GB2496232A - A low slope roof edge membrane retaining and sealing system - Google Patents

Abstract

The invention relates to a low slope roof edge system comprising two assemblies for retaining and sealing a roofing membrane 1. For roof edges with guttering 2 the invention provides a two part retaining drip edge assembly 5 of which the upper horizontally recessed retainer housing channel 30 of the primary part 6, mountable behind the overlapping membrane 1, envelopes, supports and retains the entire membrane retaining part 7 which uniformly secures and returns the membrane 1 to the outer face and lower flange 35. For roof edges without guttering 4 the invention provides a two part cooperatively dynamic interlocking opposing hook upstand assembly 8 for raising and retaining the membrane 1, comprising an inner retainer part 9, mountable to the roof edge under the membrane 1 and outer fascia part 10, mountable to the retainer 9 over the membrane 1 thereby raising, sealing and anchoring it uniformly and securely.

Description

Description: A Low slope Roof Edge Membrane Retaining & Sealing System This invention concerns a low slope roof edge system comprising two assemblies both of two parts for mechanically retaining and sealing a roofing membrane to a roof fixture.

Background:

Traditional upstand edge systems for roof edges without guttering in the UK, depend on adhesives bonding roofing materials such as single ply membranes, particularly EPDM rubber, to and over timber upstands then cladding them with an inverted L' shaped steel elongate fascia profile over the roof edge, such that if membranes contract they may peel away from the vertical aspect of the upstand becoming raised above the height of the roof substrate or decking, making them susceptible to condensation forming underneath as well as making them more vulnerable to wind uplift vortices and subsequent dangerous billowing which can lead to total system failure. More recent upstand systems in the UK involve overlapping the edge of the roof with the membrane and clamping it down with either PVC section or blown PVCu extruded singular flexible upstand profiles and employing a plurality of side fixings to retain them, providing an inherently non-uniform frictional retention to the roofing material, being strongest where each fixing is installed. The upstand edge clamping systems developed in the USA, whereby the membrane is mechanically clamped to a roof edge underneath a raised inferior retaining profile which is capped with a superior fascia profile, provide adequate retaining friction because they use metal components of specified engineering strength. With the exception of the US upstand system used as described, other inventions and common place roofing practices do not generally secure membranes with uniform anchorage by themselves as effectively as strong winds and membrane contraction can require. The waterproofing integrity and stability of some roofing systems can therefore be compromised due to insufficient and inconsistent mechanical retaining strength.

With the exception of the traditional timber upstand system as described all other upstand systems require additional labour and waterproofing measures such as mastic, compressed foam, vulcanised flashing tapes or heat welded flashings, in order to create a seal preventing standing water ingression at upstand edges. Compressed foam is particularly likely to fail to retain standing water especially on an uneven roof creating inconsistent compression which may lead to streaks of discoloured standing water staining the outer fascia of the building as well as the build up of unsightly lichen. The waterproofing integrity of some roofing upstand systems can therefore be compromised or significantly more expensive and inefficient to install, by the main body of the roofing material not covering the vertical aspect of an upstand structure.

Wind uplift creating negative pressure at the perimeter of a roof is the most common cause of roof edge assemblies being torn away and subsequent roof failure during storms. The 2 part US upstand perimeter clamping assemblies comprise an overlapping spring-like clip-on fascia profile attached over a corresponding cleat or retaining profile. They rely purely on shear strength resisting deformation to remain clipped on but also require flexibility of the upper extremity of the fascia part in order to depress it vertically to allow the fascia's lower extremity to overlap the lower extremity of the cleat or inferior part, then the material's memory raising the fascia to engage them. The very same engineered flexibility allows the deformation which is always the cause of assembly separation and failure of these systems under tension. As a result they have to be manufactured from metals with specified engineering tolerances to allow for this inherent weakness in the design.

Furthermore, although the original versions of the US systems did allow for the membrane to be raised between the two part assemblies to create a seal, the propensity for the flexibility described to lead to failure was yet further exacerbated by lateral and particularly diagonal upward tension applied to the membrane being referred solely to the weakest outer extremity of the outer fascia part which meant that the very membrane being retained would be responsible for unlocking the engaging clipping mechanism and before doing so entirely would typically delaminate or peel from the substrate as it followed the raised relief of the inner retaining part. As a result approved versions employ the installation technique herein described to clamp the membrane to the substrate beneath the inner retaining part and additional waterproofing measures are added accordingly because the system itself does not seal the body of the membrane while securely retaining it. The waterproofing integrity and stability of some roofing upstand assemblies can therefore be compromised by the flexibility required for assembly and flaws in their means of retaining the membrane.

