap fittable over the flashing
and the extension pipe. The vent cap includes an opening for
venting to external atmosphere gases received by the extension pipe
from the vent pipe. The extension pipe and the vent cap are sized
so as to maintain a venting pressure in the extension pipe not
greater than the venting pressure in the extension pipe.
Inventors: |
Menzies, Samuel John;
(Surrey, CA) |
Correspondence
Address: |
Lance A. Turlock
Meridian Patnt Services
#471-7231-120th Street
Delta
BC
V4C 6P5
CA
|
Family ID: |
25440513 |
Appl. No.: |
09/918522 |
Filed: |
August 1, 2001 |
Current U.S.
Class: |
52/219 ;
52/220.8; 52/300 |
Current CPC
Class: |
F24F 7/02 20130101; E04D
13/14 20130101 |
Class at
Publication: |
52/219 ;
52/220.8; 52/300 |
International
Class: |
E04H 012/28; E04D
013/14 |
Claims
What is claimed is:
1. Apparatus for extending the length of a vent pipe for a
predetermined distance above the elevation of a building roof, said
vent pipe having a known inside diameter, said apparatus
comprising: (a) an extension pipe characterized by: (i) a lower end
having a cylindrical outside diameter sized to fit snugly within
said inside diameter of said vent pipe; and, (ii) an elongated
tubular portion extending upwardly from said lower end, said
tubular portion having: (A) an inside diameter greater than said
inside diameter of said vent pipe; and, (B) an outside diameter,
(b) a flashing, said flashing comprising a base attachable to said
roof and a centrally positioned tubular portion extending upwardly
from said base, said tubular portion characterized by: (i) an
inside diameter sized to fit as a sleeve over said extension pipe;
and, (ii) an outside diameter; said base including a centrally
aligned opening having a diameter corresponding to said inside
diameter of said tubular portion and extending lengthwise through
said base for permitting said flashing to be lowered as a sleeve
over said extension pipe; and, (c) a vent cap comprising an inner
wall and an outer wall with an annular space defined between said
walls, said annular space having a closed top and an open bottom,
said inner wall defining a centrally aligned opening extending
lengthwise through said cap, and wherein: (i) said inner wall has
an outside diameter sized to slidingly fit within said inside
diameter of said extension pipe; (ii) said outer wall has an inside
diameter sized to slidingly receive said outside diameter of said
tubular portion of said flashing.
2. Apparatus as defined in claim 1, wherein (a) said tubular
portion of said flashing has a tubular wall thickness substantially
less than the tubular wall thickness of said upper end of said
extension pipe; (b) said inner wall of said vent cap has a wall
thickness substantially less than the tubular wall thickness of
said upper end of said extension pipe; and, (c) said inner wall of
said vent cap has a wall thickness substantially less than the
tubular wall thickness of said upper end of said extension
pipe.
3. Apparatus as defined in claim 2, wherein said centrally aligned
opening in said vent cap has a bottom diameter not less than said
inside diameter of said vent pipe.
4. Apparatus as defined in claim 2, wherein said centrally aligned
opening in said vent cap has a bottom diameter greater than said
inside diameter of said vent pipe.
5. Apparatus as defined in any of the preceding claims, wherein
said extension pipe includes a pipe coupling having a lower end and
an upper end, the lower end of said coupling forming said lower end
of said extension pipe, the upper end of said coupling connecting
with said elongated tubular portion of said extension pipe.
6. Apparatus for extending the length of a vent pipe for a
predetermined distance above the elevation of a building roof, said
vent pipe having a known inside diameter, said apparatus
comprising: (a) an elongated extension pipe connectable with said
vent pipe to receive gases flowing upwardly from said vent pipe;
(b) a flashing attachable to said roof while fitted as a sleeve
over said extension pipe; and, (c) a vent cap fittable over said
flashing and said extension pipe to shield the annular region
between said flashing and said extension pipe from external
precipitation, said vent cap including an opening for venting to
external atmosphere gases received by said extension pipe from said
vent pipe, said extension pipe and said vent cap being sized so as
to maintain a venting pressure in said extension pipe not greater
than the venting pressure in said extension pipe.
