CA1148323A - Heat insulating roofing systems - Google Patents

Abstract

Abstract A heat insulating roof structure for an industrial building, in the form of an inter-purlin system com-prising spaced parallel purlins (10, 10A or 35, 35A or 45, 45A) having their base webs (14 or 41 or 50, 51) sheathed by a heat insulating sleeve (16, 17 or 53, 54 or 56, 57), thereby to provide lateral platforms on opposite sides of the purlin for the support of cross members (29 or 70) which form trays to support a layer of heat insulating material (31). In one form of embodiment the cross members are inverted tee bars (29), thereby forming open rectangularly framed trays for supporting the insulating layer. In another form of embodiment the cross members are closed tray bases (70) especially suitable for a vapour sealed system. In all embodiments the insulating sleeve assembly (16, 17 or 53, 54 or 56, 57) serves to minimise or avoid the creation of a cold bridge between the warm building interior and the cold space above the insulating layer (31).

Description

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This inve~tion relates to an insulating ~oofing system, more especially an insulatin~ roofing system for ~ i~dustrial buildings~
: In roofing structures for industrial buildings, the outer skin is usually formed by roofing shee~s, e,g, asbestos sheets 9 which are clzmped by mea~s o~ hook :~ members to the turned back edges of the upper lateral ~; fla~ges of the purlins, Conventionall~, the pu~lins ~ ha~re a Z-sh~ped cross-section and are k~own as Z-purlins, ':' At the present time3 there invariably exists a requirement to incorporate insulation in the roof structure, and it has been the usual practice to employ an over-purlin insulating system, wherein the insulation is fixed und~r the outer roofing sheets, supported b~ suitable irlDer roofi~g shee~s~ the respective layers all being ~` clamped in position over the tops of the purlins b~ means of lvng-s~emmed hook members, As higher standards of insulation are demanded, possibly to a U-va~ue as low as 0,6 or even 0.4, it is also necessary ~o employ spacers to create an air gap between , ' the insulating layer and -the outer skin of the roof, and additi.onally to provide an insulating layer of increased thickness, re~uiring the use of hook membars of ~urther increased stem length This gives rise to variou~ disadvantages, however, especially 1n placing additional strain on the hook-shaped membe.rs and on the top flanges of the purlins, thereby giving increased risk of substantial deformation, and in creating a cold space between the insulation and the outer skin which is not ~eadily ve~tllated, so that severe condensatioD problems can arise due to the escape of warm moist air from the m~in i~teI-ior of the building ~ upwardly into said cold space.
;: Alternatively, under-purlin systems are known, involviDg the suspension of a fra~ework of longitudinal ~: and lateral tce-bars be~eath the base webs of the purlins, :
`~ said framework carrying the required heat insulating layer ~hese systems are complex, complicated to erect1 and are therefore expensive It is an object of this inVeDtiOn to provide a heat insulati~g roofing system which minimises or avoids the disadvantages of known over-purlin insulating system3, without introducing the complexity, expense and differing disadvantages which ariss with alternative under-purlin `' :, .

