Title:
Barrier screen and method for protecting a gutter from debris
Kind Code:
A1


Abstract:
A mesh screen capable of providing a barrier for protecting a drainage gutter from ingress of debris; the screen comprising a generally planar sheet of mesh having a first face and a second opposite face; wherein, the first face comprises strands disposed parallel to each other; the second face comprising strands disposed parallel to each other and at an angle other than 90 degrees to the strands on the first face.



Inventors:
Carpenter, David (Kingsgrove New South Wales, AU)
Morgan, Fabian (Kingsgrove New South Wales, AU)
Application Number:
10/926324
Publication Date:
05/19/2005
Filing Date:
08/26/2004
Assignee:
CARPENTER DAVID
MORGAN FABIAN
Primary Class:
International Classes:
E04D13/076; (IPC1-7): E04D13/00
View Patent Images:
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Primary Examiner:
HORTON, YVONNE MICHELE
Attorney, Agent or Firm:
STITES & HARBISON PLLC (ALEXANDRIA, VA, US)
Claims:
1. A mesh screen capable of providing a barrier for protecting a drainage gutter from ingress of debris; the screen comprising a generally planar sheet of mesh having a first face and a second opposite face; wherein, the first face comprises strands disposed parallel to each other; the second face comprising strands disposed parallel to each other and at an angle other than 90 degrees to the strands on the first face.

2. A mesh screen according to claim 1 wherein, the strands comprising the first face form a first layer and the strands comprising the second face form a second layer of the mesh screen.

3. A mesh screen according to claim 2 wherein the second layer lies above the first layer and provides said first face.

4. A mesh screen according to claim 3 wherein the first layer of strands lie along an X axis of X-Y orthogonal axes and the strands of the second layer lie at an angle to the Y axis of the orthogonal axes.

5. A mesh screen according to claim 4 wherein the strands in the first layer are spaced apart and equidistant.

6. A mesh screen according to claim 5 wherein, the strands on the second layer are spaced apart and equidistant.

7. A mesh according to claim 6 wherein, two strands on said first layer and two strands on said second layer together define an aperture shaped as a parallelogram.

8. A mesh screen according to claim 7 wherein the mesh has a plurality of parallelogram shaped apertures formed by said strands.

9. A mesh screen according to claim 8 wherein the strands on the first layer and the strands on the second layer are disposed at an acute angle to each other within the range of 30-70 degrees.

10. A mesh screen according to claim 9 wherein the second layer of strands are ovoid in cross section.

11. A mesh screen according to claim 10 wherein, the screen is fitted over a gutter between a roof edge and a lip of the gutter.

12. A mesh screen according to claim 11 wherein a distance traversed by each strand of said second layer between the roof edge and the lip of the gutter is greater than the shortest distance between the roof edge and lip of the gutter.

13. A mesh according to claim 12 wherein, runoff from the roof adopts a path along said strands of said second layer and drops though said apertures at any location along the distance defined by said strands of said second layer of said mesh.

14. A mesh screen according to claim 13 wherein the strands in the second layer are disposed at an angle other than 90 degrees to a line defined by the lip of the roof edge.

15. A mesh screen according to claim 14 wherein the strands have a cross section which provides a damming effect on water runoff to ensure that water is inhibited or prevented from mounting the strands of said upper surface thereby enabling it to drop into the apertures.

16. A mesh screen according to claim 1 wherein the strands are ovoid in cross section.

17. A mesh screen for providing barrier protection of a draining gutter from sticks, leaf litter, debris and the like, the screen comprising a generally planar length of mesh having a first face and a second face; wherein the first face is an outside face facing away from the gutter and comprising an array of strands disposed parallel to each other but at an angle other than normal to a longitudinal axis of said gutter; the second inner face opposing the gutter and comprising an array of strands disposed parallel to each other and also parallel to said longitudinal axis of said gutter; such that the strands on the first face and the strands on the second face are disposed at an angle to each other than 90 degrees defining a plurality of parallelogram shaped apertures, wherein, the strands on the upper face deflect run off water along a path which is longer than a path normal to said longitudinal axis of said gutter, thereby allowing water to drop through apertures in said mesh screen anywhere along the length of the angled strands.

