Title:
Convex profile rot preventer
Kind Code:
A1


Abstract:
A wood rot preventer for use between two intersecting portions of lumber, and having a preventer for attachment over the upper edge of a lower portion of lumber, the preventer having a web overlying the upper edge of the lumber, and in some cases having side walls, an upper surface of the web having convex profile with a central apex and sloping side portions forming surfaces extending outwardly on each side of the apex. In one embodiment the preventer has continuously curved side edges extending outwardly from the edges of the lumber to a width greater than the width of the lumber to carry moisture away from the lumber and allow it to drip downwardly. In another embodiment the preventer may have side walls extending down partially over each side of the piece of lumber. Also disclosed is a coil of an extended length of the wood rot preventer.



Inventors:
Shaw, John G. (Newcastle, CA)
Application Number:
10/282299
Publication Date:
04/29/2004
Filing Date:
10/29/2002
Assignee:
SHAW JOHN G.
Primary Class:
Other Classes:
52/483.1, 52/716.2
International Classes:
E04B5/12; E04F15/04; E04B1/26; E04F19/02; (IPC1-7): E04D13/00; E04B2/30
View Patent Images:
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Primary Examiner:
HORTON, YVONNE MICHELE
Attorney, Agent or Firm:
John G Shaw (Newcastle, ON, CA)
Claims:

What is claimed is



1. A wood rot preventer of elongated channel shape for attachment over the upper edge of a lower portion of lumber, for use between two intersecting portions of lumber, namely an upper portion of lumber and a lower portion of lumber having an upper edge, and comprising; a web for overlying the upper edge of the lower portion of lumber; side walls for extending partially downward from said web along either side of the lower portion of lumber; an upper surface of said web defining an upper profile of convex shape defining a central apex, and two side portions extending from said central apex, said side portions having upper surfaces which slope outwardly and downwardly from said central apex, thereby promoting drainage of moisture outwardly and downwardly and permitting airflow to take place along said two side portions of said web and said upper portion of lumber; and said side walls defining inner surfaces for contacting the sides of said lower portion of lumber.

2. A wood rot preventer as claimed in claim 1 and including ridges formed along the underside of the web for contacting the upper edge of the lower portion of lumber, the ridges defining load bearing surfaces for transmitting the load of the upper portions of lumber to the upper edge of the lower portion of lumber, whilst at the same time defining air flow passages between the ridges to permit air flow along the upper edge of the lower portion of lumber.

3. A wood rot preventer as claimed in claim 1 wherein said preventer is formed of resilient thermoplastic material and is dimensioned whereby said side walls make a snug friction fit over the upper edge of the lower portion of lumber.

4. A wood rot preventer as claimed in claim 3 wherein said preventer is formed by extrusion techniques so that said preventers can be made in extended lengths, at low cost.

5. A wood rot preventer as claimed in claim 1 wherein said side walls are formed with a gripper rib on each side, the ribs having a pointed or hook shape so as to partially bite into the sides of the lumber.

6. A wood rot preventer as claimed in claim 5 wherein said side walls have drip edges which are spaced away from contact with the wood thereby causing moisture running down the exterior of the side walls to drip off the side walls clear of the sides of the lumber.

7. A wood rot preventer as claimed in claim in claim 1 wherein the inner surface of the web of the preventer is formed with parallel grooves, defining load bearing surfaces between the grooves.

8. A wood rot preventer for use between two intersecting portions of lumber, namely an upper portion of lumber and a lower portion of lumber, and comprising; a generally elongated web strip, having upper and under sides; said upper side defining a an apex and a continuously curved convex profile, with a median load bearing surface along said apex; two side portions defining curved surfaces extending downwardly away from said apex, for draining moisture outwardly; said underside of said preventer having load bearing means for transferring the load of the upper portion of lumber to the lower portion of lumber; a plurality of air flow grooves formed in said planar under surface to allow air circulation along the upper surface of the edge of the lower portion of lumber; said under surface lying in a generally flat plane whereby said preventer can be rolled into a coil, for application to extended lengths of lumber in continuous strips; said side edge strips of the rot preventer extending outwardly of the width of said portion of lumber to a width, greater than the actual width of the portion of lumber so as to provide for a drip edge outwardly of the side surfaces of the portion of lumber, allowing moisture to drip down without penetrating the lumber side surfaces.