Another problem with all other upstand edge' systems except traditional timber and some US systems, because their steel can be fixed from above to the substrate vertically, is that they are solely fixed from the side edge of the roof so if extra insulation has been retrofitted to an existing roof structure then the additional height comprising rigid foam would require that to provide purchase for side fixings either extra timber cladding be added to the side, or more commonly the existing fascia / cladding arrangement be replaced entirely to give fixing purchase, adding more material and labour costs.

Traditional low slope gutter or drip edg& systems employ a steel retaining profile over the membrane which is usually attached to the roof edge with fixings directly through the membrane allowing water to ingress at these points and often damage the immediately adjacent timber or areas of substrate leading to roof failure. More recent systems comprise two part assemblies made of either PVC or blown PVCu extruded flexible profiles which trap the membrane. The extruded PVC assembly is known to disengage on occasion because of expansion and contraction of the material when employed in the manner prescribed by the manufacturer. Furthermore it requires that the installer pulls the outer retaining part of the assembly upwards to push the membrane under the extended upper vertical lip of the inner part, mounted to the side of the roof, then simultaneously maintain that position while striking the outer face of the retaining part at the corresponding height of its lower male member pushing it into the lower female recess of the inner part thus trapping the membrane above, a process which can prove both ergonomically tiring and mechanically awkward. The membrane must also be cut at precisely the right length before mounting the retaining part or the locking lower male and female parts cannot engage. The blown PVCu assembly allows water to ingress between the outer retaining part and the membrane unless mastic is applied across the join, as well as retaining it with non-uniform friction where the fixings are employed. The system used universally in the USA provides that the membrane is sealed by firstly clamping the main body of the membrane under a steel drip profile then flashing it to the profile covering the fixing punctures but therefore requiring more material and labour whilst creating a water checking lip which can cause less aesthetically pleasing pooling issues.

Another problem with all other drip edge' systems, with the exceptions of the traditional and US systems described, because the steel can be fixed vertically to the substrate from above, is that they are solely fixed from the side edge of the roof, so if extra insulation has been retrofitted to an existing roof structure then the additional height comprising rigid foam would require that to provide purchase for side fixings, either extra timber cladding be added to the side, or more commonly the existing fascia I cladding arrangement be replaced entirely to give fixing purchase, adding more material and labour costs.

Statement of Invention:

According to the present invention there is provided a two part, elongate cooperatively dynamic interlocking opposing hook upstand assembly comprising an inner retaining part mountable to the roof edge and an outer fascia part mountable to the retainer over the membrane by engaging their interlocking opposing hooks. The invention solves the aforementioned issues because; being rotationally engaged it requires no flexibility to interlock which would enable it to be unlocked through an inherently flexible aspect. It retains the membrane between both parts with uniform friction whilst raising and therefore sealing the upstand against ingress of standing water without the use of additional waterproofing measures. The upper internal geometry of the cooperatively dynamic interlocking opposing hook-like structures is designed to actively increase friction on the membrane and depress the outer fascia part and material downwards when lateral tension is applied to the material, further improving the retaining properties and preventing uplift or peeling therein. The lower cooperatively interlocking opposing hooks resist lateral separating force primarily with material tensile strength and can therefore withstand exponentially greater lateral tension than any system relying purely on shear strength to remain interlocked. The assembly does not strictly require fixings on the outer fascia part making it ostensibly of a hidden-fixing aspect but more economical versions may employ appropriate fixings instead of the lower opposing hooks to maintain the vertical, locked aspect of the outer fascia. The stability of the assembly is such that it will remain engaged under lateral tension on the membrane even without fixing the outer fascia member to the roof though this is not recommended it demonstrates the uncompromising integrity of the design. The invention can overcome uneven roof edges in two ways; the inner retaining part of the assembly is fixed to the side of the roof edge not the substrate or deck, so the fascia member will sit straight and the roofing material is raised and sealed regardless of the roof's relief. Alternatively the inner retainer part can be provided with the vertical fixing plane as a horizontal fixing plane to be fixed to the substrate vertically thereby sacrificing the lower hook structure. This variation allows that the inner retainer part follows the contour of the uneven roof but that the outer fascia part remains straight whilst interlocked due to the inbuilt travel between their upper internal opposing hooks again regardless of the roof's relief. Furthermore this alternate version addresses the last problem raised with other upstand edge systems whereby retrofitting insulation requires extra side cladding to provide purchase for horizontal fixings. The horizontal fixing plane of this version of the retaining part can be fixed to the substrate from above the insulation with longer fixings or as additional insulation is often over-boarded with an extra layer of decking to give structural strength, it can be fastened to this, then a plurality of appropriate fixings used to fix the fascia part to the extra decking edge or through the fascia's lower extremity into the substrate below the insulation if the depth allows. One further solution to this issue which preserves the lower hook of the inner retaining part is a version which is outwardly the same but with a lower inwardly extended horizontal fixing plane which is mountable directly to the substrate or deck below the insulation, naturally this version requires consideration for the depth of insulation to provide the correct height to the upper hook-like structure above the deck. The upstand assembly may be enhanced to encapsulate a parapet wall with an inner retaining part which is mountable vertically to the substrate of the roof through a horizontal fixing plane of the inner retainer part and a second inner retaining part with a lower hook fixed to the outside of the wall at the correspondent height for the larger outer fascia part to engage, thereby serving as a membrane retaining and sealing coping assembly. The retaining part expressed with a horizontal fixing plane may also be installed along a wall edge and a fascia part which terminates on the upper horizontal plane may run into a chased wall joint then sealed, offering a mechanically retaining and sealing wall trim system.