18. A mesh screen for providing barrier protection for a gutter to prevent entry of objects such as leaf litter sticks branches and the like into the gutter, the mesh screen comprising an array of parallel spaced apart strands disposed in a first direction and an array of parallel strands disposed in a second direction; characterized in that the strands define an array of parallelogram shaped apertures which allow water to flow therethrough.

19. A mesh screen according to claim 18 wherein a first layer of strands are disposed in a longitudinal direction and a second layer of strands are disposed at an angle to said first layer of strands between 20-60 degrees.

20. A mesh screen according to claim 19 wherein the strands are ovoid in cross section.

21. A method for providing barrier protection for a gutter to prevent entry of objects such as leaf litter sticks branches and the like, into the gutter, wherein the barrier protection comprises a mesh screen, the screen comprising: a generally planar length of mesh having a first face and a second face; wherein the first face is an outside face comprising an array of strands disposed parallel to each other but at an angle other than normal to a longitudinal axis of said gutter; the second face comprising an array of strands disposed parallel to each other and also parallel to said longitudinal axis of said gutter; wherein the strands on the upper face deflect run off water along a path defined by the strands on the first face and which is longer than a path normal to said longitudinal axis of said gutter, thereby allowing water to drop through parallelogram shaped apertures in said mesh screen anywhere along the length of the angled upper strands. the method comprising the steps of; a) placing the mesh screen over an open face of a gutter such that a first edge of the mesh engages a lip of the gutter and a second edge engages a roof structure; b) securing the screen to said gutter and said roof structure.

22. A mesh screen according to claim 1 wherein the strands are either made from the same or two different materials.

23. A mesh screen according to claim 22 wherein, the strands on the first layer are made from a first plastics material and the strands on the second layer are made from a second plastics material.

24. A mesh screen according to claim 23 wherein the strands thickness falls within the range 0.5-3 mm.

25. A mesh screen according to claim 24 wherein the strands spacing falls within the range 3-9 mm.

Description:

BACKGROUND

The present invention relates to barriers for preventing debris from entering drainage gutters but more particularly relates to a mesh screen with improved water penetration and barrier properties. The invention further provides a method for protecting a gutter from ingress of debris but which allows more efficient penetration of water through a gutter barrier. More particularly, the invention provides an improved screen to prevent unwanted entry of debris such as leaves sticks branches yet improves efficiency of water penetration before reaching a lip of the gutter.

PRIOR ART

Barrier screens for preventing unwanted ingress of leaves sticks and other debris into gutters are well known. Typically barrier screens are manufactured from metals or plastics and comprise an array of strands usually disposed at right angles and which define apertures through which runoff passes. Absence of the screens causes debris buildup in a gutter which eventually clogs the gutter and causes blockages and unwanted overflow of rainwater.

There are a wide variety of screens which are manufactured as a mesh to cover an open mouth of a gutter. Known meshes may be screw fastened generally to the lip of a gutter via one edge and inserted under a roof tile along the other edge. Alternatively the mesh may be arced so that its elastic memory causes the mesh to bias itself in position between internal gutter faces or between one internal gutter face and part of a roof such as a tile.

The objective in manufacture of mesh screens is to ensure that on one hand debris is prevented from entering a gutter which is protected by the screen and on the other hand ensuring that water drops through apertures in the mesh before spilling over the edge of the gutter. The mesh configuration is critical to its performance. Mesh apertures must be large enough that they allow roof runoff every opportunity to overcome surface tension and penetrate the gutter but small enough to prevent unwanted debris entering the apertures. Also, the disposition of the strands is critical to achieving these objectives. In the case where a strand runs parallel to a line of the gutter this will tend to retard the flow of the runoff causing water to cascade over the longitudinal strands. In the case where upper strands are normal to the line of a gutter, water may run right over the surface of the mesh without dropping into apertures due to an inability of the runoff to overcome surface tension created by the mesh. Attempts to overcome surface tension by increasing aperture size have resulted in an increase in the tendency to trap leaf stems and sticks in the larger size apertures. It has been found that water penetration through the mesh increases if the aperture size is increased. Water penetration is also increased if strands on an upper face of a mesh screen are normal to the direction of a gutter and to strands on a lower or underside face of the screen. However if a longitudinal strand is too deep. This may increase the longitudinal stiffness of the mesh making it much harder to install. One attempt to overcome the aforesaid prior art problems is disclosed in Australian patent 741254 which teaches a mesh screen for application to guttering which is characterized in that the thickness of longitudinal strands extends for substantially the full thickness of the mesh from the top and also characterized in that the holes in the mesh are increased in length in the direction of flow of water running across the width of the guttering in a direction at right angles to the length of the guttering. The strands of the mesh aligned longitudinally to the guttering project below the plane of the mesh to facilitate water removal on the underside of the mesh. Mesh screens of this type suffer from the disadvantage that water is prone to flow over the lip of the gutter before penetrating the mesh due to surface tension rending the mesh described in that patent less efficient than it might otherwise be. Parameters which effect the performance of a mesh barrier screen include the planar relationship between lateral and longitudinal strands, thickness of strands in each layer, center to center spacing between strands, depth of longitudinal strands and lateral strands, size of apertures defined by respective lateral and longitudinal strands. Various attempts have been made to improve the performance of mesh screens for gutters to ensure that all runoff penetrates the screen, and that no debris enters a gutter. Satisfaction of these objectives have involved compromise of parameters but there is further room for improvement.