7. Apparatus as defined in claim 6 wherein said opening in said
vent cap has a bottom diameter not less than said inside diameter
of said vent pipe.
8. Apparatus as defined in claim 6 wherein said opening in said
vent cap has a bottom to diameter greater than said inside diameter
of said vent pipe.
9. On a building where a new roof is constructed atop an old roof,
and where an existing vent pipe extending above the old roof is of
insufficient length in relation to the new roof, a method of
extending the length of the existing vent pipe above the elevation
of the new roof, said method comprising: (a) connecting an upwardly
extending, elongated extension pipe with said vent pipe to receive
gases flowing upwardly from said vent pipe, said extension pipe
having sufficient length to extend from said vent pipe to a desired
distance above said new roof; (b) fitting a flashing as a sleeve
over said extension pipe; (c) attaching said flashing to said new
roof when so fitted; and, (d) fitting a vent cap over said flashing
and said extension pipe to shield the annular region between said
flashing and said extension from external precipitation, said vent
cap including an opening for venting to external atmosphere gases
received by said extension pipe from said vent pipe, said extension
pipe and said vent cap being sized so as to maintain a venting
pressure in said extension pipe not greater than the venting
pressure in said extension pipe.
10. A method as defined in claim 9, wherein said extension pipe and
said vent cap are sized so as to maintain a venting pressure in
said extension pipe less than the venting pressure in said
extension pipe.
11. A method as defined in claim 9 wherein said vent pipe and said
extension pipe are generally cylindrical, said extension pipe
having an inside diameter greater than the inside diameter of said
vent pipe.
12. A method as defined in any of claims 9 to 11, further
comprising the step of cutting a top part away from said extension
pipe leaving an upper rim of said extension pipe flush with an
upper rim of said flashing.
Description
BACKGROUND TO THE INVENTION
[0001] The present invention relates to vent pipes for building
roofs and to methods for extending the length of such pipes.
[0002] Many existing flat roof buildings are simply flat and lack a
suitably effective roof drainage system. Depending on the size of
the roof, hundreds and sometimes thousands of gallons of water can
collect, and this may lead to significant structural damage. When
it comes time to upgrade or to repair the roof, the water must be
removed and this can be a very difficult job. To avoid reoccurrence
of the problem, it is not uncommon for the roof to be redesigned
with an effective drainage system.
[0003] When an existing roof is redesigned, one technique that has
evolved is to build a new roof atop the old roof. The old flat roof
is built up higher on its perimeter with a new roof that slopes to
a slight but sufficient degree towards one or more appropriate
drains. Once installed, water cannot pond on the roof and the risk
that water will produce a significant amount of weight on the roof
is eliminated.
[0004] However, as representationally illustrated in FIG. 7, the
raising of an old roof can lead to other problems. FIG. 7 depicts
part of an old building roof 100, an existing cylindrical vent pipe
150, a new building roof 200 constructed atop the old roof, and
insulation 250 carried between the old roof and the new roof.
Although imperceptible in the drawing, care will have been taken to
ensure that new roof 200 has sloping characteristics (lacking in
old roof 100) to ensure adequate drainage.
[0005] With the addition of a new roof 200, but not in all cases, a
decision may also be made to add a layer of insulation such as
insulation 250. Styrofoam insulation, tapered to provide the
desired sloping characteristics of the new roof, may be used to
provide insular qualities.
[0006] Typically, the purpose of a vent pipe such as vent pipe 150
is to vent gases* from one or more areas of a building (e.g. the
building plumbing system, a kitchen, a shower, etc.). Several such
vent pipes may be present in any given building. As is plainly
evident from FIG. 7, an immediate problem is that vent pipe 150
does not extend above the elevation of new roof 200. Other vent
pipes (not shown) similarly may not extend above the elevation of
new roof 200 or, if they do, not by a sufficient amount. * Herein,
the term "gases" includes air, fumes, moisture laden air, steam and
mixtures of the foregoing.