9. A wood rot preventer for use between two intersecting portions of lumber, namely an upper portion of lumber and a lower portion of lumber, said lower portion having a predetermined width and comprising; planar strip, having upper and under sides; said upper side having a median load bearing surface parallel with the plane of the upper surface of said lower portion of lumber; said upper side defining an apex and a continuously curved convex profile, with a median load bearing surface along said apex; two side portions defining convex curved surfaces extending downwardly away from said apex, for draining moisture outwardly; load bearing ridges formed on said under side for transferring load to said lower portion of lumber; a plurality of air flow grooves formed between said load bearing ridges to allow air circulation along the upper surface of the edge of the lower portion of lumber; and, said side edge strips of said planar rot preventer extending outwardly of the width of said portion of lumber to a width greater than the actual width of the portion of lumber so as to provide for a drip edge outwardly of the side surfaces of the portion of lumber, allowing moisture to drip down without penetrating the lumber side surfaces.

10. A coiled strip formed of a wood rot preventer for use between two intersecting portions of lumber, namely an upper portion of lumber and a lower portion of lumber, and comprising; a generally elongated web strip, having upper and under sides; said upper side defining a an apex and a continuously curved convex profile, with a median load bearing surface along said apex; two side portions defining curved surfaces extending downwardly away from said apex, for draining moisture outwardly; said underside of said preventer having load bearing means for transferring the load of the upper portion of lumber to the lower portion of lumber; a plurality of air flow grooves formed in said planar under surface to allow air circulation along the upper surface of the edge of the lower portion of lumber; said under surface lying in a generally flat plane whereby said preventer can be rolled into said coil, and from which said preventer can be unwound for application to extended lengths of lumber in continuous strips; said side edge strips of the rot preventer extending outwardly of the width of said portion of lumber to a width, greater than the actual width of the portion of lumber so as to provide for a drip edge outwardly of the side surfaces of the portion of lumber, allowing moisture to drip down without penetrating the lumber side surfaces.

Description:

FIELD OF THE INVENTION

[0001] The invention relates to a rot preventer for use with joists, trusses, decks and any other wood structures liable to accumulate moisture, in which the rot preventer has two sloping upper surfaces meeting at a peak, for drainage.

BACKGROUND OF THE INVENTION

[0002] Moisture accumulation on and around lumber is known to cause wood rot and the only cure is simply to replace the rotted wood with fresh wood. The problem is most acute in exterior wooden structures, in particular wooden decks, balconies, and other wooden structures which are erected out of doors and are exposed to frequent soaking moisture accumulations. Rain, snow melt, and simply humidity can all cause accumulations of moisture on and in such structures, leading to rotting of the wood. The problem is further added to by the lack of air circulation between the two portions of lumber where they intersect.

[0003] The problem can also occur however in interior wooden structures, particularly in roof joists and basement joists. The problem occurs most often where two portions of lumber are located and fastened across one another with one overlying and crossing the other, although any lumber exposed to moisture which does not readily run off will eventually rot.

[0004] Thus in exterior decks and balconies, and stairs or steps, joists are usually erected at appropriate spacings, typically about twelve to sixteen inches apart. Decking lumber is then nailed across the joists typically, although not exclusively, at right angles. The decking lumber is usually spaced apart by not more than one quarter of an inch. This allows rain and snow melt to drip down off the deck action of the wood drawing the moisture upward. The more the upper exposed surface of the deck dries out, the greater will be the wick action of wood drawing moisture upward from the underside of the deck lumber.

[0005] This problem is aggravated by the area of contact between each portion of deck lumber and the underlying joists. Most deck lumber has a nominal width of four inches, and the joists, which are on edge, in most cases have a nominal width of two inches.

[0006] The area of contact at each crossing or intersection is thus nominally two inches by four inches making a total nominal contact area of eight square inches. This considerable area at each crossing thus provides a substantial area for accumulations of moisture, and also the prevention of air circulation.

[0007] The problem of moisture accumulation can also occur to a lesser extent on the upper edges of the joists where they are exposed in the gaps between the deck lumber. This is caused by the fact that it is desirable from the aspect of the users of the deck to place the portions of deck lumber as close as possible to one another, allowing only a minimum of spacing between the deck lumber portions for water drainage. Any noticeable spacing between the portions of deck lumber may damage shoes, and may permit small objects to fall through and be lost underneath the deck. The spacing is therefor minimised.