INVENTION

The present invention employs some of the known characteristics of mesh screens but provides an improved geometry which increase the efficiency of the mesh in at least the areas of water penetration and prevention of unwanted debris penetrating the mesh.

In its broadest form the present invention comprises;

  • a mesh screen for providing barrier protection of a draining gutter, the screen comprising a generally planar length of mesh having a first face and a second face; wherein the first face is an outside face comprising an array of strands disposed parallel to each other but at an angle other than normal to a longitudinal axis of said gutter; the second face comprising an array of strands disposed parallel to each other and also parallel to said longitudinal axis of said gutter; wherein the strands on the upper face deflect run off water along a path which is longer than a path normal to said longitudinal axis of said gutter, thereby allowing water to drop through apertures in said mesh screen anywhere along the length of the angled strands.

Preferably, the angled strands have a cross section which provides a damming effect on water runoff to ensure that water is inhibited or prevented from mounting the strands of said upper surface.

In another broad form the present invention comprises:

    • a mesh screen for providing barrier protection of a draining gutter from sticks, leaf litter and the like, the screen comprising a generally planar length of mesh having a first face and a second face; wherein the first face is an outside face facing away from the gutter and comprising an array of strands disposed parallel to each other and when the mesh is mounted on a gutter at an angle other than normal to a longitudinal axis of said gutter; the second face opposing the gutter when the mesh is installed and comprising an array of strands disposed parallel to each other and also parallel to said longitudinal axis of said gutter; such that the strands on the first face and the strands on the second face are respectively disposed at an angle other than 90 degrees, wherein the strands on the upper face deflect run off water along a path which is longer than a path normal to said longitudinal axis of said gutter, thereby allowing water to drop through apertures in said mesh screen anywhere along the length of the angled strands.

In another broad form the present invention comprises:

  • a method for providing barrier protection for a gutter to prevent entry of objects such as leaf litter sticks branches and the like, into the gutter, wherein the barrier protection comprises a mesh screen, the screen comprising: a planar length of mesh having a first face and a second face; wherein the first face is an outside face comprising an array of strands disposed parallel to each other but at an angle other than normal to a longitudinal axis of said gutter; the second face comprising an array of strands disposed parallel to each other and also parallel to said longitudinal axis of said gutter; wherein the strands on the upper face deflect run off water along a path which is longer than a path normal to said longitudinal axis of said gutter, thereby allowing water to drop through apertures in said mesh screen anywhere along the length of the angled upper strands.
    the method comprising the steps of;
  • a) placing the mesh screen over an open face of a gutter such that a first edge of the mesh engages a lip of the gutter and a second edge engages a roof structure;
  • b) securing the screen to said gutter and said roof structure.

The present invention described herein still may employ some of the known mesh characteristics and manufacturing techniques of the prior art save for unique characterizing features described. The present invention seeks to provide an alternative to the known barrier mesh screens by providing a screen having optimal stiffness properties, optimal water penetration properties and optimal barrier properties.

It is an object of the invention to provide a double layer mesh screen which increases water penetration properties of the mesh by relative disposition of strands on upper and lower faces of the screen.

Preferably the strands of the mesh layers are made from the same material but it will be appreciated that strands may be made from different materials.

