Fixing Stuff To The Roof with Sikaflex

[Kannon Fodda]

So, I'm about to embark on some modifications, initially adding a WiFi aerial on a hold off bracket, but also contemplating a bit more solar.

I have a Ducato based PVC. So it's a ribbed type painted metal roof no doubt with some form of insulation under the metalwork and then the internal ceiling linings. I don't want to be pulling the ceilings apart to try and find methods of mechanical fixings through the metalwork. It's going to be challenging enough just to find a suitable small route for any cables above perimeter cupboard areas.

Plenty of posts suggest I should be using Sikaflex 552, being some a structural adhesive. Is this also waterproof to seal around fittings where the cable then passes through, preventing corrosion on the edges of the hole cut?

How do I ensure an adequate bond? Is it sufficient to clean and degrease the paintwork, and with what, some sort of alcohol cleaner? Will the paint be adequately bonded to the metalwork, or do I have to somehow abrade the paint back to bare metal (with the inevitable risk of corrosion)?

It does appear the existing, manufacturer fitted, 100W solar panel on aluminium bracket rails, and other fittings are simply bonded to the roof without mechanical fixings, so hoping I can repeat that process.

Thanks

 

[Lenny HB]

A good sand to roughen up the area to be fixed to will tell you if the paint is solid enough.
I use Sika 291i for my panels & 292i for the sat dish. If fixing any plastic items check the Stika you are using is suitable as not all Stika's are suitable for plastics. I clean the area with meths then alcohol.

 

[Richard n Ann]

Will the paint be adequately bonded to the metalwork

It's very often not bonded very well on fiats. There's a recent thread about Fiat paint flake where it just peels off the bonnet. I would definitely use screws too

 

[Richard n Ann]

Here it is

I've got the dreaded FIAT Flake!!

Our Van is a 2012 and we have had it from new. I thought I had avoided the dreaded FIAT flaking paint that many have experienced as it had not reared its ugly head UNTIL! I was looking around the van yesterday and noticed what looked like a small paint flake on the bonnet. It was about 6 -...

www.motorhomefun.co.uk

 

[Johnra]

I cleaned my Fiat pop top with meths, then bonded a 170W flexible Sunpower panel on with Sikaflex 291i.

Then used 75mm roofing Bostick flashband from Screwfix around the edges. It sticks really well, it has a protective aluminium foil top and it can be removed if the panel fails.

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[Barti Ddu]

Hi Kannon Fodda - I've an Autotrail PVC too and added a 100w solar panel last year, before a 3 month trip around France, Spain, and Portugal.

I intended to just use black Sikaflex 252i adhesive, and it did seem a good strong bond, but I knew that every time I was on a motorway at 65mph with a 20mph headwind, I'd be waiting for it to tear itself off the roof - the reputation of Fiat paint unbonding itself didn't inspire confidence. I therefore also used short self-tapping screws, and now don't give the panel a moment's thought when travelling. It is absolutely rock solid.

Regarding, cable entry and routing, after a lot of investigation, I found that I could go from the roof adjacent to the mushroom vent, behind the bathroom wall and down below the toilet cassette, and from there into the rear locker where the leisure battery is located. No drilling of any internal lockers or cabinets required at all. I'm guessing your layout is similar if not identical. I've got pictures somewhere showing the routing if it would help.

 

[Gellyneck]

Assuming you will be using a roof entry gland when I fitted our Snipe to the roof of our motorhome I had some concerns (just being paranoid!) over this maybe leaking so when I drilled the hole I made it the size of the diameter of a piece of electrical conduit which I pushed through leaving an upstand and sealed around it. The gland was then stuck down over this.
If you got an appropriately IP rated gland \ box that has a sealed removable top you can then use the same hole for any subsequent kit you put on the roof.

 

[Kannon Fodda]

So far it seems there is no consistency as to what version of Sikaflex to be used, I'm not even sure whether they are long term external stable. I suspect I'm going to be poring over a lot of data sheets in the next couple of days.

Seems there is widespread paranoia that the Fiat paint won't be a good bond. Interesting the factory fitted 100W panel seems only to be stuck down without further mechanical fixings. I was hoping to avoid self tapping screws and stuff so as to minimise physical penetrations through the metal roof. Issue will then be if the Sikaflex I use is truly waterproof to create that long term seal, or if it is really just an adhesive.

The hold off bracket for the aerial is metal. Instructions show that being bedded to the roof with the adhesive and four small cross headed self tapping screws to each corner. Separately I'll need a cable entry housing. Will try and fit all of these on the top, rather than bottom ribs so they have less risk of sitting in any pooling water.