[0008] Run off moisture can accumulate on the small lengths of joists exposed between the portions of deck lumber, and due to the very small spacing, in most cases, it will eventually start to cause rot in these locations also. In addition moisture falling in these areas on the exposed lower timbers will tend to be drawn in under lumber through the gaps between adjacent portions of deck lumber and allows the surface of the deck lumber to dry out. However where the deck lumber intersects or crosses over the joists, moisture will inevitably penetrate between the deck lumber and the joists. This moisture is then trapped and cannot run off in the usual way. Further, due to the contact between the two portions of deck and joist lumber no air circulation can take place and this delays or entirely prevents the drying of the two portions of lumber at each intersection. The joist is then simply soaking up the moisture and this will cause rotting of the joist beneath the overlying deck lumber. In some cases the accumulation of moisture in these locations can also cause rotting of the underside of the deck lumber as well as rotting of the joists. Even where the two portions of lumber are closely bonded together, capillary action of moisture will cause moisture to seep in between them. This moisture is then trapped and remains there long after the upper or exposed surfaces of the lumber have dried out. The problem is somewhat aggravated by the nature of the nails or other fastenings, fastening the deck lumber to the joists. When nails pass through the deck lumber and penetrate the top of the joists the nails cause depressions in the joists around the nails. Any moisture entering between the two portions of lumber or drawn in by capillary action is then trapped between the deck lumber and the joists will thus tend to collect in these depressions and will gradually seep down into the joists around the nails. The same moisture can be drawn upwardly into the underside of the deck lumber, again by capillary action similar to the action of a wick. The more the upper surface of the deck lumber dries out, the greater will be the wick the adjacent overlying upper timbers a cause rot in these areas. Also any vegetation lying on the joists or growing between them will hold moisture and increase the speed of decay.

[0009] Clearly it is desirable to avoid the accumulations of moisture on the joists and under the deck lumber, and to provide a simple means for causing run off of rain and snow melt, in particular, from the deck, without accumulating on the joists. It is also advantageous if the contact area between the upper deck portions and lower joist portions of lumber can be reduced. This will reduce the area available for moisture accumulation, and thus reduce the quantity of moisture which can be trapped at any given location. This will greatly speed up the drying out process.

[0010] Further it is desirable to provide for air circulation through the intersections so as to again speed up the drying out process. The same factors are true for many outdoor structures where lumber is exposed to weathering and moisture, and for certain indoor structures as well. It is also desirable to provide some means for preventing migration of moisture from the lower timbers where they are exposed to falling moisture back under the adjacent overlying timbers.

[0011] At first sight it would appear to be fairly straightforward to provide a cap of some moisture proof material to lay over the upper edges of the joists. In the past there has been a proposal to provide a solution to a somewhat related problem. For example U.S. Pat. No. 559,194, title, Means For Protecting Foundation Timbers from Rot, issued in 1896, proposed dealing with a problem caused by moisture ascending up building foundation piles, due to capillary action, which would then damage the underside of the foundation timbers laid on top of the piles. This is the opposite of downward drainage.

[0012] The solution proposed was to provide metal caps which were to be nailed to the underside of the timbers. These caps would then overlie the tops of the building piles, and prevent moisture from ascending up the piles and rotting the foundation timbers by moisture entering from below. However this proposal did not deal with the problem of downward flow of moisture accumulating on the under surface of the lumber. In fact it increased this problem because the metal caps had to have an area greater than the area of the tops of the foundation piles. This would then provide a greater area of moisture entrapment on the underside of the timbers or joists.

[0013] A greatly improved for of rot preventer is shown in U.S. Pat. No. 6,108,992 issued Aug. 29, 2002, inventor John G Shaw, title Rot Protector.

[0014] This device was a plastic channel which could be applied to the upper edges of the joists. It had a planar center portion for bearing the load of the deck lumber laid on top of the joists, and angled side surfaces for drainage. While this device was successful from many aspects, the existence of the planar center section could tend to leave a small area for accumulation of moisture, between the deck lumber and the center portion of the channel. Under conditions of extreme continued soaking such as during the spring snow melt, for example, or even during periods of continuous heavy rainfall, of high humidity, moisture could collect there.

[0015] It is considered therefor that for such conditions, at least, provision may be made for even greater drainage of moisture, so that under extreme conditions, moisture will continue to drain away from the area between the joists and the deck lumber, in the case of outdoor structures.