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, insulating s~stems, According to one aspect of the present invention, there is provided a~ interpulin heat insulatin~ roofing structure comprising a plurality of spaced parallel roof purlins each having at least one lateral base web, a heat i~sulating slseve sheathin~ the base web or webs of each purlin, and cross members supported between the purlins Qn the sheathed base webs thereof, said cross members co~prisin~ or carrying a layer of heat insulatin~ material, 10~he insulatiDg sleeve preferably co~prises the assem~ly of a rigid outer sleeve with a he~t inslllating : filler recessed or slotted to accommodate the base web or webs of the pu.rlin~
~hus t according to another aspect of the present in~entioD, there is pro~ided, for incorporation in a heat irlsulating roof structure of the above-defined form, a : heat insulating sleeve assembly adapted to sheath the ~ase web or webs of each purlin, said sleeve ~s~embly comprisi~g an ou~er relatively rigid sleeve of metal or fire-retardant plastics material, said sleeve being of U-shape with inturned flanges at the upper ends of its limbs, and an infilling of less rigid heat insulating material which is recessed or slotted to acc~mmodate the web or we~s of the purlin. The insulating sleeve assembl~ can readily be constructed with both good heat insulating and good fi.re-retarding properties, ~hus, the o~ter sleeve ma~ be of metal or~P fire-resistant plastics material such as P~V,C~ protecting the heat insulating infilling which ma~ be a fo~med plastics s~ch as expanded polystyrene or polyuretha~e.
In one form of e~bodiment of the present invention, ~: said cross members supported between t~e purlins comprise cros5pieces~ such as inverted tee-bars 9 which ~orm rectangularly framed ~ra~s each defined by two opposed iDsulatîng sleeves and two opposed crosspieces. Said trays may receive rig~d heat insula~ing boards cut to size, or inner roofing sheets on which a loose heat i~sulating material is laid, Clips are preferabl~
~ 15 provided to hold the heat insulatlng layer down in the ;: trays and prevent possible "lift" thereof.
In another form of embodiment of the invention;
said cross members supported b,etween the purliDs comprise a plurality of tray bases~ ~his structure is especiall~
adapted to the production of a vapour sealed roof system, Thus, each tray base ma~ have opposed side walls transverse to the purlins, said side walls being adapted for interlocking engagement through a sealant to provide a vapour seal at the adjacent side edges of adjacent : . . . . - - , - : . ..
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tra~s, and a strip sealant may be sandwiched between the i~sulating sleeves and the end edge portions of ~he tra~
bases. Strip ~ealants can also be employed to enable production of a vapour sealed roof system using cross membe~s iD the form of in~erted tee bars, The importanc~ of the insulating sleeve assembly, i~
all ~orms o* e~bodiment, should be emphasised, ~his sleeve asse~bly substantially minimises or a~oids any cold bridge between the warm and possibly moist building 10 interior aMd the cold space above the insulating la~er, ~hus, the u~ersldes of the purlins are covered by the sleevos to prevent upward h~at conduction through the purlins from the bases thereof, and the cross members are insulated from the purlins to prevent heat transfer from ~hese members to the purliDs, ~he roof structure in accordance with the invention also faGilitates ventilation of the cold space above the insul~ting layer~ ~or example by means of lsuvred barge boards at the eaves of the ~uildin~, so that problems of condensation, especially in a non-vapour sealed system, are minimised, It is also apparent that it is possible to re~ert to the use of standard length hook members for securing the outer roofi~g sheets in position, thus reducing the possibility of deformation occurring within the roof structure, . .

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ID practice of ths invention, conventlonal Z-purlins are preferabl~ employed, but thi~ i8 no~
essential, aDd other ki~ds of purlin having a bottom flange to one ~ide, such as a so~called multlbea~ purlin having a fold in its main web, or purlins havin~ two oppo~itely directed base webs, such as an inverted J-; purlin, may be employed in.stead. In the case of a purlin having a base web ~o one side onlyt the insulating sleeve is employed to provids a lateral pla~orm on the side of the pu.rlin opposite said web, In a preferred arrangement/ the insulating sleeveassembl~ is of a wide U-shape, the outer sleeve havi~g an i~turned flange along the free edge of at least ona of its limbs. This inturned flange, with a downwardly ~: ~ 15 angled lip along its outer edge, can be hooked over the upturned edge por~ion of ~he bottom flange of a ~ conventio~al ~-purli~, temporarily to provide sole :~ support for the outer sleeve and the in~ulating filler ~: within it, until the filled sleeve i5 pivoted up against ; 20 the purlin bottom flange and the other limb of the outer sleeve is fixed in position. ~his other limb of the outer sleeve is pre~erably ~ounted to the main web of the purlin by means of a retai~ing clip having a U-portion to mbrace said other limb and an upstanding ;
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3~3 flange secured~ preferably by means of a nut ànd bolt~
to the purlin main web.
The outer sleeve o~ the insulatin~ Qleeve assembly preferably has inturned flanges along the upper edges of both its limbs, at the same level in relation to the purlin, and it is the~e inturned ~langes which provide direct support for the insulating layer~
;~ ~hus, in the preferred arrangement, inverted tee-bars are laid in parallel relationship between acljacent purlins, thereby to form open rectangular trays for receiving inner roofing or ceiling sheets, As previousl~ indicated, these sheets may be thick rigid sheets of insulating material, or thin rigid sheets such as plas~erboard on which flexible or loose i~sulating material is laid.
: Although not es3ential, it is pre~erred for the inverted tee-bars to seat in locating slots pressed out from the iDturned flanges of the outer sleeve of the insulating sleeve assembly, retai~ing clips b~eing :~ 20 located over said inverted tee-bars and under the ends of the inturned fl~nges adjoining the slots i~ order to .~ secure the inverted tee-bars in position, Alternatively, again as previously indicated~ it ; is possible to lay separately fabricated metal trays ., , ~ , . . ,~

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~ 3Z 3 between the purlins to support the insulating la~er.
In another embodiment of the invention, purlins each having two opposed base webs, for example an inverted J-purlin, are emplo~ed, Since this kind of purlin is unconventional, it shoula be explai~ed that a J-purlin is a purlin havi~g a main web extending between ~r~nsverse webs ~erpe~dicular to the mai~ web at the respective opposite longitudinal edges of the latter ~
wherein at one longitudinal ed~se a si~gle transverse web ; 10 pro~ects laterally o~ly to one side of the main web and has a lon~itudinal outer edge portion turned back ~ parallel to the ~ain web, while at the other lon~itudinal ; ~ edge of the main web transverse webs project laterAlly :~ ~ respectively to opposite sides o~ the main web. In 15 practice, a steel J-purlin ma~ ~e produced by cold rolling, the oppositely directed webs, which may be referred to as base webs, being formed b~ folding a steel sheet back beneath itself to form onetrans~erse web having a double ~ ~ thickr~ess of metal, the sheet t~en extending continuously :~ 20 past the bottom of the main web to form the other trans-:
verse web, which has a single thick~ess of metal, Pre~erably7 to strengthen the latter tra~verse web~ its . f~ee longitudiDal edge i9 rolled over to form a stiffening lip.