In another broad form the present invention comprises:

  • a mesh screen capable of providing a barrier for protecting a drainage gutter from ingress of debris;
  • the screen comprising a generally planar sheet of mesh having a first face and a second opposite face; wherein, the first face comprises strands disposed parallel to each other; the second face comprising strands disposed parallel to each other and at an angle other than 90 degrees to the strands on the first face.

Preferably, the strands comprising the first face form a first layer and the strands comprising the second face form a second layer of the mesh screen wherein the second layer lies above the first layer and provides said first face.

Preferably the first layer of strands lies along an X axis of X-Y orthogonal axes and the strands of the second layer lie at an angle to the Y axis of the orthogonal axes.

The strands in the first and second layers are spaced apart and equidistant.

Two strands on said first layer and two strands on said second layer together define an aperture shaped as a parallelogram and the mesh overall has a plurality of parallelogram shaped apertures formed by said strands.

The strands on the first layer and the strands on the second layer are disposed at an acute angle to each other within the range of 30-70 degrees.

The first and/or second layer of strands are ovoid in cross section.

The angle of repose of the mesh strands on the upper layer is such that a distance traversed by each strand of said second layer between a roof edge and a lip of the gutter is greater than the shortest distance between the roof edge and lip of the gutter. Runoff from the roof adopts a path along the strands of the second layer and drops though the parallelogram shaped apertures at any location along the distance defined by said strands of said second layer of the mesh.

The strands in the second layer are preferably disposed at an angle other than 90 degrees to a line defined by the lip of the roof edge, wherein the strands have a cross section which provides a damming effect on water runoff to ensure that water is inhibited or prevented from mounting the strands of said upper surface thereby enabling it to be retarded for sufficient time despite its velocity drop into the apertures.

According to one embodiment the strands are ovoid in cross section.

In another broad form the present invention comprises:

  • a mesh screen for providing barrier protection of a draining gutter from sticks, leaf litter, debris and the like, the screen comprising a generally planar length of mesh having a first face and a second face; wherein the first face is an outside face facing away from the gutter and comprising an array of strands disposed parallel to each other but at an angle other than normal to a longitudinal axis of said gutter; the second inner face opposing the gutter and comprising an array of strands disposed parallel to each other and also parallel to said longitudinal axis of said gutter; such that the strands on the first face and the strands on the second face are disposed at an angle to each other than 90 degrees defining a plurality of parallelogram shaped apertures, wherein, the strands on the upper face deflect run off water along a path which is longer than a path normal to said longitudinal axis of said gutter, thereby allowing water to drop through apertures in said mesh screen anywhere along the length of the angled strands.

In its broadest form the present invention comprises:

  • a mesh screen for providing barrier protection for a gutter to prevent entry of objects such as leaf litter sticks branches and the like into the gutter, the mesh screen comprising an array of parallel spaced apart strands disposed in a first direction and an array of parallel strands disposed in a second direction; characterized in that the strands define an array of parallelogram shaped apertures which allow water to flow therethrough.

Preferably, a first layer of strands are disposed in a longitudinal direction and a second layer of strands are disposed at an angle to said first layer of strands between 20-60 degrees.

In another broad form of a method aspect the present invention comprises:

  • a method for providing barrier protection for a gutter to prevent entry of objects such as leaf litter sticks branches and the like, into the gutter, wherein the barrier protection comprises a mesh screen, the screen comprising: a generally planar length of mesh having a first face and a second face; wherein the first face is an outside face comprising an array of strands disposed parallel to each other but at an angle other than normal to a longitudinal axis of said gutter; the second face comprising an array of strands disposed parallel to each other and also parallel to said longitudinal axis of said gutter; wherein the strands on the upper face deflect run off water along a path defined by the strands on the first face and which is longer than a path normal to said longitudinal axis of said gutter, thereby allowing water to drop through parallelogram shaped apertures in said mesh screen anywhere along the length of the angled upper strands.
    the method comprising the steps of;
  • a) placing the mesh screen over an open face of a gutter such that a first edge of the mesh engages a lip of the gutter and a second edge engages a roof structure;
  • b) securing the screen to said gutter and said roof structure.

DETAILED DESCRIPTION

The present invention will now be described in more detail according to preferred but non limiting embodiments and with reference to the accompanying illustrations wherein:

FIG. 1 shows a perspective view of a mesh screen according to a preferred embodiment;

FIG. 2 shows a cross sectional view of strands of an upper layer of the screen of FIG. 1.