[0007] Parenthetically, it may be noted that existing plumbing vent
pipes typically may be extended approximately 11 inches above an
existing flat roof deck. Depending on the overall size of the
existing roof, a new sloped roof such as roof 200, including a
layer of insulation such as insulation 250 may, in some cases, add
more 16 inches to the height of the existing roof.
[0008] Accordingly, pipes such as vent pipe 150 have to be
extended. Typically, this has been done by inserting an extension
pipe of desired length within the existing vent pipe. A flashing,
sleeved over the extension pipe and attached to the new roof, is
added in a conventional manner, and a vent cap is placed over the
extension pipe and flashing in a conventional manner. However, this
convention has been found to lead to further problems. It has been
realized that moisture from venting gases may pass between the
extension pipe and the flashing with consequent damage to the
building structure, and that this problem is not resolved by
conventional designs.
[0009] Thus there is a need for improved apparatus and a method to
extend the length of existing vent pipes which discourages or at
least does not encourage the passage of moisture laden gases
between an extension pipe and its flashing.
[0010] It is an object of the present invention to provide new and
improved apparatus for extending the length of an existing vent
pipe for a predetermined distance above the elevation of a building
roof - more specifically, apparatus that serves to obstruct or
discourage venting gases from passing between an extension pipe and
related flashing.
[0011] Further, it is an object of the present invention to provide
a new and improved method of extending the length of an existing
vent pipe in an building above the elevation of a new roof added
atop the old roof of the building.
[0012] In meeting the foregoing objects, it is also an object of
the present invention to provide apparatus for extending the length
of a vent pipe which is easy to manufacture, and which is easy to
assemble and install on a roof, including a new roof which is
constructed atop an existing roof.
SUMMARY OF THE INVENTION
[0013] In a broad aspect of the present invention, there is
provided apparatus for extending the length of an existing vent
pipe for a predetermined distance above the elevation of a building
roof, the apparatus comprising
[0014] an elongated extension pipe connectable with the vent pipe
to receive gases flowing upwardly from the vent pipe;
[0015] a flashing attachable to the roof while fitted as a sleeve
over the extension pipe; and,
[0016] a vent cap fittable over the flashing and the extension pipe
to shield the annular region between the flashing and the extension
pipe from external precipitation.
[0017] The vent cap includes an opening for venting to external
atmosphere gases received by the extension pipe from the vent pipe.
Further, the extension pipe and the vent cap are sized so as to
maintain a venting pressure in the extension pipe not greater than
the venting pressure in the extension pipe.
[0018] The present invention recognizes that the problem noted
above can be attributed to back pressures caused by the reduction
of flow areas. Since the region within the extension pipe will be a
region of reduced pressure compared to the pressure within the
existing vent pipe, the present invention serves to avoid any undue
choking effect at the outlet as provided by the opening in the vent
cap. This is advantageous because when gases are choked at the vent
cap outlet, the higher choke pressure may force at least some of
the gases into the annular space between the extension pipe and the
flashing. Since this space is a sleeve space it typically may have
a small width. Nevertheless, it exists. In the absence of glues or
other sealing mechanisms which are desirable to avoid (and which in
any event may deteriorate over time), the space provides a path
where some moisture carried by venting gases may find its way with
eventual damage to the building structure. This risk can be higher
when the venting gases are moisture laden and have a relatively
high temperature. At higher temperatures components that are
otherwise relatively tight fitting may expand and loosen.
[0019] In a preferred embodiment, the extension pipe is
characterized by a lower end having a cylindrical outside diameter
sized to fit snugly within an inside diameter of the vent pipe, and
an elongated tubular portion extending upwardly from the lower end.
