GB2052044A - Combination Roof Stack Vent - Google Patents

Abstract

A roof vent for ventilation of a roof structure includes a body 12 having an open bottom closed off by a surface 24 and a top 1 with internal tabs so that an opening is maintained with the body. An opening 25 in the surface 24 permits 2-way ventilation. On insertion of a flexible flapper valve 4 the vent can be converted to a one- way vent which may be utilized for relieving the build up of vapour pressure within a roof structure but preventing ingress of moisture from ambient surroundings. <IMAGE>

Description

SPECIFICATION Combination Roof Stack Vent The present invention relates generally to moisture vapor release vents and more particularly to a combination moisture vapor vent.

A roof structure for which the present invention is designed includes a roof deck, roof insulation, and a built-up roof disposed over the insulation. It is recognized that this type of roofing includes residual moisture within, particularly at the time said roof is assembled. The problem is enhanced when the deck is constructed of light weight concrete since concrete typically includes a high percentage of moisture at the time it is installed.

There is also a tendency for moisture to be captured between the various layers of the roof structure during the long period of construction where said structure is exposed to the ambient moisture for a long period of time.

As a result of the changes in temperature, the moisture within the structure has a tendency to heat up during the day and to convert to vapor in a pressurized state greater than that of the ambient surrounding. This pressurized vapor is a main cause of blistering in built-up roofing which can be reduced by providing positive venting points for the passage of said vapor to the ambient surroundings. To try and solve this problem, some built-up roof structures include conventional two-way vents located at various points along the structure. The present invention consists of a combination two-way vent capable of simple conversion to a one-way vent. The twoway vent being perfectly satisfactory for venting moisture from within the roof structure, whereas the one-way vent is used in situations where it is necessary to prevent moisture from re-entering the roof structure.

In situations where a normal back pressure within the roof would draw moisture from the ambient surroundings back into the roof the oneway vent system would be used, whereas where this draw is of no concern a two-way vent would be used. The one-way vent is especially useful where moisture vapor which builds up within the roof structure during the heat of day and passes out through the vent is prevented from being drawn back through the vent during the cooler night conditions. The prevention of said moisture is important since it is not usually true that the entire intake of the moisture during the cooler periods will be completely vented back into the ambient surrounding the next day. Therefore, it is quite possible that some of the moisture never escapes, but rather aids in the blistering of the roof.

As will be seen hereinafter, the present invention is directed to minimizing if not eliminating, the drawback of moisture when the vent is used as a one-way vent, while still maintaining the generai standard vent features and capabilities to be used as a two-way vent.

In operation the pressure from moisture vapor builds up within the roof structure until it is higher than the ambient and then if the vent is being used as a one-way vent the pressure causes a flapper valve to lift off its seat and the vapor is allowed to escape into the atmosphere. If the vent is used as a two-way vent there is no flapper valve so the vapor vents into the atmosphere until the pressure within the roof and the atmosphere equalize. In order to prevent moisture vapor from being drawn back into the roof structure through the vent the vent must be used with the flapper valve so that the flapper valve seals off the opening between the atmosphere and the internal portion of the roof when the higher atmosphere pressure causes the flapper to seat over the opening and prevent flow.

An object of the present invention is to have a combination built-up roofing vent with improved means for venting gas and moisture vapor to the ambient surrounding from within the roof structure with the capability of preventing reverse flow from the ambient to within the roof structure while still maintaining the standard features of the normal two-way vent. In this way the cost of producing two types of vent is reduced since the same tooling can be used for both. In addition, it also allows the contractor the freedom of changing his mind even after installation as to whether or not the vent is to be a one-way or two-way vent.

Another object of the present invention is to provide a roof structure comprised of a roof deck, roof insulation, and built-up roof in combination with a vent for providing passage of moisture vapor to the ambient surroundings and depending on the mode of use preventing moisture vapor from the ambient surroundings from being drawn back into the roof structure through the vent.

Still another object is to provide a roof-vent that can be simply changed from a one-way to a two-way roof vent depending upon needs and to reduce the amount of vent inventory that must be carried by the manufacturer, wholesaler, retailer and contractor.

An overall roof arrangement including a roof structure and a vent is disclosed herein. The roof structure itself includes a roof deck, roof insulation disposed over the deck and a built-up roof disposed over the insulation. The vent has an open entry end position against the roof structure, specifically around an opening in the built-up roof and exit space upward from the entry point next to the roof structure whereby gas or moisture vapor is allowed to escape from the structure to pass through the entry and thereafter through the exit into the ambient surroundings.

In accordance with the present invention, the vent includes removable means connected across its exit end for opening the vent to the ambient surroundings through the exit when the pressure within the vent or roof is greater than the pressure outside the exit end and closing the exit end when the pressure within the vent or roof is less than the pressure outside the exit end. In this way, when gas, generally, and moisture vapor in particular, from the roof structure builds up pressure within the vent, it is passed through the exit end in the vent; however, should the passage of the moisture create a low pressure condition within the vent, a lower pressure than that of the ambient surrounding, the flapper valve mean, if in use, which is connected across the exit of the vent will prevent gas and particularly moisture from being drawn back into the vent.When the flapper valve is not in use the vapor may flow in both directions.