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g An inverted J-purlin can have greater resistance to twisting than the conventional Z-purlin~ especially ~y incorporating one or m~re bends or fold~ i~ the mai~
web, as is the case with the J-purlin used in the alternative embodime~t ~f roof struct;ure of thi~
iDVeD ti OR .
In the case of a roo~ structure usi~g J-purlin~, the insulating sleeve comprises ona or more recessed or slotted elongate members of heat insulating material which are assembled, for example with the aid of `~: relativel~ rigid outer sleavi.n~ and retaining bands~ to en~ase the oppositely facing base webs at the bottom o~
each purlin, thereby both covering the undersurface of said base webs with a lower iDsulating layer and providing : 15 an upper insulatin~ la~er above at least part of each such base web, the upper surface of said upper insulating la~er -~ ~ providing a support for the inverted tee-bars or other : cross members, : ~ ID other respects, the roof structure based on J-: 20 ~purlins is gen~rally similar to that based on Z-purlins.
When multi~eam purliDs are employed in the roof structure of this invention~ an insulating slee~e as~embly similar to that used for Z-purlins is employed, Some practical embodiments of the heat insulating ' :., ~ , . . - :

~ : . '' ' . ~ ' . , 33;~3 roof structure of this invention will now be described by way of example with reference to the accompanying drawings~ in which:-~igure 1 is a diagrammatic perspedtive view of paxt of a preferred roof structure ir1corporating Zpurli~s;
Yigure 2 i~ a similar view of a modifibd roof structure ~ased on multi-b~am purlins;
Figure ~ is a similar ~iew of an alternative ar.rangement of roof st~ucture incorporating J-purlins;
Figure 4 is an end view of an insulating slee~e assembly sultable fo.r a ~ purlin or multibeam purlin;
:~ Figure 5 is a similar ~iew of an insulating sleeve ~.: assembly suitable ~or a J purlin;
:~ 15 Figure 6 is a similar view of a longitudinally split insulating slee~e assembly suitable for a J_purlin;
~ igure 7 shows the sleeve a~sembly of ~igure 4 assembled ~o a ~ purlin;
Figure 8 shows the same sleeve assembly of ~igure 4 assembled to a multibeam purlin;
Figure 9 shows the sleeve assembly of ~iguxe 6 assembled ~o a J-purlin;
Figure 10 is a diagrammatic perspectlve view illustrating location of inverted tee-bars on the sleeve ''~ ' ~ - , ~ . - . ~

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33~d3 assembl~ of Figure 4, the purlin being omitted for clarity;
Figure 11 illustrates, in conjunction with Figure 10, the analogous location system employed with the sleeve as~embly of ~igure 6;
~ igure 12 shows i~ diagrammatic perspec~i~e ~iew a vapour sealed roof structure based on Z purlins;
Figure 13 is an end view o~ a tray base empl3yed in the arrangement of Figure 12; and ~igure 14 shows, in like manner to ~igure 12, a vapour sealed roof structure based on J-purlins~
Referring to Figures 1, 4 and 7, the references 10, 10~ denote two of a number of spaced parallel purlins conventionally mounted on ~he trusses or stanchions (not shown3 in order to c~rry a roof ~tructure for an industrial building. The roof is assumed to b~ a pitched roof, so that the purlin lOA is at a lower level than the purlin lOo The purlins 10, lOA are conventîo~al Z-purlins, each with a top fla~ge ~1 having a ~urned down lip 12 pro~
jectin~ to one side of the main web 13 and a bottom flange 14 with a~ upturned lip 15 projecti~g to the other side : of the main web. It is to be noted that the bottom flan~e~ 14 pro j ect away from the ridge and towards the .