The tubular portion has an inside diameter greater than the inside
diameter of the vent pipe. The flashing comprises a base attachable
to the roof and a centrally positioned tubular portion extending
upwardly from the base. The tubular portion of the flashing is
characterized by an inside diameter sized to fit as a sleeve over
the extension pipe. The base of the flashing includes a centrally
aligned opening having a diameter corresponding to the inside
diameter of the tubular portion of the flashing. The opening
extends through the base for permitting the flashing to be lowered
as a sleeve over the extension pipe. The vent cap comprises an
inner wall and an outer wall with an annular space defined between
the walls, the annular space having a closed top and an open
bottom. The inner wall defines a centrally aligned opening
extending lengthwise through the cap. Also, the inner wall has an
outside diameter sized to slidingly fit within the inside diameter
of the extension pipe. The outer wall has an inside diameter sized
to slidingly receive the outside diameter of the tubular portion of
the flashing.
[0020] In another aspect of the present invention, where a new
building roof is constructed atop an old building roof, and where
an existing vent pipe extending above the old roof is of
insufficient length in relation to the new roof, there is provided
a method of extending the length of the existing vent pipe above
the elevation of the new roof, the method comprising:
[0021] connecting an upwardly extending, elongated extension pipe
with the vent pipe to receive gases flowing upwardly from the vent
pipe, the extension pipe having sufficient length to extend from
the vent pipe to a desired distance above the new roof;
[0022] fitting a flashing as a sleeve over the extension pipe;
[0023] attaching the flashing to the new roof when so fitted;
and,
[0024] fitting a vent cap over the flashing and the extension pipe
to shield the annular region between the flashing and the extension
from external precipitation, the vent cap including an opening for
venting to external atmosphere gases received by the extension pipe
from the vent pipe.
[0025] The extension pipe and the vent cap are sized to maintain a
venting pressure in the extension pipe not greater than the venting
pressure in the extension pipe.
[0026] The foregoing and other features and advantages of the
present invention will now be described with reference to the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is an exploded view of component parts of vent pipe
extension apparatus in accordance with the present invention.
[0028] FIG. 2 is an enlarged section elevation view of the coupler
shown in FIG. 1.
[0029] FIG. 3 is an enlarged section elevation view of the
extension pipe shown in FIG. 1.
[0030] FIG. 4 is an enlarged section elevation view of the flashing
shown in FIG. 1
[0031] FIG. 5 is an enlarged section elevation view of the vent cap
shown in FIG. 1.
[0032] FIG. 6 is an enlarged section elevation view of the
apparatus shown in FIG. 1 when installed on a roof and connected to
an existing vent pipe
[0033] FIG. 7 is a representational view illustrating an old roof,
a new roof, insulation therebetween, and an existing roof vent pipe
that is too short to extend beyond the elevation of the new
roof.
[0034] FIGS. 8a to 8g illustrate a progression of steps using the
apparatus shown in FIG. 1 to extend the roof vent pipe shown in
FIG. 7.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0035] As best seen in FIGS. 1 to 5, the vent pipe extension
apparatus shown in the drawings comprises an extension pipe
coupling generally designated 10, a tubular, generally cylindrical
extension pipe generally designated 20, a flashing generally
designated 30 and a vent cap generally designated 40. Such
apparatus can be used to resolve the problem as described above in
relation to FIG. 7 by following the steps indicated in FIGS. 8a to
8g.
[0036] It should be noted that the combination of coupling 10 and
extension pipe 20 itself may be regarded as an extension pipe. This
combination is sometimes referred to herein as composite extension
pipe 60 or composite pipe 60.
[0037] Also, with reference to FIG. 6 which shows the apparatus of
FIG. 1 when installed on roof 200 and connected to vent pipe 150,
it should be noted that for clarity of illustration section lines
are not shown in the case of coupling 10, flashing 30 and cap 40.
Appropriate section lines for these components are shown in FIGS.
2, 4 and 5.