[0016] It has now been found that the requirement for load bearing, at each intersection of each piece of decking lumber with each piece of joist or support lumber, was much less significant than was previously understood. Each piece of decking lumber will usually be supported by a joist every 12 to 16 inches, along its length, in normal construction. The typical load on a deck will be persons, usually located spaced around the deck. Consequently the loading on any one piece of decking lumber, at any one joist intersection will be relatively slight.

[0017] It has therefor been determined that the life of the deck can be even further prolonged by reducing the contact area between the underside of the deck lumber, and the protective strip overlying the joists, to a simple line contact There is also on the market a form of synthetic decking, formed of plastic compounded to have the appearance of wood. This decking resembles decking lumber and is used in much the same way. It is most usually applied by fastening it onto the upper edges of conventional wooden joists. While this decking does not rot from moisture, it does not solve the problem of rotting of the wooden joists.

[0018] The invention is deemed to be useful in conjunction with this type of plastic decking. Where the term “lumber” is used herein, it is deemed to include lumber substitutes, such as plastic decking and the like.

BRIEF SUMMARY OF THE INVENTION

[0019] With a view therefor to providing a solution caused by entrapment of moisture between two intersecting portions of lumber the invention provides, in one embodiment, an elongated rot preventer strip for attachment over the upper edge of the lower portion of lumber, the rot preventer having a web for overlying the upper edge of the lower portion of lumber, in which the web has an upper surface defining a profile which is continuously sloped in opposite directions having an peak along its center line, and side sections which slope continuously downwardly on either side of the peak, and thus reducing the area of contact with the upper portion of lumber so that contact is confined to the line of the peak of the strip, and permitting airflow to take place along the spaces between the two side sections of the strip and the under side of the upper portion of lumber. Preferably such a strip will have channel side walls extending downwardly from the side sections around both sides of the underlying lumber.

[0020] The invention further provides ridges formed along the underside of the web for contacting the upper edge of the portion of lumber, the ridges defining contact load bearing surfaces for transmitting the load of the upper portion of lumber to the upper edge of the lower portion of lumber, whilst at the same time defining air flow passages between the ridges to permit air flow along the upper edges of the lower portion of lumber.

[0021] The preventer is of resilient thermoplastic material so that it can make a snug friction fit over the upper edge of the portion of lumber. Preferably it is formed by extrusion techniques so that the preventers can be made in extended lengths, at low cost. This enables the end user to purchase sufficient lengths of the preventers to extend along and cover the entire upper edges of all the lower portions of lumber, at minimum cost.

[0022] In one form the preventer will have side walls be formed with a rib on each side. The ribs may have a pointed or hook shape so as to partially bite into the sides of the lumber. In this form the side walls of the preventer are spaced away from the sides of the lumber and have drip edges which are spaced away from contact with the wood thereby causing moisture running down the exterior of the side walls to drip off the side walls clear of the sides of the lumber.

[0023] In another form the inner surface of the web of the preventer would simply be formed with parallel grooves, defining load bearing surfaces between the grooves.

[0024] In one preferred form the side sections will have an upper profile which is curved.

[0025] In a simplified embodiment of the invention the rot preventer make take the form of a generally planar strip, having upper and under sides, the upper side having a median load bearing peak parallel with the plane of the upper surface of the joist, and having two sloping side sections extending downwardly away from the peak, for shedding water outwardly, and the underside of the strip would have a generally planar load bearing surface for transferring the deck load to the joist, and there would be a plurality of air flow grooves formed either in the planar load bearing surface, or between load bearing ridges, to allow air circulation along the upper surface of the edge of the joist. In this embodiment there would be no preventer side walls as such, but instead given a joist of a predetermined width, say nominally two inches, usually meaning about one and seven eighths inches in fact, the side edges of the joist rot preventer would extend outwardly of the joist to a width, greater than the actual width of the joist, so as to provide for a drip edge outwardly of the side surfaces of the joist, allowing moisture to drip down without penetrating the joist side surfaces.

[0026] This preventer can be rolled up into coils of great length, having advantages for shipping storage, and for application to lengths of joists without a break.

[0027] The preventer is of resilient thermoplastic material, preferably being formed by extrusion techniques so that it can be made in extended lengths at low cost. This enables to purchaser to obtain sufficient lengths of the preventers to cover all the upper edges of all joists deemed to require protection.