FIG. 3 shows a plan view of the mesh screen of FIG. 1 inverted.

FIG. 4 shows a side profile of a mesh screen fitted over a roof and gutter.

FIG. 5 shows a perspective view of a mesh fitted to a roof and gutter edge.

As shown in FIG. 1, the present invention provides a mesh screen 1 for use with a drainage gutter for protecting the gutter from ingress of leaf litter sticks and other debris. Mesh 1 comprises a first upper layer 2 formed from an array of strands 3 and a second lower layer 4 formed from an array of strands 5. The geometry of the mesh 1 to be described in more detail below increases the efficiency of the mesh in at least the areas of water penetration and prevention of unwanted debris penetrating the mesh. This is in part due to the relative disposition of the strands 3 forming first layer 2 relative to the strands 5 forming lower layer 4. As may be seen in FIG. 2, upper layer 2 comprises a first upper face 6 and lower layer 4 forms a second opposite face 7. Upper face 6 is formed by strands 3 disposed parallel to each other but at an angle other than normal to a longitudinal axis of a gutter to which the mesh 1 is attached. The second and lower face 7 comprises an array of strands 5 disposed parallel to each other and also parallel to a longitudinal axis of a gutter to which mesh 1 is fitted. Strands 3 are disposed at an angle to strands 5 such that the apertures 8 so formed in the mesh form a shape resembling a parallelograms. FIG. 2 shows an end view of mesh 1 formed by upper layer strands 3 which are disposed over lower layer strands 5 forming parallelogram apertures 8. In a typical arrangement, edge 9 engages a lip of a gutter to which mesh 1 is attached. As shown in FIG. 1, during rainfall, water flows along upper strands 3 in the general direction of arrow 10. Strands 3 act as a barrier to roof runoff water cascading over mesh 1. According to the prior art, strands 3 would be disposed at 90 degrees to strands 5 as it was previously thought that this would facilitate water travel normal to the lip of the gutter and into apertures 8. However, it was found that in heavy downpours and even in moderate rainfall, surface tension was maintained preventing water from naturally dropping through mesh apertures so that some of the water passed over the mesh and thence over the gutter. This defeated the purpose of the mesh, as although it prevented some debris from entering the gutter, a substantial amount of the runoff was also excluded. In order to find a compromise, the inventors found that if the distance the water travels before it reaches the lip of the gutter can be significantly increased, it will have an increased chance of breaking the surface tension as the velocity of the water will reduce due to the increased distance it must travel between a roof and a lip of the gutter.

Strands 3 on the upper face 6 deflects run off water along a path (arrow 10) which is longer than a path normal to the longitudinal axis of said gutter, thereby allowing water to drop through apertures 8 in the mesh screen 1 anywhere along the length of the angled strands 3 but before the water reaches edge 9 of screen 1. Preferably, strands 3 are, when the mesh is in situ disposed above strands 5 such that strands 3 lie in a plane parallel to a plane in which strands 5 are disposed but elevated above the latter plane. This, together with the angle of repose of strands 3 relative to strands 5 enhance the damming effect of strands 3 on water traveling in the direction of arrow 10.

Preferably, the angled strands 3 have a cross section which provides a damming effect on water runoff to ensure that water is inhibited or prevented from mounting strands 3 of upper surface 6.

Due to the disposition of strands 3 relative to strands 5, water runoff cannot take its logical shortest normal (90 degree) path from a roof line to a lip of a gutter as it is deflected along a predetermined angle. According to one embodiment, strands 3 have an elliptical shape but it will be appreciated that other cross sectional shapes may be adopted. It will also be appreciated that strands 3 may be rotated 90 degrees from the angle shown in FIGS. 2 and 3 so that strands 3 travel towards edge 9 from left to right instead of from right to left. According to the prior art mesh, apertures were elongated along a line normal to the longitudinal direction of the gutter to which the mesh was attached. It was thought this would decrease surface tension of runoff and increase the prospects of penetration of water through the elongated holes to prevent skimming over the upper surface of the mesh. This increased the risk of sticks and debris entering the larger apertures. The parallelogram shape of the apertures 8 of mesh 1 does not increase the potential for unwanted leaves, sticks and debris entering apertures 8 but the disposition of strands 3 substantially reduces or eliminates water escape over the end of edge 9. Size of aperture 8 may be varied according to the number of strands 3 disposed per unit area or length of mesh. A reduced number of strands 3 will increase size of aperture 8. Likewise a reduced number of strands 5 will also increase aperture size. The size of apertures 8 may be determined according to prescription but strands 3 should be disposed at an acute or oblique angle to strands 5 to maintain a runoff path which is longer than a path where runoff travels normally to the line of a gutter. Taken over the area of the mesh there is a substantial retardation of runoff so that most if not all water running over upper surface 6 of mesh 1 may enter apertures 8 before it would otherwise jump off the lip of the gutter.

