Leak Detection in Roof Membranes

Abstract

Leaks in a roof membrane are detected in plurality of separate zones arranged in rows and columns. By applying to the roof in a location underneath the membrane and on top of the deck in each zone at least one length of a moisture detection sensor comprising a substrate carrying two parallel conductors on one surface of the substrate detecting changes in resistance between the conductors so as to detect moisture permeating into the respective zone. The moisture detecting sensors are separate in each zone so as to detect changes in resistance in the respective zone independent of any changes in resistance in other zones so that the system can detect within the rows and columns any zone where changes in resistance occur. In order to detect across the zone, the sensor is applied in a two dimensional pattern for example by two lengths at right angles.

Claims

1. A method of detecting a leak in a roof, wherein the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied above an upper surface of the support deck, the method comprising: dividing the membrane into a plurality of separate zones arranged side by side in rows and columns; in each zone applying to the roof in a location underneath the membrane and on top of the deck at least one length of a moisture detection sensor arranged to detect moisture in between the deck and the membrane; the moisture detection sensor comprising a substrate of a dielectric material carrying first and second elongate, parallel, conductors secured to one surface of the substrate; said at least one length being arranged in a two dimensional pattern in the zone; detecting by a sensing system changes in resistance between said first and second conductors of said at least one length so as to detect moisture permeating into the respective zone in the location between the membrane and the roof deck; detecting said changes in resistance in the respective zone independent of any changes in resistance of said at least one length in other zones; and identifying within said rows and columns any zone where changes in resistance occur indicative of moisture permeating into that zone.

2. The method according to claim 1 wherein the said at least one length of each zone is electrically separated from said at least one length of each of the other zones.

3. The method according to claim 1 wherein said at least one length comprises at least first and second lengths arranged to lie in different directions in the zone.

4. The method according to claim 3 wherein said first length is arranged at an angle to the second length.

5. The method according to claim 4 wherein the first and second lengths are arranged at a right angle.

6. The method according to claim 3 wherein said first and second lengths cross.

7. The method according to claim 3 wherein the first conductor of the first length is connected to the first conductor of the second length for common connection to said sensing system and wherein the second conductor of the first length is connected to the second conductor of the second length for common connection to said sensing system.

8. The method according to claim 7 wherein the first conductor of the first length is connected to the first conductor of the second length at a crossing point and wherein the second conductor of the first length is connected to the second conductor of the second length at a crossing point.

9. The method according to claim 3 wherein the zones are rectangular and each of the first and second lengths spans across the zone passing substantially through a center of the zone, either diagonally or parallel to sides of the zone.

10. The method according to claim 1 wherein said at least one length is in contact with insulation material between the deck and the membrane so as to detect moisture permeating in the insulation material.

11. The method according to claim 10 wherein said at least one length is underneath the insulation material and the conductors are on a top surface of the substrate.

12. The method according to claim 10 wherein there is a vapor barrier on top of the deck and underneath the insulation material.

13. The method according to claim 1 wherein there is provided a protective layer of water pervious material secured to the top surface of the substrate and extending over the conductors.

14. The method according to claim 1 wherein there is provided a mounting adhesive on a surface of the substrate opposite to the conductors.

15. The method according to claim 1 wherein the substrate is an elongate tape, and wherein the conductors extend along the tape.

16. The method according to claim 1 wherein each of the conductors is a flat metal strip.

17. The method according to claim 1 including operating switches in sequence to measure and record the resistance from the conductors in each zone sequentially.

18. The method according to claim 1 wherein a resistor is provided across the conductors to ensure continuity of the circuit where a resistance value of the resistor is substantially higher that the expected parallel value across the conductors when moisture crosses the conductors.

19. The method according to claim 1 wherein, when a leak occurs, stored measurements are used to determine a location of the first zone that went into alarm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:

[0039] FIG. 1 is an exploded schematic cross-sectional view of a typical conventional roof assembly

[0040] FIG. 2 is an illustration of an X and Y sensor zone using detection tape with two flat conductors joined at the intersection of the tapes

[0041] FIG. 3 is a circuit schematic showing the measuring and control circuit for multiple zones and shows the microprocessor controlled switching arrangement and internet gateway linking the system to a cloud based monitoring center.

[0042] FIG. 4 is a cross-sectional view at the connection between two lengths of the moisture sensing tape at the cross-over within one zone.

[0043] FIG. 5 is a top plan view at the connection between two lengths of the moisture sensing tape at the cross-over within one zone.

