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Fixing Dibond to cladding issues?
Done a search and can’t find the info I’m looking for but I seem to remember some discussion about issues arising from fixing dibond straight to cladding. Have a client who wants to fix unframed 8’x2′ dibond sheets using hex head fixings. Is this ok to do?
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30 Replies
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yes, totally fine Harry. Make sure you have the hex-head tech screws with the rubber washers as some suppliers don’t offer these as standard.
also make sure your using tech-screws for soft metals like alluminium. you get various types. the ones with the close tight threads are for steel, open/wide threads are for softer metals and the open threads that come to a point (non-self taping/drilling is for wood) -
Cheers Rob…..was there something about making the holes in the dibond a little wider for expansion?
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Hi Harry,
expansion is only going to be a major issue for darker colours as the material itself is fairly stable and moves well with the cladding material.
A tech screw every 2-3 ridges takes care of that most of the time – and depending on the height – a few well placed ones mid-panel.
Contraction is probably more of a long term issue…putting up in the warm…shrinks back in the winter creating gaps & bursting any seam joins.
Dave
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Cheers David…..want to be sure I have no comebacks on this.
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Just noticed the size of your sign – you’ll have no issues with screws every 2-3 ridges top & bottom.
You though about a folded panel…or is this just client doing the usual "sign – cheap as possible – now"
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quote David Rogers:You though about a folded panel…or is this just client doing the usual “sign – cheap as possible – now”
You’re telepathic gifts never cease to amaze me! 😀 😀
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rather than the big ugly tech screws, you could use the countersunk self drill and tapping from screwfix, and stick a circle of vinyl over the heads.
far nicer finish, and no extra costPeter
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They are nicer looking Peter but….I’m always a lickle bit concerned about using them on cladding. It seems to me that the countersunk bit is a bit of a weak point in the sheet, whereas a washered fitting spreads the load a bit, so to speak.
What I do with the tech screws is paint them the day before, the same colour as the sign. I keep a bunch of enamel paints in my toolbox just for this. -
Andy,
I have used both types of screws many times, on a 2′ deep sign the countersunk will be more than adequate. tech screws are ugly,
the weight of a composite panel requires very little to hold it in place. not sure why you think a countersunk is a weak point?
Peter -
Regarding the countersink screws – I agree this is a much neater solution but concur with Andrews concern that the countersink action (and its consequent removal of some of the surrounding material) may well weaken the substrate.
I hope this makes sense. -
Phil,
aeronautical engineers used countersunk rivets on the spitfire to reduce drag,
but consequently found out it was a better and stronger fixing than the previously used method of surface rivetsCountersunk is still used on aircraft. so a piddly sign is not an issue, surely?
Peter -
Interesting, I’ve always figured that the aluminium on comp aluminium so thin that removing half of it to countersink screws not a great idea. This is more so on cladding for me as the wind can easily get in behind and put extra force than than on a flat fitted sign.
I see you point about planes Peter but is it not the case that the material they are countersinking is far stronger than composite aluminium, even considering the much higher forces it’s put under?
G
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When using composite, and countersunk screws, it is not necessary to countersink the composite the screws sink into it on their own, so no material is removed. I have fitted many panels this way without problems.
Peter
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As you rightly said Gavin, Aircraft material can hardly be compared to a composite board.
Peter, we make and assemble dozens of signs like this on a daily basis, and have done for many years now.
I much prefer Aluminum to composite any day but composite is easier to get hold of, cheaper to buy and comes in many more colours off the shelf.We use both tech screw fixings and Rivet fixings on most of the signs.
If i need to use Composite on the likes of channel and clip signs. we double up every single rivet with 3-4 inches of VHB behind it. why? because some years ago we did an order for a company for freestanding post signs scattered around their site. about a dozen of them had to be re-done because the panel had been, or was in the process of, tearing away from the rivet. by that i mean the rivet still in place, but it had tore through the face of the composite panel were it had been fixed. I have never seen this happen with aluminum signage.Also, when you actually pop a rivet into Composite, you can often see a sort of faint ripple around the rivet on the surface of the composite where the rivet is actually pulling itself into the face of the soft material.
a rivet head is probably half the diameter of a tech screw fixing so half the load spread? tech screws have a rubber bungee type washer also which helps prevent damage to the panel by over tightening but also allows a bit of movement of the panel before any sort of tear action occurs. i would also imagine this possibley helps with expansion/contraction issues.