According to the present invention there is also provided a two part, geometrically interdependent elongate retaining drip edge assembly comprising a primary part with an upper horizontally recessed retainer housing channel with a lower leaf deflecting drip edge flange, mountable to the roof edge through the channel's vertical wall and a reciprocal membrane retaining part. The invention solves the aforementioned issues because; it does not require an ergonomically difficult simultaneous raising, maintaining and engaging process as the overlapping membrane is conveniently tucked into the horizontally recessed retainer housing channel prior to inserting the reciprocal membrane retaining part over it. This is simply pushed in by hand starting at one end and working along, where it is cooperatively supported by the lower extended channel flange and retained by the outwardly and downwardly diagonal retaining flange of the flexible upper arm. The membrane is securely retained and returned to the outer face where it is easily and accurately trimmed effectively forming its own gasket.

It exerts a uniform frictional retention on the membrane and cannot be disengaged by the expansion or contraction because of the use of a prescribed plurality of appropriate washered self drilling retaining fixings. Water cannot ingress back under the diagonal retaining flange of the flexible upper arm of the retainer housing channel or via the retaining fixings so it does not require any additional waterproofing or sealing measures. The assembly uses significantly less material than a two part system requiring the interlocking of a lower male and female arrangement cooperating with an upper vertical retaining lip feature.

Where retrofitted insulation would ordinarily require extra cladding to the roof edge to provide purchase for horizontal fixings the invention can be provided with a horizontally extended upper flange so it can be fixed to the substrate vertically through the insulation with longer fixings or as additional insulation is often over-boarded with decking) it can be affixed to this. The retaining part can then be stitched to the first part securing the membrane therein. One further solution to this issue is a version with a lower extended horizontal fixing plane which is mountable directly to the substrate or deck below the insulation, naturally this version requires consideration for the depth of insulation to provide the correct height and position of the horizontally recessed retainer housing channel of the fascia part. Yet another solution is to provide the assembly in its standard form and mount it to the lower substrate and simply extend the membrane downwards to reach. In such instances the inventor would prescribe installing the insulation proud of the existing roof and flush with the outer edge of the diagonal retaining flange so the material would descend neatly and vertically to it.

The inventor prescribes that preferably both assemblies be made from mechanically folded or roll-formed metal but may also be made with extruded aluminium or rigid polymer such as PVC. Embodiments of the invention in metal may have any variety in the depths of assembly required whereas extrusions will be restricted to the dimensions of dies.

Substantial clip-on antennae mounting plates, snap-on stop ends, butt-strips and external and internal corners with overlapping flanges situated at both upper and lower extremities will be provided at correspondent dimensions to the outer fascia part of the cooperatively interlocking upstand edge assembly to maintain continuity in the assemblies and protect corner details of the roofing material. The drip edge assembly can be mitred at corners and tabs are to be cut to provide an overlapping seal which may be riveted or fastener stitched and where the drip edge is provided as an integral gutter, corners, stop ends and running outlet sections will overlap and seal in the direction of the water flow.

Both assemblies can be manufactured with the minimal amount of materials required to allow their fundamental locking and retaining functions as indeed they may be augmented to provide functional or aesthetic enhancements such as integral guttering to the drip edge or roof garden retaining features and that the materials maybe of any colour or finish such as gloss or matt, corrugated or flat, thereby allowing that a version of the system can be made to meet almost any budget, aesthetic or functional requirement.

