Bubbling Roof (1 Viewer)

[GerTee]

Dear All

Just had a look at the roof of our van after it had a wash and spotted some bubbling in the surface. Some bits have broken away completely. Pictures attached.

Any ideas? What it might be, how it may have been caused? What do I need to do to either got it fixed or halt the progress?

Any thoughts/comments gratefully received.

Alan

 

[filopastry]

That looks like the gel coat is breaking away from the resin below possibly a manufacturing fault when laying up the resin. Assuming this is not a new or under warranty vehicle I would patch it up very quickly moisture may enter which will then expand when frozen and create a bigger more serious problem. Car body shop or boat builders repairers are a good port of call if beyond your skill level. DO NOT leave it long

 

[funflair]

Basically the same as @jetlag03 says above, you could fill it with white sikaflex but Gelcoat would be better but only in that you could flat it back and polish it so you wouldn’t know, Sikaflex would seal it but look dirty after a while.

Martin

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[filopastry]

The problem with filling the holes is you are playing "catchup" and need to find out why it happened in the first place and is it likely to continue happening. When laying up the resin layers if by chance something has been splashed onto the gelcoat before the resin is applied then this could create multiple points where the gelcoat does not bond resulting in something similar to your photos after a period of time. I see you have been over this side of the water for a while and the increased heat could have accelerated this delamination process. My advice would be to seek advice from either a car body shop or of boat builder/repairer and brace yourself for a costly repair. SORRY. Just reviewed your profile @funflair recon you would have much better and indepth knowledge than I Martin.

 

[filopastry]

Don't be such a tease, tell us what you think it may be, gives other avenues of research and hopefully proves my theory wrong

 

[Tumerc]

We had problems with gell coat on roof,smc at newark sorted it.

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[CazPaul]

Is it poor construction in the first place, coat not thick enough or prepared properly?

I prefer aluminium construction although you can get corrosion with that so all have potential problems.

 

[GerTee]

Thanks all for your replies. I appreciate that the pictures were not the best, but it was chuffin' cold hanging off the steps this morning. I'm a little surprised at the fault potentially being at manufacture as the van is a Burstner. We live near the Hamble so a quick 'phone round of local boatbuilders is in order on Monday as well as a quick email to Southdowns where we got her from (well and truly out of warranty tho!).

 

[CazPaul]

Does this look like a fault on the rear panel, just above the red light fitting.

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[CazPaul]

Its not my van, we have been considering buying it but have only seen photos so far.

 

[filopastry]

Good luck at the boatbuilders yard, I'm sure they will be able to bottom the problem they are pretty much the experts with this stuff, as @airwave said, try to keep it dry if you can and don't be nesh it's only a bit fresh

 

[funflair]

Well back to @GerTee 's roof and to honest it looked better this afternoon on my phone screen than it does on the computer, when you said "bubbling" I thought well I can only see a couple of chips out of the gelcoat hence the dab of Sikaflex comment BUT I can now see the bubbling that you refer to and it does need more than a little local repair, I think you are lucky to live near a boatyard as this could turn out to be a slightly bigger repair than a bit of localised gelcoat, SORRY.

Martin

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[138go]

It needs repairing water will have wicked its way between the gel coat and the glass mat. It needs to be dry and then a braided so the gel coat can stick to the glass mat.. The gel coat will need covering or it will not set. Some have a wax in them that forms on the surface to keep the air out. You get something similar with boats it’s called osmosis. Only cure is to strip off gel coat and refinish with a two pack paint. Down to bad practice laying up, contamination, cheap materials. If it was flexing that caused it you would see hundreds of little tiny cracks. Had that on our Swift roof. The habitation survey guy took a look at it and just said stress cracks loads of them like it. Work for the future as water gets in. Freezes and bingo.

 

[mfw]

You could try plastic padding gel coat filler in white you would have to clean area up first might work and its under £10 a tube with hardener mask round each area in turn put gel coat right over and remove masking straight away leaves a fairly tidy repair

 

[Lazyboy]

You say it is way out of warranty. How old is your van? I would not expect that sort of "damage" without there being an external force and it would appear that this is not the case. Do you have any redress under the sale of goods act I wonder? "Fit for purpose"? How long could a consumer reasonably expect the roof of a motorhome to last? May be someone with more knowledge than myself maybe able to help.

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[138go]

@airwave .. I seem to have hit a bit of a raw nerve. After having a boat for a number of years I can imagine what you are going through if your boat has cancer .. I have seen some examples of it when boats get hauled out at the end of the season. Hope you get it all sorted. Regards QFour

 

[Blue Knight]

Alan,

I hope this works out well for you soon as it's a terrible thing to happen.

Is the van fairly newish.

Good luck,

Andrew

 

[TheBig1]

sadly the news is I concur with the assessment that the damage is grp cancer and likely to be a very expensive repair involving nearly the whole roof by a specialist

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[Tibbo]

Looking at the photo 2a (the one showing the 2 large blisters). The first thing that struck me was the thickness of the delaminated layer. Now I've only been in the autobody industry since 1968 but I don't think I've ever seen gelcoat that thick. Typically, gelcoat has a film build of 50 - 100 microns (2-4 thou) although it could be thicker in the concave area of a curved panel (caused by pooling of the gel).

It is always difficult to suggest a cause from a picture but here is my opinion for what its worth.

