Fixing Stuff To The Roof with Sikaflex

[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.

Each to their own. I was only tried to help here, not to question ppls choice. As a roofer with 22+ experience, and over 6 years fitting solar panels at industrial scale, I have filled many wear houses on thin roof with panels. I had a fair share of failure on self drilling tek’s done by partner installers. They could not be bothered to order the right screws.

 

[Kannon Fodda]

My expectation is the adhesive / sealant, if correctly selected, is itself fine. In this instance the concern is whether what it is being stuck to is fine, i.e. is the spray paint finish on the standard Fiat Ducato van, an adequate bond? After all paint itself is not expected to have strength, it's there as protection to the substrate.

Lighter weight items directly stuck to the roof, such as cable entry gland fittings aren't the concern. It's the heavier items, particularly where there are risks of suction uplift (can a large solar panel effectively act as a form of wing or spoiler).

 

[Barti Ddu]

My expectation is the adhesive / sealant, if correctly selected, is itself fine. In this instance the concern is whether what it is being stuck to is fine, i.e. is the spray paint finish on the standard Fiat Ducato van, an adequate bond? After all paint itself is not expected to have strength, it's there as protection to the substrate.

Lighter weight items directly stuck to the roof, such as cable entry gland fittings aren't the concern. It's the heavier items, particularly where there are risks of suction uplift (can a large solar panel effectively act as a form of wing or spoiler).

Yes. That was exactly my own thoughts and concerns. Probably misplaced, but with using "belt and braces", I've now total peace of mind.

 

[BusyBuilder]

I just sand the area on both roof and item, cleaned with brake cleaner and stuck down with Stickslike ****. In 5 years nothing has moved.

 

[Ditcha]

I have always used Puraflex 40 never had any problems.

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[cunning]

My expectation is the adhesive / sealant, if correctly selected, is itself fine. In this instance the concern is whether what it is being stuck to is fine, i.e. is the spray paint finish on the standard Fiat Ducato van, an adequate bond? After all paint itself is not expected to have strength, it's there as protection to the substrate.

Lighter weight items directly stuck to the roof, such as cable entry gland fittings aren't the concern. It's the heavier items, particularly where there are risks of suction uplift (can a large solar panel effectively act as a form of wing or spoiler).

Hi KF, this discussion has been very helpful as I am contemplating the exact same question and doubts! What was your decision in the end (including what brackets did you use)?

TIA.
ps the cabling is easy for me because my Ducato PVC is prepped with solar cabling from the distribution board to a point near the ceiling behind a wall cupboard (even has a concealed section to fit an MPPT)!

 

[triky]

I mounted my 100w solar panel onto the roof of previous Mo-Ho using 'Sikaflex'.
First lightly abrade the contact area of the feet/brackets with a fine sand paper .Also do that to the feet/brackets .
Apply the adhesive to both areas at the same time. Position and set down the panel and feet ,clean off any surplus squeezed out adhesive.
Leave to cure for the advised time period.
The panel/feet never moved even at high speeds and gales on my vehicle.

 

[ROCHESB]

I wasn't happy with relying upon FIAT paint bond when I fitted a solar panel to the roof of our Autocruise Rhythm panel van so I used blind nuts /rivet nuts to hold aluminium angle brackets to the roof, these were then bolted to the frame of the solar panel with bolts & nyloc nuts. The holes in the roof were dosed with Sikaflex before the rivet nuts were 'set' and the aluminium angle was bedded down on Sikaflex before covering the bolt heads with more Sikaflex.

I made my own aluminium angle brackets from offcuts bought from local metal stockholder.

 

[mitzimad]

i always make my own brackets from 2x3 aluminium angle with the wide side down this gives a huge footprint for the adhesive

 

[Sandancers]

i always make my own brackets from 2x3 aluminium angle with the wide side down this gives a huge footprint for the adhesive

So are your panels held down by adhesive alone ? What size are the panels ?

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[Northernraider]

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.

The whole point of blind rivets is you don't need access to the rear of them. You could also consider rivnuts which you would then bolt through the panel brackets in to the rivnut.

 

[Northernraider]

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.