[0028] The various features of novelty which characterize the invention are pointed out with more particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

IN THE DRAWINGS

[0029] FIG. 1 is a sectional illustration of a typical deck or exterior wood structure, illustrating the invention on the upper edges of underlying lumber in this case, joists;

[0030] FIG. 2 is a perspective of another embodiment of preventer;

[0031] FIG. 3 is a section of another form of the invention;

[0032] FIG. 5 is a perspective of FIG. 3

[0033] FIG. 6 is a section of another form of preventer;

[0034] FIG. 7 is a section of another form of preventer, suitable for forming into a coil;

[0035] FIG. 8 shows the embodiment of FIG. 7 applied to a piece of lumber;

[0036] FIG. 9 is a side elevation of a coiled strip of preventer, such as that shown in FIG. 7; and,

[0037] FIG. 10 is a section of FIG. 9.

DESCRIPTION OF A SPECIFIC EMBODIMENT

[0038] Referring to FIG. 1, it will be seen that the invention is there illustrated in use in a typical outdoor wood structure, in this case a wooden deck indicated generally a D. Typically such structures will have lower portions of lumber known as joists and indicated as J, set on edge to support the load on the deck. The joists will, in most cases be supported at each end, and possibly at intervening locations, by vertical supports, or in some cases foundations, (not shown). However in many cases such decks are simply formed by outward extensions of joists located within a home or building, in which case they may be simply cantilevered, and are free of any support at their outboard ends, or in some cases may be supported on columns. All of this is very well known, but is repeated here so as to give the fullest appreciation of the advantages of the invention.

[0039] As explained above the invention is not restricted to wooden decking but is applicable to plastic decking and other forms of decking materials. All of such decking materials may be collectively considered herein as “decking lumber”, or simply “lumber” as the context requires.

[0040] On the joists the actual decking lumber indicated as L is laid crosswise and is typically secured to the joists by fastenings F which may be such as nails or screws or the like. The decking L is usually although by no means always at right angles to the joists. Consequently where each portion of decking intersects a joist there exists an area of close contact which is a simple multiple of the joist thickness and the decking width, and the angle of the decking if it is other than a right angle. The joists typically having a nominal two inch thickness, but in some cases 4×4 or more joists are used. The decking typically will be of two by four lumber, although in some cases it may be two by six. Thus the contact area at each intersection will be eight square inches, nominal, or even twelve square inches nominal, or more. This provides a substantial area, at each intersection, which will be increased in the case of non-right angular structures, where moisture can collect and be absorbed and where there is no air circulation either around the upper edge of the joist, or around the underside of the decking.

[0041] It is well known that moisture collecting in these areas leads to rotting of the joists and also of the decking, due to moisture which is collected and absorbed and trapped and due to lack of air circulation.

[0042] This can cause a deck to rot and require complete replacement at intervals in the life of a house or other building. This may be accepted in many cases simply as a cost of upkeep, but clearly users would prefer not to have this burden. However in the case of cantilever decks the problem is much more serious. The joists supporting a cantilever deck are simply extensions of floor joist from the interior of a building. Once those cantilever joists start to rot, the deck is totally unsupported and is unusable. However, in addition to this the rot will usually travel along the joists back into the interior of a house, and endanger the entire floor structure of what appears to be an otherwise sound building. Purchasers of this type of building, usually vacation homes, often do not realise the hazards of such cantilevered decks. Usually they purchase the vacation homes as a package from a manufacturer, and the problem does not appear until they attempt to sell the building, which may be ten or twenty years later. The new purchaser may have the structure inspected and it is only then that the seriousness of the problem becomes evident.

[0043] Clearly therefor there is a serious problem of wood rot with exterior wood structures of this type. The problem may also arise in interior joists and flooring, or for that matter roofing, especially in damp or semi tropical climates.

[0044] In accordance with the invention there is provide a rot preventer which separates the two portions of lumber, typically the joists J from the decking L, and which reduces moisture accumulation on the joists, by allowing freer drainage of moisture, and freer air flow for drying out. The preventer also reduces the contact area on the underside of the decking thereby reducing the area for moisture wicking upwards into the deck. This promotes free air circulation around a greater area of the underside of the decking L, leading to faster drying of the underside of the deck, and in the spacing between the joists t and the decking.