The upstand assembly need not strictly require the use of additional fixings to the original mounting procedure though will benefit from them through stop ends, corners and butt-strips because few roofs are geometrically perfect and fixings give the opportunity to align where necessary. Once engaged the corners themselves provide an integral structural strength to the upstand assembly because once vertical each adjacent outer fascia part prevents the other from disengaging so providing mutual stability.

The installer may bring the roofing material between the lower interlocking opposing hooks thus sealing the membrane and providing a convenient edge along which to accurately trim the excess neatly. The inner retaining part of the cooperatively interlocking upstand edge assembly may be provided with a compressible foam tape at the lower inside extremity to provide a seal against the fixture and If the upstand assembly is made according to any alternative version which does not incorporate the lower opposing hooks to seal the membrane between them, the same tape may be applied to the inner and outer faces of the fascia and retainer parts respectively to provide an airtight seal thereof. The inventor recommends that if the lower opposing hooks have been sacrificed to accommodate any additional functionality as described that the outer fascia part will benefit from a small inward and upward lower return to add structural rigidity to the outer fascia part.

An example of the invention will be described by referring to the accompanying drawings: Fig 1. is a diagrammatic cross sectional perspective of a low slope roof fixture with an edge system for mechanically retaining and sealing a roofing membrane instaled according to the present invention. At the edge with guttering 2 the invention provides a retaining, sealing and leaf deflecting drip edge assembly 5 comprising a flexible upper horizontally recessed retainer housing channel 30 of the primary fascia partS, mountable behind the overlapping membrane 1, which receives the entire membrane retaining part 7 and returns the membrane ito the outer face and lower leaf deflecting drip edge 35. At the edge without guttering 4 the invention provides a two part cooperatively dynamic inter-locking opposing hook upstand assembly 8 for raising and retaining the membrane i, comprising an inner retainer part 9, mountable to the roof edge under the membrane i and outer fascia part iO, mountable to the retainer 9 over the membrane i thereby raising, sealing and anchoring it securely between them.

Fig 2. is a diagrammatic cross sectional perspective of the inner retaining part 9 of the two part cooperatively dynamic interlocking opposing hook upstand assembly comprising an elongate profile which at its upper extremity has a downward facing hook-like structure having a vertical strip ii suspended from a diagonal strip i2 upwardly inclined from a vertical substantially planar fixing strip i3 with an outwardly horizontal and downward facing hook i4 at its lower extremity.

Fig 3. is a diagrammatic cross sectional perspective of the outer fascia part 10 of the two part cooperatively dynamic interlocking opposing hook upstand assembly comprising and elongate profile which at its upper extremity has an upward facing hook-like structure having a steeply diagonal upward strip 19 supported by a vertical strip 20 which is suspended from a horizontal strip 21 extending from a vertical substantially planar fascia strip 22 with an inwardly horizontal and upward facing hook 23 at its lower extremity.

Fig 4. is a diagrammatic cross sectional perspective of the horizontal attitude of the outer fascia part 10 as it is introduced underneath the upper downward facing hook-like structure of the inner retaining part 9, prior to being rotated to engage the lower opposing hooks 14 and 23.

Figs. is a diagrammatic cross sectional perspective of the opposing upstand assembly engaged. The tight angle between strips 19 and 20, which allowed it to pass beneath strip 11, now gives strip 19 a taller aspect increasing the depth of engagement between the structures. The lower hook-like structures 14 and 23 have engaged stabilising and locking the assembly 8.

Fig 6. is a diagrammatic cross sectional perspective of a variation of the inner retaining part which is mountable vertically to the substrate of the roof through a horizontal fixing plane 39 of the inner retaining part rather than from the side.

Fig 7. is a diagrammatic cross sectional perspective of a variation of the inner retaining part which is mountable vertically to the substrate of the roof through a horizontal fixing plane 42 before the upper hook structure as well as from the side.

Fig 8. is a diagrammatic cross sectional perspective of a variation of the inner retaining part extended vertically above the roof edge with a right angled horizontal return 40 to the hook structure thereof in order to provide extra vertical load strength to the outer fascia part if it were required.

Fig 9. is a diagrammatic perspective of an external clip-on corner piece 25 for upstand assembly 8 to demonstrate the position of the upper and lower flanges relevant to all clip-on accessories.