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eavesO
Mounted to the base of each purlin 10, as also shown in Figure 7, is an i~sulating slee~e assembly co~sisting of an outer sleeve 16 of cold rolled steel, or o~ a relatively rigid fire retardant plastics such as P.V~C~, containing an insulating filler 17, e.g. of polystyrene blocks or pol~isocyanurate extruded in situ within the sleeve~ Figure 4 shows the asse~bl~ of the out2r sleeve 16 and its infilling 17 separately, In practice, the outer sleeve 16 may be filled b~ a composite insulating block 17 made up of three sub-blocks~
two filling the sides of the sleeve and one linin~ the centre of the sl~eve between the two ~ide sub-blocks~
: Refer~ing speci~ically to Figure 4, the sleeve :~ 15 assembly 16, 17 has a relatively wide U-shape. '~he outer sleeve 16 has lnturned ~langes 1~1 19 alonæ the u~per edges of its side limbs 20, 21, The flange 18 on one side has a downwardly an~led lip 22, In addltion, portions ~3 of the flanges 18, 19 are pressed out to form shallow slots, for a purpose to be ~escribed later.
The ~illed sleeve 16 forming the insulating sleeve assembly is mounted to the base of the purlin 10 in the manner most clearly shown in Figure 7, The angled lip 22 of the inturned flange 18 on one limb 20 of the U is , .
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hooked over the upturned lip 15 of the purlin bottom flange 14, and the remote side of the sleeve 16 is held in place by retaining clips 24 each having a U-portion 25 which embraces ~he other li~b of the U~ including its inturned ~lange 19~ and an upstanding flange 26 which is ~ixed to the main web 13 o~ the pur:Lin 10 by a nut and bolt assembly 27, which may i~clude a heat insulating ~ washer.
; The purlin 10 is drilled at approxi~ately one metre intervals to take the nut and bolt assembly 27, assuming ~: a purlin approximately 6 to 7 metres long, The outer sleeve 16 and ~iller 17 contained thereiD may be produced as sub-units approximately 3 mstres long~
It will ~e obser~ed that the ~lange ~9 of the filled sleeve 16, 17 provides a pla~form to the side o~
the purlin 10 opposite to the bottom fla~ge 14 of said purlin, at the ame level in relation to the purlin as : the flange 18 whi~h has the ~ngled lip 22 hooked over the :: .
upturned llp 15 on said purlin bottom flange 1~, : 20 Duri~g ~ssembly, which is inherently difficult in - ~n elevated roof location, the angled lip 22 is hooked : : over the upturned lip 15 of the purlin bottom fl~nge 14 temporarily to provide sole support for said sleeve, The latter is then pivoted up against the underside of , ~:;

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: :' the purlin bottom flange 14, and fixed in position b~
means of the retaining clips 24, This is a relatively simple task~ SiDCe it requires no matchin~
of the holes in the purlin 10 wi-th a:ay particular points ~ the ~leeve 16, as ~he retaining clips can be positioned substantially anywhere along the sleeve 16 subject to the requirement for reasonably u~iform ;` support~ A strap 16A (see Figure 1) fits over the ~utt joint betwee~ adjacent slee~es 16 10~ In~erted tee-bars 29 (one shown detached in Figure 1) are then laid betwean the purlins 10, lOA etc. in spaced p~rallel relationship, the e~ds of the crosspiaces of the tee-b~rs bei~g located in the shallow slots 23 in : the sleeve flanges 18, 19~ ~ee-bar retaining clip5 7>~J~
1$ two of which are shown indi~idually in ~igure 1, fit over the main web o~ a tee-bar 29 a~d locate under the end portions o~ ~langes 18, 19 adaacent the pressed out shallow slots 23 to secure the tee-bar i~ position J It will be noted that the clips ~0 provide a substantially . 20 flush continuation of the top surfaces of the flanges 18, 19 up to the m~in web of the located tee-bar 29.
: With the arrangement ~escribed, a degree of mis-alignment or de~ormation between the purlins 10, lOA is tol~rable, b~cause a tee-bar 29 can only slip '( h j ~
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' longitudinally down the pitch of the roof as far a~
permitted by the relatively narrow supporting platform (say 25 m~ wide) pro~ided b~ the flange 19 of the slee~e 16 on ~he purlin lOA~ while a~ the higher le~el of the purlin 10 the e~d of the tee-~ar ca~ remaiD properly supported and located by the ~la~ge 18 of the sleeve 16 at a distance of up to about 80 mm from the main web 13 of the purlin9 This fairly high degree of tolerance results from ~he mounting of the purlins 10, lOA with the bottom .~langes 14 directed away from the rid~eO
Rigid self-supporting panel3 31 o~ insulating~
fire~retardant plastics matarials ~re laid in the open rectangular trays formed b~ the substantially coplanar top surfaces of the flanges 18, 19 and of the cross-pieces of the inv~rted tee-bars 29, ~he panels 31 are held down i~ the trays agai~st lift by suitable pressure clips (not shown) mounted on the purlins and/or tee-4ars.
~hese panels 31 form a ~ubstantiall~ir fl~t ceilin~s to the building iDterior.
The above-described arrar~gement has the advantages of substantially eliminating an~ oold bridge which could permit heat transfer through the purlirls 10, lOA from the warm building interior to the cold space above tke insula~ting layer 31, and of providing ~ cold , ' .'~ ' .-3~3 space o~ substantial depth below the outer roof covering ~not sho~n) which is fixed in a conve~tional manner to the top f`lange~ 11 o~ the purlins. By the use of louvrad barge boards at the eaves or other suitable means, this cold space of substaDtial volume is readily entilated, thus minimisi~g risk of coDdensation pr~blems It is also to be noted that the whole structure is ! assembled o~ fire-retardant materials It is also to be noted that the positioning o~ the drilled holes for the . 10 ~ixings 27 in the purlin for the clips 24 is not critical~
:~ since thcre is no requirement for positioning of these retaining clips in relation to the length of the insulating sleeve assembly except in so far as a reasonably uniform support is desirable The outer sleeves 16~ the insulating sleeve retaining clips 24 and butt straps 16A pro~ided to cover the butt joints bet~een adjacent insulating sleeve assemblies, may all be formed ;;: of cold rolled steel cut to length as ~ecessar~, although, .:~ as previously men~ioned, the outer sleeves 16 may alternatively be produced o~ ~ relativel~ rigid plastics material~ ~he filler in the outer slseves will, as previously indicated, be a plastics insulating ~aterial such as polystyrene inserted in the form o~ cut blocks or polyisocyanurate extruded in situ in the outer sleeve~