Cable routing in the van will be a separate issue. I'm aiming the aerial will be over the microwave housing (rarely used) for least disturbance to visible areas in the van. If I do change the solar, that will use existing cable routes which are over the shower room area. Even so I've somehow got to get other 12V power round to the microwave area to do the WiFi router. Nothing is simple and given I once vowed not to do anything to my van so it would remain pristine, free of DIY ....

 

[jockaneezer]

it can be removed when the panel fails.

Corrected that for you, BTGTTS

 

[Nanniemate]

Kannon Fodda, hi mate is your van still not under warrantee and could messing about invalidate it? I have no idea it is just a thought could you not put the solar onto a roof rack type fixing I have seen a few similar on self builds
seeing post 8 If i fix anything It always seems to be fixed worser.....

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[Wissel]

Might be worth calling Sika and getting up to date info. It's changed a few times in the last few years.

Also, regarding the Fiat paint issue (which I have), you could drill just through the skin, then rivet and seal with Sika. If you do this, add a few washers around where the rivets are so you get the 2mm (from memory) space that Sika recommend for it to properly bond.

I did this on my own roof. Zero leaks, but I'll guess it would be a nightmare to remove.

 

[stevewagner]

When I stick stuff to the roof I use tile spacers to make sure that all the adhesive is not squeezed out. I've stuck down sat dishes, PV panels and various other bits of kit over the years and never had an issue yet.

 

[Kannon Fodda]

Van will be three years old this summer (doesn't time fly). At this stage most of the things fitted to it wouldn't have warranty left, it's now only really coverage against water penetration. Even with a new vehicle there shouldn't be anything legally that prevents you making your own alterations, you'd just give a warranty provider scope for a bit of an argument if they tried to claim your change had caused the damage. I'd already had major changes to the manufacturer spec by having assistance from Vanbitz to fit alarm, a lithium battery with B2B and MPPT controller to overcome some of the pants standard habitation electric. Now it's time for me to tweak other stuff.

 

[Kannon Fodda]

Might be worth calling Sika and getting up to date info. It's changed a few times in the last few years.

Also, regarding the Fiat paint issue (which I have), you could drill just through the skin, then rivet and seal with Sika. If you do this, add a few washers around where the rivets are so you get the 2mm (from memory) space that Sika recommend for it to properly bond.

I did this on my own roof. Zero leaks, but I'll guess it would be a nightmare to remove.

Can't do the riveting though as this is an existing van so ceilings insulation already in place, and I don't want to be stripping that all to get access to underside of the roof. If it were a new conversion then riveting becomes easy as part of the fit out.

 

[mitzimad]

i glued a panel onto the roof of a ducato lasted the five years we kept the van i used white stixall from tool station lightly roughed up the paint and wiped of with alcohol my prefered method to go through the roop ia an ip rated box stuck down

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[mitzimad]

if you realy want a mecanical fixing use self drilling screws

 

[Wissel]

Can't do the riveting though as this is an existing van so ceilings insulation already in place, and I don't want to be stripping that all to get access to underside of the roof. If it were a new conversion then riveting becomes easy as part of the fit out.

I did it on mine when it was already insulated. The insulation is soft, so not really a problem.

In reality, as long as you have a good surface area that's Sika'd down with one of their structural adhesives, it's unlikely to be an issue as the flaky paint problem seems to fail in small patches at a time. That doesn't mean the flaky part might not expand over time though (mine has).

Just read what mitzimad has written before I posted. That's a good idea, but again use washers to get the 2mm gap for the Sika.

 

[SJA42]

I fitted a solar panel to my Boxer which has the same ribbed roof as the Ducato and basically followed a lot of the advice already mentioned.

Cleaned and degreased roof and then sand / roughen where brackets would sit to give a good key.

Adhesive used was Soudal 102643 Soudaflex 40FC as recommended by panel supplier.

I then used L shaped aluminium mount brackets which were adhered to van roof and then used self tappers with 2mm washers for additional security. Then covered the screw heads with adhesive to waterproof those.

Panel supplier recommended 6 mounting brackets but I decided to use 10 (2 on each side of each corner and one in middle of each long side).

Overall very happy with the fit and I give it a once over whenever I clean the van to check no movement or failure of adhesive. Fitted a year ago and all looks fine so far.

 

[Barti Ddu]

Solar Panel Mounting Z Bracket Set of 4

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These are what I used on my Ducato Autotrail PVC roof for attaching solar, bonded with Sikaflex 252i (using a floor tile spacer under each bracket to maintain a good thickness of sealant, and the paint lightly abraded). I positioned the panel so that they were mounted on the raised ribs rather than in the valleys. Once the sealant had cured, I then used the self tapping screws below. (The ones that came with the brackets were too long). These screws contain their own washers, but to be honest they are pretty much self-sealing as they cut through the layer of Sikaflex before going through the van roof.