It isn't the glue that folk don't trust. I'd happily just glue panels to a grp roof . But a fiat painted metal roof I would seriously think twice. The glue will just pull the paint straight off the metal

 

[Otter Spotter]

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

The paint on the roof is not fully gloss style paint it’s more of an semi Matt, so I suspect it will not flake as much as the bonnets do. For my sins I regular clean my roof and it does have a less finished look and feel to it.

 

[cunning]

Hi All,

My current plan is:
A 175 watt Renogy panel (small footprint for watts) with mountings as post #6 and a Victron MPPT smart (oversized so a I can add more panels later).

I will bond and screw the mountings. Just 4 mounts for the panel. I have spoken to a Weinsberg dealer who said they would screw!

Please shoot me down because I listen and learn! I do get the cobweb theory and think it is a good point but I have OCD!

TIA, James

 

[mitzimad]

So are your panels held down by adhesive alone ? What size are the panels ?

ive got two 100wattsbutmy sons which we fitted on the front roof of a sprinter is over 300w and thats not moved in four years

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[Kannon Fodda]

Ended up with angle brackets from photonic universe on the sides of the panel, bottom flange just about matching the width of the roof ribs. Bolted to the panel and stuck to the roof with Sikaflex 252.

Took the view that the large area of the bracket base would suffice for a wide loading and be secure. 2500 miles later panel is still there!

Panel front edge is quite exposed and I get a fair bit of wind noise. Looking at fitting a small spoiler. Centre of the front has a small metal angle bracket fixed with Sikaflex and couple of self tapping washered screws into roof. I needed to drive within 12 hours of fixing panel so the screws were belt and braces as curing time of Sikaflex looked to be around 48 hours.

Cable entry thing was expensive, from 12V Planet. Standard double plastic gland things were too wide for a roof rib.

 

[cunning]

Oops! I didn't consider that the plastic double gland would not fit (just been on the roof to measure and confirm!). I assume that you purchased a Scanstrut (and, yes, they are expensive!)?

I have ordered a 200 watt Renogy panel as it fits snuggly between my roof windows (without snagging them when opening) so I need to use mounting brackets on the long edge. I am not expecting an issue with wind noise because the panel sits behind a large roof window.

I am opting for the Z brackets like those on post 6 and hoping that 4 will be adequate for a 1.5M long panel! The panel is pre-drilled for 4 brackets, so Renogy must think that is adequate! I will bind with Sikaflex 522 and screw (interested you chose 252).

Still grappling with the self drilling / self tapping debate. The screws supplied with the Z brackets are self drilling and look a tad long!

 

[Kannon Fodda]

I took one look at supplied screws with brackets, and went to Screw fix for alternatives.

4 Z brackets may be OK but fixing area onto the van roof is small and given vehicle speed isn't enough? Dunno.

Yes it was Scanstrut cable entry. Note any connectors on cables won't pass through the glands and have to be cut off. But it's a neat bit of kit designed for marine environments so motorhome should be easy for them.

 

[cunning]

I took one look at supplied screws with brackets, and went to Screw fix for alternatives.

4 Z brackets may be OK but fixing area onto the van roof is small and given vehicle speed isn't enough? Dunno.

Yes it was Scanstrut cable entry. Note any connectors on cables won't pass through the glands and have to be cut off. But it's a neat bit of kit designed for marine environments so motorhome should be easy for them.

Thanks.
I'll probably purchase 4 more brackets cos I am also not confident (I'll only screw the 4 brackets).
I have been looking at Screwfix self tapping / drilling screws. Which ones did you choose?
Why did you choose Sikaflex 252 (rather than 522)?
Thanks.

 

[Kannon Fodda]

No idea now why 252. I'd read through threads on MHF and elsewhere and also looked at data sheets. Some adhesives seemed more intended for auto dnvironments, had better resistance to UV, salt water. Others had strength versus elasticity.

Not sure now what screws I used. Purpose made roofing fixings were too long. Ended with combo of stainless self tapping screws with nylon washers and loads of sealant.

Biggest issue for bracket position is the roof rises from sides to centre of PVC so centre ridge higher than outside. If you panel is arranged like mine side to side, you need different height brackets to fix on long edge.

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[Reallyretired]

I took one look at supplied screws with brackets, and went to Screw fix for alternatives.