Tech screws also win hands down on speed. so quick and easy to fit with a single cordless gun. a rivete requires a 5mm pilot hole to be drilled.
then lazy-tongs to fix the rivet in place. not forgeting the possible damage to the sign face should the snapping action be a bit sketchy.
which can easily happen when up the side of a building.Cosmetically, the rivet wins hands down over the Tech Screw, but chrome techs, uniform spaced, up on the side of a building look neat, tidy and very secure.
counter-sunk is fine and dandy, but your again reducing the load capability of composite as your now through one side of the aluminium face, so only gripping a couple of millimetres of nylon core and a thin skin of aluminium. and thats weather you countersink prior or self countersink into the sheet, your still burying the head further into the sheet.
Also remember, it is tech screws that are holding up all the sheeting on new factory units all over the UK. How many do we see that are built using rivets?
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quote Peter Normington:Phil,
aeronautical engineers used countersunk rivets on the spitfire to reduce drag,Peter
Do you remember that from when you were a lad then Peter? :lol1:
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Joe I used to fly them over Koln escorting the lancasters 😀
Rob, I wasnt talking about rivets, i was talking about using self drilling and tapping cs screws, and direct to cladding, not free standing panels, which is entirely different, I would not use composite for free standing, that is post mounted.
I was just suggesting an alternative to tech screws, for attaching comp to cladding, especially if at low level, so visually better.
The screws do work and I have never had a problem.
Tech screws work also, even though not designed for attaching panels to cladding. They are for attaching cladding to purlings (steel frame of the building)
Peter -
cheers folks, informative and fun as usual. Have given the client the options, he’s gonna go with the tech screws.
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Yes Peter, you were talking about self drilling counter sunk screws initially. But you also veered off onto talking about rivets being used on aeroplanes, and the use of the countersunk method being stronger again. Which I think was you making your point on the strength of countersinking the screw. But your example was not an aeroplane made of di-bond.
I simply used an actual “experience of mine”, using “surface mounted” rivets on Composite board to explain that it is not necessarily the fixing you are using, but the actual Composite board itself that will fail. Rivet or Screw, under wind load pressure, it can tear the fixing through the face of the sign unless some form of fixing is used that can spread the load. Hence why I said we now use a strip of VHB every rivet when the need arises to use a composite on a free standing sign.
Further more, It is perfectly fine to use composite on free standing post mounted signage. I have been doing it since I was introduced to the product about 6 or 7 years ago and have used it hundreds, if not thousands of times since… So I am speaking from “tried and tested, good & bad experience” of something I do on a daily basis Peter.quote Peter Normington:Tech screws work also, even though not designed for attaching panels to cladding. They are for attaching cladding to purlings (steel frame of the building) PeterThat’s a rather niave comment Peter…
2 days ago I purchased ;-
1500 no. Tech screws for fixing into aluminium and similar soft metals.
400 no. Tech Screws for fixing into steel.
400 no. Tech Screws for Fixing into wood.I have also attached to this post, part of a PDF based on Techs made for fixing “composite” to steel framing. Same applies when fixing Composite to the cladding, same screws, different thread because the cladding is a softer metal.
The techs large hex head is to help spread the load. The rubber washer is there to allow movement of the panel as well as preventing the screw from loosening.
Back to the initial question.
quote Harry Cleary:I seem to remember some discussion about issues arising from fixing dibond straight to cladding. Have a client who wants to fix unframed 8’x2′ dibond sheets using hex head fixings. Is this ok to do?So the answer to Harry’s tech screw question is “YES”
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OK Harry they will be fine,
but at the end off the day, it does not matter how big the head is on the exterior, or what material is used, the cladding is only about 1mm thick, that is what determines how strong the fixing is,
on cladding, a rivet or some type of expanding fixing is best, unless you can fix direct to the framework. with the screws that rob has pictured, but you would need to know where the purlings are, and usually go through insulation and an interior layer as well
Peter -
Good grief charlie brown… :ball:
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Rob
we appear to have a difference of opinion,
so do you fix panels to the cladding or the purlins?