I've got another pack of 4 of the brackets somewhere if I can find them (silver rather than black), and if you're interested I'd post them out to you for a tenner, and throw in a handful of the self-tappers too.

 

[SJA42]

Good point above there re. putting any mounts on the raised ridges on your van rather than the valleys.
I did the same to save them from being sat in water unnecessarily.

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[grasscutter]

Just to throw another one into the mix I fixed all my mounting brackets with CT1.

 

[Raul]

There is confusion between self tapping and self drilling screws. What you want is self tapping with washer, not self drilling like in post 19. The self tapping roofing screws, are conical shape at the tip, and the tread goes all the way to the tip around the conical tip. The self drilling are not so good for thin skin. It removes/ cuts to much material and water finds its way down the screw shaft later. Also the thin skin will only grab one tread if it’s drilled, where the self tapper will push it down and cut more treads into it.

 

[Barti Ddu]

There is confusion between self tapping and self drilling screws. What you want is self tapping with washer, not self drilling like in post 19. The self tapping roofing screws, are conical shape at the tip, and the tread goes all the way to the tip around the conical tip. The self drilling are not so good for thin skin. It removes/ cuts to much material and water finds its way down the screw shaft later. Also the thin skin will only grab one tread if it’s drilled, where the self tapper will push it down and cut more treads into it.

If you zoom in on the picture of the product in post 19 it gives the specification and intended usage on the packet - perfect for attaching a metal bracket to a metal van roof.

I would say there is zero possibility of leaks because in addition to the sealing washer, the screw itself has cut through a decent thickness of Sikaflex before cutting through the roof.

I was on top of the van yesterday washing a layer of orange, fine Saharan sand off (yes even in Pembrokeshire), and the panel is rock solid. Should I ever decide to add another panel I'd use the same brackets and self drilling screws, (plus Sikaflex) as last time.

 

[Richard n Ann]

There are 2 types of self drilling screws (or tek screws) , course and fine thread. The fine thread are for thick metal like girders and the course thread for tin roof sheets or vans (actually the thread is very similar to self tappers)

 

[Richard n Ann]

If you zoom in on the picture of the product in post 19 it gives the specification and intended usage on the packet - perfect for attaching a metal bracket to a metal van roof.

I would say there is zero possibility of leaks because in addition to the sealing washer, the screw itself has cut through a decent thickness of Sikaflex before cutting through the roof.

I was on top of the van yesterday washing a layer of orange, fine Saharan sand off (yes even in Pembrokeshire), and the panel is rock solid. Should I ever decide to add another panel I'd use the same brackets and self drilling screws, (plus Sikaflex) as last time.

I'd still cover the screw head with sikaflex, I've been told water would eventually track down the screw.

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[Barti Ddu]

I'd still cover the screw head with sikaflex, I've been told water would eventually track down the screw.

That was my original intention, but the sealing washers compressed so tight over the bracket that I decided there was no need, and as previously mentioned, the screw thread is embedded in a decent thickness of Sikaflex, and is essentially self-sealed.

 

[Peter Beeston]

Sika produce an "activator" that they recommend for cleaning/preparing the surface before bonding. I bought a can a few years ago and determined that it was just pure isopropanol (iso-propyl alcohol [aka rubbing alcohol]). since then I have just bought and used pure isopropanol (amazon) and never had an issue.

 

[triky]

As per many installations mentioned here ,'Sikaflex ' was my choice of adhesive when fitting a solar panel to my previous Mo-Ho. Clean the areas and rub down with fine abrasive paper, including the brackets .For the cable entry the BEST are 'DECK GLANDS' as used by yachts/boats from " Force 4" ,on page 145 of the 22 catalogue.,,Tel' 0345.1300.710. (www.force4.co.uk).

 

[Fragle]

Just moved our solar panel to have air con fitted and used

SIKA SIKAFLEX EBT+ ALL-WEATHER SEALANT​

Seems to do the job and I certainly can’t move the panel by pulling. Suppose only time will tell

 

[Swiss]

I find it amusing that people have no trust in glue, it has come on a long way nowadays, most of the panels on modern vans are glued together, I know that the chassis on my car is fully bonded. It seems that the problem people highlight the most is going down the motorway at 60 and the solar panel, sat dish or whatever flying off. Have a thought next time you see a spiders web on your side mirror and see where that goes at 60 miles an hour, nowhere, and it's not held on with self tappers either.

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