Fig 10. is a diagrammatic cross sectional perspective of the primary fascia partS of the elongate retaining drip edge assembly comprising an outwardly and downwardly diagonal retaining flange 31 at the extremity of an upper horizontal flexible arm 29 supported at a right angle by a downwardly vertical strip 32 which suspends a lower right angled outwardly horizontal strip 33 to form a horizontally recessed retainer housing channel 30 of substantially rectangular aspect beneath which the outer fascia extends downwardly to the leaf deflecting drip edge 35.

Fig 11. is a diagrammatic cross sectional perspective of the retaining part 7 of the elongate retaining drip edge assembly comprising a flexible horizontal upper strip 36 and a flexible horizontal lower strip 37 both of which extend from a vertical outer fascia strip 38.

Fig 12. is a diagrammatic cross sectional perspective of the two part elongate retaining drip edge assembly S fully engaged to clearly demonstrate the geometrically reciprocal aspect of their interlocking whereby cooperatively supporting and retaining functions are fulfilled respectively by the flexible horizontal strip 33 and the diagonal upper retaining flange 31 of the horizontally recessed retainer housing channel 30. This diagram also shows a variation of the primary fascia part of the drip edge assembly with an integrated gutter 41.

Claims (1)

1. <claim-text>Claims 1 A two assembly low slope roof membrane enveloping, retaining and sealing system comprising an upstand assembly of two elongate parts having dynamically cooperative interlocking opposing hooks which proportionally and actively increase uniform retaining friction and depressive anchorage of a membrane when subjected to lateral tension while raising it to provide an immediate seal on an uninterrupted membrane body, and a two elongate part geometrically interdependent drip edge assembly having a primary upper singular horizontally recessed cooperatively supportive and retaining housing channel with a lower deflecting flange part and a reciprocal membrane retaining open sectional counterpart, which seal and uniformly retain a membrane exclusively and locally between them and jointly form a substantially planar fascia above the deflector.</claim-text> <claim-text>2 An upstand assembly according to claim 1 wherein when lateral force is applied to the membrane, the upper hook of the outer fascia part is actively drawn towards the upper hook of the retaining inner part by the membrane thereby proportionally increasing the retaining friction between them and therefore on the membrane itself.</claim-text> <claim-text>3 An upstand assembly according to claims land 2 wherein when lateral force is applied to the membrane, the upper hook of the outer fascia part is also actively forced downwardly as its diagonal plane travels against the vertical plane of the upper hook of the retaining inner part, thereby proportionally increasing the depressive anchoring and retaining friction directly on the membrane between the substrate and the outerfascia, preventing peeling or uplift and further stabilising the assembly.</claim-text> <claim-text>4 An upstand assembly according to claims ito 3 wherein an upward diagonal tension to the membrane clamped between both parts is shared cooperatively between them thereby resisting substantial force before an extent of deformation of both parts would result in disengagement and failure.</claim-text> <claim-text>S An upstand assembly according to claims 1 to 4 comprising a lower interlocking opposing hook-like arrangement which resists separating tension substantially with its opposing shanks and therefore the material's tensile strength or maximum stress it can withstand while being stretched before failure occurs.</claim-text> <claim-text>LAn upstand assembly according to claims ito 5 which may comprise an internal cooperative arrangement of one or more interlocking opposing hook-like structures providing active retaining friction and downward force or not against any angle of tension on a membrane or separating tension directly to the assembly and which may retain and! or raise a roofing material between them or not but fundamentally function and / or interlock in the same general cooperative way described by the present invention.</claim-text> <claim-text>7 An upstand assembly according to claims ito S which may imitate the form of or indeed be an overlapped parallel hook arrangement or may incorporate one or more additional features such as any extra elongate point Cs), hook (s), strip Cs) or angle Cs) but fundamentally function in the same fundamental cooperative way described by the present invention.</claim-text> <claim-text>SAn upstand assembly according to claims ito 7 which may augment the upper hook of the inner retaining part by returning it to the vertical plane to add strength to the assembly or any other prescribed enhancement which is based on the fundamental shape or functionality of the assembly herein described including but not exclusively retention and down force or merely maintaining the membrane at a given height by the same fundamental principles derived by the present invention regardless of any disguising adjustment to form.