you have shown the screws that fix to purlins, which is the ideal way to do it for maximum strength, they have a small head and no washer, the ones with a rubber washer are for cladding to purling, the washer is to make a watertight seal,
Peter -
Peter
i agree composite panels fixed direct to cladding are better with big head rivets. Cladding is normally .5mm or .7mm, you can buy stitching bolts which are used to join panel to panel but again are only screwing into max of 1.4mm of steel at a joint. I personally use Peel Rivets which split into 4 prongs and spread on the rear of the panel giving a wide area back & front. Rivets are easily covered but if a nice uniform pattern is used are a perfectly acceptable feature. I never have liked using cladding bolts direct into cladding and i know there are many who will state how many jobs are still up many years after fitting but looking at the mechanics of it most people would have doubts of using them. Just my opinionKev
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thank you Kevin,
Peter -
quote Peter Normington:Rob
we appear to have a difference of opinion,
so do you fix panels to the cladding or the purlins?
you have shown the screws that fix to purlins, which is the ideal way to do it for maximum strength, they have a small head and no washer, the ones with a rubber washer are for cladding to purling, the washer is to make a watertight seal,
Peterno peter, i fix directly to the cladding. if i ever feel the need to tap into the steel frame work i can. i simply change the screw, using the same bit, and drive in that tech.
quote Peter Normington:unless you can fix direct to the framework. with the screws that rob has pictured, but you would need to know where the purlings are, and usually go through insulation and an interior layer as well, Peteranother naive comment peter…
cladding buildings are riddled with tech fixings holding the cladding in place.
where there is a row of techs, there is a length of steel running behind the cladding.the image attached was not to show you what i use peter, it was was to contradict your last comment that techs are only for fixing cladding to steel framework. the image shows they are also specifically made to fasten "composite", not all, but mostly the head section of the tech stays the same, it is only the threads of the tech that changes dependent on what it is taping into. e.g. the thread on steel taping thread is tight and shallow. the thread on a tech for wood is broad and open.
I actually use "WOOD" techs to fit huge illuminated flexiface signs directly to cladding buildings. I have lots of them dotted all over the UK now. never have i had a problem with any and they have been up some 4-5 years now. now dont just take my word for this, I was given the "tip" by guys from a national sign installaton team first hand, i told them i was peppering the sign box with the open threaded techs and fastening directly to the cladding, but also hitting the steel framework where ever i could. i was told "not to worry" by all means use fasten to the frame work for peice of mind, but the wood techs grip and grip strong. they were right… 5mm pilot hole followed by the wood tech. (only because wood techs are not self taping in metal)
why thank Kev? as you said, you were talking about countersunk screws and regular sized rivets. Albeit a type of rivet, Kev’s method of fixing is different to the ones being discussed. "Your recommendation" of a fixing was a regular sized "countersunk screw".
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Missed this last night – my go…
You are correct Peter – the Supermarine Spitfire was indeed held together by rivets. However, it’s a little known fact that the Focke-Wulf was held together using tech screws which gave it greater inherent strength for an equivalent weight. This gave the Focke greater acrobatic abilities (it was able to sustain higher G forces without rippping apart) which made the Focke a better dogfighter than the Spitfire.
It’s also a little known fact that when Bomber Harris was asked by Churchill what he needed to help win the war he replied "A Squadron of Fockes" 😕
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Blimey, did I set this one off? I was simply stating that I don’t particularly like countersinking composite panels. I have, especially when using a cordless screwdriver, accidentally overtightened the screw (and not necessarily a lot) and had it pull through the sheet. If that can happen with a screwdriver set on a fairly low torque level then you can bet your arse that the wind getting behind it could do the same. If I do use regular screws I would rather use a pan head with coloured screw caps – much less chance of it happening then.
And, if someone isn’t prepared to spend a bit extra on a folded tray then they have to accept that the finished result isn’t going to look as neat as a folded tray. Safety before looks, that’s my motto. It’s a motto I’ve just made up, but still….. -
quote Andy Gorman:Safety before looks, that’s my motto. It’s a motto I’ve just made up, but still…..
:lol1: :lol1: :lol1: and a damn fine motto at that andrew, you should be proud of yourself. 😉
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Ha ha, I use it when I pick women up too!
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:lol1: :lol1: :lol1:
I don’t pick women up anymore mate, last one i tried done my back in. 😉
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Try some skinnier ones.
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