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1~-The outer sleeves 16, retaining clips 24 and butt straps 16A therefor ma~ be painted or plastics coated to impro~e appearance, e.g. to provide a substantially flat uniformly white ceiling expanse. It is a further adv~Dtage ~f the in~en~ion over an over-purli~
iD~ulating sys tem t~at the lower part~ of the purlins are ~ot exposed to the building inte:riorO A still further advantage of the roo~ structure of this invention is that it may be erected entirely from above, dispensing with the requirement for scaffolding w:ithin the building, ~ nother important factor to be understood in relation -to the above-described roof structure of this in~ention is that the insulating sleeve assembly 16, 17 minimises any cold bridge between the building interior and the cold ~pace above the insulating layer 31, Only a minimum of heat conduction can occur through the insul.ating sleeve retaining clips 24, aDd this can be substantially eliminated by int~oducing the above-mentioned insulating washer on the bolt ~ixing said clipsto the main web of the purlin, In addition, the cold space above the insulating layer 31 ca~ readil~ be venti-latedS for ex~mple b~ n3eans of louvred barge boards at the gable ends of the buildingO Problems of condensation ;~

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3~ 3 are ~herefore also minimised, It will also be apparent that it is possible to revert to the use of standard length hook members for securing the outer roofing sheets i~ position, thus re~ucing the likeli-hood of de~orma~ion occurri~g within the roof structure.
;~ ~igures 2, 4 and 8 serve to illustrate a modified arr~gement o~ roof structure which is substantially identical to that previo~sly described except that multi-beam purlins 35t 35A are employed instead o~ 2 purlins~
In Figure 2, identical ra~erence numerals to those of ~igura l are employed for all components and parts except the purlin~, since the modified arran~ement h~s the same basic features and give~ rise to the s~me advantages as the Z-purlin syst~m, The form o~ a multibeam purlin appears clearly .
~- from Figure 8, It has a main web }6 with angled portions 37, 38 to provide improved stiffDess again~t , .
~: twis~ing and ~eformatio~ ge~erally, an upper tra~sverse web 39 wi~h depending lip 40, and a lower tra~sverse web 41 with an upstandin~ lip 42. ~he insulating ~leeve assembly 16, 17 is substantially identical with that previously described, although it can be seen by comparison of ~igures 7 and 8 that, for the multibeam :."
~ purlin 35, the limbs o~ the U-shaped insulating fi ller 17 :.' '', ~. . : ,. .

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can be of equal width instead of the unequal widths shown for the Z-purlin, It is also to be observed, in con~ection with ~igure 2, that in a pitched roof the multi-beam purlin 35A will be at a higher le~el than the multibeam purlin 35.
Figures 3, 6 and 9 illustrate an alternative roof structure based on J-purlins 45~ In Figure 3~ the J-; purlin 45A will~ in a pitched roof, be at a higher le~el : 10 than the J-purli~ 45, 50 that in Fisures 7, 8 and 9 the illustrated purlins are all shown in the same relationship, i,e, pointing up the g~ble slope to the right in the ~igures, In Flgure 3, ideDtical reference numerals to Figures 1 and 2 are again employed for similar components and parts, and many of the previously staked ~eatures and adv~ntages are again applicable, Howeverg a modified insulating sleeve assembly is e~plo~ed for the J-purlin, as shown in ~igure 6, Referring first to Figure 9, the J-purlin 4~ has a main we~ 46, preferably but not essentially inc~rpora-ting an angled portion 47 connecting to an upper trans-verse web 48 having a depending lip 49. ~he angled portion 47 stiffens the fold where the main web 46 : connects to the transverse web 48, assuming the purlin .~ .