[0038] Referring now to FIGS. 1 to 6, coupling 10 includes
cylindrical lower and upper ends 11, 12. Extension pipe 20 includes
a lower reduced diameter portion 21 and an elongated tubular
portion 22. As best seen in FIG. 6, the inside diameter d3 of
extension pipe 20 is greater than the inside diameter d1 of vent
pipe 150.
[0039] Lower end 11 of coupling 10 has an outside diameter sized to
fit snugly within the inside diameter of vent pipe 150. The fit
should be sufficiently tight to preclude the escape of any gases
except into extension pipe 20 under worst case pressure conditions
that are apt to develop in vent pipe 150. To avoid or minimize the
choking of gases exhausting through pipe 150, coupling 10
preferably has a thin wall construction (e.g. 0.050") such that its
inside diameter d2 is only very slightly less than inside diameter
d1 of pipe 150. Further, to minimize the likelihood that gases will
escape, and although a strong press fit may avoid the necessity, it
generally is considered preferable to use a caulking or plumbing
sealant (e.g. silicone) between coupling 10 and pipe 150 as
indicated by 16 in FIG. 6. As well, to avoid vertical separation
between coupling 10 and pipe 150, it generally is considered
preferable to secure these component together by suitable fasteners
such as fasteners 15 indicated in FIG. 6.
[0040] Upper end 12 of coupling 10 has an inside diameter sized to
snugly receive lower end 21 of extension pipe 20. Once again, the
fit should be sufficiently tight to preclude the escape of gases
except into extension pipe 20. A suitable coupling may be
fabricated from various metals (e.g. aluminum, copper).
[0041] Extension pipe 20 may be readily fabricated from
off-the-shelf standard size pipe. For example, ABS plastic pipes
having standard outside diameters sizes ranging from about 11/4" to
about 12" and wall thicknesses ranging from about {fraction
(1/16)}" to about 1/2" are commonly used for vent pipes for
buildings. Reduced diameter portion 21 can be quickly and easily
formed using a lathe.
[0042] It will be understood by those skilled in the art that
coupling 10 and extension pipe 20 could be fabricated as one
integral piece. However, at the present time, it is considered more
cost effective to custom fabricate coupling 10 and then to join it
with an off-the-shelf pipe in the manner described above.
[0043] Flashing 30 comprises a thin sheet circular base 31 and a
centrally positioned cylindrical or tubular portion 32 extending
upwardly from the base to a top rim 35. The inside diameter d5 (see
FIG. 4) of tubular portion 32 is sized such that the flashing fits
as a sleeve over the outside diameter of extension pipe 20. A
centrally aligned cylindrical opening 33 having a diameter
corresponding to the inside diameter of tubular portion 32 extends
lengthwise through base 31 thus permitting flashing 30 to be
lowered down over extension pipe 20.
[0044] Flashing 30 may be readily fabricated from thin sheet metal
and thin walled metal tubing (e.g. aluminum, copper); tubular
portion 32 being welded around its lower perimeter to base 31. As
indicated in FIGS. 6, 8e and 8f, flashing 30 is adapted to be
attached to roof 200 by means of conventional fasteners 37.
[0045] As best seen in FIG. 5, vent cap 40 includes a cylindrical
inner wall 41 and a cylindrical outer wall 43 with an annular
region 45 defined therebetween. Annular region 45 is closed around
its top by top 46 and open at its bottom 47. A centrally aligned
opening 48 defined by inner wall 41 extends lengthwise through cap
40 to allow the venting gases to external atmosphere. Lower end 42
of inner wall 41 has a slight inward flair. Likewise, lower end 44
of outer wall 43 has a slight outward flair.
[0046] Annular region 45 is sized to telescopically receive the
combined wall thickness of tubular portion 22 of extension pipe 20
and tubular portion 32 of flashing 30. A corollary is that inner
wall 41 of cap 40 has an outside diameter sized to slidingly fit
within the inside diameter of extension pipe 20, and that outer
wall 42 has an inside diameter sized to sliding receive the outside
diameter of tubular portion 32 of flashing 30. The inward and
outward flairs of lower ends 42, 44 of walls 41, 43 provide some
initial play that assists to guide cap 40 when being installed to
the position shown in FIG. 6 (see also FIGS. 8f, 8g).