[0045] As illustrated in FIG. 1, the rot preventer is there illustrated in the form of a preventer indicated generally as 10. The preventer has a web 12 defining an upper surface 14 which is of convex arcuate shape for the load bearing surface. It has a central peak or apex 16 and convexly curved side sections 18-18 along either side of the apex. The apex 16 is designed to contact the underside of the decking L and transfer the load of the deck to the joists J. The apex 16 hence forms a minimum contact area with the underside of the decking L.

[0046] The side sections 18-18 are formed with profiles which are continuously curved outwardly and downwardly from the apex 16. Moisture can therefor flow off the upper surface readily, and at the same time promotes better air circulation between the decking and the joists. Thus the moisture is both drained and dried off more rapidly.

[0047] On either side of the web 12, in this embodiment, there are integrally formed preventer side walls 20-20. As mentioned the preventer is preferably formed by extrusion techniques, with the web and side walls integral with one another. This permits manufacture of the preventers in considerable lengths, and the purchaser can simply cut them to fit his project. Conceivably other forms of fabrication might be used in some cases. However the invention is not restricted solely to the integral form of fabrication as shown but is deemed to include any form of fabrication producing the inventive advantages. The lower edges of the side walls 20 are formed as outwardly extending drip lips 22-22. On the inward edges of the sie walls 20 there are formed gripper beads 24-24. These are designed to grip onto the upper edge of the lumber, and hold the rot preventer in place.

[0048] On the underside of the web 12 the surface is planar, giving a good load transfer contact with the lumber.

[0049] Another modification is shown in FIG. 2. In this case the side surfaces 18-18 of web 12 are planar slopes, sloping down away from a peak 16.

[0050] The embodiment of FIGS. 3 and 4 is basically similar to FIG. 1, with the exception that the preventer 30 has a web 32 with a central ridge 34 for contacting the lumber. On either side of the rdige, the web is clear of the lumber allowing for air circulation.

[0051] FIG. 5 shows another embodiment of preventer 40, in which the web 42 is thinner than FIGS. 1 and 3. The side walls 44 are also thinner than FIG. 1, and are designed to flex more readily to be press fitted over the lumber.

[0052] The drip lip 46 is curved in profile and extends outwardly.

[0053] Wall 44 curves inwardly to grip the lumber.

[0054] FIG. 6 shows another embodiment of preventer 50, in which the upper surface profile of the web 52 is convexly curved, and the side walls 54 are spaced outwardly from the lumber. Gripper beads 56 grip the lumber.

[0055] On the undersize of web 52 a series of ridges and grooves 58 are formed.

[0056] These may be formed as generally rectangular shaped protrusions from web 12 or may be defined simply by grooves in the underside of the web. The term “ridge” as used herein is deemed to be generic to all such formations and is without limitation.

[0057] The ridges 58-58 contact the upper surface of the edge of joist J and transfer the load of the decking D to such joists. Between such ridges there are defined air circulation grooves for permitting air circulation along the interior of web between itself and joist Joist

[0058] FIGS. 7 and 8 show another embodiment which might serve adequately in many cases. In this case the preventer 60 has a web 62 having an upper convexly curved surface defining a peak or apex, and convexly curved side edges 64 on each side, as before. The undersurface of the web is designed to transfer load to the joists, and may be formed with a planar load bearing surface with air grooves 66 formed therein. Although not shown it will be understood that it could equally will be formed with load bearing ridges.

[0059] However in this embodiment there are no preventer side walls as such. Instead the side edges 64 are extended outwardly to form drip edges 68. These are spaced outwardly from the width of the joist. In this way water will run down the convex curved surfaces of the side edges 64 and drip down off the drip edges 68, failing clear of the sides of the joist. Thus where the joist has a predetermined width w, the drip edges define a width W greater than w. Preferably this excess is in the region of 10% to 20% greater to ensure water dripping clear of the joist.

[0060] This form of preventer is advantageous in that it enables the preventer to be extruded in great lengths and then rolled up into coils.

[0061] When this type of preventer is applied to the joists, it can simply be unrolled to the length required to cover the whole length of the joist, without a break. Such a coiled preventer 60 is shown as coil 70 in FIGS. 9 and 10.

[0062] The foregoing is a description of a preferred embodiment of the invention which is given here by way of example only. The invention is not to be taken as limited to any of the specific features as described, but comprehends all such variations thereof as come within the scope of the appended claims.





 
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