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to be produced by cold rolling. The J-purlin has base webs 50, 51 respectively projecting to opposite sides of the main web 46, ~he J-purlin is p:re~erably ~ormed . from steel plate by cold rolling, and in accordance with this ~ethod of production, the two appositely directed b~se webs 50, 51 ~re for~ed by folding the steel plate back beneath itself to form one base web9 the web 50, of a double thickness of metal (although the two steel ::~ layers ~hereof are not necessarily in close contact~, -The other base web 51 has a single ~hickness of metal, but is s~iffened with an upstanding lip or, as .:, illustrated, a re-entrant lip 52, ~ he insulating slee~e assembly ror the J-pu:rlin, as shown in Figure 6, consists of a lonæit~dinall~ split 15 outer slzeve 53, 53A hcusing two slotted fillers 54~ 54A.
he materials used ~or the insulating sleeve assembly 5~, 53A, 54, 54A may be the same as those previously mention~d in connection wi~h the slee~e assembly 16, 17 of the preceding embodiments. The two part slee~re 20 assembly of Figure 6, one par~ for each base web 50, 51 of the J-purlin 45, is assembled to the purlin with the aid of retaining bands, one of whieh is indicated by ; reference 55 in Figure 9.
ID the J-purlin arrangement, it is to be noted that ' .
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~ f~ 23 the insulating sleeve assembl~ 53 t 5~A, 54, 54A does not in itself have to provide a tee-bar supporting platform on one side of the main web of the purlin, It will also be noted from Fi~ures 3 and 9 that ~he sleeve retaining clips 24 are no longer requir~d, ~ igure 5 i~ ~rovided to show that, in the J-purlin arra~gement also, it is possible to employ a unitary insulating sleeve assemblyO In this figure, the out.er sleeve is referenced 56 and the heat insulating filler 57, A disadvantage which can arise with the sleeve assembly 56 "~ 57 .s that it must be slid on to the base of the J-purlin 45 from one end of the latter9 and this will often only be possible before the purlin is raised and fixed to the roo~
stanchions, Equally, however, it is co~enient to me~tion at ;` this poi~t that, if desired, a longitudlnally spl:it insulati~ slee~e assembly could be employed with a Z-purlin or a multibeam purlin; provided that suitable retaining bands or other suitabl~ retaining means are provided to hold the parts together in assembled conaition sheathing the base of the purlin, Figure 10, employing identical reference numerals to Figures 1 and 4, is employed to show in enlargement the manner in which the sleeve assembl~ 16, 17 ser~es to .
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locate the ends of the tee-bars 29, The form of a tabbed retaining clip 30 in relation to a broken-off tee-bar 29 is clearly shown on the left-ha~ side of the fi~ure, while the manner in which a 1.ocating recess 23 5 i~ ~ormed in the upper ~lange 18 of the o~ter sleeve 16 of the sleeve assembly, by partly se~ering and folding a portion 23A of said flange 18, is also more clearly shown, : ~he lateral tabs 30A on the retair,ing clip ~0 fit u~der the edge portions 18A of the flange 18 adjacent the recess 23 in order to ~ecure the tee-bar 29 in position, Figure 10 also serves to illustrate an alternati~e locati~g means for the end o~ a tee-bar 29, which may be optionall~ provided in place of the locating reeess 2~ in the upper flange 19 ~f the outer sleeve 16 on the opposite 15 side OI the purli~ from the flange 18 (the purlin, alld likewise the angled lip 22 o~ the flar~ge 18 of ~he ou~er :
sleeve 16~ are for clarity omitted in ~igure 10)l This c~mprises a ~-slot 60 cut i~ the fla~ge 19, into which the end of the tee-bar 29~is recei~ed directly, the lateral webs of the tee-bar engaging u~der the ~lange 19 at the edge portions theraof adjoi~ing the ~-~lo~, This alter~ative form of loca~ing means in the form of a T-slot 60 is oDly suitable for the flange 19 of the outer sleeve 16 at the higher level in the roof, iOe. the flange ~,~ ,,) ., .