DETAILED DESCRIPTION OF THE INVENTION

[0044] Referring now to the drawings, a cross-sectional view of a typical conventional roof assembly is shown in FIG. 1. The structural deck 1 which supports the rest of the roof assembly is covered with a vapor barrier 2. Placed immediately above and on top of the vapor barrier is the moisture detection system detection conductors 3 in a zoned X and Y configuration shown best in FIG. 3. Thermal insulation 4 is installed above the vapor barrier then a protection board 5 is installed above the thermal insulation 4. The water impervious membrane 6 is then installed on top of the protection board to complete the assembly. The detection system is placed on top of the vapor barrier as this is where any moisture will tend to migrate to.

[0045] Referring to FIG. 2, an X and Y detection zone using moisture detection tape with flat conductors is shown. The detection tape 7 is placed in the roof assembly in a cross configuration the tip conductors 8, 11 and the ring conductors 9, 12 are spliced together at the tape intersection 13 along with the cable pair 10 that connects to the zone switch 18. The length of the detection tape 7 defines the grid spacing for the detection system. The shorter the tape section the tighter the zoned grid pattern which subsequently increases the sensitivity and leak location resolution of the system.

[0046] FIG. 3 provides a simple schematic illustrating the zone configuration and wiring connection along with a block diagram if the measurement system and Internet connection. A vertical view of a roof vapor barrier 6 is shown. The X and Y detection zones 14, are placed directly on the vapor barrier. The tip and ring detection tape conductors are connected together along with the zone connecting pair at the tape intersection 15. The zone connecting cable 17 terminates the zone pairs on the zone switching circuit 18. On command from the cloud based monitoring center (CBMC) 21 via the Internet gateway 20 the controller and measurement circuit 19 will initiate a measurement cycle. The X and Y detection zones 14 are measured in sequence and the resultant measurement stored in memory at the microprocessor control and measurement circuit 19. The CMBC 21 with then retrieve the measured values for analysis. If a leak occurs, the stored measurements are reviewed to determine the particular location of the first zone that went into alarm so as to locate the leak, even if moisture movement later masks the specific location.

[0047] The sensor tape is of laminated construction with the preferred configuration having a substrate 20, 20A of high-dielectric strength and two flat copper conductors 11, 13 and 8, 9 adhered to the dielectric substrate 20. The high-dielectric strength substrate provides mechanical strength and electrical insulation from the surface it is applied to. The substrate is coated with a pressure sensitive mounting adhesive 21, 21A that provides adequate adhesion to standard building materials such as wood, wood laminates, concrete, steel, galvanized steel, PVC, ceramic, etc for attachment to the vapor barrier 2. The adhesive backing is desirably non-water soluble and selected to provide good adhesion characteristics over the anticipated application temperature range, e.g. 10 C. to +50 C. The adhesive backing is protected prior to installation by a peel-off release layer (not shown). A protective non-hygroscopic dielectric layer 22, 22A over the conductors provides mechanical and insulating properties such that contact with metal surfaces does not cause a short circuit across the conductors while allowing water to penetrate to the conductor surfaces and bridge the gap between the conductors.

[0048] The conductors are preferably flat metal strips typically no less than 6.5 mm wide and spaced apart by a distance no less than 13 mm, preferably 13.6 mm.

[0049] FIG. 3 demonstrates a cross grid detection zone using moisture detection tape with flat conductors is shown. The detection tape is placed in the roof assembly in in a cross configuration, see FIG. 3 for layout of multiple cross grid detection zones. It will be noted that the two sensing tapes 14 and 14A are arranged at right angles and intersect at the middle of the zone.

[0050] As best shown in FIGS. 4 and 5, the conductors 8 and 11 are connected at the cross-over point by a splice connector 14E which is U-shaped and is inserted into the tapes at the conductors to provide a connection to each. Similarly a connector 14F connects the conductors 9 and 13. Connectors of this type which can be inserted a crimped to the conductors are commercially available. The conductors in each zone are separated each from the next at the separation lines 14C, 14D defining the edges of the zones. The tip conductors and the ring conductors are spliced at the cable pair connections at connectors 14E, 14F along with the cable pair 17 that connects to the zone switch. The length of each detection tape 14, 14A defines the grid spacing for the detection system. The shorter the tape section the tighter the zoned grid pattern.

[0051] In another embodiment, a loop back test to verify circuit continuity can be implemented by placing termination resistors 23, 24 at the end of the detection tape circuit. The control and measurement module 19 can be switched remotely to test for circuit continuity with an expected value of the parallel combination of the termination resistors 23,24.