In a preferred embodiment of the present invention a flapper valve is connected across the exit end of the vent and movable between the first position where the pressure within the vent is greater than that of the pressure outside the exit end and a second position when the pressure within the vent is less than that outside the exit end. The flapper valve includes at least one securing stem to secure the flapper to the vent housing as well as means within the vent for the attaching of the securing stem.

Embodiments of the invention will now be described with reference to the accompanying drawings, wherein: Figure 1 is a perspective view of the top of one type of cap for the vent.

Figure 2 is a side view of the first cap.

Figure 3 is a top view of the first cap.

Figure 4 is a bottom view of the first cap.

Figure 5 is a bottom perspective view of the first type of cap.

Figure 6 is a perspective view of the cap of Figure 1 elevated from the base and flapper valve.

Figure 7 is a side view of the cap base and flapper valve.

Figure 8 is a perspective view of the assembled vent.

Figure 9 is a perspective view of the top of another type of cap for the vent.

Figure 10 is a side view of the second cap.

Figure 11 is a top view of the second cap.

Figure 12 is a bottom view of the second cap.

Figure 13 is a bottom perspective view of the second cap.

Turning to the drawings, wherein like components are designated by like reference numerals throughout the figures. As seen in Figure 6, the vent 21 includes a rectangular body 12 having an open bottom or entry end not shown which outwardly flanged at 22 (see Figure 8). In use, the entry end is placed over an opening in the built-up roof with flange 23 covering the nonopen portion of the roof around the opening.

The flange 23 is then covered by the roof covering to secure it in its location on the roof.

Vent 21 includes a top 1 which has on its inner surfaces tabs 2 and 3 as disclosed in Figure 4.

Tab 2 is to be constructed so that it has an interference fit with tabs 11 on base 12. Tabs 3, on the other hand, are positioning tabs which control the distance that cap 1 is inserted over base 12 to allow for the proper opening between the top 1 and base 12 so that venting can occur.

Included in base 12, as shown in Figure 6, is a flat surface 24 which closes off the bottom entry opening of the base 12 from the top portion 23 of base 12. Within flat portion 24 are openings 25 with reinforcing struts 9 for centering securing hole 8. Said reinforcing struts 9 are tapered upward as they approach centering securing hole 8 so as not to interfer with flap 4 which may be inserted into hole 10 for covering openings 25.

These openings 25 allow the open-end portion of base 12 to be in communication with the atmosphere even when top 1 is inserted in its proper position over base 12 to form a two-way vent for the built-up roof.

When flapper valve 4, usually of umbrella shape for better sealing, is inserted in hole 10 by means of securing tie 6 which has a tapered surface 5 and an interference surface 7 which when inserted in securing hole 10 forms an interference fit with said hole 10 to securely hold flapper valve 4 over openings 25. It should be remembered, however, that the secured flapper valve 4 has exerted on it a tension due to it being secured which tension should be of such a degree that the valve 4 will seat completely all around hole edge 8 when the ambient pressure equals the pressure within the roof and unseats from hole edge 8 when the roof pressure exceeds the ambient pressure.This system thereby prevents air, moisture or gas flow from the built-up roof through the open end of base 12 and into the atmosphere unless the pressure built up under top flapper valve 4 is greater than the atmosphere pressure at which time flap 4 raises and allows the pressure built up to escape until the pressure within the vent base 4 is equal or less than atmospheric pressure at which time flap 4 reseats itself over openings 25 to prevent flow of gasses into the interior of base 4. Test results of this one way vent indicate that a silicone rubber flapper valve give the best results since it retains its tensile strength for a long period of time and over the wide range of temperature that a roof vent is subjected to, however, this does not preclude the use of other flexible materials.

It is to be understood that the present invention is not limited to the particular description as herein set forth but may include all similar structures.

Claims (7)

Claims

1. An improved roof stack vent wherein the improvement comprises means for converting a two-way roof stack vent into a one-way stack vent without changing the structure of said vent.

2. The vent according to Claim 1 wherein said means for converting a two-way stack vent into a one-way stack vent is a flexible flapper valve with securing means.

3. The vent according to Claim 2 wherein the securing means is a flexible tapered stem having an interference fit with the roof stack vent.

4. The vent according to Claim 2 or Claim 3 wherein the flapper valve is made of silicone rubber.

5. A roof stack vent constructed to permit throughflow of air vapour in each of two opposite directions, together with means for converting the vent to a form arranged to prevent flow in one of the said directions but permitting flow in the other.

6. A vent according to Claim 4 which includes an aperture through which all flow takes place, and the means for converting the vent is a separate part attachable to the vent so as to provide a non-return valve at the aperture.

7. A roof stack vent substantially as any herein described with reference to the accompanying drawings.