;23 --~3--which after erection of the purlin and sleeve assembl~ in the roof structure is directed away from the roof apex, so that the purlin 29 tends to slide longitudinally down the gable slope i~to the T-slot.
A located tee-bar is indicatecl at 29A in ~igure 10, In Figure 11, the right-harla part 5~A, 54A of a longitudi~ally split sleeve assembly of the kind shown in ~igure 6 is illustrated in e~largement. The pu.rpose is to show the locating reces~ 23, In a J-purlin arrange-~ent, it is preferred not to employ locati~ T-slots of the form shown in Figure lO, However, in all embodiments, various alternative forms of tee-bar locating means ma~ be employed, preferably means carried by the in~ulating sleeve assemblyO
A vapour sealed heat insulating roo~ structure in accordance with the inve~tion is s~own in ~igu~e 12, ~he preferred arrangement Gomprises a plurality of spaced .; parallel roof purlins, CoD~eniently, these purlins are : ~-purlins lO, lOA as previously described with reference to Figure 7, and the same reference numerals are again employed, Again~ as previously described with reference to Figures 4 and 7, the base webs 14 o~ the purlins lO, lOA are she2thed with insulating sleeve assemblies l6, 17, Supported between the insulating sleeve assemblies -' ~ ' ' , ~ . .

33;23 16, 17 on the purlin~ 10, 10A are sheet metal trays 70,~ne o~ which is also shown in end Yiew in Figure 13, Each tray 70 has upstanding walls at its side edges, - One such wall 71 has a depending lip 72, the other side wall 73 has a hooked or re-e~trant upper edge 74.
During assembly of the roof, the hooked edge 74 of the one side wa~l 73 is filled with a plsstic or mastic sealant, ~: 1'he trays 70 are supported in side-by side . 10 relationship alonæ the lengths of the purlins 10, lOA
with the side walls, 71 and 73 respectively, of ~djacent trays juxtaposed. The lipped upper edge 72 of the wall 71 interlocks with the hooked upper edge 74 of the wall : 7~ of the ad~acent tray, and is received into the plastic sealant to fo.rm a vapour seal therewith, The sheet metal trays 70 are insul3ted from the baqe webs 14 of the purlins 10, 10A by the insulating ~, ~; sleeve assemblies 169 17, In addition9 however, strips 75 of plasti~ or mastic sealant are laid along the ; 20 inturned ~langes 1~9 19 of the outer sleeves 16, on which the end edges of the trays 70 are received when the trays are placed in position, The trays 70 are then rivetted through the sealant to the inturned flanges 18~ 19, as i~dicated at 76, i~ order to prevent vacuum :: ~

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3 ~ 3 lift, i e lifting of the trays due to air pressure changes in the building space below. ~he sealant strips 75 ensure a vapour seal between the trays and the purlin assemblies Insulation, conveniently in the form of slightly oversized insulating panels 31, is thsn located in the trays 18. The panels 31 being oversized, they expand to abut one another over the tQpS of the interlocked side walls 71 and 73 of the trays 70 In a modiflcation, a pattern of apertures is provide~ in the sheet metal trays 70, which are then liDed, beneath the insulating la~er 31, with a plas~ics sheet, preferabl~ secured to the metal sheet with ~ adhesive, which covers the apertures to maintain a vapour :: 15 seal However, the apertures will permit passage of ~: sound through the plastics lining sheet into the insulation, where such sound is largely absorbed It is to be understood that the above-described :~
arrangement is essentially an i~ter-purlin heat insulating ; 2Q system, like that described with previous reference to an~
~ of ~igures 1 to 3 The outer roof skin, co~ventionslly : asbesto~ sheets, can ~e secured to the tops of the purlins 10, 10A in the usual manner, i e by means of hooksd bolts which fix to the upper lateral webs 11 of :~ .

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-2~-the purlins. However, various modifications are possible within the scope of the i~ventio~ ~or example, the above described inter:Locklng side walls ~or the tra~s are not essential, since other means can be devised fcx producing a ~apour seal between the juxta-posed ~ide ed~es of ~djacent tra~s, Other sealing means may be employed between the sheet metal tra~s and the purlins, and such means may also serve as insulation~
~;However, it rem~ins necessary to sheath the bases of the purlins with insulation in order to eliminate a cold bridge, The esse:ntial point of ~he system, whatever modifications may be introduced~ is that a vapour seal is formed between the trays and the purlins, and also between ad~acent trays9 which substantially preve~ts the 15 escape of moist warm air from the under space beneath the insulation into the cold upper space above the insulation, thereby minimising or avoiding condensation difficulties.
Fi~ure 14, which will be clear without de~ailed description, shows a Yapour sealed heat insulati~g roof structure based on J-purlins 45. For idential :~components and parts, the same reference numerals are employed as i~ previously described Figures 6, 9, 12 and 1~.

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Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heat insulating roof structure comprising:
a plurality of spaced parallel roof purlins each having a main web, a lateral top web and, at least on the other side of the main web from the top web, a lateral base web with an upturned edge flange;
a heat insulating sleeve assembly sheathing the at least one base web of each purlin, said sleeve assembly comprising a rigid outer sleeve with a heat insulating filler recessed to accommodate the at least one base web of the purlin, said sleeve and insulating filler extending laterally to both sides of the purlin and upwardly to provide a heat insulated support-ing surface at the same level on both sides of the main web of the purlin above the upturned edge flange of the at least one base web; and cross members supported on said supporting surfaces to extend in parallel relationship between the purlins and form with said supporting surfaces rectangular frames for support-ing a layer of insulating material which forms an inner roofing spaced below an outer roofing.