The improved mesh herein described is preferably manufactured from an extruder which includes oblique passages which result in production of oblique/angled strands 3.

The mesh screen provides barrier protection of a draining gutter from sticks, leaf litter and the like, the screen comprising a generally planar length of mesh having a first face and a second face; wherein the first face is an outside face facing away from the gutter and comprising an array of strands disposed parallel to each other but at an angle other than normal to a longitudinal axis of said gutter. The second face opposes the gutter and comprises an array of strands disposed parallel to each other and also parallel to the longitudinal axis of the gutter. The strands on the first face and the strands on the second face are disposed at an angle to each other, other than 90 degrees, wherein the strands on the upper face deflect run off water along a path which is longer than a path normal to said longitudinal axis of the gutter, thereby allowing water to drop through parallelogram shaped apertures in the mesh screen anywhere along the length of the angled strands.

Preferred dimensions of the strands and aperture sizes are as follows:

Thickness of strands (longitudinal)0.5-3 mm
Thickness of strands (diagonal)0.5-3 mm
Strand spacing (longitudinal)  4-9 mm
Strand spacing (longitudinal)  3-9 mm
Aperture size Major axis  4-6 mm
Aperture size Minor axis  4-6 mm

The mesh is proportioned to satisfy the objectives of optimal water flow over an upper surface of the mesh, slip off of debris such as leaves and pine needles and maximizing ingress of runoff water through the apertures and into a gutter.

Suitable materials for the mesh strands are for example, high and/or low density polyethylene. The mesh is preferably constructed so that upper diagonal strands disposed at an angle to a roof line provide a damming effect whereas the lower strands which run parallel to the roof line are smaller than the upper strands to allow optimal ingress of water through the mesh and into the gutter.

The method of installation of the mesh may comprise the steps of;

  • a) placing the mesh screen over an open face of a gutter such that a first edge of the mesh engages a lip of the gutter and a second edge engages a roof structure;
  • b) securing the screen to said gutter and said roof structure.
  • c) ensuring that upper strands are at an acute or oblique angle to lower strands, the latter being disposed parallel to a longitudinal axis of a gutter.

The present invention seeks to provide an alternative to the known barrier mesh screens by providing a screen having optimal stiffness properties, optimal water retardation and penetration properties and optimal barrier properties. It is an object of the invention to provide a double layer mesh screen which increases water penetration properties of the mesh by relative disposition of strands on upper and lower faces of the screen.

Preferably, the strands of the mesh layers are made from the same material but it will be appreciated that strands may be made from different materials. The elevation or diameter of respective strands may be the same for the upper and lower strands or they may be of different elevations or diameters.

FIG. 2 shows a cross sectional view of strands of an upper layer of the screen of FIG. 1. FIG. 3 shows a plan view of the mesh screen of FIG. 1 inverted so that the angled upper layer 6 is shown on the bottom.

FIG. 4 shows a side profile of a mesh screen fitted over a roof and gutter. Mesh screen 20 has the characteristics previously described and is typically fitted at end 21 under roof tile 22 and over roof tile 23. Opposite end 24 is fitted over gutter 25 near lip 26.

FIG. 5 shows a perspective view of a mesh 30 fitted to a roof structure 31 and gutter 32. Water runoff on roof surface 33 travels in the direction of arrow 34 engaging upper strands 35 which deflects the runoff, which would usually travel normal to the line of the gutter, to an angle off normal and defined by upper diagonal strands 35. Since the strands 35 are disposed at an angle to a normal to the gutter, flow of runoff is directed over a longer distance across the mesh and along strands 35 retarding flow long enough so that all the runoff will fall through the apertures 36 in the mesh 30. It will be recognized by persons skilled in the art that numerous variations and modifications may be made to the invention as broadly described herein without departing from the overall spirit and scope of the invention.