To me it looks like it "could be" a previous repair, either during manufacture or afterwards. I have seen uneven GRP repaired/flattened using a spray polyester filler (basically a spray-on bodyfiller) which can be applied up to 1/8th inch thick. The biggest problem with most bodyfillers is that it is not moisture resistant. It's filler component is typically mineral talc and what does talc do? It soaks up moisture! Which is why you see nasty bubbles appearing under the paint from a poor corrosion repair when it's been "bodged" up..

GerTee, have you owned the vehicle from new? Have you got any of the delaminated material? If so, does it break up into little pieces or powder easily? Proper gelcoat should snap more like rigid plastic ('cos that's what it actually is). I always hate asking people to make a bad job worse but if you can pry up just a little of the layer that is peeling to see if it does break easily or crumble.

However, the bad news, any repair is going to be costly if done properly and needs to be done ASAP. Previous posts have been correct on that score, the moisture ingress will only increase rapidly now the surface is open. If you cannot get the repair done quickly, the open areas need to be sealed, if it were my van I would use Transparent Repair tape as a quick temporary fix. It's like a thick sellotape. Why wouldn't I use silicone sealer? Because it would have to be removed COMPLETELY before any repair work is started and that will add to the cost. Silicone of any kind and bodywork do not mix! It's why most bodyshops never have polishes that contain silicone.

Whatever the outcome, good luck!

 

[GWAYGWAY]

Go to a yacht Chandler there are a few Gel coat repair systems from them If it has thes already the n I would not buy it.. GRP yachts get this from standing in the water and it has allowed the water to g through by osmosis. usually spreads with cracks as the gel coats is stressed from the bulge. A little bubble of water behind each bubble of gelcoat.

 

[funflair]

Looking at the photo 2a (the one showing the 2 large blisters). The first thing that struck me was the thickness of the delaminated layer. Now I've only been in the autobody industry since 1968 but I don't think I've ever seen gelcoat that thick. Typically, gelcoat has a film build of 50 - 100 microns (2-4 thou) although it could be thicker in the concave area of a curved panel (caused by pooling of the gel).

It is always difficult to suggest a cause from a picture but here is my opinion for what its worth.

To me it looks like it "could be" a previous repair, either during manufacture or afterwards. I have seen uneven GRP repaired/flattened using a spray polyester filler (basically a spray-on bodyfiller) which can be applied up to 1/8th inch thick. The biggest problem with most bodyfillers is that it is not moisture resistant. It's filler component is typically mineral talc and what does talc do? It soaks up moisture! Which is why you see nasty bubbles appearing under the paint from a poor corrosion repair when it's been "bodged" up..

GerTee, have you owned the vehicle from new? Have you got any of the delaminated material? If so, does it break up into little pieces or powder easily? Proper gelcoat should snap more like rigid plastic ('cos that's what it actually is). I always hate asking people to make a bad job worse but if you can pry up just a little of the layer that is peeling to see if it does break easily or crumble.

However, the bad news, any repair is going to be costly if done properly and needs to be done ASAP. Previous posts have been correct on that score, the moisture ingress will only increase rapidly now the surface is open. If you cannot get the repair done quickly, the open areas need to be sealed, if it were my van I would use Transparent Repair tape as a quick temporary fix. It's like a thick sellotape. Why wouldn't I use silicone sealer? Because it would have to be removed COMPLETELY before any repair work is started and that will add to the cost. Silicone of any kind and bodywork do not mix! It's why most bodyshops never have polishes that contain silicone.

Whatever the outcome, good luck!

Surely 50-100 microns would be paint, Gelcoat either brushed or sprayed would be a lot thicker.

Martin

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[Tibbo]

Martin, thanks for pointing out my math mistake. It was midnight lol ... I'm going to blame my solar powered calculator it was dark at midnight
It should read 250 - 500 microns or 0.010 to 0.020 inches.

Just for others that may read this, the gelcoat is the first layer (after the release agent) applied into a mold, after that comes the resin and fiber material. The function of gel coat is to provide colour, gloss and UV protection, so in some ways it is the the "paint" only it is applied first instead of last.

The more I look at those pictures, I'm convinced it isn't just gelcoat delamination. It's more serious than that. Just don't know without a hands on inspection.

 

[Tibbo]

I found this rather good explanation of GRP (not just gelcoat) delamination:

GRP DELAMINATION

In these cases tiny flaws in the fiberglass itself allow air to be trapped. Water can enter through microscopic channels and enter these voids filled with air. Expansion and contraction of these tiny amounts of water will make the voids grow horizontally along the layers of fiberglass cloth and resin binder.

Temperature fluctuation causes the expansion and contraction of the water and if freezing and thawing are encountered the voids will grow quickly.

Small bumps soon become visible in the smooth finish.

These bumps are called blisters and it’s a serious condition.

BLISTER REPAIR

The only way to repair this damage is to remove the outer gel coat and underlying fiberglass material to access the damage. It is then filled with new resin and cloth, then the gel coat is replaced.

It sounds easy, but unless you have considerable experience working with composites it’s easy to make the situation worse. If the panel is going to get a new coat of paint the problem of color matching isn’t an issue. Blending a patch into existing paint is an art form and lighter colors are much easier to match than bright or dark paints.

Mechanical bonding is the larger issue since the new patch is only connected through adhesive properties. The same vibrations that formed tiny cracks will cause the boundary of the patch to loosen.

Some types of blister repair involves drilling a few very small holes and injecting an epoxy compound. The blister is then compressed while the epoxy cures. This allows the patch to become a more integrated part of the panel/structure.