4 Z brackets may be OK but fixing area onto the van roof is small and given vehicle speed isn't enough? Dunno.

Yes it was Scanstrut cable entry. Note any connectors on cables won't pass through the glands and have to be cut off. But it's a neat bit of kit designed for marine environments so motorhome should be easy for them.

I don't like the look of the supplied screws self drilling and very long. I think shorter and fatter self tappers would be much better, though if possible no screws better still.

 

[cunning]

I was on the roof (again) with a 2 metre level and low and behold, the roof rises side to centre. I didn't realise that!

Anyhow, my panel orientation has long side front to back so no issue with the chosen brackets on long side. Also, the panel is, to some extent, protected from wind by the roof window. I will use 8 mounts but only screw the 4 end mounts.

I found a Scanstrut on another site (ASAP) at a lower price.

I think I am right in saying that self tappers (non TEK type) will require pilot holes?

Thanks for the tips (has saved me some head scratching)!

 

[CamperJack]

Everything on my van is fixed with locking nuts and bolts. Several on each panel. I don't want to be the cause of something like this.

Caravan Solar Panel Tragedy: Coroner Delivers Findings

Findings of a coronial inquest in Tasmania serve as a reminder to owners of caravans with solar panels to ensure they are properly secured.

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[tonyidle]

Everything on my van is fixed with locking nuts and bolts. Several on each panel. I don't want to be the cause of something like this.

Caravan Solar Panel Tragedy: Coroner Delivers Findings

Findings of a coronial inquest in Tasmania serve as a reminder to owners of caravans with solar panels to ensure they are properly secured.

www.solarquotes.com.au

I'd be interested to know how you'd hide the locking nuts on the ceiling of anything other than a PVC. Reading the articles referenced by your link at least one suggests the problem may be caused by one or more panel suppliers suggesting the use of silicone adhesive. I would not recommend fixture using the plastic corner brackets: they have limited surface area in contact with the roof and need extreme abrasion to ensure adhesive actually sticks to them. Fabricated aluminium can be sized to provide a very substantial footprint and has no adhesion problems. Use the correct adhesive and apply it correctly and a secure fixture will result. For the paranoid an opportunity to try to lift each corner is available when cleaning the roof.

 

[cunning]

I'd be interested to know how you'd hide the locking nuts on the ceiling of anything other than a PVC. Reading the articles referenced by your link at least one suggests the problem may be caused by one or more panel suppliers suggesting the use of silicone adhesive. I would not recommend fixture using the plastic corner brackets: they have limited surface area in contact with the roof and need extreme abrasion to ensure adhesive actually sticks to them. Fabricated aluminium can be sized to provide a very substantial footprint and has no adhesion problems. Use the correct adhesive and apply it correctly and a secure fixture will result. For the paranoid an opportunity to try to lift each corner is available when cleaning the roof.

We are all doomed!!! Looks like CamperJack is a van conversion so had access.

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[Soots]

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.

On Lenny HB's advice I used sikaflex 291i on fitting 2 x 100w solar panels roughed the paint work and aluminium brackets with sandpaper, ( I did mark where the aluminium brackets were going with felt tip pen) used 3mm tilers spacers to the required spacing.
I used 1 canister of sikaflex it was still enough to fix 1 solar panel to my shed too!
Thanks Lenny HB.

 

[cunning]

So, as I search for the correct screw, can anyone tell me the material used on the Ducato van roof and it's thickness? I can then look for the correct screw for the material and thickness!

If I had this fitted by a dealer, they already told me they'd use screws (not bolts or rivets).

TIA, James

 

[Revolvor]

cunning

See my Post in thread 'Large solar panel mounting'

https://www.motorhomefun.co.uk/forum/threads/large-solar-panel-mounting.238904/post-4451102

 

[georgio]

Sika do a metal to metal adhesive although I have used ebt on lighter things and potentially less dangerous. I noticed when I had a new windscreen fitted sikaflex was used but I do not know which one.

 

[Kannon Fodda]

Sikaflex is merely a collective brand nme so the actual type varies, other makes also exist. Hand operated skeleton gun type application is very hard work on the hands as extrusion from the tube is slow and tough.

On a PVC roof isn't much more than a 1mm profiled sheet of standard steel paint sprayed. Pilot hole of very small drill will make any self tapper much much easier to fit with precision, in turn needing a centre punch start.

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