[0047] When installed, vent cap 40 will allow rain or other
external precipitation to enter a building's vent pipe system
through opening 48. However, such precipitation is anticipated and
a building's roof vent pipe system typically will interconnect with
a suitable building pipe drainage system. Concurrently, top 46 of
vent cap 40 shields the preferably tight annular space between
extension pipe 20 and flashing 30 from the rain.
[0048] Vent cap 40 is adapted not only to shield rain from entering
the annular space between extension pipe 20 and flashing 30 but, in
combination with the radial sizing of extension pipe 20, to
discourage or obstruct the movement of venting gases upwardly in
the preferably tight annular space between inner wall 41 and
extension pipe 20 then downwardly in the annular space between
extension pipe 20 and flashing 30. The obstruction of venting gases
from moving in this undesirable path is enhanced because the inside
diameters d3, d4 (see FIG. 6 of extension pipe 20 and wall 41 are
greater than the inside diameter d1 of vent pipe 150. When gases
are venting, the region within extension pipe 20 consequently will
be a region of reduced pressure compared to the pressure within
vent pipe 150, and there will be no undue choking effect at the
outlet provided by opening 48 of cap 40.
[0049] It may be observed that if diameter d4 is less than diameter
d1 then a tangible threat of choking may arise. Accordingly,
diameter d4 should not be less than diameter d1 or, if it is, not
by a material amount. Preferably, as is characteristic of the
embodiment shown in the drawings, diameter d4 is greater than
diameter d1. When extending an existing vent pipe such as vent pipe
150, this avoids the need for any complex engineering analysis of
gas flows, temperatures and pressures under anticipated (but
perhaps unknown or uncertain) conditions of operation to determine
how much if any constriction can be tolerated, and where the
choking threshold might lie.
[0050] The use of the apparatus shown in FIG. 1 will now be
described with reference to FIGS. 8a to 8g.
[0051] The first step is to join coupling 10 with extension pipe 20
as indicated in FIG. 8a to form composite extension pipe 60 as
shown in FIG. 8b. Composite pipe 60 is then coupled with vent pipe
150 as shown in FIG. 8c. Although not shown in FIGS. 8a to 8g, this
may (and preferably does) include the use of fasteners 15 and
caulking 16 as described above in relation to FIG. 6. At this
point, no new roof has been installed over existing roof 100.
[0052] Next, insulation 250 and new roof 200 is added. Then,
flashing 30 is lowered down over composite pipe 60 as indicated in
FIG. 8d until its rests on upper surface 201 of roof 200 as shown
in FIG. 8e. In this position, it will be noted that a top part 25
of composite pipe 60 extends above rim 35 of flashing 30. Also, the
flashing is ready to be attached to roof 200 by means of fasteners
37.
[0053] Next, as shown in FIG. 8f, the flashing is fully attached to
roof 200 by fasteners 37. Further top part 25 is cut from composite
pipe 60 (and discarded) leaving an upper rim 27 flush with rim 35
of flashing 30. Normally (for example when the pipe to be cut is
fabricated from ABS plastic) the cut can be made easily and quickly
with a suitable saw. Preferably, the flashing is attached to roof
200 beforehand.
[0054] Finally, the extension is capped and sealed with cap 40 in
the manner indicated in FIGS. 8f and 8g (see also FIG. 2).
Optionally, when cap 40 is in position as shown in FIGS. 2 and 8g,
it may be more firmly secured by fasteners (not shown) extending
through its outer wall and flashing 30. However, this merely serves
to discourage vandalism. It does not alter or improve the
functioning of the cap.
[0055] It will be appreciated by those skilled in the art that many
of the details provided above are by way of example only and are
not intended to limit the scope of the invention which is to be
interpreted with reference to the following claims.
* * * * *