</claim-text> <claim-text>9 An upstand assembly according to claims ito S which may be prescribed to the instaHing party for clamping of any membrane directly below the inner retaining part requiring further waterproofing measures or not regardless of application.An upstand assembly according to claims ito 0 which may be manufactured with the shank of the upper hook-like structure of the inner retaining part extended on a horizontal plane across the substrate from the roof edge before raising and either immediately or via one or more bends, hooking downward to a point thereby allowing a closer proximity of a fixing from the vertical plane to reinforce its anchoring properties thereof whilst also providing means to fix through insulation to the substrate with longer fixings.ii An upstand assembly according to claims ito iO which may employ cooperatively interlocking opposing hook-like structures of any angle and at any relative angle that may be engaged through means of flexible deformation or hinge like enhancements of one or more parts to achieve the same fundamental principles of interlocking thereof.i2 An upstand assembly according to claims ito ii which may comprise an outer fascia part with an acutely or steeply angled throat to its upper or lower hook allowing it to slide through a tight aperture between the point of a hook of an inner retaining part and the substrate or roof edge to interlock with greater and deeper effectiveness by being taller once rotated and therefore providing better retaining friction to a membrane thereof.i3 An upstand assembly according to claims ito i2 which may be provided with a compressible foam tape strip to both the inside of the outer fascia part and the outer and inner sides of the inner retaining part to seal the membrane as an airtight system thereof.14 An upstand assembly according to claims i to i3 which allows for the membrane to be extended over the roof edge beyond the depth of the lower anchoring part whereby the lower interlocking opposing hook-like structures may clasp it therein providing yet more retention, tighter and airtight interlocking and a convenient guide for the installer to trim the material perfectly flush with the base of the system further reducing labour time.iS An assembly according to claims ito i4 to be provided with accessories such as corners, stop-ends, butt-strips and anchoring members for antennae or safety rails etc which may interlock by substantially overlapping the form of the outer fascia part engaging by means of extended lips or flanges where appropriate to provide a clipping arrangement such that a corner would provide a structurally stabilising function by mutually disallowing any diversion from the vertically engaged aspect of either adjacent outer fascia part and therefore remain locked thereof.iS An assembly according to claims ito is which may sacrifice the lower hooking arrangement in favour of a plurality of fixings to save materials yet still achieve the membrane raising, sealing and retaining function.17 A drip edge assembly according to claim i comprising two elongate geometrically interdependent and reciprocal parts being a primary horizontally recessed retaining housing channel part, which is mountable to the roof edge through the back wall of the channel, and a membrane retaining part which is enveloped on three sides and cooperatively supported and retained within the primary retaining housing channel part over the membrane thus retaining it uniformly and returning it to the outer face and lower deflector of the primary housing channel part thereof.18 A drip edge assembly according to claims i and 17 wherein the upperflexible flange of the retaining housing channel has a substantially outwardly and downwardly extended retaining flange which allows the membrane retaining part to pass beneath and retains it cooperatively with the lower extended flange of the retaining housing and having secured the membrane the retaining part may be further secured with a prescribed plurality of appropriate fixings thereof.iO A drip edge assembly according to claims i, i7 and is wherein the primary retaining housing channel may be expressed with any prescribed variation to the lower deflector flange arrangement such as may be required including integrated guttering profiles with running outlet and stop end counterparts, leaf deflecting flanges extending to the outer extremity of correspondent guttering below, precipitation conducting drip edges or anti-splash plates and any decorative elements incorporated thereof.A system according to claims ito 19 wherein one or more of the component parts of either or both assemblies may be made of either formed metal, extruded aluminium, plastic or a mixture of the same or similar without exclusion from the inventive claims herein.2i A system according to claims ito 20 wherein one or more of the component parts of either or both assemblies may receive material specific preparatory enhancements to ensure effective and safe handling and interaction with the membrane such as safety edges or returns on metal edges or strengthening flanges in plastic.22 A system according to claims ito 21 wherein the overall appearance of any or all components as a part or whole of the system may vary in shape, proportion and enhanced function such as water control, ballast or roof garden retention and drainage, block paving or solar panel retention, aerodynamic or reinforced versions or finish and colour variations without exclusion from the present invention whilst adhering to the same principles herein described.Amendments to the claims have been filed as follows Claims 1 A roof membrane enveloping, retaining and sealing system comprising: an upstand assembly of two elongate parts having interlocking opposing hooks retaining the membrane between them to seal it at a raised edge, so that retaining friction and downward anchorage on the membrane are increased when it is subjected to lateral tension, and a drip edge assembly of two elongate parts comprising in use a horizontally recessed channel part carrying a lower deflecting flange and a membrane retaining part which fits into the channel part to secure the membrane and form a planar fascia above the deflecting flange. (4 r (4</claim-text>