2. A structure according to claim 1, including cross member locating and retaining means in part integrally formed on the rigid outer sleeves of the sleeve assembly, for locating and retaining the ends of the cross members supported in alignment on the supporting surfaces on opposite sides of a purlin.

3. A structure according to claim 2, wherein the rigid outer sleeve of the sleeve assembly is a cold rolled metal sleeve of U-shape with inturned flanges at the upper edges of its limbs, the locating and retaining means comprising tabs partially severed from said inturned flanges to receive between them the ends of cross members in the form of inverted metal tee-bars, and tabbed bridging clips interengaging with said tabs to hold down the ends of the inverted tee-bars on said supporting surfaces.

4. A heat insulating roof structure comprising:
a plurality of spaced Z-type or multibeam-type purlins each having a lateral top web to one side of a main web and a base web with an upstanding edge to the other side of the main web;
a heat insulating sleeve assembly sheathing the base web of each purlin, being hooked over the upstanding edge along one side of the main web and being secured by clips along the other side of the main web, said heat insulating sleeve comprising heat insulating material extending to both sides of the main web and upwardly to provide heat insulated support-ing surfaces at the same level on both sides of the main web above the level of the upturned edge of the base web;
and a heat insulating inner roofing layer spaced below an outer roofing layer and supported between the purlins by means which includes metal cross members in parallel relationship supported on said supporting surfaces.

5. A structure according to claim 4, wherein the sleeve assembly comprises a metal outer sleeve and a heat insulating filler both extending laterally to both sides of the main web of the purlin and upwardly to form said supporting surfaces.

6. A structure according to claim 5, including cross member locating and retaining means in part integrally formed on the rigid outer sleeves of the sleeve assembly, for locating and retaining the ends of the cross members supported in alignment on the supporting surfaces on opposite sides of a purlin.

7. A heat insulating roofing structure comprising:
a plurality of spaced parallel J-type purlins each having a lateral top web to one side of a main web and base webs with upstanding edges to opposite sides of the main web;
a heat insulating sleeve assembly sheathing said base webs, said sleeve assembly comprising a fire-retardant rigid outer sleeve and a less rigid infilling of heat insulating material recessed to accommodate the purlin base webs and provide heat insulating filler both above and below said base webs, said sleeve assembly forming a heat insulating supporting surface at the same level on both sides of the base webs above the level of the latter.
and metal cross members in parallel relationship supported on said supporting surfaces to extend between the purlins, insulated from the base webs of the purlin by said heat insulating filler, for supporting a layer of insulating material which forms an inner roofing spaced from an outer roofing.

8. A structure according to claim 7, including cross member locating and retaining means in part integrally formed on the rigid outer sleeves of the sleeve assembly, for locating and retaining the ends of the cross members supported in alignment on the supporting surfaces on opposite sides of a purlin.

9. A structure according to claim 6, wherein the retaining means comprises portions cut away in a top flange of the outer sleeve to provide a recessed seating for the ends of the tee-bars, and tabbed bridging clips for fitting over the ends of the tee-bars with their tabs engaging under the top flange of the outer sleeve adjacent the cut away portions.

10. A structure according to claim 1, wherein said cross members supported between the purlins comprise crosspieces which form rectangularly framed trays each defined by two opposed insulating sleeves and two opposed crosspieces.

11. A structure according to claim 1, wherein said cross members supported between the purlins comprise a plurality of tray bases.

12. A structure according to claim 11, wherein each tray base has opposed side walls transverse to the purlins, said side walls being adapted for interlocking engagement through a sealant to provide a vapour seal at the adjacent side edges of adjacent trays.

13. A structure according to claim 12, including a strip sealant sandwiched between the insulating sleeves and the end edge portions of the tray bases, said end edge portions of the tray bases being rivetted to the insulating sleeves.

14. A structure according to claim 13, wherein the insulating sleeve comprises the assembly of a rigid outer sleeve with a heat insulating filler recessed to accommodate the at least one base web of the purlin.

15. A structure according to claim 7, wherein the insulating sleeve is formed in two longitudinally split parts, one for each base web of the purlin, and retaining bands are provided to hold said two sleeve parts together in assembled condition sheathing the two webs.

16. A structure according to claim 4, wherein, on the side of the purlin main web opposite to the lateral base web, a retaining clip is provided to secure the insulating sleeve to the purlin, and wherein the insulating sleeve has a top flange with a depending lip adapted, during assembly of the sleeve to the base web of the purlin, to enable said sleeve to be suspended from said base web.